Swimming pool water treatment manual by dgz16482

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									Swimming pool water treatment manual
                                                                 and elimination chlorine reaction products




               No sore eyes and clean clear water, every pool should be like this, a safe place to play and exercise

                                                                                      Benefits of AFM
                                                                                              80% reduced chlorine consumption
                                                                                              Cryptosporidium control
                                                                                              Reduced bacterial risk
                                                                                              Solids removal down to sub micron levels
                                                                                              Lower THM levels
   A water filtration project for Life & the                                                  Reduce or eliminate trichloramines
   Environment. Support by the European                                                       Life cycle cost benefits, water & energy
   Commission LIFE 02 ENV/UK/000146 AFM                                                        give a return in capital in under 18 months
   Data from project 2001 to 2003                                                             100% environmentally sustainable

                                                                                      Application for AFM
   Dr.Howard Dryden                                                                           Drinking water
                                                                                              Tertiary treatment of sewage effluent
   Dryden Aqua , January 2004                                                                 Industrial waste water and grey water
                                                                                              Swimming pools
                                                                                              Desalination pretreatment
                                                                                              Cooling towers
                                                                                              Public aquaria
AFM filtration of swimming pool and Spa water, THM`s, trichloramine and water quality problems solved.                 2
Public health protected, asthma & respiratory related health risk reduced.


Water filtration in Swimming pools & spas
In recent years there have been many reports in the press regarding trichloramine and its
potential implications as a precursor for causing occupational asthma and asthma among
children in swimming pools, spas and sports centres. However, as yet there has been no
published mechanism why trichloramine is produced or any means of solving the problem.

In addition to Trichloramines, THM’s (chloroform) is also of concern because of the highly
carcinogenic nature of the chemical and its ability to rapidly enter your blood stream via your
lungs. Equipment such as Ultra Violet disinfections and ozone systems are now being
advocated, however in many cases this technology can actually cause the problems.

Swimming is an ideal exercise which should be encouraged, as long as the water quality and
atmospheric conditions above the surface of the water are not detrimental to health. This
report covers the source of the chlorine reaction products and for the first time their
mechanism of production and a solution to the problem. In effect we give a way forward and
strategy for the entire swimming pool industry.

Trichloramine production and bacteria levels
Chloramines are formed in water by reaction between ammonia and chlorine, the reactions are
pH and concentration dependent, the following equations are taken from German DIN
standards 19643.

NH4+ + H2O            H3O+ + NH3 (bacterial mineralisation decomposition of urea from urine, sweat, etc.)
NH3 + Cl2            NH2Cl monochloramine......................................................... pH 4 to pH 10
NH2Cl + Cl2            NHCl2 dichloramine .............................................................. < pH7.2
NHCl2 + Cl2            NCl3       trichloramine ............................................................. < pH4
NH2R + Cl2             NHRCl alkylmonochloramine
( denotes a reversible (equilibrium) reaction;  denotes a forward reaction.)

It is important to note that dichloramine, trichloramine
and      organochloramine       (alkyl-monchlorammine)
reactions are not reversible. Once the condition exists
for their formation, their concentration will continue to
increase unless the chemicals are destroyed or
removed. Coagulation followed by flocculation and
AFM filtration will remove them from the water. UVc
and Ozone will oxidise the chemicals but will form
volatile THMs and nerve toxins such as cyanogen
chloride.      The only safe route is coagulation,
flocculation and AFM filtration.

The primary source of ammonium in swimming pools
is the mineralisation of urea (NH2)2CO, amino acids
and proteins by bacteria. UVc and ozone will also
crack organics and release ammonium into the water.
With AFM systems using good filtration, NoPhos with
coagulation and flocculation but without the use of
UVc or ozone, you do not actually form ammonium and the chloramine level is extremely
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                       Tel +44 (0) 18758 22222 Fax +44 (0) 18748 22229 www.AFM.eu
                                       LIFE 02 ENV/UK/000146 AFM
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Public health protected, asthma & respiratory related health risk reduced.

low. Dichloramine and trichloramine essentially do not exist, however the DPD3 reagents
used to test for combined chlorine suffer serious interference from alkyl ammonium
chloramine groups and as such the reading for inorganic combined chlorine can be out by as
much as 90% reading too high for AFM systems in comparison to a sand filtration system.

Sand filters operate as bacteriological filters, bacteria growing on the sand will remove the
dissolved organics from the water and generate ammonium from the urea. The bacterial
biofilm also has a low pH and this is the zone in which trichloramine if formed. Sand
filtration systems will therefore tend to operate with a lower dissolved organic content but
much higher combined chloramine concentration. AFM removes organics by adsorption,
similar to the reactions found with activated carbon, however most of the organics and urea
are removed by coagulation, flocculation and then mechanical filtration by the AFM media.
Coagulation and flocculation is therefore very important with AFM systems. The added
advantage is that good coagulation and flocculation followed by AFM filtration will provide a
much more robust form of filtration and will not allow cryptosporidium oocysts to pass.

Combined chlorine analysis
DPD2 reagents are specific to mono-chloramine and do not suffer the same interference
experienced by DPD3 reagents. Total combined chlorine equates with approximately 1.4
times DPD2 (monochloramine) concentration when using sand filters. For AFM filtration
systems because dichloramine and trichloramine levels are very low, the total combined
chlorine level equates with 1 times DPD2 monochloramine concentration.

Interference from organics and surfactants brings DPD3 analysis into question for swimming
pool water, however DPD3 is still a useful analysis to perform, and the results just have to be
looked at from a different perspective. If DPD2 gives an under estimate of combined chlorine
as measure by DPD3, and there are no smells of trichloramine or sore eyes among the bathers,
this means that there are high levels of organics such as surfactants, protein and amino acids
in the water. In this situation DPD3 – DPD2 result equates with organo-chloramines and
interfering chemicals such as surfactants in the water.

The following table relates to the key aspects that will cause DPD3 to over-estimate the
combined chlorine level. Organo-chloramines are large non volatile and non toxic dissolved
molecules. This means that organochloramine molecules will not leave the surface of the
water as such they cannot be absorbed through you lung tissue nor enter your blood. Organo-
chloramines therefore do not cause a problem. Surfactants from soap and cleaning agents on
the other hand are a more serious issue, the chemicals will prevent coagulation and
flocculation reaction from working properly prior to filtration. This means that the public
could be put at risk from a plug of bacteria or cryptosporidium oocysts being dumped into the
product water after the filters. The surfactants can stop the coagulation and flocculation
reactions working properly, the chemicals can also break up the solids on top of the filter, be
it sand or AFM, and allow the solids to pass through the filter. Any cleaning agent that
contains surfactants, especially anionic surfactants should not be allowed in any swimming
pool building. There are even anionic pool products that are being added to the water, such a
situation has the potential for being very dangerous. Only use, filter media, equipment and
chemical products that have been certified safe and proper.




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                     Tel +44 (0) 18758 22222 Fax +44 (0) 18748 22229 www.AFM.eu
                                     LIFE 02 ENV/UK/000146 AFM
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   Key points that may cause high organo-chloramine levels in AFM
                    systems as measured by DPD3
      Problem                                                      Solution

high water flow
rates through the     reduce water flow through the filters to less than 15 m/hr
filters
no coagulation or
                      start APF coagulation at 1 ml of APF per cubic metre of water filtered per hour
flocculation
incorrect injection
                      inject between the pumps and the filters, directly into a ZPM unit or static mixer
point for APF
incorrect injection
                      inject chlorine after the filter (never before the filters)
point for chlorine
                       for a typical public pool the turn over rate is 4 hours through the filters, for a private pool
                       this may be 6 hours. If the turn over rate is too slow water quality will deteriorate in the
                       pool. Turn over rate through the filters should be appropriate for the installation, however
slow turn over rate
                       it is also a good idea to recycle the water the water around the filters and through the pool
                       and a ZPM unit at a higher rate. The simple action of moving the water actually improves
                       water quality and insure a more stable chemistry.
                       what goes into a filter must come out again or the organics retained by the filter will react
back-wash filters at with the chlorine and be digested by bacteria. It is recommended that you air purge for 5
correct flow rate      minutes at 95 m/hr prior to a back-wash. Back-wash frequency should be at least once a
                       week at 45 m/hr for 2 to 5 minutes. For private filters the air purge is not necessary.
                       all bathers must shower before entering the pool, oils soap, sun tan lotion etc etc must be
the bathers
                       removed for hair and skin, this is very important
                       do not use surfactants, and especially anionic surfactant anywhere near the pool. 5ml of
                       anionic surfactant in a 50m pool will through the DPD3 readings off the scale and will
surfactants and
                       seriously affect the performance of the coagulation reactions. Best cleaning agent is pool
cleaning chemicals
                       water and sodium bicarbonate, use a dilute acid on occasions such as hydrochloric acid to
                       remove scale. Do not use chemical thermal blankets
                       a. contamination below filter bed, best to use a DIN standard filter with nozzle distribution
                       plate. Do not use filters with an octopus arrangement for the laterals
                       b. dirty scum channels, keep them clean
                       c. dirty balance tank, clean on a regular basis or fit in place cleaning
                       d. filter back-wash pipe work should go down to the floor immediately after the filter, not
                       up to the roof
dead or dirty areas in
                       e. poor pipe work installation that leaves a gap in between joins, dirt and bacteria collect in
the system
                       the gaps and cracks
                       f. pipe work that leaves a dead end containing static water
                       g. in correct hydraulics, filter flows not balanced
                       h. poor grout between tiles, allows bacteria and organics to collect
                       i. contaminated plastic toys, or pool blanket in contact with the water
                       j. a condensing environment and drips of contaminated water into the pool
                       A high free chlorine level will tend to produce more chlorine reaction product, operate the
                       pool with as low a chlorine concentration as possible. AFM pools with NoPhos and APF
                       will generally use up to 90% less chlorine that regular pool system. The chlorine
Chlorine level
                       concentration will also be more stable, so it is easier to reduce the levels. For public pools
                       we recommend a minimum concentration of 0.5 mg/l, but are testing levels as low as
                       0.1mg/l on system with a high recycle by pass
                       check the mains water supply it main be contaminated with organic matter, or ammonium.
mains water supply Water companies often add ammonium to municipal supplies to form mono chloramines to
                       help prevent the formation of THM`s




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. While DPD3 is subject to serious interference from oregano-chloramines and surfactants etc, we
now have public pools operating in Scotland in which the DPD2 and DPD3 are giving the same
reading and the value is less than 0.01mg/l. Whenever DPD2 & DPD3 tests give the same reading
you know that there is no dichloramine, trichloramine, organo-chloramines of surfactants in the water,
also when DPD2 - DPD1 is less than 0.01 mg/l you also know there is no ammonium or mono-
chloramine in the water. In effect for the first time in the swimming pool industry we have a simple
means of identifying and end point in terms of the best possible pool water quality that you can
achieve.

