Development and application of novel soil-based membrane in microbial fuel cell for wastewater treatment

Background: Earthen membranes are reported as an efficient cation exchange membrane (CEM) in microbial fuel cell (MFC) for effluent treatment. However, membrane thickness, inflexible and brittle nature of ceramics are the challenges to their use in MFC. Method: In this work, a polymeric matrix of polyvinyl alcohol (PVA) and sodium alginate (Alg) was used to prepare a base CEM PVAlg of micrometer thickness. Various concentrations of microsized red soil (RS) from 0.25 -1.0% (w/v) were doped in PVAlg membrane to prepare soil polymer composite CEM- 0.25 RS, 0.5 RS, and 1.0 RS. Significant findings: Morphological, surface functional groups and thermal characterizations showed the strongest intermolecular interaction in 0.5 RS. An optimal soil-polymer ratio achieved in 0.5 RS gave a high proton diffusion coefficient (1.20 x 10-5 cm2/s) in comparison to the proton diffusion coefficient of PVAlg (7.56 x 10-6 cm2/s). The maximum power output obtained for aerated cathode MFC treating domestic wastewater with PVAlg, 0.25, 0.5 and 1.0 RS were 116.30, 75.05, 376.07, and 287.83 mW/m3 respectively. Applicability 0.5 RS was also verified for dye wastewater treatment giving 54 mW/m3 power output and 69 % decolorization. Such soil-based polymeric CEM can be studied in large-scale MFC reactors for wastewater treatment.