Fate of Heavy Metals in Sewage and Polluted Water Bodies

There is a major knowledge gap and a multifarious problem involving metal chemistry, physical interac-tions of metals, microbiology, aerobic and anaerobic processes in understanding the precipitation of heavy metals in sewage and polluted water bodies. This study focuses on determining the most feasible metal-salt that can be formed using standard Gibbs free energy change for each possible reaction of all the heavy metals in wastewater. Solubility limits of all possible metal salts are computed. It is shown that even in the short anaerobic stage, any heavy metal will have the propensity to precipitate as sulphides and form insoluble salts, thus rendering the wastewater free from heavy metals. The measured heavy metal concentration in treated wastewater from Bangalore’s K–C Valley and Bellandur sewage treatment plants is presented as a validation of the theory.