Variations in the organic load of Many have heard the idiom_ “Kill

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Variations in the organic load of Many have heard the idiom_ “Kill Powered By Docstoc
					August/September 2009                                                                              Volume 8, Number 4

On-line Assessment of Wastewater Quality Variability
A novel approach for the real-time analysis of potential activated sludge problems
Marie–Pierre Denieul, Olivier Daniel, Marielle Coste, Cyrille Lemoine, Karim Essemiani, and Chuck Blumenschein


V     ariations in the organic load of
      industrial wastewater constitute
a major risk for wastewater treatment
                                             used, and no specific data related to
                                             the wastewater or the treatment pro-
                                             cess are required and input into the
                                                                                       involves statistics and fuzzy logic
                                                                                       computation to determine abnormal-
                                                                                       ity levels, as shown in Figure 1 (see p.
and its constitutive processes, espe-        system. After a learning period during    4). In other words, the system takes a
cially biological processes. The ability     which a database of the influent is       “snapshot” of parameters and com-
to prejudge the potential risks that         constructed, the system automatically     pares this with a defined number of
could provoke the loss of biomass in         calibrates itself.                        previous snapshots, which are used
the case of biological treatment is a                                                  as the reference point. This refer-
necessity to ensure reliable treatment.      How It Works                              ence point evolves in time as more
    On-line alert systems that identify          The on-line alert system, devel-      recent snapshots are integrated and
influent characteristics and highlight       oped by Veolia Environnement (Paris),     replace the older snapshots. The
variations can assist treatment plant        uses a variability analysis based on      method allows the user to select key
operators in making critical decisions       changes in parameter values (“single-     parameters used for the detection. It
and complying with increasingly strin-       parameter tendencies,” or time evo-       is possible to evaluate variations of
gent environmental regulations. This         lution), as well as changes between       several parameters to obtain a single
article presents a new approach for          several parameters (“cross-parameter      and global variability indicator. Severity
the on-line and real-time risk evalua-       tendencies,” the simultaneous evolu-      criteria are applied to each calculation,
tion due to influent quality variations in   tion of parameters compared to each       thus making the algorithm as sensitive
industrial wastewater treatment plants,      other). The variations in values are      as possible. The computed alert levels
based on parametric and nonpara-             evaluated by comparing them with a        are then assimilated with color codes
metric measurements. The approach            historical data set to detect abnormal    that correspond to traffic-light colors.
uses fuzzy logic and statistics to           changes. The detection algorithm
                                                                                                          Continued on page 3
evaluate the variability of wastewater
quality and then translates this vari-
ability into color codes that are easily     Weeding Out the Best Solution
read by operators. No modeling is
                                             After more than a decade of research, scientists discover that duckweed can
                                             perform effluent nutrient removal and serve as a great renewable fuel source

 In This Issue                               M      any have heard the idiom, “Kill two birds with one stone.” Well, scientists
                                                    at North Carolina State University (Raleigh) are trying to do exactly that
                                             with their decadelong research into the use of the aquatic plant duckweed
 7 Problem Solvers                           as a secondary-level treatment of animal wastewater. They said not only do
                                             experiments show that duckweed can reduce nutrients in effluent, but duck-
                                             weed also has a high-starch content that makes it ideal for the production of
 10 Wisconsin File The
    Drought Effect:
                                             the renewable fuel ethanol.
                                                “Forty-six percent of duckweed’s dry biomass is starch,” said Jay J. Cheng,
 12 Crude Answers                            professor of environmental engineering and renewable energy processes at
                                             North Carolina State. (Cheng has conducted the experiments into duckweed
                                             and effluent with fellow researcher Anne-Marie Stomp, an associate profes-
 15 Briefs                                                                                              Continued on page 2


                                                                                             AUGUST/SEPTEMBER 2009            1
Figure 6. Correlation of Detected Alarms With Parametric Measurements                                                                                                                                                                                                                                                                                                                                                                                                                                                                The operator can thus
                1000
                                                     Influent equalization basin
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     immediately implement
                                                     Influent activated sludge
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     appropriate solutions to
                 900
                                                     Effluent activated sludge
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     prevent malfunctioning of
                 800                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 the treatment process,
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     such as directing the
                 700
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     influent to an intermediate
COD (mg O2/L)




                 600                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 storage tank.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         This tool also can be
                 500                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 used for the on-line eval-
                 400                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 uation of the qualitative
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     variability of other types
                 300                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 of wastewater, as well as
                 200
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     surface waters.

