In order to further understand the transfer processes of radionuclides from soil and air to plants in tropical areas affected by coal mining and burning, the absorption of 234U, 238U and 210Po by ferns, lichens, mosses, soybean, wheat, pine and eucalyptus cultivated around a coal-fired power plant and coal mining area in southern Brazil was evaluated in Chapter One. In Chapter Two, the authors show how biomethanisation of biogas by primary and secondary treatment of activated sludge from a wastewater treatment plant (WWTP) can be used as an alternative to fossil fuels. Chapter Three applies a statistical methodology in order to distribute the consumption during the production cycle so that it is affected as less as possible.