Docstoc

Slide foam

Document Sample
Slide  foam Powered By Docstoc
					 Large scale foam fractionation: a different approach to
creating mixed species environments for marine systems

L’écumage de protéines à grande échelle : une approche
     différente pour la création d’environnements
            multispécifiques en milieu marin
             A. AIKEN1, D. WARMOLTS2, D.L. LABONNE3, S.L. BAILEY4
           1
             National Aquarium In Baltimore; Baltimore, MD 21202 USA
              2
                Columbus Zoo & Aquarium, Columbus, OH 43065 USA
                       3
                         IDEA, Inc., Cambridge, MA 02138 USA
                  4
                    New England Aquarium; Boston, MA 02110 USA

                                           ABSTRACT

    Recent advances in life support engineering design are routinely including a more aggressive
use of foam fractionation (protein skimming) for marine applications. The resultant benefit to
the environmental stability of a habitat, as well as long-term water quality, continues to be
documented. The fractionator’s ability to remove dissolved and suspended organic material, and
thus short circuit the negative effects of that materials biodegradation in sand filters, can
dramatically alter the biological load on a life support system. When applied on a large scale in
conjunction with good mechanical, chemical and biological filtration, fractionation becomes a
key design component in the successful execution of a mixed species environment. While a
multi-taxa approach to exhibiting marine animals is challenging from a husbandry perspective,
the demands on water quality can be even more so. The Columbus Zoo & Aquarium’s “Manatee
Coast” exhibit provides an excellent example of this innovative use of foam fractionation. The
design includes a significant emphasis on fractionation to control the enormous biomass
expected of manatees. A benefit in this engineering is that the resultant water quality allows the
successful exhibition of birds, fish and reptiles in the first closed seawater life support system
designed for manatees.

                                            RÉSUMÉ

    Les progrès récents réalisés dans la conception des systèmes de traitement de l’eau de mer
font que l’on y inclut de plus en plus fréquemment l’utilisation importante des écumeurs. Les
bénéfices qui en résultent pour la stabilité de l’environnement, et la qualité de l’eau à long terme
continuent d’être évalués. L’écumeur est capable d’enlever la matière organique dissoute ou en
suspension et permet donc de court-circuiter les effets néfastes de la décomposition de ces
matériaux dans les filtres à sable, ce qui peut sérieusement alléger la tâche des systèmes
d’épuration en ce qui concerne les déchêts organiques. L’utilisation d’un écumeur à grande
échelle, en conjonction avec de bons filtres mécaniques, biologiques, et chimiques, devient une
composante clef quand il s’agit de préparer avec succès un environnement pour diverses
espèces. Il est déjà difficile d’élever et de préserver une collection d’espèces diverses, mais le
traitement des eaux pour une telle collection peut être encore plus compliqué. L’exposition
“Manatee Coast” à l’Aquarium et Zoo de Columbus est un exemple excellent de cette utilisation
novatrice de l’écumeur à grande echelle. Le système met l’accent sur l’utilisation de l’écumeur
pour contrôler l’énorme bio-masse produite par les lamantins. Un des intérêts de cette méthode
est que la qualité de l’eau permet de mettre en place avec succès la présentation simultanée de
reptiles, oiseaux et poissons dans le premier circuit fermé d’eau de mer conçu pour des
lamantins.




Bulletin de l’Institut océanographique, Monaco, n° spécial 20, fascicule 1 (2001)
                                      INTRODUCTION

    When applied effectively, Foam Fractionation (FF), or Protein Skimming
(PS), provides continuous removal of organic contaminants from solution while
at the same time providing disinfections via coliform removal. This is achieved
via the processes of adsorption, coagulation and micro flocculation. With the
addition of relatively small doses of ozone, organics removal and disinfections
are enhanced. By including FF in the Life Support System (LSS) design,
significant benefits can be achieved. These include: increased pH, increased
dissolved oxygen concentration, increased redox potential, improved water
clarity, reduction in turnover rate and a reduction in the dependency of sand
filters and other traditional LSS components (Aiken, 2000).

    The Manatee Coast Exhibit at the Columbus Zoo emphasizes the use of FF to
control hi biomass loads expected by manatees, providing an innovative and
highly effective LSS. Disinfection is achieved strictly by means of FF; there is
no ozone contact chamber or chlorine injection on the system. Use of sand
filtration is greatly reduced as compared to marine mammal exhibits of equal
volume and bioload.


