28 Enhanced metal removal from wastewatery by coagulant addition

摘要

Besides metallurgical industries, metal-containing wastewaters are generated in the manufacturing/processing of batteries, petroleum, photographic materials, paints, inks, leather, and wood. The heavy metals of concern are cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), nickel (Ni), solver (Ag), and zinc (Zn). The volume of metal-laden sludges, wastewaters, and treatment residues generated in 1984 was about 5.8 billion gallons~1. A large number of pulbicly owned treatment works (POTWs) also accept metal-containing wastewater from industries.~2 The toxic nature of the heavy metals has resulted in the promulgation of standards requiring very low concentration of metals in the treated effluent. To comply with the strict regulatory requirements, it is necessary to treat the wastewater (both industrial and municipal) before discharging them into natural water bodies.