Removal of cyanide from synthetic wastewater by combined coagulation and advanced oxidation process

Abstract

Cyanide is a toxic contaminant which exists in some industrial wastewaters. This substance is considered a serious threat, causing adverse effects on the environment and human health. The current study investigated the efficiency of the combined coagulation/advanced oxidation process (C/AOP) in the removal of cyanide from wastewater. The effect of this process was examined through the investigation of changes in pH, contact time, initial cyanide concentration, poly-aluminum-silicate-chloride (PASIC) dose, current intensity, and H2 O2 concentration, and the optimal conditions were obtained. Data analysis was performed with SPSS 17. Through usage of the combination of PASIC as coagulant and the sono electro fenton process, 94% of cyanide was removed. The maximum removal percentage of cyanide in the coagulation process with PASIC was observed at the dose of 1.2 mg L–1, retention time of 60 min, and pH = 6.5. In the combined C/AOP, the maximum removal percentage was obtained at the concentration of H2 O2 = 2,500 mg L–1, contact time of 60 min, pH = 3.5, and current intensity of 10 mA cm–2. Cyanide removal by the combined process of coagulation and advanced oxidation can be considered efficient in the treatment of water and wastewater.