Clarification of rubber mill wastewater by a plant based biopolymer - comparison with common inorganic coagulants

BackgroundIn this study, the efficiency of Guar gum as a biopolymer has been compared with two other widely used inorganic coagulants, ferric chloride (FeCl3) and aluminum chloride (AlCl3), for the treatment of effluent collected from the rubber-washing tanks of a rubber concentrate factory. Settling velocity distribution curves were plotted to demonstrate the flocculating effect of FeCl3, AlCl3 and Guar gum. FeCl3 and AlCl3 displayed better turbidity removal than Guar gum at all settling velocities. ResultFeCl(3), AlCl3 and Guar gum removed 92.8%, 88.2% and 88.1% turbidity, respectively, of raw wastewater at a settling velocity of 0.1 cm min(-1), respectively. Scanning electron microscopic (SEM) study conducted on the flocs revealed that Guar gum and FeCl(3)produced strong intercoiled honeycomb patterned floc structure capable of entrapping suspended particulate matter. Statistical experimental design Response Surface Methodology (RSM) was used to design all experiments, where the type and dosage of flocculant, pH and mixing speed were taken as control factors and, an optimum operational setting was proposed. ConclusionDue to biodegradability issues, the use of Guar gum as a flocculating agent for wastewater treatment in industry is highly recommended. (c) 2013 Society of Chemical Industry