Manatee Coast Exhibit & Project information
   The Manatee Coast is a high biomass and a multi taxa exhibit.
Approximately 130 pounds (59 kg) of food is added each day to an exhibit of
roughly 200,000 gallons (757 m3). Total biomass in the exhibit is roughly 7,000
pounds (3.180 kg). The species list for the exhibit includes birds, fish, reptiles
and mammals and is shown in Table 1.


5.0. West Indian Manatees                        0.0.2 Kemp’s Ridley Sea Turtles
1.1.0 Ruddy Ducks                                1.2 Hooded Merganser
0.2.3 Cownose Rays                               0.0.100 White Mullet
0.50 Atlantic Spadefish                          0.0.36 Doctorfish
0.0.25 Porkfish                                  0.0.20 French Grunt
0.0.15 Beau Gregory                              0.0.24 Sargent Major
0.0.3 Redfin Needlefish                          0.0.10 Mojarra
0.0.100 Sail fin Mollies                         0.0.5 False Pilchards
0.0.3 Red Drum

                      Table 1: Species list for the Manatee Coast Exhibit



  The base criteria for the LSS design are shown in Table 2. Achieving water
quality standards for fish and elasmobranches was imperative.



Mixed Species Exhibit (see table 1)




Bulletin de l’Institut océanographique, Monaco, n° spécial 20, fascicule 1 (2001)
One Hour Turnover
Ozone Use as Microflocculant
Temperature: 75 °F (22 °C)
Salinity: 14 ppm
<100 Coliform Colony Count

                          Table 2: Manatee Coast LSS Design Criteria



   Tables 3 and 4 list the manufacturers of the major LSS components and the
project participants, respectively.


Drum Filter (Hydrotech)
Foam Fractionation w/Ozone (RKII)
Rapid Sand Filters (Neptune Benson)
5 Lb. Ozone generator (Osmonics)
Biological Filter Media (Brentwood)
Pumps (Fybroc)
Redox Controllers (Panel Builders, Inc.)

                            Table 3: Manatee Coast LSS Equipment



Participants
Architect: URS Greiner
Construction Manager: Ruscilli Construction
LSS Engineer: Syska & Hennesy, Inc.
Exhibitry Design & Fabrication: Cemrock
Mechanical Contractor: Sauer Inc.
LSS Consultant: David LaBonne

Facility
23,500 Square Feet or 2,200 Square Meters
200,000 gallons or 760 Cubic Meters
Project Budget: $ 10.3 million

                      Table 4: Project Participants and Facility Parameters



Sequence of Operation of LSS
   The sequence of operation is shown in Figure 1. All exhibit water first passes
through the Drum Filter. This is the first line of defense in filtering the impact of
manatee diet, approximately 120 pounds (54 kg) of lettuce/day. The discharge
from the drum filter all goes to a sump that provides positive supply for the main
system pumps. These pumps split the flow between sand filters and
fractionators. After leaving the sand filters and fractionators, water flows to the
biofilters and from there returns to the exhibit via gravity. There is also a side
stream sand filter on the sump of the biofilter tower. This is used to “super




Bulletin de l’Institut océanographique, Monaco, n° spécial 20, fascicule 1 (2001)
polish” the water before it returns to the exhibit. The turnover time is 60
minutes.

   There are a total of four 2.45m x 1.22m diameter sand filters in this 200,000
gallon system. Only three of these share “front-line” duty with the fractionators.
The fourth is used to “super polish” the water in the biotower before it returns to
the exhibit. This reduction in the number of sand filters is a direct result of the
benefits of foam fractionation when it is used effectively.


Emphasis on Foam Fractionation
   The presence of organic carbon (both dissolved and suspended) lowers the
value of D.O., pH and redox potential. Sand filters are limited in their ability to
eliminate or otherwise control organic carbon. By design, sand filters trap
material to improve water clarity. Organic carbon present in this trapped
material hydrolyzes and is released back into solution. Biofilms of heterotrophic
bacteria develop, utilizing the hydrolyzed carbon and give off CO2, lowering
system pH. (Hovanec, 1996) This affect is only partially diminished by
backwashing, since not all of the biofilm is purged during backwash. Depressed
pH, D.O. and redox potential characterize traditional LS systems that rely
primarily on sand filters. (LaBonne, 2001)
   Alternatively, FF provides continual removal of organic carbon (LaBonne
1998, Aiken 1997). By design, it pulls long-chained organic molecules out of
solution and flocculates this material into thick foam, which is continuously
discharged. Trapped within the sticky foam are particles, which include a
significant concentration of suspended organic carbon. Thus, the negative
effects of organic biodegradation of sand filters are short-circuited by aggressive
use of fractionation. Additionally, the loading on sand filters is reduced,
allowing them to perform more efficiently.


