Convenient renewable energy from bacterial metabolism of organic wastes

The recycling of the greenhouse gases to produce biogases (H2, CH4 etc.) seems to be a prerequisite for the mitigation of carbon dioxide (CO2 ) pollution in atmosphere at a sustainable cost; according to the Wood-Lijungdahl pathway this target may be reached through the acetogenesis that is the process by which bacteria called acetogens use (CO2 ) to synthesize volatile fatty acid (VFA), mainly acetates, which in turn are used by methanogenic bacteria to produce methane. In the present study different chemical parameters such as elemental analysis, pH, heavy metals content, organic C were used to monitor an acetogenic process followed by a methanogenic fermentation in a two step semi-continuous digester at a laboratory scale. Special focus was placed on characterization of organic matter using diffuse reflectance infrared transform spectroscopy (DRIFT) and thermal analysis (TG- DTA) to provide information about the phase of degradation or stabilization of urban wastewaters organic matter. The obtained results suggested that the addition of CO2 is followed by an enhanced synthesis of acetate and finally a greater amount of methane is produced. The whole transformation process is considered in respect to the sustainability of a greenhouse effect mitigation and fossil fuels substitution.