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Energy Efficient Combined Process Of Microbial Fuel Cell (mfc) And Membrane Bioreactor (mbr) For High Efficiency And Reliable Treatment Of Organic Wastewater
Project Description :

A combined approach of treating domestic wastewater using microbial fuel cells (mfc) and membrane bioreactor (mbr) technologies is an energy-efficient, novel and promising process of reliable wastewater treatment. wastewater treatment in single stage mfc has a limitation to achieve the required treatment efficiency for inland surface water disposal or to utilize the effluent for irrigation without further treatment. therefore, a two-stage continuous process was developed combining mfc and submerged mbr, with intermittent suction of high quality effluent through ultrafiltration membrane, which could be used for treatment of sewage as well as medium strength industrial wastewater. the air-cathode mfc was constructed with a low-cost ceramic cylinder, considered as the anodic chamber of mfc. the outer surface of the cylinder was coated with layers of c/tio2 suspension with a loading of 0.5 mg of vulcan carbon powder xc 72/cm2 of cathode surface area and 0.75 mg of tio2 nanoparticles (mixture of anatase/rutile)/cm2 of cathode surface area, a hydrophobic binder polyvinyl alcohol (pva, 1.5 mg/cm2 of cathode surface area) and acetone was used as a mixing solvent. untreated carbon felt was used as anode and cathode current collector. the mfc was kept in an open environment under the influence of fluorescent light. synthetic wastewater with sucrose as carbon source, having cod of 3 kg/m3, was introduced in mfc in a fed-batch mode at a constant organic loading rate of 1.2 kg cod/m3.day during the experimental period. the mfc was operated with hydraulic retention time (hrt) of 2 days and effluent was continuously collected in the aerobic mbr, operated with hrt of 10 h. suspended solid concentration in mbr was monitored to ensure the mixed liquor suspended solids concentration remained at 7.5 ± 0.34 kg/m3, by wasting calculated volume of sludge in regular interval. the quality of effluent at each stage of operation was determined adopting the procedure described in standard methods. submerged hollow-fibre ultrafiltration unit was attached inside the aeration tank and effluent extraction was carried out under constant membrane flux at a regular interval of 10 h with vacuum pressure adjusted at 0.1 bar. the first stage of mfc generated a stable operating voltage of 260 mv (100 Ω) over 5 months of operation and mfc effluent with reduced total and soluble cod of 0.760 ± 0.07 kg/m3 and 0.370 ± 0.012 kg/m3. the electrical behaviour of mfc was studied by polarization curve resulting in a maximum volumetric power density of 1.021 w/m3. the effluent of mfc was collected in an aeration tank of mbr as a carbon/nutrient source for aerobic microorganisms to grow. a mixed liquor suspended solids concentration in the range of 6.6 ± 0.2 kg/m3 to 7.5 ± 0.34 kg/m3 over the period of 10 h was maintained in the mbr. the f/m ratio was very low and equal to approximately 0.06 kg cod/kg mlss.day. both total and soluble cod removal from aeration tank after the stipulated time period was around 85%. very high permeate flux of 38 l/m2.h was maintained to extract effluent from the aerobic tank through hollow-fibre ultra-filtration membrane followed by frequent membrane back-flushing. furthermore, the required electrical energy for this combined treatment process at all stages of operation was estimated as 0.0041 kwh/m3, which was much lesser than the electrical energy generated in mfc (0.0144 kwh/m3). the study revealed an energy efficient and two-stage process of mfc–submerged mbr technology minimizing the organic matter load in final effluent by more than 98% (0.050 ± 0.010 kg/m3 of total cod) with complete removal of suspended solids and consequently generating high – quality effluent and bio-electricity in this process.

 
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Project Details :
  • Date : Dec 26,2015
  • Innovator : Sreemoyee Ghosh Ray
  • Team Members : Gourav Dhar Bhowmick
  • Guide Name : Prof. M. M. Ghangrekar
  • College : Indian Institute of Technology, Kharagpur
  • Submission Year : 2016
  • Category : Biological Sciences & Bioengineering
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