Laserfiche WebLink
4.6 Filter Cake from Metal Finishing Pretreatment Facility <br />Input Materials: <br />Non -hazardous <br />wastdwater from metal <br />plating operations, <br />spent cleaning and <br />plating baths (Category <br />A Hazardous Waste) <br />Treatment including: <br />pH adjustment, Filter Cake <br />precipitation, coagulation, from MFPF <br />solid separation, filtration, (CWC 18 1) <br />and drying <br />Discharge of Off-site <br />treated water disposal <br />to POTW <br />11C3UI�• .Ui.4.G. RII�1SE WATER TREATMENT PROCESS AND WASTE GENERATION FLOW <br />DIAGRAM <br />Hazardous Waste and Process Description <br />The major generator of this waste stream at SLAC is the Metal Finishing Operation Group <br />(1VaF'O) in the Mechanical Fabrication Department (MFD), which performs plating of carbon <br />steel, stainless steel, copper and aluminum parts. The various baths clean parts and plate <br />them with metal such as .nickel, copper, tin, rhodium, indium, silver and gold. <br />Non -hazardous rinse water is generated by using tap or de -ionized water to rinse residual <br />plating solutions from parts being plated. The non -hazardous rinse water and spent plating <br />baths (Category A wastes — acids and alkaline with metals but not cyanide baths) are treated <br />at the Metal Finishing Pretreatment Facility (MFPF), which allows SLAC to meet the <br />sanitary sewer discharge requirements to the local POTW authorized under the Clean Water <br />Act. The quantity of the filter cake will in part fluctuate from year to year based on the <br />quantities of Category A wastes - alkaline cleaners (CWC 12 1) and spent acids (CWC 792) <br />treated. Since these baths are more concentrated than the rinse water, these waste streams <br />can generate a higher quantity of filter cake and thus raise the ratio of the pounds of filter <br />cake to gallons of rinse water treated. Other variations in this ratio are not easily accounted <br />for; however, overall there is a trend toward decreasing this ratio that is discussed later in this <br />section. <br />The treatment process includes pH adjustment, precipitation, coagulation, soli <br />d separation, <br />filtration and dx}►ing processes to remove metals and adjust the pH of the water before <br />discharge. As a result of the process, a filter cake is generated, which is subsequently sent <br />off-site for disposal to a permitted treatment, storage and disposal facility. <br />Because the filter cake from Category A aqueous hazardous waste treatment and fr <br />om non- <br />hazardous rinse water treatment are not segregated, some double -counting of filter cake <br />September 1, 2015 SB14 Plan III -13 <br />