                           Best possible swimming pool water is as follows;
                                 DPD2 - DPD1 is less than 0.05 mg/l
                                     DPD3 = DPD 2 + /- 0.02 mg/l



Trichloramine production mechanism
According to the equations trichloramine production occurs predominantly below a pH4.
However swimming pool water will normally have a pH between 6.8 and 7.6, so how can
trichloramine be produced? Certainly trichloramine cannot be produced in the water because
the pH is too high, however every surface in contact with pool water will have a thin biofilm,
and within the biofilm the pH of the water will be acidic. Trichloramine production therefore
takes place on every surface in contact with the water that has a biofilm and the thicker the
biofilm the greater the production.

The single largest surface area in any swimming pool or spa is the sand in the sand filter.
Every cubic meter of sand will have a surface area in the order of 3000 square meters. We
have known for many years that sand acts as an excellent substrate for the growth of bacteria,
and that new sand will become colonized by a range of bacterial species in a matter of a few
days. The alginate bond between the bacteria and a substrate can form in less than 30 seconds.
In addition, the bacteria will continue to excrete alginates as a protective mechanism against
oxidation by chlorine. The levels of chlorine used in most swimming pools and spas will not
affect the growth of bacteria on the sand, or indeed bacteria growing on any surface in contact
with the water.




Fig 1. New sand showing no bacteria and sand after a few days showing almost a 100% cover by bacteria

Fig 1 shows that within a few days, new sand has become colonised by bacteria. The bacteria
film (biofilm) develops on the sand as well as on every other surface in contact with the
water. As the biofilm develops it becomes thicker and more stable. Eventually the alginates
              Dryden Aqua Ltd | Butlerfield | Bonnyrigg | Edinburgh EH19 3KQ | Scotland UK |
                     Tel +44 (0) 18758 22222 Fax +44 (0) 18748 22229 www.AFM.eu
                                     LIFE 02 ENV/UK/000146 AFM
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Public health protected, asthma & respiratory related health risk reduced.

excreted by the bacteria start to glue the sand grains together which leads to channelling of
water through the filter bed. This situation normally takes one to two years, although in
heavily loaded systems such as spas, the high levels of organics act as a food source for the
bacteria, and alginate coagulation of the sand can occur in a few months.

Coagulation or gluing of the sand grains leads to filter bed channelling which will eventually
happen with every sand filter. This glue is often referred to as body fat, the statement is wrong
the material is bacterial cell biomass and polysaccharide alginates excreted by bacteria. This
is particularly relevant because the only sure mechanism limiting the spread of the protozoan
infection cryptosporidiosis is the sand filter, and if the sand grains are coagulated by alginates
then there will be channelling of water straight through the filter bed along with the
cryptosporidium oocysts.

The thicker the biofilm, the lower the pH on the biofilm, which in turn leads to increased
production of di and tri-chloramine. There is therefore a direct correlation between system
loading, organic content in the water, bacterial biomass and trichloramine production. Good
hygiene, system design and operation all have a major role to play. The biomass of bacteria in
a swimming pool sand filter can be as high as 5% of the total weight of the sand. The health
protection Agency 2004, reported that “1Out of 88 premises, 23 spa pools were found to
contain Legionella bacteria. Sixteen of these had passed current accepted levels for routine
microbiological parameters. Bacteria may be present in high numbers, even although routine
microbiological and safety checks appear satisfactory”

Chlorine will not affect the bacteria within the biofilm of the sand filter, but it will rapidly
oxidise and kill bacteria when they are washed out of the filter. However there is a short
period when large colonies of viable bacteria can enter the pool and this occurs for about 1
hour after back-washing a filter. Periodically the filters will also become unstable, and high
levels of bacteria (as bacterial floc) can again be discharged making the pool water cloudy,
this can happen every few weeks or months depending on the bather loading. Chlorine will
kill most individual bacterial in the water in 30 seconds, however bacterial floc measuring 50
to 100 microns in diameter will take considerable longer to oxidise.

Many of the water quality issues in swimming pools can be related to the sand filters and the
biofilm that develops on the sand. A properly designed, purged, and well managed system
can work well, but fundamentally sand is an excellent substrate for bacteria. At Dryden Aqua
we use fluidised beds of sand as biological filters for waste water treatment, we can therefore
categorically say that no amount of back-washing of sand will remove the bacteria, so a sand
filter will also be a source of trichloramine production.

AFM an Active Filter Media
At Dryden Aqua, we developed AFM (Active Filter Media) as a direct alternative to filter
sand. The media actively resist bacteria growth, and on average the bacterial levels on AFM
will be a 1 million times lower than in an equivalent sand filter. Catalytic oxidation on the
surface of AFM prevents the bacteria from growing, it is a similar mechanism that stops
bacteria from growing on a wooden food chopping board in comparison to a plastic board.
Changing the sand to AFM media or any media that actively resist biofouling will make a

1
  Press Release 14 September 2004 Health Protection Agency conference highlights spa pools as a cause of
legionnaires’ disease
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huge difference to the quality of the water and the production of trichloramine, but this is not
the full story.




              Dryden Aqua Ltd | Butlerfield | Bonnyrigg | Edinburgh EH19 3KQ | Scotland UK |
                     Tel +44 (0) 18758 22222 Fax +44 (0) 18748 22229 www.AFM.eu
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Flocculation and food for bacteria
Bacteria can grow at a tremendous rate in water above 25 deg C, on average the doubling time
will be around 60 minutes. This means that one bacterium can become 8 million after 24
hours, and after 48 hours the biomass of bacteria could increase to 140Kg. Clearly this does
not happen in swimming pools because the food supply is limiting. However it explains why
pools with a heavy bather load, or spas experience problems with the sand after a few months.
If the food supply can be reduced then the growth rate of bacteria can be slowed down. It is
essential that bathers have a good shower before entering the pool, the makeup mains water
supply may need to be filtered to remove phosphates and organics and no surfactants or
cleaning agents should be allowed to enter the pool.

The performance of the filters also needs to be optimised to achieve maximum removal of
organics. This can be achieved by employing efficient coagulation and flocculation to remove
the dissolved components as well as the fine solids. Aluminium based flocculent or their
equivalent may be used in swimming pools. The efficient use of coagulation and flocculation
will reduce the food available to the bacteria, which will slow down bacteria growth and
minimise trichloramine production.

NoPhos trace nutrient control
Irrespective of the type of media used and the efficiency of the backwash, you can not
eliminate all of the bacteria. We also know that at normal swimming pool levels, chlorine
will not oxidise the bacteria on the sand, pipe work, pool tiles or any surface in contact with
the water. At Dryden Aqua we are biologists and for many years we have been controlling
bacteria levels in aquatic systems, not by trying to kill the bacteria but by eliminating their
food source. All bacteria require certain trace nutrients, and if you remove the trace nutrients
from the water, you completely stop bacteria in their tracks. Dryden Aqua has developed a
product called NoPhos that removes the phosphate and trace minerals to form and insoluble
precipitate that is then synergistically removed by the AFM filters. The charge on the NoPhos
is positive and the charge on AFM is negative, this is why the two products work well
together. When NoPhos is used, not only is the algae growth stopped, but bacteria growth
rates slow down, and may actually start to decline. However it is essential that you use a
surplus of NoPhos to insure a zero total phosphate reading for the pool water.

The combination of AFM to eliminate biofilm in the filters, flocculent to remove the bacteria
food supply and NoPhos to remove bacteria trace nutrient can effectively eliminate bacteria
from swimming pool and Spa systems. By elimination of the bacteria, we prevent the acid
biofilm layer developing on the pool surfaces, and hence we eliminate or greatly reduce
trichloramine production.

Chlorine dioxide can mimic the effect of NoPhos to some degree, it is not as strong an
oxidising agent as hypochlorite, however because chlorine dioxide it is gaseous and lipid
soluble, it will diffuse into biofilm and kill the bacteria from the inside out. Hypochlorite is
not lipid soluble so it has to work from the out-side; this is fine for individual bacteria for
which hypochlorite is very effective. However, whenever you have a colony of bacteria or a
biofilm on a surface, the alginate excreted by the biofilm protects the bacteria from oxidation.
Indeed the use of hypochlorite can actually promote, or is selective for Pseudomonas species
because Pseudomonas bacteria are very good at generating copious quantities of muco-

              Dryden Aqua Ltd | Butlerfield | Bonnyrigg | Edinburgh EH19 3KQ | Scotland UK |
                     Tel +44 (0) 18758 22222 Fax +44 (0) 18748 22229 www.AFM.eu
                                     LIFE 02 ENV/UK/000146 AFM
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Public health protected, asthma & respiratory related health risk reduced.

saccharide alginates. The alginate then provides a protective mechanism for a whole host of
other organism and bacterial species.

Chlorine dioxide is very effective against biofilm, and it may have a useful role to play in the
swimming pool industry. However there is one potential problem, chlorine dioxide works
because it is lipid soluble, and because it is lipid soluble it may diffuse through the skin of
bathers directly into their blood stream, this would not be good news. In drinking water it
doesn’t matter because the chlorine dioxide in bound up in the organic matter in your
intestine, but in a swimming pool it is a different situation. Irrespective of the form of
chlorine dioxide, if it kills bacteria it will diffuse through your skin. No literature could be
found to confirm or deny this comment, or quantify the risk; however the chemical
characteristic and biological probability can not be refuted.

