Performance and mechanisms of constructed wetland integrated microbial fuel cell for remediation and detoxification of leather tannery wastewater

Abstract

Several previous studies concerned of microbial fuel cells integrated into constructed wetlands, nevertheless, their application as a convenient treatment for wastewater is still developing. In this experimental investigation, five CW-MFC systems were similarly designed, setup, and operated in a batch mode for two subsequent cycles. Each cycle lasted for 10 days to evaluate the performance of CW-MFC system for the remediation of real leather tannery wastewater (LTW). Four CW-MFCs were planted, each with different type of vegetation including Conocarpus, Arundo donax, Canna lily, and Cyperus papyrus in CW1-MFC, CW2-MFC, CW3-MFC, and CW4-MFC, respectively. The fifth CW5-MFC was maintained unplanted and considered as the control system. The performance of each CW-MFCs systems was evaluated mainly based on the removal of organic content (COD), total dissolved solid (TDS) elimination, and power generation. The results demonstrated that the four types of plants maintained healthy and no sign of wilting was observed during the 20 days of monitoring. For the first cycle of batch operation, maximum removal efficiencies of COD were 99.8%, 99.5%, 99.7%, 99.6% and 99.5% with power outputs of 10,502.8, 10,254.6, 9956.4, 10,029.6, and 9888.0 mW/m3, while, maximum TDS elimination were 46.7%, 39.7%, 60.8%, 55.5%, and 13.8% observed in CW1-MFC, CW2-MFC, CW3-MFC, CW4-MFC, and CW5-MFC, respectively. Very comparable results were observed in the second operation cycle. Results of phototoxicity test indicated that the germination of Hordeum vulgare and Triticum aestivum were 100% watered with treated effluent compared to 90% accomplished with tap water as the control solution for both types of seeds.