State Key Laboratory for Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China. Electronic address: [Email]
Biodegradation of recalcitrant organic contaminants such as organic dyes is a fundamental challenge in wastewater treatment. We report herein the integration of nanoscale zero-valent iron (nZVI) with membrane bioreactors (nZVI-bio system) to achieve enhanced degradation of Congo red (CR) in wastewater. nZVI pretreatment converts the large and bio-recalcitrant CR molecules into smaller and more biodegradable organic compounds in continuous flow stirred tank reactors (CFSTR). A nZVI-bio system was experimented continuously for 52 d with a color removal efficiency of 99% and a reduction of chemical oxygen demand (COD) from 167 mg L-1 to less than 70 mg L-1. However, a conventional biotreatment system treating identical wastewater achieved color removal efficiency of just 30-70% and the COD reduction to 116 mg L-1. This suggests that integrated nZVI-bio system has potential for the treatment of recalcitrant organic dyes. On-line measurements of pH and redox potential in the CSFTR can be conveniently used to monitor and regulate treatment performance.