                 100                                                                                                                                                                                                                                                                                                                                                                                                                                                                       Marie–Pierre Denieul
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       is a senior researcher,
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                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       Olivier Daniel is a
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                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       senior researcher,
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       Cyrille Lemoine is
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       a research program
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       manager, and Marielle
                                                                                                                                                                                                                                                              Date                                                                                                                                                                                                                     Coste is a research
COD = chemical oxygen demand.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       program manager at the
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       Maison–Laffitte, France,
analysis unit was able to detect strong                                                                                                                                                                              early assessment of wastewater quality                                                                                                                                                                                                              office of research and development at
abnormal variations of the influent on                                                                                                                                                                               is an effective on-line monitoring tool.                                                                                                                                                                                                            Veolia Environnement (Paris). Karim
June 17 to 18 (see Figure 6, above)                                                                                                                                                                                  The developed tool is able to highlight                                                                                                                                                                                                             Essemiani is a business and market-
that were not affected during the resi-                                                                                                                                                                              variations of wastewater quality that                                                                                                                                                                                                               ing manager at Veolia Water Solutions
dence time in the equalization basin.                                                                                                                                                                                can or cannot be detected by para-                                                                                                                                                                                                                  and Technologies North America
On the contrary, no abnormal variations                                                                                                                                                                              metric measurements (such as COD                                                                                                                                                                                                                    (Houston), and Chuck Blumenschein
were detected on June 7, although the                                                                                                                                                                                and pH). Thanks to the alarms pro-                                                                                                                                                                                                                  is vice president of process engineer-
organic load of the basin influent was                                                                                                                                                                               vided in real time, abnormalities can be                                                                                                                                                                                                            ing at N.A. Water Systems, a Veolia
higher than usual.                                                                                                                                                                                                   detected before observing their con-                                                                                                                                                                                                                Water Solutions and Technologies
   As shown in these case studies,                                                                                                                                                                                   sequences on the treatment process.                                                                                                                                                                                                                 company (Moon Township, Pa.).



   Pro b l e m S o l ve r s
VRTX Cooling-Water Treatment Reduces Scale and Water
Consumption for Increased Efficiency Without Chemicals
   Problem: Chemical treatment                                                                                                                                                                                          Since 1909, Spoetzl Brewery                                                                                                                                                                                                                      and a water volume of approximately
of cooling water does not prevent                                                                                                                                                                                    (Shiner, Texas) has brewed Shiner                                                                                                                                                                                                                   11,355 L (3000 gal). The makeup
calcium carbonate scale formation                                                                                                                                                                                    Beers. Originally only sold in Texas, its                                                                                                                                                                                                           water for the cooling system is
on condensing equipment. Scale                                                                                                                                                                                       beers are now sold in 41 states. The                                                                                                                                                                                                                municipal water, which runs to four
buildup significantly reduces the heat                                                                                                                                                                               brewery has an annual production of                                                                                                                                                                                                                 cooling towers.
transfer rate across condenser tubes,                                                                                                                                                                                400,000 barrels.                                                                                                                                                                                                                                       On average, calcium carbonate
requiring more energy to run the                                                                                                                                                                                        The brewery’s refrigeration sys-                                                                                                                                                                                                                 gives the makeup water a total hard-
refrigeration system.                                                                                                                                                                                                tem uses anhydrous ammonia as its                                                                                                                                                                                                                   ness of 130 ppm, a calcium hardness
                                                                                                                                                                                                                     primary coolant. The system uses                                                                                                                                                                                                                    of 100 ppm, and a total alkalinity of
   Solution: Implement VRTX                                                                                                                                                                                          three evaporative condensers to cool                                                                                                                                                                                                                400 ppm. The pH is about 7.7 with
Technologies (Schertz, Texas) con-                                                                                                                                                                                   down the recompressed ammonia.                                                                                                                                                                                                                      total dissolved solids of approximately
trolled hydrodynamic cavitation tech-                                                                                                                                                                                They have a total cooling capacity of                                                                                                                                                                                                               400 ppm.
nology to treat cooling water.                                                                                                                                                                                       approximately 1360 Mg (1500 ton)                                                                                                                                                                                                                       The original chemical water treat-



                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               AUGUST/SEPTEMBER 2009                          7
                                                                                                                                                        VRTX Technologies
Spoetzl Brewery (Shiner, Texas) has brewed Shiner Beer since 1909. In the brewery’s refrigeration system, chemical treatment of cooling water did not
prevent calcium carbonate scale formation on condensing equipment so the brewery purchased a unit from VRTX Technologies (Schertz, Texas) that
uses controlled hydrodynamic cavitation technology to treat cooling water.



