Laserfiche WebLink
<br /> M <br /> l!? <br /> '<;1l <br /> N <br /> c! <br />'~. C <br />:;.., <br /> <br />.:. <br /> <br />23 cycles of concentration to minimize blowdown, yet stay below the upper to- <br />tal dissolved I imit of 60,000 mg/I. The process controls calcium, magnesium, <br />silica and phosphate in the sldestream softener by precipitating calcium and' <br />magnesium from the circulating water feed with caustic and soda ash. The sof- <br />tener effluent Is control led to meet the operating limit of 600 mg/I calcium, <br />150 mg/I sil ica and less than 5 mg/I phosphate. A one mil I ion gallon surge <br />pond collects the sldestream flows from the cooling towers for transfer to the <br />softeners. The softened effluent is collected in another 1 mill ion gallon- <br />surge pond for neutral izatlon with acid and distribution back to the cooling <br />tower basins. The cool ing tower blowdown is used to regenerate the ion ex- <br />change resin with the spent regenerant desupersaturated from calcium sulfate <br />In two reactlvators operating in parallel. The reactlvator effluent Is trans- <br />ferred to the wastewater surge pond for further treatment. The calcium sul- <br />fate sludge is transferred to the evaporation ponds for disposal. <br /> <br /><~. <br />" <br /> <br />The ash system discharge, miscellaneous power block drainage, Ion exchange <br />waste effluent and condensate system regeneration waste are collected In a 7.5 <br />mill Ion gallon wastewater surge pond. Two 550 gpm vapor compression <br />evaporator units operating in parallel are used to concentrate the was- <br />tewaters. The average processing rate is 661 gpm, from which 617 gpm of dis- <br />tillate Is reclaimed for makeup to the condensate system first with any excess <br />available for the ash and FGD systems. The waste brine of 45 gpm Is dis- <br />charged to the evaporation ponds. <br /> <br />I,; <br /> <br />The ash and scrubber system makeup requirements are satislfied by a blend of <br />resIdual concentrator product and the Lower Virgin RIver water. Acid treat- <br />ment may be necessary to control the bicarbonate In the ash system makeup. <br /> <br />Non-recylable wastewater including the waste brine, regenerant sludge and <br />sldestream softener sludge Is discharged to 110 acres of evaporation ponds. <br /> <br />Option II-LV - SIde5tream Softening/VCF/Ev~poratlon Ponds <br /> <br /> <br />The process flow diagram and process flow and material balances for Option I I <br />are presented In FIgure 4-2 and Appendix C, respectively. <br /> <br />Lower Virgin River water for cooling tower makeup, at an average flow of 8,000 <br />gpm, Is delivered directly from the reservoir to the cool ing tower basins. <br />Sulfuric acid, scale inhibitor and chlorine are Injected for scale control and <br />control of microbloglcal activIty. <br /> <br />The sldestream softening system Includes a 5.5 mil lion gallon softener surge <br />pond that collects the average cool ing tower system sldestream flow of 4,200 <br />gpm and feeds two 6,000 gpm softeners operating In paral lei. A 5.5 mill ion <br />gallon neutralization pond collects softener effluent for proportional dis- <br />tribution back to the cooling towers. The cooling towers are operated at 20 <br />cycles of concentraton based on a silica I imit of 150 mg/I and a calcium limit <br />of 600 mg/I. The circulating water TDS Is 52,000 mg/I and Is high in <br />chlorides at 8,000 mg/I. The sldestream softener effluent Is controlled at <br />100 mg/I calcium, 0.5 mg/I phosphate and 95 mg/I silIca through the addition <br />of 85% lime and 98% soda ash. CIrculating water alkalinity Is control led by <br />sulfuric acid. <br /> <br />4-15 <br /> <br />.:, -.ro'.--.' ....' _,."".____~_._____,___.__. ____ <br />