The first step is therefore to use NoPhos and remove as much of the bacteria food as possible.
Operating a pool in the manner described in this report will greatly improve water quality and
the appearance of the water. The chlorine demand of the system drops and water chemistry
will become more stable, indeed the system becomes very easy to operate and manage.

Optimise filter performance
AFM filtration will reduce the bacterial growth within the filter bed, however bacteria can
also develop on the solids removed by the filter. It is therefore important to backwash the
filters, even although the pressure differential across the filters does not warrant a backwash.
The growth of bacteria on the collected solids is so rapid that it will start to impact on water
quality after just one week. Ideally the filters should be back-washed once each week, with
two week cycles as the absolute limit.

The performance of all filter media, be it AFM, sand or other substrates varies inversely
proportionally to the flow of water passed through the bed. The slower the flow the better the
performance. Ideally the flowrates for swimming pools should be limited to a rate less than15
cubm/hr per square meter of filter bed surface area. It is just as important to insure that all of
the collected solids are removed during the backwash. If solids remain in the filter, they
simply act as a food source for bacteria, and trichloramine levels will start to increase. In
order to insure thorough cleaning, the filters should be air scoured at a rate between 70 and 90
cubm/hr/sqm for a period of 5 minutes before a backwash. The backwash rate should also be
at a flow that expands the bed by at least 15%. In order to achieve this expansion using AFM
or sand, a water flow of between 40 and 45 cubm/hr/sqm is required. Few swimming pools
operate their sand filters in this manner, which is unfortunate because it makes a huge
beneficial impact on water quality.




              Dryden Aqua Ltd | Butlerfield | Bonnyrigg | Edinburgh EH19 3KQ | Scotland UK |
                     Tel +44 (0) 18758 22222 Fax +44 (0) 18748 22229 www.AFM.eu
                                     LIFE 02 ENV/UK/000146 AFM
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Public health protected, asthma & respiratory related health risk reduced.

Filter Configuration, Horizontal or Vertical?

Sand or AFM media may be contained in horizontal or vertical filters. Horizontal filters have
been gaining favour because they offer a more competitive price per unit surface area of filter
bed. In many cases horizontal filters can also be stacked to maximising plant room space.

However with horizontal filters, the bed depth is a variable over the across section of the
filter. The distance the water has to travel through the sand is further at the edges of the filter
than it is down the centre. Water will travel the route of least resistance, this means that
preferentially more water will pass down the centre than at the edges. Also during a back-
wash the water will tend to force itself up through the centre line. Any organic matter around
the sides of the filter will be consumed by bacteria and the extra alginates produced will cause
coagulation of the sand around the sides and ends of the bed. The filter may appear to be
working okay but in actual fact only a small percentage of the bed is being used, and the
water is being seriously forced through the middle of the filter. If the filter hatch is opened,
the filter bed must be level, if it is not level or if there are any holes in the bed, then the filter
is not working.

In horizontal filters examined after the first 6 months of use, most of the filters were found to
exhibit channelling of water straight through the bed. It is therefore highly recommended that
only vertical pressure filters are used with sand and AFM. In situations where horizontal sand
filters have been used, changing the media to AFM can make a big difference, because AFM
is much less prone to channelling and coagulation and therefore it has a chance of working in
horizontal filters.

Vertical filters will increase the capital cost of the installation and space required, however if
you want good water quality with reduced chlorine reaction products then there is no choice,
only vertical filters should be used.

At Dryden Aqua we have designed our own pressure filters in accordance to a specification
that exceeds the German DIN standards.




              Dryden Aqua Ltd | Butlerfield | Bonnyrigg | Edinburgh EH19 3KQ | Scotland UK |
                     Tel +44 (0) 18758 22222 Fax +44 (0) 18748 22229 www.AFM.eu
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Diatomaceous Earth or perilite
Diatomaceous earth (DE) gives very good mechanical filtration of the water, however the dust
from DE is highly toxic because of the free silica content. Indeed DE has been compared to
asbestos in terms of its toxicity. Perilite is a manufactured product which performs in a
similar manner to DE, however it does not contain free silica, as such the dust is much safer.
However any fine dust is dangerous and precautions must always be taken when handling the
product.

DE and perilite act as a mechanical filter, and will remove most particles down to around 1
micron. However neither process with remove dissolved components from the water. The
oxidation of dissolved components may represent as much as 90% of the chlorine or oxidation
demand of the water. With DE or perlite systems you therefore have two scenarios;

    1. The system will have a high chlorine oxidation demand and will produce a high concentration
       of chlorine reactions products because of the high dissolved organic matter concentration.
    2. If in sufficient chlorine is used, the un-oxidised organic matter will act as a food source of
       bacteria. The biofilm and bacterial levels can be very high.

Sand or AFM filtration will remove particles down to around 15 and 5 microns respectively.
However with media bed filtration systems pre coagulation and flocculation can be used with
products such as PAC (polyaluminium chloride) and NoPhos. By using good coagulation and
flocculation, the media bed filters will remove most particles and colloidal matter in the water
down to less than 1 micron. However coagulation and flocculation will also remove a high
percentage of organic matter directly from solution, and reduce the chlorine demand and
reaction products by up to 80% and even as high as 90%.

Coagulation and flocculation can not be used with DE or perilite systems, because the
coagulants simply block the DE filters. It is therefore recommended that, only good quality
media bed filtration system with pre-coagulation and flocculation be employed.

UVc irradiation, of pool water
UV irradiation of water is effective at reducing the concentration of chloramines and in killing
bacteria. In a public swimming pool the free chlorine will oxidise most bacteria within a
period of 30 seconds. Residual disinfectant is also required in the pool to prevent horizontal
transmission of disease among the people in the pool, so the relevance of UV is not with the
disinfection of the water but with the control of water quality.

The process is effective because the wavelength of light normally used is 254nm which chops
up protein molecules such as DNA at the centre of bacteria. Low pressure lamps will give a
tight wavelength around the 254nm wave length, however it is more common to use medium
pressure lamps which will give a wider spectrum of light.

UV generates a series of highly reactive free radicals, which will oxidise organic matter and
chloramines. Above 254 nm chloramines are removed and as the intensity of the UVc
irradiation increases and the wavelength becomes shorter, organic matter is broken down, and
below 200nm chlorine is reduced to chloride. The application of UVc irradiation therefore
increases the chlorine demand, indeed UV can double the chemical requirement of a typical
swimming pool.

              Dryden Aqua Ltd | Butlerfield | Bonnyrigg | Edinburgh EH19 3KQ | Scotland UK |
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UV will reduce the total concentration of carcinogenic chlorine reaction products (DPB), and
because of this property, the process has found favour in drinking water treatment. However
while the general level of DBP (disinfection by-products) is reduced, the levels of volatile
DBP`s such as the THM (trihalomethane) chloroform is increased after UV. In swimming
pool systems because the public are not drinking the water, but are breathing the air above the
surface of the water, the concentration of volatile DBP in the atmosphere is of much more
importance. The highest concentration of THM’s are found just above the surface of the
water, even in out-door pools, or public pools with good ventilation, there will be high levels
of THM’s at the water surface.2 Delphine Cassana, University of Montpellier, 2005 report
that “the additional formation of chloroform and bromodichloromethane may be explained by
the increase in active chlorine and by radicalizing mechanisms initiated by UV radiation”.
3
 Ole Bisted, from Danish Technological Institute Department for Swimming Pool
Technology, reported that if UVc light is used, activated carbon should also be applied in
order to reduce the dissolved organics and THM’s. However, if you use activated carbon, you
also remove chlorine, a biofilm develops on the carbon and you produce trichloramines. The
only way in which you can use carbon would be change the media every one to two weeks,
which is not practical, or you can dose the system with powdered activated carbon, which is
effective, but it can be messy and easy to get wrong.

UVc irradiation is being advocated as a green friendly means of disinfecting swimming pool
water. However chlorine is effective in this task and the application of UV simply increases
chlorine demand. UV will also increase trichloramine levels and THM’s which are highly
carcinogenic. It is the opinion of the author that UV should not be used for public swimming
pools, indeed it is dangerous and constitutes a public health hazard.

Ozonation
Ozonation is written into the German DIN standard specifications for public swimming pools.
However ozone works in a similar manner to UVc in as much that the process oxidises and
chops up organic molecules into smaller components. However it is also a DIN standard
requirement to use activated carbon after Ozonation which eliminates the THM problem.
However the activated carbon absorbs the free chlorine and forms chlorides which increases
the chemical demand by the pool, typically the chlorine requirement will increase by 500%.
In addition to removing chlorine, activated carbon also absorbs organics, which makes it a
perfect environment for the incubation of bacteria and the production of trichloramine gas.

In Germany and in any swimming pool system using ozone and activated carbon there will be
a high level of trichloramine in the atmosphere. This is demonstrated by the excessive
corrosion of the ventilation systems and stainless steel metal work, the structural steel for the
building may also be affected. Every year there are at least one or more cases of swimming
pool roof failure in Europe caused by trichloramines. At low levels trichloramine will
predispose your lungs to infection, or in the case of children it may sensitise the lung tissue to

2
  Delphine Cassana, , , Béatrice Merciera, Françoise Castexb and André Rambaudc aUPRES 2991, Efficience et Déficience
Motrices, Faculté des Sciences du Sport, Université Montpellier 1, 34090 Montpellier, France
3
  Presented at the School of Water Sciences 1 day conference on Swimming Pool Water Quality and Treatment
2002 Cranfield University, ISBN 1 86194 020 3


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an allergic reaction which may in turn lead to asthma when the child becomes a teenager. It is
unlikely that we will ever quantify the damage caused by trichloramine on public health, in
the same manner that it has taken decades to appreciate the dangers from smoking and
asbestos. However we should not advocate a technology that actually promotes the
production of a toxic gas. Ozonation systems are being promoted in many European
countries, and they are written into the German DIN standards, however it is a technology that
is actively causing damage to the lungs of the public visiting swimming pools.

