Tanneries Wastewater Treatment by Coagulation and Reverse Osmosis

Leather production in tanning industries is mainly done by the addition of chromium sulfate [Cr2(SO4)3]. Effective hazards occur through the disposal of chromium sulfate solutions from tanning industries directly with their wastewater in the form of Cr+3. This research aims to find a sustainable process to conserve agriculture, human health, and aquatic environment from the interaction with water containing chromium by treating this wastewater. This research was done by the pH adjustment process, coagulation–flocculation process, filtration process, and reverse osmosis (RO) membranes for the production of purified water. The neutralization process was done using alkaline solution. The coagulation–flocculation process was applied by using FeSO4 and CaO. In the filtration and purification processes, the polypropylene filter, carbon block (CB) filter, the granular activated carbon (GAC) filter were gathered in the form of a pretreatment process. Reverse osmosis (RO) membrane gave impressive results in the removal of organic matters, dissolved solids and Cr+3. Heavy metals were measured using ICP-MS spectrophotometer. Surface morphology and elemental analysis of PP filter, CB filter, GAC filter, and RO membrane were monitored by using SEM and EDX microscope respectively. Zeta potential was measured in order to identify and determine the best pH situations to remove chromium from tanneries wastewater. By applying this treatment procedure on several tanneries wastewater samples. The effectiveness of removal of COD and BOD achieved 100%. Total dissolved solids were significantly decreased up to 99.93%. Cr+3 ions were remarkably captured up to 88.57%. Suggested tanneries wastewater treatment process revealed great treatment results in comparison with commercial processes.