Advantages/Limitations of Solvent Extraction, Ozonation, and Carbon Adsorption for Reduction of Nonbiodegradable Residuals in METC Fixed-Bed Gasification Wastewaters. Final Report

摘要

This (second) year of effort examined the roll of solvent extraction, ozonation, and carbon adsorption for incorporation into the wastewater treatment scheme for purposes of enhancing process stability, decolorization, elimination of dilution water requirements, and minimization of nonbiodegradable residuals. This approach, while more costly, will better allow for direct discharge or reuse of gasification wastewaters. Di-isopropylether (DIPE) and methyl-isobutyl ketone (MIBK) were incorporated into a pretreatment step with free and fixed ammonia stripping followed by activated sludge treatment. Solvent extraction did not result in a decrease of nonbiodegradable residuals from the bioreactor, but did result in a highly stable operation of the bioreactors with no dilution water requirements and a minimal tendency for foaming and biodeflocculation. Ozonation of biofeed resulted in phenol being kinetically favored for oxidation. Ozonation of bioeffluents resulted in decolorization of wastewaters at low dosages, and first order kinetics in the reduction of nonbiodegradable TOC residuals. Steam stripping for ammonia removals, coupled with an understanding of anion/cation chemistry, led to a treatment system with minimization of salt additions. This is desirable if waste-waters are to be concentrated via evaporative techniques for partial reuse. Use of ozone followed by activated carbon further reduces nondegradable organics as may be desired for discharge or reuse purposes. (ERA citation 08:022925)