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This research determined the removal and fate of 11 selected RCRA compounds in a pilot‐scale activated sludge system with a 4‐day SRT and 7.5‐hour HRT. Screened and degritted raw wastewater from a Cincinnati, OH, wastewater treatment plant was used for this study at the U.S. EPA's Test and Evaluation (T&E) Facility. A continuous feed of spike toxic cocktail of 0.25 mg/L each of acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, carbon tetrachloride, 1,1,1‐trichloroethane, 1,1,2‐trichloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, and ethylbenzene was used to produce an acclimated biomass. The test was run for 7 weeks. Volatilization losses in primary sedimentation exceeded 10% for carbon tetrachloride, 1,1,1‐trichloroethane, 1,1,2‐trichloroethane, and tetrachloroethylene. Sorption of the 11 compounds to primary and secondary sludge ranged from 0.6 to 5.1%. Nine of the 11 test compounds were removed >94% with estimated biodegradation ranging from 0 to 93.4%.

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The research objective was to develop a correlation between bioavailable cadmium (Cd) and toxicity in anaerobic systems. Toxicity assays were performed with acetate-using methanogens in serum bottles. The bioavailable. free dissolved Cd was measured at the end of the experiments after separation in cation-exchange resin inside dialysis bags placed in the cadmium-spiked serum bottle samples at the end of the experiments. Measured free soluble Cd showed a good correlation with inhibition of gas production. Up to 0.09 mgjL caused~5% inhibition, whereas concentrations of 0.12 mg/L and higher showed >90% inhibition. Measured total soluble cadmium failed to show a good correlation with inhibition of gas production. Systems with total suspended solids (TSS) exceeding 2 400 mgjL showed less inhibition than systems with TSS of approximately ) 400 mgjL. However, when bioavailable Cd was less than 0.09 mg/L, systems with the lower TSS showed little inhibition even with spiked Cd concentrations as high as 100 mgjL.