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CONCENTRATION AND TREATMENT OF DRINKING WATERS IN THE FOUR LAB STUDY
Citation:
PRESSMAN, J. G., T. F. SPETH, R. J. MILTNER, M. G. NAROTSKY, E. S. HUNTER, S. D. RICHARDSON, L. K. TEUSCHLER, G. E. RICE, AND J. E. SIMMONS. CONCENTRATION AND TREATMENT OF DRINKING WATERS IN THE FOUR LAB STUDY. Presented at Toxicology and Risk Assessment Conference, Cincinnati, OH, April 15, 2008.
Impact/Purpose:
to inform the public
Description:
The purpose of the four lab study was to address concerns related to potential health effects from exposure to complex mixtures of DBPs that cannot be addressed directly from toxicological studies of individual disinfection by-products (DBPs) or simple DBP mixtures. In order to achieve the overall project purpose, disinfection byproducts from a natural water source must be concentrated to accomplish the subsequent health effects studies. Therefore, the purpose of the research conducted in this investigation was to treat and concentrate the natural organic matter (NOM), which was then disinfected by chlorination to form highly complex mixtures of DBPs. A reverse osmosis membrane treatment technique was applied to concentrate NOM from natural water such that health effects testing could be accomplished. The selected water source was Ohio River water from a municipal drinking water utility. The treatment units were installed at the selected utility’s Water Treatment Plant (WTP). The raw settled water was fed to a ceramic ultrafiltration (UF) membrane process that removed turbidity, particles, bacteria, protozoa, and viruses. The ultrafiltration process was required as a pretreatment for the RO membranes. Following the UF process, the water flowed through an ion exchange (IEX) column charged with hydrogen form cation exchange resin. The IEX process removed cations such as calcium which cause fouling of the subsequent membrane system. Following the IEX process, water flowed to the reverse osmosis (RO) membrane system. Water and some small chemical constituents passed through the membrane (permeate), while the majority of chemical constituents in the feed water remained on the feed side of the membrane (concentrate). After the RO process, a batch barium precipitation process was used to remove sulfate in the solid form barium sulfate. The concentrate was then pumped through a cartridge filter to remove barium turbidity and pH adjusted to 6.8. Overall, 1724 liters of concentrated Ohio River water was prepared for the four lab study. Total organic carbon was concentrated from 2.34 mg/L to 318 mg/L for a concentration factor of 136x.