Feasibility of nanoscale zero-valent iron (nZVI) for enhanced biological treatment of organic dyes.

Affiliation

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]

Abstract

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.

Keywords

Biodegradation,Congo red wastewater,Continuous flow stirred tank reactor,Nanoscale zero-valent iron,

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