The chlorine free solution
There will always be a place for chlorine, or a fast acting broad-spectrum disinfectant to
prevent horizontal transmission of infectious organisms between bathers in the pool.
According to the German DIN standards the disinfectant must kill all bacterial in a pool
within 30 seconds. Alternative disinfectants such as copper based products take up to 90
minutes to achieve a similar result. Chlorine is still the best and most efficient disinfectant
and it is likely to remain so for many years until an alternative can be found which works just
as quickly. Until the alternative is found, chlorine should always be used in public pools, and
every effort should be taken to reduce chlorine demand and generation of chlorine reaction
products.

Conclusion
At Dryden Aqua we manufacture UVc and Ozonation systems, however UVc and Ozonation
systems should not be permitted in a chlorinated swimming pool or spa because they increase
the requirement for chlorine and result in higher levels of trichloramine and THM’s in the
atmosphere.

Sand should not be used in any public swimming pool because it promotes the growth of
bacteria and provides the low pH environment necessary for the production of trichloramine.
Sand filters are also the primary source of bacteria such as Legionella.

The way forward for the swimming pool industry, is to change the sand in all public and
private swimming pools to AFM, and to use good coagulation and flocculation prior to AFM
filtration. NoPhos also helps to reduce the biofilm and trichloramine production.

The performance of any media bed filter works inversely proportionally to the flow of water
through the filter. In essence, the slower you run the filters the better the performance. If this
strategy is followed with AFM, the chemical demand will be reduced by at least 80%, THM
levels will be reduced by 80% and trichloramine production will essentially be eliminated.

Critics argue that because we do not know the full implications of trichloramines and THM’s
on public health we should do nothing until the research has been concluded. However the
research will probably never reach a final conclusion. We know that trichloramine is toxic and
causes lung damage in children, and we know that THM’s are carcinogenic, these are basic
facts. Through the European Commission funded research project we also know that AFM
makes a huge improvement and will reduce the concentration of these chlorine reaction
products in the water and in the atmosphere. We now have the information and knowledge to
make a difference to your Life and our Environment, let’s hope we don’t have to wait for 20
years for its implementation.

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AFM in swimming Pools
Basic system operating parameters.


Equipment

       Only DIN standard equipment should be employed
       Magflow meters or an accurate means of measuring water flow through each filter during the
        run phase and back-wash cycle is essential.
       Static inline mixers
       Electro chlorination
       Calcium chloride
       Peristaltic dosing pumps for coagulants and NoPhos
       Monitoring and control systems



Operating parameters

       No surfactants should be used near the pool and they must be absolutely prevented from
        entering the water. Surfactants are used in most soaps and cleaning agents.
       It is essential that the public thoroughly shower before entering the water, preferably without
        soap of shampoo

       Turn-over rate for a public pool                                             = typically 4 hours
       Teaching or training pool                                                    = 1 to 2 hours

       Run phase water velocity (recommended) through AFM filters                   = less than 15 m/hr
       Back-wash water velocity                                                     = more than 45 m/hr

       Flocculent (PAC) dose rate                 0.5 to 1.0 ml per cubm of water filtered per hour
                                                   If water filtration rate is 100 cubm/hr, 50 to 100ml of
                                                   PAC flocculent will be required per hour.
       NoPhos                                     Dissolve 2kg into 25 litres of water and dose at a
                                                   rate of 0.5 to 1.0ml per cubic metre of water filtered
                                                   per hour.




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Chemical parameters

       Free chlorine level                        0.5 to 1.5 mg/l
       Combined chlorine level                    should always be less than 0.5mg/l, and often less
                                                   than 0.05mg/l.
       pH                                         6.8 to 7.6
       TDS                                        200 to 1000 mg/l
       calcium as CaCO3                           50 to 200mg/l
       alkalinity as CaCo3                        50 to 200mg/l
       sulphate                                   as low as possible (will affect grout/concrete)
       Turbidity                                  <0.1 NTU
       Redox potential                            >700mv
       Phosphate as PO4-P                         < 0.01 mg/l
       TOC (total organic carbon)                 < 2mg/l


Important Notes.
Water analysis
Standard colorimetric chlorine analysis is subject to serious interference giving much higher or lower
levels than is actually present in the water. Tablet reagents in particular may not dissolve completely
in the water sample, and as such they tend to give an over estimate for the analysis. Liquid reagents or
non compressed powder reagents are in general more accurate than tablets

Free chlorine analysis with DPD1 appears to be accurate below 1 mg/l, however it gives an over
estimate when the concentration exceeds 1mg/l.

Combined chlorine is a sum of mono, di and tri-chloramines, the total combined chlorine is
determined by subtracting DPD1 (free chlorine) analysis from DPD3 (total chlorine), the difference is
your combined chlorine. DPD2 is used to measure monochloramine, and from the equations and
graph on page 1, the total combined chlorine can be determined from the monochloramine value
because there is a relationship between mono-chloramine concentration and total chloramine
concentration.

The application factor is approximately 1.4 for sand filters and just 1 for AFM systems, for example if
the mono & di chloramine concentration as measured by DPD2 – DPD1 is 0.1mg/l, the total combined
chlorine will be 0.1 x 1.4 = 0.14mg/l total combined chlorine for a sand filtration system and just
0.1mg/l for an AFM system. If you now analyse the water for total combined chlorine by subtracting
DPD3 from DPD1, it is likely that you will get a much higher reading than 1 x DPD2-DPD1. The
reason for this is that the DPD3 reagents are also reacting to organo-chloramines and other interfering
chemicals. In some cases the combined chlorine analysis may be in error by as much as 95%.

In sand filtration systems, bacteria in the sand filter will digest organic matter, however they then
create ammonium and a low pH environment in the biofilm that generates dichloramine and
trichloramine (see equations on page 1). The reactions are not reversible, so the combined di &
trichloramine levels tend to increase with time. If AFM is used then there will be a much lower
concentration of bacteria in the filter, so you don’t have the low pH biofilm zone. This means that
there will be virtually no production of trichloramine. With AFM systems the DPD2 application
factor is 1 and in sand filters it is closer to 1.4 to 2.0, but there may still be quite a high combined
chlorine level due to the organo-chloramines in AFM systems, the DPD3 reagent is therefore not
giving the correct reading. In order to reduce the organics it is important to employ good coagulation
and flocculation with APF and NoPhos. The dosing rates should equate with 0.5ml to 1.0ml of APF
and NoPhos per cubic metre of water filtered per hour. For example if the water flow to the filters is

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100 cubm/hr, then the APF and NoPhos dose rate is 50ml to 100ml per hour.                      The NoPhos
concentration is 1Kg per 23 litres of water.

While DPD water analysis gives a good indication what is going on in the water, the best indicators
are your eyes, the water should be clear blue colour. There should be no sore eyes among the bathers
and there should be no nasty chlorine (trichloramine) smell.

Calcium concentration
In soft water locations, if calcium hypochlorite is used, and if you switch from sand to AFM, the
quantity of calcium hypochlorite required will drop by around 80%. This means that the calcium levels
will also drop, it is important to maintain a good calcium level otherwise there may be problems with
the grout between the tiles. Calcium chloride flake must be added to maintain a calcium level above
200mg/l.

Coagulant dosing
When you move over to AFM, there is no longer the bio-metabolism by bacteria in the filters. The
system is now working on the basis of physio-chemical adsorption of organics by the AFM media.
AFM media works synergistically with the coagulant which must include either standard PAC or APF,
and NoPhos. It is very important that the coagulant dose rate is adjusted to the levels given in this
report. Immediately after the injection point the water should enter a static inline mixer to insure best
use of the coagulant.




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Integrated Water Treatment
The primary role of a Swimming pools water treatment system is to prevent the transmission of
human pathogens and disease, this is a biological problem, but most of the swimming pool industry
is either non technical or is based on a chemical or engineering perspective and have failed to factor
in the biological component. In this context Dryden Aqua is the only biologically centred research &
development company with a strong manufacturing base providing an integrated approach to pool
water treatment in Europe.

In addition to viewing pool systems as a biological process, Dryden Aqua have also considered the
impact the systems have on the health and wellbeing of the pool staff and the public using the
facility. There are two issues;

    1. water quality
    2. air quality above the surface of the water.

Choramines

There has been a great deal of emphasis on inorganic combined chlorine (trichloramine) as a key
water quality parameter. Research conducted by many laboratories around Europe confirm that
trichloramine is implicated in lung damage and respiratory disorders as well as stress corrosion
cracking of the pool buildings and corrosion of ventilation systems, the human and infrastructure
costs are enormous. The primary production mechanism of trichloramine is bio-chemical, and
through detailed understanding of the mechanism, Dryden Aqua is able to completely solve the
problem.

In addition to inorganic chloramines, there are also organo-chloramines that are less dangerous
because most are non-volatile, they are detected by DPD3 reagents, and as such they are often
confused with inorganic trichloramine. The analytical procedures used by the pool industry
therefore do not reflect the true nature or chemistry of the water.

Volatile lipid soluble gas

Of more concern are volatile lipid soluble chemicals including THM`s such as chloroform, or
chemicals including cyanogen chloride that are nerve toxins. The lipid soluble nature of the gas
means that they diffuse through the water surface into the air, and then readily pass through lung
tissue and enter your blood stream. Blood chloroform levels can increase 50 fold in as short a time
span as 10 minutes and one exposure to high levels of nerve toxins can result in long term
neurological problems and health related issues. Children under two years of age are most at risk
because they do not have a fully developed blood brain barrier and lipid soluble chemicals may reach
spinal nerve tissue.

