Optimization of process parameters for catalytic conversion of solid bio-waste during thermophilic anaerobic digestion

Biomethanation is a process by which organic material is microbiologically converted under anaerobic conditions to biogas. Three main physiological groups of microorganisms are involved: fermenting bacteria, organic acid oxidizing bacteria, and methanogenic archaea. Microorganisms degrade organic matter via cascades of biochemical conversions to methane and carbon dioxide. Syntrophic relationships between hydrogen producers (acetogens) and hydrogen scavengers (homoacetogens, hydrogenotrophic methanogens, etc.) are critical to the process. Determination of practical and theoretical methane potential is very important for design for optimal process design, configuration, and effective evaluation of economic feasibility. The present work is undertaken for generating bio-gas from food waste, kitchen waste, water hyacinth and Parthenium biomass separately using anaerobic digestion process. Attempts have been made to optimize various parameters viz. pH, temperature, volatile fatty acid (VFA), chemical oxygen demand (COD) in order to determine the most favorable condition for maximum biogas production from the different substrates. The biogas yields have been determined using batch anaerobic thermophilic digestion tests with a retention time of 55 days using biogas plant slurry and water treatment plant sludge separately as inoculum and bakhar, acetic acid and cow urine as catalyst. The methylotroph consortium present in the biogas slurry or water treatment sludge use the carbon source from methane for their growth due to which there is a significant change in methane production in different substrates under different conditions. The total biogas generated in the system over the experimental period was the sum of methane and carbon dioxide. Biogas produced from the decomposition of food waste produced a mixture of 65% methane and 24% carbon dioxide.