WASHING PROCESS WITH WASTE WATER RECYCLING

摘要

A process for washing fat- or dye-soiled materials involving: (a) providing a fat- or dye-soiled material; (b) providing an aqueous detergent-containing liquor; (c) contacting the fat- or dye-soiled material with the aqueous detergent-containing liquor, thus forming a washed material and wash wastewater; (d) providing a source of rinse water; (e) rinsing the washed material with the rinse water, at least once, thus forming rinsed material and rinse wastewater; (f) collecting both the wash and rinse wastewater; (g) chemically pretreating the collected wash and rinse wastewater by contacting it with a compound selected from the group consisting of a demulsifier, an oxidizing agent and mixtures thereof to form waste particles; (h) mechanically removing the waste particles from the collected wash and rinse wastewater by flotation or sedimentation to form prepurified wash and rinse wastewaters; (i) biologically treating the prepurified wash and rinse wastewater by introducing it into a fixed-bed reactor containing activated sludge to form a mixture of treated wastewater and sludge; (j) separating them treated wastewater from the sludge; and (k) recirculating the treated wastewater back into the aqueous detergent- containing liquor, the rinse water, or both.