Climate change is a global phenomenon, which is due to emissions of greenhouse gases, mainly from fossil fuels combustion and deforestation. It may have far-reaching harmful impacts: changes in rainfall patterns might have serious impacts on food production; floods and droughts could become more frequent and may accelerate emigration; many human and ecosystem services could face serious impacts due to changes in temperature and rainfall patterns. The research described here attempted to evaluate and quantify the greenhouse gases emitted from different points of wastewater treatment systems under various temperatures and oxygen levels.