• Energy Research

This study aimed to assess the impacts of organic loading rate (OLR) (435-870 mgCOD/L·d) on nutrients recovery via a double-chamber microbial fuel cell (MFC) for treating domestic wastewater. Electricity generation was also explored at different OLRs, including power density and coulombic efficiency. Experimental results suggested the MFC could successfully treat municipal wastewater with over 90% of organics being removed at a wider range of OLR from 435 to 725 mgCOD/L·d. Besides, the maximum power density achieved in the MFC was 253.84 mW/m2 at the OLR of 435 mgCOD/L·d. Higher OLR may disrupt the recovery of PO43--P and NH4+-N via the MFC. The same pattern was observed for the coulombic efficiency of the MFC and its highest value was 25.01% at the OLR of 435 mgCOD/L·d. It can be concluded that nutrients and electrical power can be simultaneously recovered from municipal wastewater via the dual-chamber MFC.

This paper is to explore the use of rural solid waste (RSW) for pyrolysis-gasification-combustion in pilot plant scale aiming at sustainable management of rural waste in remote areas. Based on the experimental data obtained during pilot scale operation, the temperature in the furnace needs to be kept at least at 600 °C through analyzing the pyrolysis weight loss of the main combustibles in the RSW. Besides, the effects of the air supply method and ventilation rate on the pilot plant performance were explored. Results indicate that the active air supply method positively contributes to the performance of the pilot plant. The plant processed 10 t RSW/d, producing 12.82 g/Nm3 of tar with 1.75 % of ash. This study confirms the feasibility of the pilot plant for RSW disposal and provides theoretical support for the optimization of pilot plant operation.

In the present study, a dual-compartment microbial fuel cell (MFC) was constructed and continuously operated under different influent concentrations of ammonium-nitrogen (5-40 mg/L). The impacts of ammonium on organics removal, energy output and nutrient recovery were investigated. Experimental results demonstrated that this MFC reactor achieved a CDO removal efficiency of greater than 85%. Moreover, excess ammonium concentration in the feed solution compromises the generation of electricity. Simultaneously, the recovery rate of phosphate achieved in the MFC was insignificantly influenced at the wider influent ammonium concentration. In contrast, a high concentration of ammonium may not be beneficial for its recovery.

Nutrients recovery has become a meaningful solution to address shortage in the fertilizer production which is the key issue of nations' food security. The concept of municipal wastewater is based on its ability to be a major potential source for recovered nutrients because of its vast quantity and nutrient-rich base. Microbial fuel cell (MFC) has emerged as a sustainable technology, which is able to recover nutrients and simultaneously generate electricity. In this study a two-chambered MFC was constructed, and operated in a continuous flow mode employing artificial municipal wastewater as a substrate. The effects of hydraulic retention time (HRT) on the recovery of nutrients by MFC were studied. The COD removal rates were insignificantly influenced by varying HRT from 0.35 to 0.69 d, that were over 92%. Furthermore, the recovery rate of nutrients was insignificantly affected while increasing the HRT, which fluctuates from 80% to 90%. In contrast, the maximum power generation declined when HRT increased and the lowest one was 510.3 mV at the HRT of 0.35 d. These results demonstrate that the lab-scale double chamber MFC using municipal wastewater as the substrate can provide a highly effective removal strategy for organic matter, nutrients recovery and electricity output when operating at a specific HRT.