Disinfection
As previously stated, the Manatee Coast LSS relies heavily on fractionation to
achieve excellent water quality. A main function of the fractionators is
disinfection. Foam that is discharged from fractionators contains within it
suspended materials. Coliform bacteria, ranging in size from 0.4-0.6 µm x 2-
3µm (Quinn, 1994) is suspended in the water column and is easily trapped
within the sticky foam discharged from fractionators. Thus, disinfection is
achieved by coliform removal. With the addition of a relatively small dose of
ozone, coliform destruction is also achieved.

   Neither ozone contact chambers nor chlorine addition is used in the Manatee
Coast LSS. Because no chlorine is used in the Manatee Coast LSS, filamentous
algae and other organisms are allowed to compete for nutrients that would
otherwise be available for coliform growth. Thus, disinfection in the Manatee
Coast Exhibit is non-invasive and involves more natural processes than do most




Bulletin de l’Institut océanographique, Monaco, n° spécial 20, fascicule 1 (2001)
marine mammal LS systems. This approach to disinfection is only possible by
relying solely on effective use of FF coupled with efficient dosing of ozone.
Coliform counts for the first year at Manatee Coast are shown in figure 2.
During this time, coliform counts were not higher than 20 counts per 100mL. At
various times after the first year, ozone-generating equipment was off-line due
to mechanical problems. During these times of no ozone addition, coliform
counts still remained relatively low, peaking at 415 counts per 100 ml, and
having an average “no-ozone-addition colony count” of 135.5 per 100mL. This
shows the disinfection capacity of FF, even without the aid of ozone.


Control and efficient dosing of ozone
   The function of the ORP controller is to manage the dosing of ozone within
the fractionation process. A basic but very important component of the
controller is the ozone flow meter. It is sized for a range of flocculant doses that
match an expected range of bioloads. Although this is a very simple concept, the
accuracy of the flow meter size is paramount to the successful operation of the
fractionator. Placing protein skimming on an LSS has measurably less value
when chemical control technology such as this is not accurately specified.

   In a protein skimmer, the aim is to collect micro constituents and organics in
solution, and bring about their adsorption to bubble surfaces where they will be
carried out of the foam chimney. It is important to point out the very simple fact
that fractionators operate perfectly well with no ozone at all. Only a small
amount of ozone is necessary to enhance the processes of adsorption and micro
flocculation normally achieved in the air-water interface.

   When a high dose of ozone is applied in a fractionator, the processes of
adsorption and micro flocculation are inhibited. It is well known that high doses
of ozone tear apart organic molecules. Instead of enhancing micro flocculation,
the result is very poor foam production, and hence, poor removal of organic
materials. The irony is that it costs more money to produce diminished water
quality.


Comparison of 4 Manatee Exhibits in the US
    Table 5 compares and contrasts Manatee Coast to three other recently built
manatee exhibits in the United States. All four exhibits are in the range of
100,000 to 250,000 gallons (375-950 m3). Although Manatee Coast is of equal
or larger volume than the other exhibits, it has 40% less mechanical sand
filtration. Its turnover time is 60 minutes as compared to 40, 30 and 20
respectively on the others. It only uses 7 pounds of ozone specified as compared
to 20 to 30 pounds for the others. It is also the only marine manatee exhibit; the
others are all freshwater one. As previously stated, it is the only manatee exhibit
that does not use an ozone contact chamber or chlorine, but instead relies solely
on fractionation to achieve coliform removal and destruction. All of these




Bulletin de l’Institut océanographique, Monaco, n° spécial 20, fascicule 1 (2001)
achievements translate into huge cost savings and are examples of the kinds of
benefits that are available when protein skimmers are effectively applied.
Furthermore, the success of the Manatee Coast project signals a significant
departure from typical American Life Support design.


