Analytical methods to determine oil and grease concentration and identify specific organic fractions in water and wastewater are reviewed. Important aspects of the development of these procedures are extraction technique, solvent type, and identification and quantification methods for the extracted material. The material presented will assist researchers and regulatory investigators in selecting appropriate analytical procedures and interpreting results.
Chlorination of various waste-waters as well as drinking water produces an abundance of nonvolatile halogenated organics. Many of these compounds are unsaturated and contain chlorine and oxygen atoms. Dechlorination with sodium sulfite prior to extraction changes the concentration of the halogenated organics. Certain types of halogenated compounds are reduced more than others. This observation implies that laboratory dechlorination should only be practiced if the compounds of interest (e.g., THM's) are unreactive with the added reducing agents. The potential use of dechlorination as a treatment for halogenated byproducts is explored.
trichloroethane (TCA) is more challenging than bioremediation of other chlorinated solvents, such as tetrachloroethene (PCE) and trichloroethene (TCE). TCA transformation often occurs under methanogenic and sulfate-reducing conditions and is mediated by Dehalobacter. The source area at the project site contains moderately permeable medium sand with a low hydraulic gradient and is approximately 0.5 acre. TCA contamination generally extended to 35 feet, with the highest concentrations at approximately 20 feet. The concentrations then decreased with depth; several wells contained 300 to 600 mg/L of TCA prior to bioremediation.The area of treatment also contained 2 to 30 mg/L of TCE from an upgradient source. Initial site groundwater conditions indicated minimal biotic dechlorination and the presence of up to 20 mg/L of nitrate and 90 mg/L of sulfate. Microcosm testing indicated that TCA dechlorination was inhibited by the site's relatively low pH (5 to 5.5) and high TCA concentration. After the pH was adjusted and TCA concentrations were reduced to less than 35 mg/L (by dilution with site water), dechlorination proceeded rapidly using whey (or slower with sodium lactate) as an electron donor. Throughout the remediation program, increased resistance to TCA inhibition (from 35 to 200 mg/L) was observed as the microbes adapted to the elevated TCA concentrations. The article presents the results of a full-scale enhanced anaerobic dechlorination recirculation system and the successful efforts to eliminate TCA-and pH-related inhibition. O
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