Optimization of coagulation-flocculation process for treatment of industrial textile wastewater using okra (A. esculentus) mucilage as natural coagulant

The use of natural coagulant in coagulation/flocculation treatment (CF) of wastewater shows many advantages over chemical agents, particularly biodegradability, low toxicity, low residual sludge production and low-cost. We investigate the coagulant activity of okra mucilage (Abelmoschus esculentus) as natural coagulant and their efficiency was compared to chloride ferric (chemical agent) in CF of textile wastewater. Optimization assays were conducted by the standard jar test method. The effect of pH, coagulant dosage and mucilage dosage on the percent removal of chemical oxygen demand (COD), turbidity and color were analyzed. A high removal of color (93.57%), turbidity (97.24%), COD (85.69%) was obtained using a low amount of the okra mucilage; 3.20 mg L-1, 88.0 mg L-1 Fe3+ at pH 6.0. The amount of Fe3+ can be reduced up to 72.5% (from 320.0 to 88.0 mg L-1) and can increase the COD removal about 35.74% with addition of okra mucilage. The mucilage of residual okra has coagulant activity in the textile wastewater treatment and showed to be an available, biodegradable and non-toxic coagulant. (C) 2015 Elsevier B.V. All rights reserved.