Towards a sludgeless heavy metal finishing industry for a cleaner environment

Abstract

The treatment of heavy metals is based primarily on chemical coagulation and precipitation where substantial amounts of toxic sludge are normally generated. A study using an electrolytic processes has been carried out to recover heavy metals from a mixed plating bath in a metal finishing factory. The unit uses a RETEC system consisting of a high surface area cell based on a simple theory of electrolysis and produces a very large surface area about 10-15 times the geometrical surface area of the cathode. This paper presents cases where 95% tin, lead, and 98% copper, nickel, and zinc were successfully recovered, and discusses economic considerations.

Electrolytic recovery of dilute copper from a mixed industrial effluent of high strength COD

“…In view of the measures exposed above, electrolytic treatment is a promising process that has been investigated as an alternative to treat wastewaters since the early 1960s [3] without producing or with minimum quantities of sludge [4] permitting the recovery of metal along with the oxidation of organic contaminants in solution with minimum consumption of chemicals. This method has been successfully tested with various industrial wastewaters such as metal plating industries [5] in the detoxification of wastewater containing cyanides [6][7][8], phenols [9][10][11][12], wastewater from dye production [13,14], tannery [15,16] and others [17][18][19].…”

Copper recovery and cyanide oxidation by electrowinning from a spent copper-cyanide electroplating electrolyte

“…Considering the measures exposed above, electrolytic treatment comes out with an alternative process to treat wastewaters without producing, or producing minimum quantities of sludge [6], permitting the recovery of copper along with the oxidation of most of the cyanide in solution without using a considerable amount of toxic chemicals. The main cathodic and anodic reactions in an electrolytic cell for a copper-cyanide stream can be represented by reactions (5)- (8) and (9) and (10), respectively.…”