Environmental characterization of Hygas pilot plant water streams

The composition of wastewaters from the 3 ton/hr coal pilot plant using the Institute of Gas Technology Hygas process includes soluble components (total dissolved solids, total organic carbon, and chloride, thiocyanate, and sulfide ions) in the quench and cyclone slurry waters during operation on lignite and bituminous and subbituminous coals; the ammonia and phenol found in the product gas quench and cyclone slurry waters; and the phenolic compounds found in four wastewater streams during tests on Illinois No. 6 bituminous coal. Biological oxidation performance factors and water characteristics have been determined for Hygas condensate and cyclone slurries. These process wastewaters, after reductions in alkalinity and ammonia concentration can apparently be successfully treated via the activated sludge process at mean cell residence times of 10-40 days. At high aqueous concentrations, phenol recovery as a by-product may be economically attractive.