Abstract:
Water pollution is an ever increasing environmental problem in todays industrialized world. Amongst various sources of water pollution, one major source is textile effluent being directly released in natural environmental settings. Textile waste water contains many organic and inorganic pollutants with varying degree of toxicity. Although banned in many developed countries, textile industry of Pakistan still uses Azo reactive dyes to color fabric. Azo dyes are xenobiotic compounds and potential carcinogens, with high toxicity potential. In a country like Pakistan that is undergoing serious energy crisis, an environmental friendly system that could degrade dyes and simultaneously produce electricity would be a major break through in the field of textile waste water treatment technologies. The current study presents a lab scale single chambered microbial fuel cells (MFCs) technology that biodegrades azo reactive dyes and produce electricity as a by product. To biodegrade dyes, microorganisms were sampled from Nala Lai, a natural watercourse that receives wastewater from the cities of Islamabad and Rawalpindi. Microbial inoculum was produced by culturing sludge from nala lai in 100 mL of nutrient broth, incubated at 30C for 24h. A total of 6-lab scale MFCs were developed to evaluate effect of different mediators on over all performance of MFCs. The mediators used were glucose, acetic acid and ammonium acetate. An initial 5% w/v mediators were used to select one best mediator. Blue dye 5% (v/v) was used as substrate throughout the experiment. Performance of MFCs was evaluated on the basis of dye degradation, microbial growth, current, current density, voltage, power density and columbic efficiency. Maximum overall performance of MFC was observed when acetic acid was use as mediator, 77% dye degradation, 83% increase in microbial growth, 0.1003 mA current and 0.1128 mV voltage after 14 days of experiment. Glucose showed least mediating capacity with 0.0133 mA current and 0.0160 mV of voltage. Results suggested that increased dye degradation results in increase in microbial growth, current and voltage out put. The study suggests that use of Microbial Fuel Cells to treat azo dyes contaminated textile waste water is a promising technology in the field of waste water treatment.
