Variation in bioelectricity production in integrated CW-MFC: An insight into coliform inactivation affected by HRT...

In the current study, domestic wastewater was treated in three identical vertical up-flow reactors; R1 (constructed wetland), R2 (CW-MFC), and R3 (unplanted CW-MFC) under different HRTs of 36 h (Phase 1), 24 h (Phase 2), and 18h (Phase 3). Periodic reduction of HRT from Phase 1 to Phase 3 resulted in deteriorated organics and fecal coliform removal by the reactors. R2 showed higher pollutant removal and voltage generation in every phase of the study compared to R1 and R3. R2 exerted 93%, 87%, and 57% mean COD removal during Phase 1, Phase 2, and Phase 3; with maximum open circuit voltage generated as 925 mV, 695 mV, and 429 mV respectively. Linear regression analysis showed that operating voltage and power density had significant effects on the variance of effluent fecal coliform concentration. The regression analysis also revealed that 36 h-24 h HRT was critical where power density influenced the pathogen inactivation considerably. Multiple batch studies revealed the main role of reactor media and plant roots was to support the attached microbial growth for biodegradation of the organics. Radial oxygen loss did not affect the anaerobic environment at the anode after 800 days of reactor operation.