REAL TEXTILE WASTEWATER RECLAMATION USING A COMBINED COAGULATION/ FLOCCULATION/ MEMBRANE FILTRATION SYSTEM AND THE EVALUATION OF SEVERAL NATURAL MATERIALS AS FLOCCULANT AIDS

Abstract

A coagulation/flocculation/membrane filtration process was applied to two real textile wastewaters in Turkey. Aluminum sulfate and ferric sulfate were used as coagulants and several natural materials, namely limestone, magnesite, kaoline, pumice, and sedipür (polyelectrolyte), were used as flocculant aids. The effects of pH, coagulant dosage, and the type and dosage of flocculant aids on the color and chemical oxygen demand (COD) of wastewater were studied. The experimental results showed that treatment with aluminum sulfate (0.5 g/L) and ferric sulfate (0.18 g/L) at a pH of 6 was very effective. The color removal for aluminum sulfate and ferric sulfate reached 81% and, 86%, respectively, and the COD was reduced by 70% and 47%, respectively. The natural flocculant aids behaved differently for color removal and COD reduction. Treatment with aluminum sulfate and limestone at pH 6 removed 89% of the color and reduced the COD by 80% in the presence of magnesite. Treatment with ferric sulfate aided with natural materials at pH 6 did not significantly remove the color and reduced the COD value by 50% in the presence of magnesite. Cellulose nitrate membranes can be easily cleaned using nitric acid.

Keywords

• Textile wastewater
• coagulation
• flocculation
• membrane filtration

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