Integrating sludge microbial fuel cell with inclined plate settling and membrane filtration for electricity generation, efficient sludge reduction and high wastewater quality

- A novel inclined plate sludge microbial fuel cell (InPSMFC) was developed.
- Electricity generation and excess sludge reduction were accomplished in situ.
- Inclined anodes of InPSMFC doubled maximum power density and halved resistance.
- Inclined anodes accelerated sludge sedimentation and sludge reduction.
- Membrane module realized a continuous operation with better effluent quality.

Disposal of excess sludge generated in wastewater treatment plants is complicated, energy-consuming and potentially produce secondary pollution. In this study, sludge microbial fuel cell (SMFC) was innovatively introduced into secondary settling tank to complete sludge reduction in situ. Anode of SMFC was embedded in the sediment and cathode suspended in the supernatant, besides, inclined plate anodes were installed in the middle of tank to enlarge the area of anode significantly and facilitate the utilization of biomass in the middle of settler. What's more interesting is that, due to the inclined arrangement, anodes in the middle of reactors also stopped sludge from floating and accelerated the sludge sedimentation. The results showed that power density increased by 2.1 times, internal resistance decreased 50%, sludge reduction rate increased by 1.5 times with the installation of inclined anodes compared with normal SMFC (without inclined anodes). In addition, inclined anodes provide better conditions for the continuous operation of the reactor. Compared with static-stage, Rint of inclined plate SMFC and normal SMFC during continuous-stage were decreased by 29.77% and 35.67%, respectively. COD and SMP in supernatant decreased by 21.51% and 17.80%, respectively, and the membrane fouling of membrane module arranged in cathode was mitigated significantly.

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