                                        Manatee Coast                       Others
Turnover Time                             60 Min.                         20-40 Min.
Ozone Required                             5 Lbs.                        20 to 30 Lbs.
Disinfection                            Fractionation               Ozone Contact Chambers
Water Type                                 Marine                         Freshwater

  Table 5: Comparison of Manatee Coast LSS or Three Other American Manatee LS systems



                                        REFERENCES

AIKEN A., ANDREW B.- Application and Benefits of Retrofitting Foam
  Fractionators to Existing Life Support Systems-. Proceedings of the 2000
  American Zoo and Aquarium Association National Conference. Orlando,
  Florida, USA.
AIKEN A., ANDREWS B.- Use of Foam Fractionation in Aquatic Exhibits: Its
  Impact and Importance to Successful Life Support Design-. Proceedings of
  the 1997 AZA National Conference. Albuquerque, New Mexico, USA.
HOVANEC, TIM A., Aug. 1996.- Comparative Analysis of Nitrifying Bacteria
  Associated with Freshwater and Marine Aquaria-. Applied and
  Environmental Microbiology.
LABONNE D.L., DAVID L., Spring 2001.- Aquarium Life Support System Design
  Entering the 21st Century-. Marine Technology Society Journal. Vol. 35, #1.
LABONNE D.L., DAVID L.- Today’s Innovations in Life Support Technology Set
  the Stage for the 21st Century-. Proceedings for the 1998 AZA Eastern
  Regional Conference. Boston, Massachusetts, USA.
QUINN, P.J., 1994.- Clinical Veterinary Microbiology. Wolfe Publishing.




Bulletin de l’Institut océanographique, Monaco, n° spécial 20, fascicule 1 (2001)
                                                                                      HIGH RATE SAND FILTERS (x3)
                                                     FRACTIONATORS (x3)
                            BIOFILTER
     EXHIBIT TANK                                                 HIGH RATE SAND FILTER (x1)




                                                PUMP




                                              DRUM FILTER                 PUMPS(x5)


                                  Figure 1. Manatee Coast LSS Schematic




Bulletin de l’Institut océanographique, Monaco, n° spécial 20, fascicule 1 (2001)
   date                                coliform                                date                          coliform                                      date      coliform
 30/06/99                                     2,6                            03/11/99                                0                                   09/03/00            0
 08/07/99                                     2,4                            10/11/99                                0                                   09/03/00            0
 13/07/99                                     2,4                            17/11/99                                0                                   15/03/00            0
 23/07/99                                    7,82                            24/11/99                                0                                   22/03/00            0
 28/07/99                                      31                            01/12/99                                0                                   29/03/00            0
 02/08/99                                     2,2                            08/12/99                                0                                   07/04/00            0
 10/08/99                                     7,3                            15/12/99                               19                                   12/04/00            0
 17/08/99                                    19,5                            23/12/99                                0                                   19/04/00            0
 23/08/99                                     4,9                            28/12/99                                0                                   26/04/00            0
 30/08/99                                    14,6                            05/01/00                               14                                   02/05/00            0
 09/09/99                                    14,6                            13/01/00                                0                                   10/05/00            0
 15/09/99                                    14,6                            20/01/00                                0                                   18/05/00            0
 21/09/99                                       5                            26/01/00                                0                                   24/05/00            0
 22/09/99                                       0                            02/02/00                               20                                   31/05/00            0
 06/10/99                                      12                            09/02/00                                0                                   07/06/00            0
 13/10/99                                       3                            16/02/00                                0                                   14/06/00            0
 20/10/99                                       2                            23/02/00                                0                                   21/06/00            0
 27/10/99                                       0                            01/03/00                                0                                   28/06/00            0




                                                                  Figure 2. M anatee Coast Coliform Counts
                                                                        First Year (30/6/00 - 28/6/01)


                      500
                      450
                      400
     MPN per 100 mL




                      350
                      300
                      250                                                                                                                                              coliform

                      200
                      150
                      100
                       50
                       0
                            30/06/99

                                         30/07/99

                                                    30/08/99

                                                               30/09/99

                                                                          30/10/99

                                                                                     30/11/99

                                                                                                  30/12/99

                                                                                                             30/01/00

                                                                                                                        29/02/00

                                                                                                                                   30/03/00

                                                                                                                                              30/04/00

                                                                                                                                                          30/05/00




                                                                                                Date




Bulletin de l’Institut océanographique, Monaco, n° spécial 20, fascicule 1 (2001)

				
DOCUMENT INFO
Shared By:
Categories:
Tags: Slide, foam
Stats:
views:64
posted:6/30/2010
language:French
pages:8
Description: Slide foam