ment system automatically injected                 out of his ballistics tank solution and             out of the system by a side-stream
additives into the makeup-water hold-              settling at the bottom.                             filter loop.
ing tank, based on water conductivity.                 VRTX was formed in 2003 and has                      The strong vacuum (27.5 to 29.5
It used sulfuric acid for pH control, a            sold more than 500 cooling-water                    in.Hg [93.1 to 99.9 kPa]) in the cavita-
molybdenum based metal stabilizer                  treatment systems in North America                  tion chamber strips carbon dioxide
and a biocide. Cycles of concentra-                and through its European division,                  from the water. This maintains the
tion were between 2 and 2.5 during                 HydroVRTX (Almere, Netherlands).                    water pH at or above 8.5. By keeping
summer months and less than 2 for                      At the Spoetzl Brewery, the patent-             a high pH, eliminating solid particles,
the rest of the year; however, signifi-            ed VRTX system pumps water from                     and removing chemical additives, cor-
cant calcium carbonate accumulated                 the holding tank into a side-stream                 rosion also is controlled.
around condenser tubes and inside                  treatment loop, where a pressure-                        As a result, Spoetzl Brewery saw
condensers. Additionally, Shiner’s                 equalizing chamber sets the pressure                positive outcomes in scaling, cor-
remote location caused less than                   at approximately 483 kPa (70 lb/in.2).              rosion, bacteria count, and water
optimal support from the chemical                  From there, the water enters the cavi-              usage. After 2 months of VRTX treat-
supplier, said Peter Koestler, brewery             tation chamber, where two opposing                  ment, most of the existing scale was
engineer at Spoetzl Brewery.                       nozzles impart rotation, angle, and                 removed from the refrigeration system,
    To solve this problem, in 2001 the             velocity to the water, creating micro-              and no new scale formed.
Spoetzl Brewery replaced its chemi-                sized bubbles in the water. As the two                   During more than 2 years, bacte-
cal cooling water treatment system                 streams collide, the bubbles collapse,              ria counts averaged 1000 CFU/mL,
with a VRTX Technologies (Schertz,                 and hydrodynamic cavitation occurs.                 where they can normally average as
Texas) 227-L/min (60-gal/min) unit and             This causes localized extremes of                   much as 2500 CFU/mL. The cycles
a 189-L/min (50-gal/min) disk filter               temperature and pressure, as well as                of concentration were increased from
and has seen improvements in scale                 high-energy microjets.                              2.3 before the installation to 6.9 with
deposit formation while also increasing                “The high localized temperature                 the VRTX treatment. Corrosion rates
its water conservation practices.                  during bubble collapse kills bacte-                 were less than 0.056 mm/yr (2.2 mil/
    VRTX Technologies developed its                ria, while pressure and high-velocity               yr) for galvanized steel, 0.064 mm/yr
chemical-free water treatment system               microjets perforate microbial cell struc-           (2.5 mil/yr) for carbon steel, and less
in the early 1990s. According to Abby              ture,” Harris said.                                 than 0.008 mm/yr (0.3 mil/yr) for cop-
Harris, public relations coordinator at                These changes in the water tem-                 per alloy.
VRTX, the controlled hydrodynamic                  perature and pressure force solid                        The brewery’s most noteworthy
cavitation technology was developed                calcium carbonate to form and bond                  improvement came in the water sav-
by Cliff Ashbrook, a ballistics engineer,          with other calcium and carbonate                    ings department. Makeup consump-
who discovered sediments dropping                  ions. These colloids are separated                  tion decreased from 72,350 L/d



 8     I N D U S T R I A L W A S T E W AT E R
                                                                                                                                                              Peter Koestler
The VRTX unit by and filtration skid (lower center of frame) controls scale and corrosion while reduces water consumption to treat the cooling tower water.



(19,115 gal/d) to 28,857 L/d (7624                  requires little upkeep.                                   Water and energy conservation can
gal/d) with VRTX. Blowdown rates also                  “Maintenance consists mainly of                    go a long way as a company con-
dropped from 31,745 L (8387 gal) to                 changing out the two filter stacks                    tinues to grow and as environmental
5008 L (1323 gal) per day — a reduc-                once a week,” Koestler said. “The                     regulations tighten. Spoetzl Brewery is
tion of more than 85%. This provided                system has run 24/7 since August                      so pleased with the VRTX system that
a savings of more than 6.8 million L                2001 without a major failure. I would                 they “chose to install VRTX technology
(1.8 million gal) of water per year.                call that reliable.”                                  at its sister brewery in Berkeley, Calif.,”
   Because the VRTX system is                          With the old chemical system,                      Koestler said.
chemical-free, the discharge water                  Spoetzl Brewery spent approximately
is clean and can be reused for any                  $15,000/yr on water treatment.
nonpotable application, according                   However, with the VRTX treatment
to Harris. To further the brewery’s                 system, the brewery experienced
sustainability, the removal of scale                average annual water savings of
deposits increased the condenser’s                  $3463 and effluent savings of $7076,
heat-transfer efficiency, requiring less            and is now operating its system with
energy overall.                                     5% more efficiency and with $17,496
   Furthermore, with the VRTX sys-                  energy cost savings.
tem, there was no longer the need                      According to Koestler, the return on
to purchase, store, and manage haz-                 investment came in about 2.3 years.
ardous chemicals used in the older                  The total annual savings were approxi-
treatment system, and the VRTX unit                 mately $35,390.



                                                                                                                  AUGUST/SEPTEMBER 2009                  9

				
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