It is the opinion of Dryden Aqua that the acute and chronic toxicity of volatile lipid soluble chemicals
have either not been fully appreciated, or the authorities are not aware that a potential serious
public health hazard actually exists. Given the biological back-ground of Dryden Aqua we understand
the importance of lipid soluble toxic gases, and have serious concern regarding the system design
configuration and chemicals used in both the private and public sectors of the pool industry.

Cloudy pool water



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The cloudiness or turbidity of the water may be caused by solids breaking through un-stable filters
due to transient worm-hole channelling. System instability can be caused by many factors, but most
sand filters or filters containing poor quality media will be unstable. Little concern is expressed over
slightly cloudy pool water, as long as the chemistry is okay and no bacteria can be detected. However
turbidity is usually due to a colloidal suspension of lipo-polysaccharide molecules with bits of
bacterial cell walls or dead bacteria, there may also be other solids, oocycts and flocculant chemicals
present. Chemicals excreted by bacteria or
                                                                          AFM filters
the remains of bacteria are exotoxic &
endotoxic, and while they are non                    Resonating
pathogenic they can sill cause an allergic          ZPM activates
                                                       ACO
response or a fever, and as such they are                                                                ZPM
                                                                                                         Zeta Potential Mixer
almost as dangerous as living bacteria.                                                                  flanges into pipe-work
                                                                                                                between pumps and filters

Solution to the problem                                                                                            peristaltic
                                                                  Electrical                                       dosing pump
                                                                    earth         System pumps
Problems have been identified in the           Chlorine ACO
                                                        Active Catalytic                pH correction
swimming pool industry, but little has                  Oxidation                                        APF
                                                                                                     Active PolyFloc
been done to correct the problems,                                                                   and / or NopHos

especially in the UK. There are parallels in                                                                From pool
industry, for example we are all aware of                                                                 Back to pool
the risk and dangers from smoking and                                                 on-line sensors
                                                                                      pH, redox, chlorine
asbestos, but very little was actually done                                           turbidity, temperature
to rectify the situation until recent years.
We also know that exposure to high levels of trichloramine in pools causes the same biochemical
indicator of lung damage in children as seen in adult smokers, we also know that lipid soluble gases
are implicated in neurological health problems and cancer. We know about these problems but the
extent of the damage and harm caused is not known, but this should not be an excuse to sit on the
fence and do nothing.

If you are aware of a problem then this gives the opportunity to either avoid or eliminate the
problem, and if this can be achieved by also reducing the running costs, carbon foot print and
chemical costs, then it is a win:win situation. In order to achieve this task Dryden Aqua has
developed an integrated approach to water treatment using AFM® Active Filter Media, APF® Active
Polyfloc, ZPM® Zeta Potential Mixers and NoPhos®. The products all work together to provide a
system performance much greater than the sum of the parts to eliminate more than 90% of the
chlorine and oxidation by-products. The Dryden Aqua system not only reduces chlorine demand but
also the oxidation demand of the water, which allows chlorine or chlorine free products to work
much more effectively.


Certification for safe products & chemicals

AFM® is an activated filter media manufactured under ISO9001-2008 procedures to the best
European drinking water standards. Inevitably companies will try to copy products and procedures,
but without the knowledge or understanding the consequences can often be dangerous.

Crushed glass has been used in various forms for the last 50 years for water filtration, this is not a
new idea. Indeed glass such as glass fibre filter has been used in laboratories and industry for
decades. Sintered forms of glass coated with silanes and metal ion catalysts are also being used,
again this is not new. What is new is the use of un-controlled and non-certified or regulated crushed
glass as a filter media for the treatment of water in contact with humans in the swimming pool

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industry. Given that the majority of the products on the market are derived from recycled waste
source, Dryden Aqua consider there to be a potential very serious health and safety risk associated
with such products.

We need product certification and regulation in accordance to acceptable standards to protect the
pool installers as well as the public. There are many good products manufactured for the pool
industry but sometimes the combination with other products and chemicals can have really
dangerous side affects. By way of example, some pool products contain surfactants, if the products
are added to the water they destabilize the sand filters and the solids in the filter along with bacteria
and cryptosporidium oocysts will be instantly discharged into the pool. The only way to avoid these
problems is to have proper certification of pool products and chemicals. However until this situation
is reached, Dryden Aqua can provide a completely integrated approach to pool water treatment, for
which we are now winning recognition and innovation awards through-out Europe.

Benefits of DrydenAqua integrated water treatment

       95% lower inorganic chloramines
       90% lower THM’s
       95% + elimination of endotoxins
       High protection against cryptosporidium
       50% to 80% reduction in water
       Up to 90% reduction in chlorine
       Up to 90% reduction in pH correction chemicals
       18 month return in capital out of revenue savings
       Safe water for the public and your family

Dryden Aqua is re-writing the text books on how to treat pool water. Fundamentally most pool
systems require only minor modification, and with proper training and support of the pool plant
operator, major improvements to water quality, air quality and costs savings are easy to achieve.




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     The Following Report is a technical appraisal




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Water Flow-rates
The performance of any media
bed filtration systems such as                                                                100    Graph 1. AFM and sand filter
sand or AFM®          is inversely                                                                  performance against water flow
proportional to the flow of water                                                             90




                                       Performance % reduction of chlorine oxidation demand
through the filter bed.       This
means that the slower you pass                                                                80
the water through the filter, the
better the performance of the
                                                                                              70
filter media. By way of example,
if we take a typical filter with a
                                                                                              60
water flow of 30 m/hr and reduce                                                                                   sand
the flow velocity by half to 15
                                                                                              50                   crushed glass
m/hr, filter performance will be
increased by a factor of four                                                                                      AFM
times.      The relationship is                                                               40
                                                                                                                   AFM, APF & ZPM
exponential and demonstrates
that irrespective of the filter                                                               30
media used, best performance is
achieved when water flows are                                                                 20
less than 15 m/hr.
                                                                                              10
Graph 1 shows the relationship
between      water     flow     and
                                          0
performance in terms of the
                                             1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39
oxidation demand.        We have                                 water flow m/hr
used oxidation demand as the
key parameter because it relates, not only to particles in suspension but also to chemicals that are in
solution. Since most (greater than 90%) of the oxidation demand of swimming pool water is due to
chemicals in solution, this parameter provides a more realistic interpretation of filter performance.




Table 1. Filter Performance at different flow rates

                                     Filter performance % reduction of chlorine oxidation demand at
                                     two water flow-rates
                                     30m/hr                          15m/hr
Sand                                 8                               50
Crushed glass                        12                              61
AFM®                                 22                              88
AFM® + APF® & ZPM®                   28                              97




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Sand

The data presented in the graph 1 and table 1 is based on new sand and filter media. New sand
behaves very differently from sand that has been in a filter for several weeks or months. When
dealing with new sand, the sand works as a mechanical filter media trapping suspended solids as
they pass through the filter bed. In some cases new sand can work better than a crushed glass
media or even AFM® especially if a poor quality rough sand or a zeolite is used. The irregular
structure of the sand surface traps solids that may otherwise slip past AFM®, especially at high water
flow-rates in excess of 30 m/hr. As suspended solids and organic matter accumulate in the sand
bed, they start to act as a food source for the growth of bacteria, and the performance of sand will
start to deteriorate. However at high water flows in excess of 60 m/hr, bacteria have difficulty
colonising the surface of sand due to the scouring affect of the water, and under these conditions the
performance of sand may continue to be better than AFM®, but overall filter performance is very

                                                  Graph 2. Backwash performance of Sand & AFM


              70



              60



              50
   turbidity NTU




              40



              30



              20



              10



                   0
                       0         50         100         150        200         250         300        350   400    450
                                                                  time seconds

                                                  Backwash performance of Sand & AFM
poor as illustrated in Graph 1.



At start up of a new sand filter, more solids will be removed by sand than are discharged in the back-
wash water, as illustrated by graph2. The graph shows that 30% more solids are discharged from
AFM® during a back-wash in comparison to sand.

During the first few weeks, solids are accumulating and bacteria are growing on all the sand grains.
Initially the bacteria help to improve water quality by removing dissolved organics and nitrogen
compounds such a urea and ammonium. However, biological activity of the filter is un-stable, and
after the first few weeks the growth of bacteria will start to impact on filter performance. The lipo-

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polysaccharide alginate coat excreted by bacteria provides them with protection against oxidation by
chlorine, this behaviour allows the bacteria to continue to grow and develop irrespective of the
concentration of chlorine and after a short while the alginates start to stick (coagulate) the sand
grains together. Coagulation of the sand promotes instability leading to the development of transient
worm-hole channelling of un-filtered water directly through the sand filter.

Sand filters tend to go through cycles, sometimes they work well and then all of a sudden the water
will go cloudy for no apparent reason, this is due to their biological instability or the opening of a
transient worm-hole through the filter bed. The high turbidity is caused by the lipo-polysaccharides,
dead bacteria and bits of bacteria cell wall, there may also be some coagulants and suspended solids
that had been dumped from the top of the filter bed through a worm-hole channel. The instability
means that sand filter can discharge high levels of cryptosporidium oocysts into the water, or organic
matter. However of more concern is the endotoxic nature of the polysaccharides, dead bacteria and
bits of bacteria cell wall. The bacteria do not need to be alive to cause an allergic response or an
endotoxic fever. Indeed dead bacteria are almost as dangerous and living bacteria from a health
perspective. This aspect of swimming pool public health has been completely ignored by European
health authorities and is one of the reasons for Dryden Aqua developing AFM® .

Crushed glass & AFM®

There are many different grades and qualities of sand and given the un-controlled nature of crushed
glass we have also identified major inconsistencies in the performance of basic crushed glass as a
filter media. Poor quality media will experience a lensing effect in the filter. Mechanical filtration
performance will be good, but the pressure differential will increase rapidly necessitating frequent
back-washing up to 2 to 3 times per week. While solids removal may be okay, there will be a
differential water flow across the bed due to the lensing effect giving rise to high water velocities
around the periphery of the filter. A crushed glass filter does not work with coagulants such as PAC
or Dryden Aqua APF® and NoPhos as illustrated by graph1, and as a consequence the oxidation
demand or chlorine demand of the water will not be reduced. Given that we are trying to reduce
chlorine reaction products and oxidation demand there is little advantage to be gained from using a
crushed glass because you still have the toxic reaction products, poor performance with chlorine free
products and the public health hazard from using an un-regulated product.

