Production of a bioflocculant from chromotropic acid waste water and its application in steroid estrogen removal

Abstract A novel strain (designated as SW-2) which could convert chromotropic acid into bioflocculants was isolated from chromotropic acid wastewater. Conditions for bioflocculants production were optimized by response surface methodology (RSM) and determined to be inoculum size 7.74%, initial pH 6.9, and COD Cr of the chromotropic acid wastewater 425 mg/L. The yielded bioflocculant was primarily consisting of polysaccharide and protein. It could maintain its flocculating activity to 0.4% (w/w) kaolin suspensions over pH 3–9 and 20–80 °C. In addition, conditions for the removal of estrogens with the bioflocculant were investigated and determined to be bioflocculant dosage 50 mg/L, initial pH 3, reaction time 60 min, and temperature 45 °C. Under these optimal conditions, the removal efficiencies of E1, E2, EE2, and E3 were 87%, 92%, 88% and 96%, respectively. The bioflocculant was shown to offer a promising alternative method of removing estrogens from water in pretreatment applications.