The conversion of organic waste material to energy can proceed along three main pathways – thermochemical, biochemical and physicochemical. Thermochemical conversion, characterized by higher temperature and conversion rates, is best suited for lower moisture feedstock and is generally less selective for products. Thermochemical conversion includes incineration, pyrolysis and gasification. The incineration technology is the controlled combustion of waste with the recovery of heat to produce steam which in turn produces power through steam turbines. Pyrolysis and gasification represent refined thermal treatment methods as alternatives to incineration and are characterized by the transformation of the waste into product gas as energy carrier for later combustion in, for example, a boiler or a gas engine. Bio-chemical conversion processes, which include anaerobic digestion and fermentation, are preferred for wastes having high percentage of organic biodegradable (putrescible) matter and high moisture content. Anaerobic digestion is a biological treatment method that can be used to recover both nutrients and energy contained in organic wastes such as animal manure. The process generates gases with a high content of methane (55–70 %) as well as biofertilizer. Alcohol fermentation is the transformation of organic fraction of waste to ethanol by a series of biochemical reactions using specialized microorganisms. The physico-chemical technology involves various processes to improve physical and chemical properties of solid waste. The combustible fraction of the waste is converted into high-energy fuel pellets which may be used in steam generation. The waste is first dried to bring down the high moisture levels. Sand, grit, and other incombustible matter were then mechanically separated before the waste is compacted and converted into pellets. Fuel pellets have several distinct advantages over coal and wood because it is cleaner, free from incombustibles, has lower ash and moisture contents, is of uniform size, cost-effective, and eco-friendly.
Image via Wikipedia Municipal solid wastes represent the best source of biomass in Jordan. In terms of quantity per capita and constituents, the waste generated in Jordan is comparable to most semi-industrialized nations. The per capita of waste generated in Jordan is about 0.9 kg/day. The total generation of municipal waste in Jordan is estimated at 1.84 million tons per year. The main resources of organic waste in Jordan that can be potentially used to produce biogas are summarized as follows: Municipal waste from big cities Organic wastes from slaughterhouse, vegetable market, hotels and restaurants. Organic waste from agro-industries Animal manure, mainly from cows and chickens. Sewage sludge and septic. Olive mills. Organic industrial waste According to a study conducted by the Greater Amman Municipality, around 1.5 million tonnes of organic waste was generated in Jordan in 2009. In addition, an annual amount of 1.83 million cubic meter of septic and sewage