Graph 1 shows a high quality crushed glass product giving a better performance than sand, but some
crushed glass products are much worse than sand and all carry a health and safety risk (see appendix
2). When crushed glass is compared against AFM® in terms of the chlorine oxidation demand, AFM®
shows on average a 30% better performance. The oxidation demand of water relates to suspended
solids and dissolved organic matter that can be oxidised by chlorine. It is absolutely critical that the
oxidation demand is reduced to the lowest possible level. The lower the oxidation demand the lower
the chlorine chemical demand, and the lower the concentration of chlorine reaction products.

We now know that when chlorine is used for water disinfection, if the water is exposed to short
wavelength UV light, or even to strong sun-light in an out-door pool, lipid soluble volatile chlorinated
organics such as cyanogen chloride will be generated. The volatile nature of the chemicals means
that a high concentration may accumulate on the water surface, this will occur in outdoor pools
unless a wind is blowing across the surface. With indoor pools it really doesn’t matter how good the
ventilation system is the in the building, you will still have a problem just above the water surface.
Chemicals such as cyanogen chloride and similar volatile lipid soluble chlorinated by-products will
enter your blood stream and may cause organ and nervous system damage. In young children under
2 years of age, their blood brain barrier is not fully developed and even one exposure to chemicals

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such as cyanogen chloride can lead to nerve damage and possible spinal deformities such as scoliosis
10 years after exposure. It is the opinion of Dryden Aqua that the Health Authorities in Europe have
either under-estimated, or are not aware of the potential serious health issues identified by Dryden
Aqua. It is for this reason that Dryden Aqua have developed AFM® and an integrated water
treatment approach in an effort to try and eliminate chlorine reaction products and oxidation by-
products.

Public swimming pools should always use chlorine to prevent the horizontal transmission of disease
among the bathers. The risk of disease transmission is a greater hazard than chlorine reaction
products in most cases, so there is no option but to use chlorine in public pools. However with
proper filtration combined with APF® , NoPhos, and ZPM® units the risk from chlorine reactions
products can be greatly reduced.

With regard to the private pool sector, it is acceptable to use a chlorine free alternative unless more
than one family use the pool, in which case we again recommend the use of chlorine. AFM® with
good filtration, APF®, NoPhos and ZPM® units will reduce the oxidation demand of the water to
almost zero. This then allows other non-chlorine based products, to be effective in controlling
pathogens in the water. The Dryden Aqua integrated approach to swimming pool water treatment
makes chlorine free products work much better, and AFM® (not sand or a crushed glass) is essential
in order to achieve this objective.

Why is the quality of the filter media important ?

AFM® is a highly engineered product manufactured from processed glass as a raw material. The
performance of AFM® is related to three aspects.

    1. Chemical composition of the raw material
    2. Particle shape, particle size distribution and fluid dynamics
    3. Processing by zeolitification to increase surface –ve zeta potential and oxidation potential

The primary focus is to prevent toxic chlorine or oxidation by-products, and to prevent disease
transmission between the bathers. To achieve this task we must remove the dissolved organic matter
which constitutes some 80% to 90% of the load on chlorine. The dissolved organic matter is also the
primary source of bacteria nutrients. The coagulation and flocculation chemicals APF and NoPhos
drag the dissolved chemicals out of solution to form small flocculated particles that can be removed
by the filter. The ZPM units makes the APF and NoPhos work efficiently and imparts a +ve charge on
all the particles.

AFM has been engineered to have a high –ve charge, to adsorb the small +ve charged particles
electrostatic attraction. AFM has also been engineered to have a high surface oxidation potential
which prevents the bacteria from growing in the filter. The particle size distribution and shape of
AFM insure that we do not have differential pressure gradients across the filter bed which would
prevent to flocculation reactions working due to the high velocity shear forces. AFM is therefore
greatly superior to crushed glass, and because it does not suffer from transient worm-holes it is many
times better than sand.

Some examples that explain the importance of good filtration

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Dryden Aqua are marine biologists specialising in water treatment systems for aquatic animals. By
way of example if you have cetaceans such as dolphins in a chlorinated system, the animals will
suffer from chlorine disinfection by-products which manifest in damage to their skin, eyes, lung
tissue and nervous system. The animals are placed under stress, their immune system is
compromised and as such they are predisposed to infection such as pneumonia. The Dryden Aqua
integrated approach using AFM, APF, NoPhos and ZPM unit solves the problems, and our work in this
field gives us confidence that we have the correct solution for public and private swimming pools.

We know that exposure to a chemical at a very early age can manifest itself in problems later on in
life, by way of example, exposure to lipid soluble chlorinated organics with under 2 years old
humans, may cause scoliosis, degenerative neural disorders and cancer 10, 20 or 60 years after the
initial exposure. The cause and effect can be decades apart, which makes quantifying the data just
about impossible. But from examination of other animals such as dolphins with a shorter life span,
we know there are problem with humans, we just don’t know how serious the long term implications
will become. There is a great deal of research being conducted by Government laboratories and
universities around Europe with regards to the impact of trichloramine in relation to lung damage
and asthma in children, the results are rather disturbing.

Most of the Government sponsored research has been devoted to identification of the problems and
quantification about how serious the problems are with regards to public health. For example we
have known about the dangers of smoking and asbestos for many decades, but it has only been over
the last 10 years that any concerted corrective action has been taken. The philosophy of Dryden
Aqua is “if you are aware of a problem and you can eliminate the problem then there is no need to
wait 40 years fully quantify how bad the problem may become or the impact that it may have on
children’s health”. You simply fix the problem, and then you can quantify how bad the problem
would have been as opposed to counting the damage that would otherwise be caused to public
health.

We are often asked why pay more for AFM® when sand is a perfectly good filtration media. This is a
reasonable question but nobody has been able to answer because up until the work of Dryden Aqua
and some Government laboratories there has been a lack of understanding of the problems
encountered in swimming pools. At Dryden Aqua our primary objective is to protect the health and
wellbeing of the public. We have identified some potential very serious health implications in pools
for which we have provided a partial solution using AFM®, and an almost complete solution as
illustrated in Graph 1 by adopting a an Integrated approach to water treatment.

The approach to zero chlorine or oxidation reaction products requires the elimination the oxidation
demand of the water. This can only be achieved be using of good coagulation and flocculation with
APF, NoPhos and ZPM unit because most of the oxidation demand and reaction product precursors
are in solution. Even if chlorine is not used, if the pool is exposed to UV irradiation, ozone or strong
sunlight in the presence of non chlorine based catalysts, toxic products may still form. For a non
chlorine based private pool, AFM® reduces the oxidation demand of the water and allows chlorine
free products to work more effectively.

Chlorine free products and external infection

Chlorine free products often taken up to 90 minutes to kill bacteria and may not be affective against
nematodes, protozoa, viri, some bacteria and bacteria & protozoan cysts. Out-door pools will be
subject to animals such as birds defecating in the water or disease transmission from insects. Non-
chlorine based products may not be affective against bird flu virus, bacteria responsible for


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psittacosis or insect disease vectored infections, so in the opinion of Dryden Aqua we have some
concern over the use of chlorine-free products for private out-door swimming pools.

Closing Comments

Water filtration in a swimming pool has been viewed as mechanical filtration process for the removal
of suspended solids in fact it is a bio-mechanical process for the removal of dissolved chemicals.
Around 90% of the oxidation demand of pool water is not from solids but dissolved organics, urea,
ammonium and other chemicals that are in solution. Once this simple fact is accepted then other
issues start to drop into place. It becomes essential to use flocculation agents such as PAC, Dryden
Aqua APF® and NoPhos combined with a ZPM®. The performance of the filtration system now
relates not only the solids but the chemicals in solution and the behaviour of the water. These
aspects of water treatment relate to the Zeta Potential or electrical charge density of everything in
the water, and it is for this reason that AFM® is manufactured to impart a high surface negative Zeta
Potential.

AFM® is approximately 40% better than sand and 30% better than the best crushed glass, this result
means that AFM® is removing 4 times more dissolved chemicals that would otherwise react with
chlorine or act as a food source for the growth of bacteria. The three characteristics of AFM® provide
AFM® with a higher performance than any other filtration media, and when combined with APF®,
NoPhos and ZPM® units we aim to eliminate the side effects of toxic chemicals and minimise the risk
to the public from disease transmission, and at the same time reduce running costs by saving on
water, chemicals and energy.




Appendix 1. Zeta Potential hydrogen bonding and electrical charge density

One of the key properties of AFM® is the high negative electrical charge, or zeta potential on the
surface of the media. Appendix 1 gives a detailed explanation of the importance of zeta potential
and how it relates to other aspects of pool water treatment to provide an integrated water
treatment approach. AFM® will improve water quality, but when combined with APF® , NoPhos
and ZPM® units, the performance is not just the sum of the parts because each component works
together to exponentially amplify the performance of the whole integrated system.




              Dryden Aqua Ltd | Butlerfield | Bonnyrigg | Edinburgh EH19 3KQ | Scotland UK |
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                                         AFM filters

             Resonating
            ZPM activates
               ACO
                                                                                 ZPM
                                                                                 Zeta Potential Mixer
                                                                                 flanges into pipe-work
                                                                                 between pumps and filters

                                                                                     peristaltic
                            Electrical                                               dosing pump
                             earth           System pumps
        Chlorine   ACO
                   Active Catalytic                          pH correction
                   Oxidation                                                 APF
                                                                         Active PolyFloc
                                                                         and / or NopHos

                                                                                From pool
                                                                              Back to pool
                                                            on-line sensors
                                                            pH, redox, chlorine
                                                            turbidity, temperature


The zeta potential of water relates to the electrical charge density of particles and dissolved
components in the water. The particles will predominantly have a negative charge, but some will be
positive while others will have a neutral charge. If you have a solution of small particles such as a
colloidal suspension of lipo-polysaccharide molecules with bits of bacterial cell walls in a swimming
pool, the water will be slightly turbid (exotoxin & endotoxic products). By way of another example,
milk is a colloidal suspension of oil drops and red blood cells are a suspension in which all the
particles have the same electrical surface charge that keeps them apart and supported in suspension.

