Treatment of silver (Ag) containing effluents using electrodialysis

Abstract

Electrodialytic recovery of Ag+ ions from industrial effluents (basically photographic effluent.s~ was.",) investigated with the aim of reclaiming and recycling of the metal Ag, mainly considering the fact that Ag being a very valuable metal and also a toxic heavy metal. Eco-toxicity of this kind of metal elements is well recognized and supposed to be due to their bio concentration and bioaccumulation nature associated with various food chains. On the other hand, in a highly competitive market and environmental conscious society, it is very important to recover these metals in more economically and environmentally sound means, than the conventional approach of disposing these effluents into common sewage lines with or without metal recovery using old electrolysis techniques. A recent study carried out in the Rathmalana- Moratuwa area, revealed that, a significant amount of ground water wells situated in this area are polluted with Ag and other heavy metals, beyond the normal acceptable levels. (Heavy metal levels of groundwater in Ratmalana-Moratuwa industrial area, A comprehensive survey carried out in 2002 by Dayani Gunawardana ). Thus the necessity of a cleaner, greener and economically viable local technology for the treatment of metal contaminated wastewaters is crucial at the moment, when comparing with conventional, inefficient and less economical treatment options