Biogas production from tannery wastes – Evaluation of isolated microorganisms effect

The disposal and treatment of wastes generated in the leather industry has been the focus of several studies around the world. They intend to meet environmental legislation and make the process environmentally and economically viable. The anaerobic digestion process, which occurs in steps that involve acid and methane forming bacteria, can be an alternative since it turns the waste into renewable energy. This work evaluated the anaerobic digestion process and the generation of biogas from leather industry waste (wet-blues shavings and sludge from wastewater treatment plant WWTP) and from parboiled rice waste. In both, microorganisms isolated from aerobic sludge of WWTP (inoculum) were added. The waste was analyzed for organic carbon and total solids content. The samples were maintained at 35°C, the volume of gas generated was measured and the composition was determined by gas chromatography. The addition of inoculum increased volume of biogas generated. The amount of biogas generated by leather waste was 23 ml (composed of 25% of hydrogen, in molar basis).The rice with the addition of tannery WWTP sludge generated 47 ml of biogas (composed of 75% of hydrogen, in molar basis). The anaerobic digestion process is efficient for leather industry waste treatment since it converts waste into renewable energy.