Utilization of heavy metals from sludge and waste

Sustainable production through innovation. Waste-free recycling. Technology prepared by a Polish consists of an innovative way to recycle all the protein-rich waste containing heavy metals. It includes selective removal of all contaminants and transforming them into products.

Bacterial biomass from municipal sewage sludge and hydrolysed protein from a sloughterhouse sewage sludge, after a thorough purification are key ingredients of a series of mixed organic/mineral fertilising compositions. Together they form slow-release products, which prevent eutrophication of midland water reservoirs and provide soil with N, P and K bound to organic matter. Highly polluted wastewater bound to tannery sludge as a hydrating shell undergoes purification to the extent, which allows either a legal discharge into surface waters or a direct use to prepare solutions applied in the technological cycle.

Liquid/liquid extraction process employing phase-transfer catalyst is used here. It removes simultaneously metallic species together with excessive chlorides, replacing all of them by sulphates, hence this is the only method, which can reduce quickly high salinity of effluents. All the inorganic salts, removed or recovered, become commercial products after purification.

Article and image from Spin Project