A review of biogas production methods from wastes and sewage and the explanation of its process

Thousands of tons of urban solid waste and human and animal waste in cities and villages of Iran have endangered the health of the environment and increased the greenhouse gases. On the other hand, the increasing trend of energy consumption has caused energy crisis phenomena in the world. Moreover, the increasing consumption of energy from fossil fuels has caused emissions from these fuels. Hence, moving towards providing clean and renewable energies has been placed at the top of the programs of the world. One of these energies is biogas energy. Not using urban and human waste as an energy resource not only increases the volume of urban waste, but also increases the pollution in villages and towns. However, the decomposition of wastes and feces and production of biogas can both provide energy for rural households and help purifying the environment. With the construction of biogas plants in addition to the provision of energy, it could be an effective way to resolve the crisis of urban waste and reduction of emissions and result in significant socio-economic effects. In this study which has been conducted with library method and in assistance with databases from 1998 to 2014, we have tried to investigate the role of bio-energy in providing energy supply, the method of production of biogas, the importance and benefits of its application, and to describe the process of decomposition of organic matter with bacteria. In this article, besides introducing different technologies of using biogas of landfill areas, their application and economic aspects in the world and techniques of using the resources of this energy have been also evaluated and a model has been presented for determining the rate of biogas production based on grade Areaction kinetics.