A combined biological removal of Cd2+ from aqueous solutions using Phanerochaete chrysosporium and rice straw

The removal of Cd2+ from aqueous solutions by agricultural residues rice straw combined with white rot fungus Phanerochaete chrysosporium (P. chrysosporium) was investigated. The results showed that over 99% of the total Cd2+ (initial concentration of 150 mg L-1) was removed at the optimal operating conditions (pH 5.0 at 35 degrees C). We also found that P. chrysosporium could survive under Cd2+ stress even with an initial Cd2+ concentration of 250 mg L-1. But when Cd2+ concentration increased to 250 mg L-1, fungus growth and reproduction were remarkably restrained, and as a result, Cd2+ removal dropped to 59.2%. It was observed that the fungus biomass and activities of ligninolytic enzymes decreased at some degree under high concentration of Cd2+ (above 100 mg L-1). Also, we found that a moderate Cd2+ stress (below 150 mg L-1) could stimulate P. chrysosporium's production of the heavy metals chelator oxalate. This study will provide useful information for the application of biological removal of heavy metal irons from wastewater. (C) 2016 Elsevier Inc. All rights reserved.