(404g) Improving Biogas Production from Agricultural Waste By Photo-Fenton Process

High energy demand and increase restriction of the use of non-renewable energy resources led researchers to look or alternative energy sources. Renewable energy resources draw attention all over the world because they are cheap, provide no environmental impact and improve economy.

Every year municipalities dispose several million tons of agricultural wastes. Traditional treatment option such as incineration, land applications and land filling were resulted in subsequent environmental problems in different parts of the eco-system; waste can pollute soil, ground water and under ground water. On other hand, incineration shows major shortage such as low capacity, low energy output and emission wide varieties of polluted gases. Thus, any other solution for solid waste disposal is highly recommended. A viable solution for this solid waste treatment is the use of anaerobic digestion process. This process is advantageous for different reasons; it can be use for treatment of different types of solid wastes, it does not has an environmental impact on the eco-system, the biogas produced from this process is consider as a valuable source of energy which can be used for different applications.

Anaerobic digestion (AD) of agricultural waste and/ or animal manure is an effective way to reduce solid waste and reduce the amounts of greenhouse gas emission. It was reported that the use of AD can play essential rule in reducing the amounts of ammonia and methane emission from manure storage facilities. The buffering capacity of manure and the presence of diverse elements have a positive impact on the anaerobic digestion process stability. One of the approaches for improving the economics of AD and to increase biogas production rate is by co-digesting different amounts of solid waste; the co-digestion strategy aims to improve the feed consistency, stabilize the feed chemical composition and enhance biogas production. The digested substrate resulted after the process can be further refined and serves as organic fertilizer, rich in nitrogen, phosphorous, potassium and other macro- and micro-nutrients necessary for the growth of the plants. Utilization of large amounts of animal manure for bio-energy purposes will reduce the nutrient runoffs and diminish the contamination of surface- and ground- water resources by further biotechnological processing and upgrading the liquid and solid bio-fertilizers for replacement of chemical fertilizers.

The effect of the photo-Fenton process on bio-gas production from agricultural solid waste, wastewater, and manure was evaluated in a batch reactor. The performance of anaerobic digestion (AD) was monitored by assessing the methane production potential, maximum methane production rate and methane production lag time. Photo-Fenton process under low reagents concentrations increased the amount of methane produced and reduce the digestion time. Pure and mixed substrates were tested, and it was found that the production of methane from pure substrate is lower than production from mixed substrate; cow manure and wheat straw generated 325 and 130 L-biogas/kg VS, while mixed substrate of wheat straw, cattle manure and wastewater generated more than 368 L-biogas/kg VS. Applying photo-Fenton process as an intermediate oxidation stage increased the % methane recovery from the ultimate value 60-85%, and reduce the total digestion time to 20 days.