Normally the charge is negative, and when the particles have the same electrical charge they repel
each other to form a stable suspension. If the electrical charge density on the particles is changed
this will have a profound impact on the way the particles and liquid behaves. If some of the particles
are changed from negative to positive, they will become attracted to other negative particles, and
dissolved components will coagulate and small particles will flocculate. When this happens, the bits
of bacteria and polysaccharides that make swimming pool water cloudy will drop out of suspension
and the water becomes clear, milk will become butter, and red blood cells starts to clot.

The Zeta potential does not only control particles in suspension or chemicals dissolved in water, it
will also dictate how the water molecules line up and behave with each other. This has the effect of
changing the hydrogen bonding or surface tension of the water. Also if you can change the hydrogen
bonding you then influence how easy it is for water to pass through desalination membranes, you
reduce the amount of energy required to pump water through pipes, and blood flows through your
veins more easily.

With regards to the swimming pool industry, in order to optimise results from the use of AFM® we
need to shift the zeta potential of the water from negative to positive before the filters. This is
accomplished by using APF® (Active Poly Floc) or NoPhos chemicals that are added or injected into
the water. PAC (Polyaluminium chloride) is a good flocculent, but APF® and NoPhos have a much
wider spectrum and as such they are more effective. Also we have found that PAC for some reason
often contains impurities such as trichlorophenol (TCP). In drinking water this is not an issue because
of the low concentration, but in swimming pool water, because the water is recycled many times,
any impurities in the PAC can accumulate to a give high concentrations in the recycled pool water.

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Products used in swimming pools therefore need to be of a higher quality than the equivalent
product used for drinking water treatment. To solve this problem Dryden Aqua manufacture APF®
Active PolyFloc and NoPhos.

 The performance of the chemicals can be dramatically amplified by use of a ZPM® unit Zeta
Potential Mixer. The ZPM® unit flanges into the pipe-work between the pumps and filters and is the
injection point for APF® or NoPhos. The ZPM® unit can improve the performance of APF® and
NoPhos 4 fold, and drop the zeta potential to a positive value. Now when the water passes through
the negative zeta potential AFM® media, virtually everything in the water will be adsorbed onto the
surface of AFM®, this does not happen to the same extent with sand or crushed glass. If you want to
reduce chlorine chemical consumption or make non chlorine disinfectants work, then it is essential
that water flows are reduced and APF®injected continuously into the water via a ZPM® unit. By this
approach we have effectively eliminated trichloramines and other disinfection by-products such a
THM`s and cyanogen chloride.

Hydrogen bonding and zeta potential also controls how nutrients and waste are transported across
semi-permeable membranes in all cells, it dictates how bacteria can absorb nutrients and it controls
the ability of any organism to osmoregulate.

The implications of hydrogen bonding and electrical charge density are profound, not only in water
treatment but in every biochemical mechanism, including nutrition, medicine, and disease
transmission. At Dryden Aqua we are at the forefront of this technology and are using our
understanding to develop new products such as www.WaterWasp.com for mosquito and bacteria
control. We have also developed ACO which is part of a new generation of coagulation and
oxidation products.

The zeta potential is related to and influenced by many mechanical, chemical and physio-chemical
inter-reactions. Water chemistry is also inter-connected, for example, if you change the pH or mono-
valent to di-valent cation ratio, this will impact on the redox potential, zeta potential, water clarity,
and bacterial activity. Indeed the simple act of just moving water or a liquid will impact on these
parameters. In this context we have developed a ZPM® r unit that flanges into the pipe work after
the filters. The ZPM®r unit physically shift the zeta potential of the water to a high negative value, so
without any chemicals, we are able to make water self sterilising. ZPM®r equipment will be available
spring 2010.

This report serves to illustrate that there can be no short cuts in the development of high
performance water filtration system, but it does not mean that the system will be expensive. Indeed
in most cases when the Dryden Aqua integrated approach has been adopted, while the capital cost
of the systems are higher, the extra cost is normally recovered out of revenue saving in chemicals,
energy and water in under 18 months. However the most important aspect of the process it that we
able improve water and air quality, mitigate disease and toxic chemicals and make swimming a
much safer and healthier activity.




              Dryden Aqua Ltd | Butlerfield | Bonnyrigg | Edinburgh EH19 3KQ | Scotland UK |
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Appendix 2. Health & Safety for the Public and our Environment

There have been several major public health issues regarding companies passing off crushed glass as
equivalent to AFM® , please be advised that AFM® and crushed glass are completely different and
should not be confused. AFM® Active Filter Media is a registered Trade Mark and Patented product
that has been through a major research and development project with the European Commission
and the UK Government authorities and has been tested for almost 20 years. AFM® is certified
under Regulation 31 of the UK Drinking Water inspectorate, AFM® is compliance with European
Water Directive (98/83/EC) & (80/778/EEC) and is manufactured under ISO9001-2008 quality in
accordance to BSEN12902 and BSEN 12904.

    If it's not AFM® it's not activated or safe to use and this is why
                                                                                                 crushed
                                                                                     AFM®
                                                                                                  glass
       AFM® ® is manufactured by Dryden Aqua and the process is
        certified under ISO9000 : 2008 to insure a quality product                                  X

       hypodermic needles, biohazard and toxic chemical risk, (not a
                                                                                        X
        risk concern with AFM® )
       Drinking water approval full certification checked by WRC-NSF
                                                                                                    X
       Surface activation gives AFM® ® a high zeta potential and
        redox potential, greatly enhances performance                                               X

       AFM® ® rejects bacterial growth and activation process
        makes it self sterilizing                                                                   X

       Activation removes micron and sub micron particles as well as
        organics that make up 80% of the loading swimming pool
                                                                                                    X
        systems

       The leading manufactured filter media for the swimming pool
        industry in Europe                                                                          X

       Risk Analysis conduct by one of Europe's largest independent
        water consultant organisations ENTEC report concludes AFM®
                                                                                                    X
        ® is safest media

       15 years track record 100% success in pools & spas
                                                                                                    X
       Backed by 1.2 million Euro research program with European                                   X
        Commission and water companies
       Protected by Dryden Aqua Patent and backed by our
        continuing product improvement by Research & Development                                    X




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Filter
                                        Risk Associated with filter media                                    Risk
media
                                            scale 0 (best) to 4 (worst)                                     Score
Type
                    Risk to
                      the
                                           Risk to the public and staff running the pool
                   supplier
                    or the
                   installer
                                   Water
                                                               building
                                  quality,                                    Eye         contamination
                     Dust /                   air quality,    structure,
                                  disease                                   damage,       issues & toxins
                   silicosis /                respiratory       stress
                                    and                                    ingestion,        or human
                    cancer                      disease       corrosion
                                 parasitic                                  abrasion         pathogens
                                                               cracking
                                 infection
             1
AFM® ®                  0           1              1              0             3               0              5
crushed
                        1           3              3              3            5                3             18
glass2
good
quality                 2           2              2              2             2               1             11
sand3
economy
                        3           4              3              3             2               2             17
sand4
zeolites 5              4           4              4              4             3               1             20
activated
                        1         1 to 3        2 to 4          2 to 4          1             3 to 4        10 to 17
carbon6
             Risk range                                               Risk implications
                 0 to 5                                  best possible mechanical filtration media
                 6 to 10                                 very good filter media for all applications
              11 to 15                             acceptable filter media should give good results
                  >15                          Considered a public health risk and should not be used

1. AFM® ® is manufactured by Dryden Aqua under very strict quality control procedures ISO 9000 :
2008 procedures with independent regular audits to insure compliance
2. Crushed glass cannot be regulated or certified, there may be everything from organic toxins to
heavy metals, hepatitis or AIDS contaminated syringes
3. A good quality filter sand is actually a very good filter media for pools and drinking water, but
AFM® ® will provide much better solids and dissolved organics removal performance
4. There is huge variability in the quality of sand and crushed glass available, if you use sand then
only use the best available sand.
5 Dr.Howard Dryden completed a PhD on zeolites and is a leading authority on zeolite filtration
systems in Europe, Dryden Aqua also supply zeolites but not for swimming pool applications
6. Activated carbon, if small carbon filters are used and changed on a regular basis then they can
improve water quality. The above table relates to activated carbon in a recycle loop, when used
properly it will give good results, but if left in the filter for months or years it will cause risk bacterial


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risk issues. The risk is therefore associated with how the product is used, and when used properly
the risk is low.




              Dryden Aqua Ltd | Butlerfield | Bonnyrigg | Edinburgh EH19 3KQ | Scotland UK |
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                                Dryden Aqua Performance Factor
                                        DAP Factor for Swimming Pools
Public pools must comply with water quality and air quality requirements, but it is often difficult to know how a pool is
actually performing or to compare one pool against another. The DAP Factor is an easy approach that can be used to
quantify the performance of any pool water treatment system in simple terms. The DAP Factor can be used as a tool to
mitigate the risk to the public, pool staff and avoid structural damage to the building, as well as a tool to help reduce
running costs and save money. Indeed we have found that a typical public pool could save up to 50% of their water
treatment costs, but only if you are aware that there is the possibility to save costs and improve performance. In this
context the DAP Factor lets you know how well you are performing, or if there is scope for improvement.

