Biological treatment to remove contaminants from drinking water is an emerging technology in the United States. EOSi has demonstrated the effectiveness of biological treatment using MicroC® to remove nitrate and perchlorate from drinking water.
Nitrate in drinking water is a particular concern in agricultural areas where groundwater wells are the primary source of drinking water. USEPA has set an MCL for nitrate of 10 mg/L as nitrate. Perchlorate is an emerging drinking water concern. USEPA has not set an MCL yet, but some states have started regulating perchlorate levels in drinking water. California and Massachusetts have set MCLs of 6 and 2 μg/L, respectively, and California is considering lowering its MCL.
Historically, nitrate and perchlorate have been removed from drinking water using physical/chemical treatment processes such as ion exchange or reverse osmosis. Although effective, these processes produce waste brines that are difficult and expensive to manage, especially when treating water with high concentrations of contaminants. Biological treatment has the advantage of converting nitrate and perchlorate into harmless compounds, and is often less expensive.
The water industry’s extensive experience using biological treatment for wastewater is readily transferable to drinking water. As in wastewater treatment systems, bacteria reduce nitrate to nitrogen gas and perchlorate to chloride ions under anoxic conditions. Instead of the activated sludge systems common in wastewater treatment, drinking water treatment typically uses fixed bed, fluidized bed, or membrane bioreactors. Unlike most wastewaters, drinking water sources do not contain readily biodegradable organic compounds that will support microbial growth. In addition, drinking water treatment requires post-treatment to produce a final product with acceptable turbidity, taste, and odor.
How EOSi can help
To create the necessary anoxic conditions, a supplemental carbon source such as MicroC® must be added in sufficient amounts to support bacterial growth that depletes the dissolved oxygen. Additional MicroC® is then needed to serve as an electron donor in the microbial processes of denitrification and perchlorate biodegradation.
EOSi’s MicroC® 4000 is NSF/ANSI 60 certified for drinking water applications. MicroC®4000 can be custom-formulated to provide any necessary microbial nutrients, such as phosphorus, that may not be present in sufficient amounts in the drinking water source. EOSi provides services such as bench-scale analyses, modeling and simulations, and equipment selection and procurement for water treatment plants evaluating using biological treatment for drinking water.