Studies on Recovery of Chromium Form Tannery Wastewater by 29 Studies on Recovery of Chromium from Tannery Wastewater by Reverse Osmosis

Chromium (Cr) is the most important element used to leather industry is still considered to be the most important industries which pollute the environment by chromium metal. Removal of heavy metals dissolved at low concentrations in water and wastewaters is often a problem that can be solved in different ways. This paper describes a study conducted to determine the recovery of chromium from tannery wastewater by reverse osmosis. The effluent is first subjected to the gravity settling, followed by alum treatment. The supernatant is then treated with the subsequent reverse osmosis after a coarse filtration by a fine cloth. The coagulant is determined by adding 0.5 to 2.5 g/L alum to the effluent and measuring BOD, COD, TDS, TSS and pH, at the different dose of alum. Therefore, 1.5 g/L is considered as the optimum alum dose. Spiral wound module with thin film composite membrane is used in this experiment. Coagulated water is treated by RO at various pressures (100, 120 and 150 psi). The best treatment efficiency was obtained at 150 psi. Initial Cr concentration in feed waster is 14.2 mg/L. The Cr removal efficiency of treatment by RO is 98.66 % at pH range of5.6 to 7 and in temperature of about 25oC at an applied pressure of 150 psi. It could be concluded that RO membrane process may be selected and developed as an effective alternative for treatment of metal contaminated effluents of leather and similar industries.