The DAP Factor is based in a simple approach; the more chlorine used per bather, the lower the system performance. Since
most of the chlorine added will gas off as a variety of chlorine by-products, the running costs and safety of the system are
directly related to the DAP Performance Factor. The DAP Factor is therefore a unifying measurement which encompasses
all chlorinated public and private swimming pools irrespective of the size or design of the facility because it is calculated
from two simple measurements;

                               1. Average daily bather load
                               2. Average daily consumption of chlorine

                                 Dryden Aqua DAP Factor pool performance table
          DAP factor
                                    Comment                     Risk associated with swimming pools water and air hazard
     Kg.Cl2/day/1000 bathers
                                                         Extremely low risk associated with water quality and air quality, achieved using Dryden
                                                         Aqua fully Integrated system operated properly with good overall hygiene and pool
               <1                                        management. AFM, ZPM, APF, ACO and ZPMr. DIN standard Filters operating at less than
                                                         15 m/hr
                               Well operated and
                                                         Very low risk associated with water quality and air quality, very good pool, fitted with
             1 - 1.9           managed pool using
                                                         AFM, ZPM and APF. Filters operating at less than 20 m/hr
                               good equipment
                                                         Low risk pool but could do better. There may be high combined chlorine but no smell or
                                                         sore eyes which indicates organic chloramine but low inorganic chloramines. Pool may be
             2 to 3.9                                    using AFM but flow rates are too high or poor quality filers are used. There may be
                                                         equipment or operational problems. Filters operating at less than 25m/hr
                                                         Low to medium risk pool, staff may be at risk from respiratory issues, there will be a
                                                         distinct smell of nitrogen trichloride, some of the public may complain about sore eyes.
             4 to 4.9                                    There may be a risk to regular bathers. Performance Factor is typical of sand filtration
                                                         systems operating at water flows below 25 m/hr, poor coagulation and flocculation.
                               Typical public pools,     Medium risk, staff may be at risk from respiratory issues. Some of the public will complain
                               could do better and       of sore eyes and skin irritation or allergic reactions, regular users of the pool may be at
             5 to 5.9          save up to 50% of water   risk from respiratory issues. Performance Factor is typical of sand filtration systems
                               treatment running costs   operating at water flows above 25 m/hr with poor coagulation and flocculation.
                                                         Medium to High risk pool, staff and public are at risk, structural damage to the building
                                                         and stainless steel will be evident. High levels of trichloramine, probably also high levels
             6 to 7.9                                    of volatile lipids soluble organic and inorganic chlorine molecules such a chloroform and
                                                         cyanogen chloride. Potential health risk to children under 2 years of age.
                                                         High risk associate with using the pool or for the staff working in the pool environment.
                               Poor quality pools        Potential bio-hazard from bacteria, oocysts, bacteria ectotoxins and endotoxins. Public
             8 to 10           should instigate          may experience an allergic response to the pool water and / or atmosphere. Increasing
                               immediate                 potential risk of health problems especially for children under 2 years of age.
                               improvement to            Very high chlorine consumption indicative of a poor system design and operating
                               procedures and            conditions. In the opinion of Dryden Aqua any pools with a DAP Factor greater than 10
               >10             equipment.                should be treated with extreme caution, especially for the pool staff, children, elderly or
                                                         immune depressed individuals.


Note. Public pools not using chlorine have a high risk associate with horizontal transmission of disease between the bathers
   unless the water has a residual disinfection potential sufficient to kill all bacteria within a time frame of less than 30
                                                           seconds.

In a poorly operated and designed pool, most of the chlorine will be discharge as chlorine reaction products to the
atmosphere in the building, this will usually account for more than 80% of all chlorine used. In a well operated and
designed pool, chlorine consumption will be a great deal lower, and the form the chlorine by-products take are usually
less toxic since they are discharged as coagulated suspended solids in the back-wash water.

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While water quality is very important from a bio-hazard disease perspective, the key factor is the amount of chlorine
actually used because this will reflect on the air quality. Most of the chlorine will end up as a gas such as nitrogen
trichloride and will be discharged through the water surface in a poorly operated pool. It does not matter if it is an indoor or
an out-door pool; you will still have a high concentration of organic and inorganic chlorinated gases at the water surface,
unless there is a wind blowing over the pool. It is chlorinated gaseous chemicals that represent the greatest health risk to
pool staff and public especially for the very young. Children under 2 years do not have a fully developed blood-brain
barrier and as such they are most at risk from neurological damage arising from lipid soluble volatile chlorine gas such as
cyanogen chloride and the THM`s.

By way of example, UVc irradiation will improve water quality by reducing chloramine
concentrations, the same situation applies to out-door pools, or pools exposed to strong sunlight.
The chlorine component of the chloramine is not removed it is simply changed into a different form
which includes volatile chlorinated chemicals that gas-off though the water surface. Volatile chlorine
by-products are much more toxic when taken into your lungs because unlike you skin, your lungs
have a huge surface area designed for gas exchange. Your skin is designed to prevent chemicals
entering your body, so in terms of toxicity the risk from chemicals in air is perhaps 1000 times higher
than the risk from the same chemicals in solution. Dryden Aqua ACO (Active Catalytic Oxidation)
was developed as a means of protecting chlorine from UV irradiation and sunlight.
Many of the chlorinated gaseous chemicals in the air do not have a smell so you may be unaware
that there is actually a problem. The DAP Factor now provides you with a tool that can be used to
evaluate any swimming pool, irrespective of the size or design of the systems. The DAP Factor may
be used to determine the potential risk factor associated with the pool and used as a means or
reducing operational costs.
How to calculate the DAP Factor
The Dryden Aqua DAP Factor for a swimming pool relates to the chlorine oxidation demand for 1000
bathers per day expressed as Kg of chlorine used. The first step is to work out the available chlorine
in the product that you use in your swimming pool; this will be a variable so check the product data
sheets for an accurate figure. The most common forms and values are as follows;

          1.Calcium hypochlorite, chlorine is approx equal to 0.68 x the Kg of calcium hypochlorite used per day
          2.Sodium hypochlorite solution, chlorine is approx equal to 0.15 x the litres of sodium hypochlorite used per day
          3. Dichloro-isocyanuric acid, chlorine is approx equal to 0.36 x the Kg of dichlor used per day
          4. Trichloro-isocyanuric acid, chlorine is approx equal to 0.42 x the Kg of trichlor used per day
          5. Chlorine gas, chlorine is equal to 1 x the kg amount of chlorine gas used per day

Example A. well operated system using AFM, ZPM and APF
          Average bather load per day = 1150 per day
          Average calcium hypochlorite consumption per day 1.8 kg
          Chlorine level in 1.8 kg of calcium hypochlorite = 1.8 x 0.68 = 1.22 kg per day for 1150 bathers
          Relate the chlorine consumption to 1000 bathers = 1000/1150 x 1.22 = 1.1 = DAP factor


Example B. typical public pool using sand filters with basic PAC flocculation
          Average bather load per day = 600 per day
          Average calcium hypochlorite consumption per day 4.8 kg
          Chlorine level in 4.8 kg of calcium hypochlorite = 4.8 x 0.68 = 3.3 kg per day for 600 bathers
          Relate the chlorine consumption to 1000 bathers = 1000/600 x 3.3 = 5.5 = DAP factor


Example C. old pool, sand changed to AFM, and PAC changed to APF and NoPhos, frequency inverter
fitted to regulate and control water flow through the filters. Filters were poor quality horizontal units
operating at a water flow of 25 m/hr. Spread sheet of costs is also given below.
          Average bather load per day = 700 per day
          Average calcium hypochlorite consumption per day 1.65 kg
          Chlorine level in 1.65 kg of calcium hypochlorite = 1.65 x 0.68 = 1.12 kg per day for 700 bathers
          Relate the chlorine consumption to 1000 bathers = 1000/700 x 1.12 = 1.6 = DAP factor reduced from 8.6




                 Dryden Aqua Ltd | Butlerfield | Bonnyrigg | Edinburgh EH19 3KQ | Scotland UK |
                        Tel +44 (0) 18758 22222 Fax +44 (0) 18748 22229 www.AFM.eu
                                        LIFE 02 ENV/UK/000146 AFM
AFM filtration of swimming pool and Spa water, THM`s, trichloramine and water quality problems solved.                          35
Public health protected, asthma & respiratory related health risk reduced.




                Example C ------Actual data for a typical 25m public pool 700 bathers/day
      Chemical usage                    2007/8 2008/9
                                         Euro Euro DAP factor has been reduced from a high risk 8.6 to a low risk 1.6
      calcium hypochlorite               6720 1249 less chlorine is required, because treatment system is more effective
      CO2 pH control                     6000 2200 because less chlorine is used less pH correction is required
      sodium bicarbonate                 640     340 lower autotrophic bacteria activity means less inorganic carbon used
      PAC                                800      0
      APF                                  0    1350 APF dramatically improves coagulation and flocculation
      NoPhos                               0     250 NoPhos used when pool is under extreme load
      Chemical costs                    14160 5389
      Chemical saving                           8771

      Water & Energy
      gas for heating                   32837 26747 less water is used so less energy is required to heat water
                                                    frequency control of pumps saves energy, gives better flow control in
      electrical consumption            26461 22000 filters
      water savings @ 3 Euro cubm        9000 2235 direct water saving, cost for water and disposal
      water & energy costs              68298 50982
      Water & energy savings                  17316
      Running costs                     82458 56371 32% saving in running costs, for a partially integrated system
      Total annual savings every year         26087 Total savings achieved for an initial one off capital cost of 19,000 Euro


Example C demonstrates the cost benefit of reducing the DAP Factor, very significant cost savings in terms of chemicals and
“carbon foot print” energy costs may be achieved. The bio-hazard and chemical risks associated with the water and air are
also reduced as well as damage caused by inorganic trichloramine and SCC stress corrosion cracking of the building fabric.
The Dryden Aqua DAP Factor provides you with a tool that can be used to determine the performance of your swimming
pool and lets you know how well the system is operating or if there is scope to make improvements.




                 Dryden Aqua Ltd | Butlerfield | Bonnyrigg | Edinburgh EH19 3KQ | Scotland UK |
                        Tel +44 (0) 18758 22222 Fax +44 (0) 18748 22229 www.AFM.eu
                                        LIFE 02 ENV/UK/000146 AFM

								
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