Laserfiche WebLink
<br />,..,." <br /> <br />OJ <br />~ <br />-..I <br /> <br />For the added cost of about 8oe/looO gals, we can hope to change the <br />effluent from a solvent extraction trea~~ent from approximately the analyses <br />of Tables 2-7 and 2-8 to about 50-100 mg/l BOD and 10-20 mg/l phenol. It must <br />be remembered that, in a cooling tower, we concentrate the phenol and BOD. but <br />also destroy about 50\ of the feed BOD and 98\ of the feed phenol. ~hether or <br />not a biological treatment is worthwhile after a solvent extraction will be <br />discussed laeer. <br /> <br />Adsorption <br />If adsorption is usee, the wastewater is passed through a resin which <br />adsorbs ~~e phenol_ Such a resin is expensive. The 2,000 gpm Lurgi wastewater <br />6 <br />stream would ~equire dual train resi~ bees costing about $4~8 x 10 ; of this, <br />$l.B x 106 is for the i~strumented vessel bed, and $3.0 x 106 is for the resin <br />which has an expected lifetL~e of five years6 Capital amortization and resin <br />3 6 <br />replacement costs amount to about $1.70 per 10 gals treated The resin has <br />to be regenerated--about every eight hou:s in ~~e example quoted. The cost of <br /> <br />regeneration is dependent on the <br /> <br />solvent regene=ant costs. In the turgi <br />3 <br />resi~ will hold 5 lb phenol/it and <br /> <br />plant <br /> <br />example, with 6,000 mgll phenol, the <br />require 1.5 :t3 resin to ~egenerate. <br /> <br />will <br /> <br />The solvent will be distilled frcm the <br /> <br />phenol, as for solvent extraction. The distillation ener~J for rne~'anol, <br />assuming 80\ re:l'~ in the still, is about <br /> <br />470 Btu x 80 1b solvent x 50 Ib phenol <br />1.8 x 1b solvent 5 lb phenol 1000 gals <br /> <br />= 0.7 x 106 Btu/1000 gals <br /> <br />At 53/106 8tu, this is $2.0/1000 gals. Solvent losses (1\) amount to a further <br /> <br /> <br />$0.6/1000 gals. If acetone is used as solvent, energy costs are halved, but <br /> <br />the cast of lost solvent nearly trebled~ to give the same cost for solvent <br /> <br />costs for resin adsorption will again not be less than <br /> <br />regeneration. Total <br />6 <br />$4.50/1000 gals., <br /> <br />net operating <br /> <br />!f credit is taken for phenol recovery, the <br />6 <br />cost will be about $2.50/1000 gals or 3~/10 Btu product output. <br /> <br />For our particular Lurgi plant examples (2,000 gpm at 6,000 mg phenol/l) <br /> <br />the cost of solvent extraction is similar to that of <br /> <br />resin adsorption. The <br />25 <br />Braun on a different <br /> <br />phenol is recovered in bo~~ cases. ~ study by C. F. <br /> <br />water stream (1,000 gpm at 15,800 mg phenol/l) found solvent extraction cheaper <br /> <br />t~an adsorption. ~o absolute costs are given, only the difference. <br /> <br />42 <br />