Tannery liming drum wastewater treatment by natural coagulants from c. spinosa, p. granatum, eucalyptus spp. and v. vinifera

The tannery industry worldwide not only represents economic growth, but is also a source of contaminants that are polluting rivers and groundwaters. Highly turbid and foul-smelling wastewaters are commonly discharged from this industry and their treatment by physical or chemical means is usually expensive. The goal of this study was to treat highly contaminated tannery wastewaters using plant extracts. Polyaluminum chloride and natural coagulants from Caesalpinia spinosa, Punica granatum, Eucalyptus spp. and Vitis vinifera were examined in their effectiveness of turbidity removal of tannery liming drum wastewater. The addition of these coagulants decreased turbidity to 99.5% using polyaluminum chloride and up to 99.1% using natural coagulants. Among these plant extracts, P. granatum had the highest phenol index (20 mg.L-1) and its extract removed turbidity between 97 and 99% by applying doses among 7.0 - 11.7 g.L-1peelextracts and 0.001- 0.03 g.L-1 polyacrylamide into 500 mL of tannery liming drum wastewater. Final clarification was obtained with a hydrogen peroxide 5% solutionwhich oxidized color residuals from treated water.The present eco-friendly remediation process enabled a remotion of chemical oxygen demand by 99.8%. Alum treatment of tannery liming drum wastewater could be replaced by an efficient remediation process with plant extracts and hydrogen peroxide in benefit of the environment.