The Isolation of Bioflocculant-producing Strains and the Application in the Oily Wastewater Treatment Process

Abstract

Three bioflocculant-producing bacteria strains were isolated by the pyridine screening method. The flocculating rate of bioflocculant produced by KL9-1-3 on kaolin suspension (4.0g/L) reached as high as 98.2%. The strain KL9-1-3 was identified as Rhodococcus sp. according to its morphological, physiological, biochemical, and 16S rDNA sequence characteristics. It was deduced that the main component of purified bioflocculant was polysaccharide through infrared spectrophotometry and GC-MS analysis. The bioflocculant KL9-1-3 can effectively deal with oily wastewater, and the corresponding maximum removal rates of oil and COD for oily wastewater were 74.1% and 42.9%, respectively, under the optimum conditions of bioflocculant dosage 0.2 mL/L, pH 10.0, temperature 40°C, and Ca²⁺ as the coagulant.

Keywords:

• isolation
• bioflocculant
• flocculating activity
• oily wastewater