Bioremediation of Cr3+ from Industrial Wastewater Using Rhizobium BJVr 12 Extracellular Polysaccharides

Abstract

The efficiency of extracellular polysaccharides (EPS) extracted from Rhizobium BIVr 12 in the adsorption of Cr’ from industrial wastewater was investigated. Wastewater containing Cr’ concentrations from a semiconductor company was obtained. It was then diluted to 1.0 ppm Cr’* concentration. It was divided into three sets, each adjusted at different pH level — pH 3, 6 and 9. Two types of adsorbent were made — sand alone and sand with EPS. Several 250 mL Erlenmayer flasks containing 100 mL aliquot of wastewater samples were prepared. Each adsorbent was submerged in the flask containing wastewater solutions. Flasks were placed in a shaker and were observed at different time intervals. Collected samples were then acidified and analyzed using Atomic Absorption Spectrophotometric (AAS) method. General Factorial Design and Duncan’s Multiple Range Test (DMRT) were used to evaluate the data. Results showed that adsorbent with EPS yielded significant reduction of Cr" concentrations from the wastewater samples. This suggests the efficiency of Rhizobium BJVr 12 EPS in the adsorption process. Maximum reduction of Cr’* using EPS was achieved after 48 hours at pH 3. The lowest residual Cr concentration obtained in the experiment was within the limit set by the Department of Environment and Natural Resources (DENR).