Frontiers of Engineering Reports on Leading-Edge Engineering from the 2007 Symposium (2008) / Chapter Skim
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Biological Treatments of Drinking Water--Jess C. Brown
Biological Treatments of Drinking Water--Jess C. Brown
Pages 135-146
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From page 135... ...
Phoenix, Arizona Microbial biomass has been used since the early 1900s to degrade contaminants, nutrients, and organics in wastewater. Until recently, the biological treatment of drinking water was limited, particularly in the United States, but recent developments may mean that biological drinking water treatment may become more feasible and more likely to be accepted by the public.
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From page 136... ...
Electron transfer in the overall reactions can be observed only by evaluating the oxidation states of individual atoms. Biological drinking water treatment processes are based on the growth of bacterial communities capable of mediating oxidation-reduction reactions involving at least one target contaminant (Figure 1)
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From page 137... ...
Contaminated water is pumped up-flow through the reactor at a high rate to fluidize the granular media bed and reduce resistance to flow. Typically, the fluidization rate is controlled to maintain a 25 to 30 percent bed expansion over the resting bed height.
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From page 138... ...
• Ammonia • Biological oxidation of ammonia to nitrate provides an alternative to chemically intensive break-point chlorination. • Iron • Biological oxidation of soluble species • Manganese (Fe2+, Mn2+)
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From page 139... ...
In one approach, ultrafiltration membranes are submerged in a reactor basin that contains suspended biomass. The reactor basin provides the detention time necessary to achieve effective biological treatment.
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From page 140... ...
Ion-Exchange Membrane Systems Yet another MBR method involves a reactor with two treatment chambers separated by an ion-exchange membrane. One chamber contains suspended biomass plus nutrients; the other chamber contains raw water.
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From page 141... ...
Commercial Models Available commercial models can be tailored to a specific treatment application and process configuration. Typically calibrated using results from benchand/or pilot-scale testing, these models can simulate steady-state or dynamic conditions and account for hydraulic-flow regimes from plug-flow to complete mixing.
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From page 142... ...
Using a targeted nutrient medium in conjunction with specific incubation conditions, pure cultures can be isolated from the mixed community of bacteria comprising a bioreactor. An enrichment of each pure culture can then be tested to identify optimal environmental conditions for that classification of bacteria.
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From page 143... ...
On the contrary, they can often provide an alternative to conventional processes that has several potential advantages: • low operating costs • high water-recovery rates • destruction, rather than sequestration or concentration, of contaminants • simultaneous removal of multiple contaminants • minimal sludge production • no hazardous waste streams • minimal or no added chemicals • robustness over a wide range of operating conditions and water qualities Overall, biological drinking water treatment is highly efficient and environmentally sustainable. As green water treatment philosophies gain traction and as regulatory and residuals-handling constraints continue to tighten, the use of biological drinking water treatment technologies and processes will likely continue to expand around the globe.
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From page 144... ...
system to remove perchlorate from drink ing waters. Paper presented at Perchlorate Treatment Technology Workshop, 5th Annual Joint Services Pollution Prevention and Hazardous Waste Management Conference and Exhibition, San Antonio, Texas, August 21-24.
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From page 145... ...
BIOLOGICAL TREATMENTS OF DRINKING WATER 145 ADDITIONAL READING Rittmann, B
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