A team headed by Prof Ajay Kalamdhad of the Waste Management Research Group at IIT-Guwahati has developed a new design for a reactor to produce methane from bio-wastes. This anaerobic bi-phased baffled reactor (ABBR) is better on two counts – it can digest any kind of biomass, including wet and hard-to-degrade stuff like weeds and water hyacinth; and it’s quicker the biomass remains in the reactor for a maximum of 15 days, roughly half that in conventional reactors. Furthermore, the system produces biogas with a higher methane content, about 70%. These advantages derive largely from the baffles – flow reducers.
The researchers worked with diverse animal dung (cow, goat, rhinoceros) and piggery waste as a source of microbes and concluded that cow dung was the best for anaerobic digestion. Some organic wastes are difficult to treat anaerobically and yield lower degradation and biogas due to their complex composition or lack of one or other nutrient. Such waste is pre-treated and co-digested for improved digestion. Pre-treatment such as heating, application of electrical force, and addition of certain chemicals or specific bacteria was used to substantially improve the biogas yield of difficult substrates such as rice straw, Ageratum conyzoides, Lantana camara, Parthenium hysterophorus.
Prof Kalamdhad told Quantum that two systems are up – at IIT-Guwahati and at a start-up company in Aizawl, Mizoram. The start-up will soon sign MoUs with a few large companies in India, he said.