In the quest for alternative, renewable and eco-friendly fuels, scientists have developed a novel method to produce bio-energy and value-added products through wastewater treatment.

Senior scientist, Dr. S. Venkata Mohan and his group at IICT, Hyderabad have adopted a bio-refinery approach and produced futuristic green fuels, bio-hydrogen and bio-electricity. In the process a value added product that came out — bio-plastics.

Dr. Mohan, who is carrying out extensive research on renewable energy generation through waste water treatment, said the combustion of fossil fuels was adding about six gigatons of carbon per year in the form of CO. Several factors have led scientists to look for renewable and carbon-neutral forms of energy.

With the aim of developing processes that could be adopted by Effluent Treatment Plants (ETPs) and to achieve objectives of treating water, producing energy as well as value-added products, the scientists have been operating a 50-litre capacity reactor to produce bio-hydrogen and bio-plastics under a project funded by the Ministry of Non-Renewable Energy.

He said the efficacy of the process for treating wastewater and producing bio-hydrogen in the 50 litre capacity reactor has already been demonstrated. Now the plan was to scale up the process for producing bio-hydrogen in a 10,000 litre capacity reactor. He said the reactor was being designed and its efficacy would be demonstrated by the middle of next year.

Once that was achieved, he said the ETPs could replace anaerobic reactors to produce the environmentally sustainable bio-hydrogen instead of methane. Currently, bio-methane was being produced by treatment plants of most distilleries and other industries. The sludge that gets generated in the process was being used as fertiliser.

The volatile fatty acids produced along with hydrogen were used as a substrate for bio-plastics synthesis. The value-added bio-plastics at present were being produced at a lab scale. These bio-plastics could replace to some extent synthetic plastics in future. “In another 4-5 years, we can upscale the process and demonstrate its efficacy for commercial application,” he added.

He said bio-electricity was being produced from anaerobic bacterial metabolism using microbial fuel cell. The organic form of pollutants in waste water was a good substrate for bacterial growth.

The scientists used an anaerobic reactor with a 100-litre capacity to demonstrate the production of bio-electricity from wastewater. by putting external electrodes in the reactor. “At present, the yield is about 20 per cent. I am trying to improve performance by using various electrode materials. If we catalyse the electrodes, the yields will improve,” Dr. Mohan added.

Significantly, besides generating bio-electricity, the waste treatment efficiency improved vastly through this method, especially with respect to toxicity, carbon and salts removal. “We have named it Bio-electric Chemical Treatment System. We are planning to file a patent application for it.” Dr. Mohan said.

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