Green approach for reclamation of leather tannery wastewater in an upflow continuously operated constructed wetland coupled microbial fuel cell system: experimental and modeling studies.

Several studies have evaluated the performance of constructed wetland coupled microbial fuel cell (CW-MFC) operated in a batch mode. However, so far, few studies have concerned the performance and behavior of the continually operated CW-MFC systems. This study explores the performance of a continually operated CW-MFC for 180 days to treat real leather tannery wastewater (LTWW) simultaneously with bioelectricity generation. Steady-state conditions were achieved within 10 days, indicating the potential of the suggested CW-MFC system to run and stabilize shortly. The results revealed that maximum removal efficiencies of organic matters (COD), TDS, and the toxic pollutants including chromium and arsenic were 98.7%, 66.7%, 100%, and 100%, respectively. Maximum generated power was 1614.5 mW/m. Three microbial growth models including Monod, Blackman, and Halden were adopted to describe the bacterial growth in terms of power output during the exponential growth period. The predicted results were asymmetric and the degree of their closeness to the experimental results was different with determination coefficient (R) values of 0.97, 0.93, and 0.27, respectively, indicating the superiority of Monod model for describing the biofilm development and growth. Electrochemical model was also, adopted to predict the performance of MFC as the principal component of the CW-MFC system. The results predicted by the electrochemical model were in an excellent agreement with experimental results with determination coefficients (R) values of 0.90 and 0.97 for polarization and power density curves, respectively, confirming the reliability of the suggested model for the proposed approach using CW-MFC system within the applied range of operating conditions. The results of the study demonstrated that CW-MFC is a potential option for the treatment of the harmful tannery wastewater associated with power generation.