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<br />~ <br />en <br />~ <br />OJ <br /> <br />Adsorption is not as established a ?rocedure as solvent extrac~ion and <br /> <br />the following remarks, based on a few designs of cur own, are tanative. <br /> <br /> <br />1) The cost of solvent extraction is highly dependent on effluent quality, <br /> <br />but the cost of adsorption is essentially independent of fractional removal. <br /> <br />Therefore. it is best to design for over 99' removal. <br /> <br />2) It is probable, but not proved, that for ~he same percent removal of <br /> <br />phenol, adsorption gives a higher removal of COO than solvent extraction. <br /> <br />3) The cost of adsorption is lower when ~~e influent phenol concentration <br /> <br />is lower, but the cost of extraction is not dependent en influent concen~ration. <br /> <br />Adsorption is a suitable procedure for ~~proving the water quality beyond <br /> <br />t~e minimum needed for feed to cooling tower. A study has been made en the <br /> <br />exemplarj turgi plant effluent, assuming 80% p~enol removal by solvent extrac- <br /> <br />tion, follcwed by as high a ~~oval as can be obtained in practice by acscr?ticn. <br /> <br />The teed to adsorption is 1,200 mg phenol/l at 2,000 gal/min. The design <br /> <br />effluent from adsorption is 12 mg phenol/l 199\ removal) but this is oeaningless <br /> <br />in fact because we do net ~,ow what will really =e adsorbed~ <br /> <br />The ~otal c~p~tal <br />.6. <br />adsorpt~on ~s <br /> <br />S3.75/103 <br /> <br />cost 0: phenol removal by ccmbined solvent extraction and resin <br />6 6 <br />about SlO x 10. The total o?erating cost is S3.92 x 10 /yr or <br /> <br />gals.,6 If credit is t~~en for phenol =ecQvery, the net operati~g cost is <br />6 <br />Sl.80/1000 gals, or 2.2~/10 Btu, which is about $0.70/1000 gals lower than <br /> <br />either solvent extraction or resin adsorption alone. <br />2.8 Cuantities, Qualities and Dis~osal 0= Cooling Tower 31o~co.Nn <br />In the preceding ~~O sections ~e have shown that a cooling to~er can accept <br />~ater that is importantly more contaminated than would be pe~issible for <br />discharge to a river. For this reason foul concensate water leaving the process <br />will be treated, using the methods discussed, to a quality required for makeup <br />to the cooling system, and not to a quality required for return to the river. <br />The consequence of this flow path, however, is that coclir.g tc~er blowcown <br />becomes the principal discharge peint for the whole plant and ~~e water will <br />contain, i~ addition to the usual somewhat concentrated salts, residues of <br />organic matter originating in the coal reactor. Disposal of cooling system <br />blowdown is not as straightfor~ard as, for example, in electric generating ~lants. <br />It is this prOblem which is faced in this section. <br /> <br />" <br />'J <br />