Bioremoval of arsenite and sulfate by a mixed culture with sulfate-reducing capacity growing on powdered chicken feathers

Abstract

A relatively unusual and low-cost waste material was investigated for As(III) and SO42− removal by a mixed culture containing sulfate-reducing bacteria (SRB). Powdered chicken feathers (PCF) were tested as an organic nutrient source for SRB growth and also as solid support for As(III) immobilization. PCF's efficiency as a growth substrate was compared with that of sodium lactate, used as a positive control. As(III) removal increased, from 38% (in the presence of sodium lactate only) to 80%, in the presence of PCF and sodium lactate together. The soluble organic part of PCF contained 2302mgL−1 of carbon, suggesting the possibility of using PCF as an electron donor for SRB growth. When PCF was the only carbon source, the achieved sulfate removal was lower (13.4%) than that observed when PCF and lactate were added to the medium (27.0%), but higher than those obtained when only lactate was employed at COD/sulfate ratios of 0.67 or 1. Arsenic removal increased from 38% (lactate, COD/sulfate=0.67) to 80% in the presence of PCF and lactate. The results suggest an alternative biological route for arsenite removal which does not require the use of a strong oxidizing agent to promote As(III) oxidation to As(V) before its removal.