Biofouling of microfilters at the Savannah River Site F/H-area effluent treatment facility

The F/H-Effluent Treatment Facility uses state-of-the-art water treatment processes to remove contaminants from low-level radioactive wastewater at the Savannah River Site, The plant replaces seepage basins that were closed to comply with the 1984 amendments to the Resource Conservation and Recovery Act (RCRA). The facility removes both radioactive and nonradioactive contaminants from the effluents originating from onsite waste management facilities. The unit processes involve filtration, ion exchange, activated carbon absorption, and reverse osmosis. The filtration step is prone to considerable fouling, reducing the overall throughput of the facility. The Filters utilized in the process are Norton Ceraflo ceramic microfilters. It was discovered that bacteria were primarily responsible for the severe filter fouling. Inorganic fouling was also observed, but was not normally as severe as the bacterial fouling. The bacteria densities necessary to induce severe fouling were not significantly higher than those often found in surface water streams. Diversion of waste streams containing the highest quantity of bacteria, and various methods of source reduction were implemented, which dramatically unproved the filter performance. Addition of aluminum nitrate at low pH further improved the filter performance. (author)