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<br />..... <br /> <br />c:n <br />~ <br />c<) <br /> <br />Since then, good measu~ements <br />22,23 <br />Wastewater and an H-Coal <br /> <br />of the biokinetics have been made on a Synthane <br />21 <br />wastewater . We find that the aeration basins <br /> <br />needed are four to eight times larger than would have been predicted from the <br />kinetics of coke oven liquoro. The high purity oxygen activated sludge plants <br />will also have to be about two times larger than previously thought and the <br />o~igen consumption estimate is higher. <br />The cost of biological oxidation is in the range of 10-20c/lb aOD removed, <br />with the high cost corresponding to air activated sludge and the lower cost <br />6 <br />correspnnding to oxygen activated sludge A cost of 15c/lb BOD removed can be <br /> <br />conver~ed to give: <br /> <br />BOD Removed <br />(mq/ll <br /> <br />20,000 <br /> <br />15,000 <br /> <br />10 , 000 <br /> <br />5,000 <br /> <br />$/1000 Gallons <br />25 <br />19 <br />12 <br />6 <br /> <br />In considering solvent extraction, we mentioned that ~~e cos~, for large <br />throughputs, is not much dependent on the concentration of phe~ol, but that <br />credi~ for ?henol recovered is proportional to the concentration. T~is means <br />that solvent extraction is preferred at high concentrations and biological <br />oxidation at low concentrations. The cost curves cress in the apprQxi~ate <br />range of 2000 mg phenol/l and 6,000-10,000 mg BOO/l. Throughput also matters, <br />but for large gasification plants, we can expect to have wastewater streams <br />for which solvent ex~=action appears preferrable to biological oxidation for <br />gross =emcval of contaminants. We must, therefore, consider the cost of <br />biological treatment ~hen it is used to follow a solvent extraction treatnent <br />for the purpose of improving the quality of the water effluent from solvent <br />extraction. <br /> <br />For low concentrations, below about 2,000 mg BOO/l, the rate of removal <br />of BOD is not a good correlator of cost. The best expression is $/1000 gals. <br />24 <br />For municipal plants, Cuip, Wesner and Culp have reported 20c/1000 gals for <br />operating costs plus capital costs which we esti~ate as 20-30c/1000 gals. We <br />use industrial, not municipal, costs of capital. This ~as in 1974 with an EPA <br />index of 200. Today the EPA index is about 300, so total costs are in the <br /> <br />range 60-80c/l000 gals. We have designed and estimated <br /> <br />biotreatment and agree with a cost of 80c/1000 gals, or <br /> <br />some second stages <br />C <br />10/10 Btu product <br /> <br />for <br /> <br />OU::'PU1:. <br /> <br />H <br />