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Attachment C Page 8 of 8 <br /> SIGMA CIRCUITS Inc . , STOCKTON DIVISION <br /> FIELD SITE <br /> TREATMENT UNIT OPERATION <br /> UNIT 2 (Continued ) <br /> Process : <br /> A) Spent stripper is pumped from the process to the BTT and <br /> may be blended with spent equipment cleaner . Other <br /> concentrated metal -bearing wastes are also pumped to <br /> this BTT for treatment . <br /> B ) The stripper (or stripper/equipment cleaner blend ) is <br /> treated by lowering the pH to about 8. 5 by addition of a <br /> sulfuric acid-based chemical mixture while the solution <br /> is being mixed . This process precipitates the resist and <br /> some of the metals . Metal precipitant and coagulant are <br /> also added to further precipitate the dissolved metals <br /> out of solution . <br /> After thorough mixing , the sludge is then allowed to <br /> digest and settle in this tank . <br /> C ) After an appropriate settling time , the sludge is pumped <br /> through the filter press and the filtrate from the press <br /> is pumped through the CWTS and processed as described in <br /> the Unit 1 Process Description . <br /> D ) After each sludge run , as with the CWTS sludge , the <br /> filter press is opened up and the sludge scraped off the <br /> plates into the bin . The contents of this collection bin <br /> are then transferred directly to reusable plastic bins <br /> for shipment offsite . <br /> E ) Other metal -bearing wastes are also treated in the BTT <br /> by various waste treatment processes . The sludge and <br /> filtrate from the press are monitored , sampled , analyzed , <br /> and handled in the same manner as with spent stripper . <br />