Biological Removal of Organic Constituents in Quench Waters from High-Btu Coal-Gasification Pilot Plants

摘要

Studies were initiated to assess the efficiency of bench-scale, activated-sludge treatment for removal of organic constituents from coal-gasification process effluents. Samples of pilot-plant, raw-gas quench waters were obtained from the HYGAS process of the Institute of Gas Technology and from the slagging, fixed-bed (SFB) process of the Grand Forks Energy Technology Center. The types of coal employed were Bituminous Illinois No. 6 for the HYGAS and Indian Head lignite for the SFB process. These pilot-plant quench waters, while not strictly representative of commercial condensates, were considered useful to evaluate the efficiency of biological oxidation for the removal of organics. Biological-reactor influent and effluent samples were extracted using a methylene chloride pH-fractionation method into acid, base, and neutral fractions, which were analyzed by capillary-column gas-chromatography/mass-spectrometry. Influent acid fractions of both HYGAS and SFB condensates showed that nearly 99% of extractable and chromatographable organic material comprised phenol and alkylated phenols. Activated-sludge treatment removed these compounds almost completely. Removal efficiency of base-fraction organics was generally good, except for certain alkylated pyridines. Removal of neutral-fraction organics was also good, except for certain alkylated benzenes, certain polycyclic aromatic hydrocarbons, and certain cycloalkanes and cycloalkenes, especially at low influent concentrations. (ERA citation 05:019985)