Perspectives in Energy Use and Greenhouse Gases at Wastewater Treatment Plants

The move towards carbon neutrality in wastewater treatment plants is commendable but the energy cost of biological treatment is sometimes exaggerated which may lead to less cost-effective carbon reduction than that which could be achieved elsewhere. Wastewater treatment should be seen as a resource for recovery of energy, nutrients and water for re-use. This paper tries to put energy use and green house gas (GHG) emissions at wastewater treatment plants in perspective by comparing outputs on a per capita basis. It is shown that the energy use for biological nutrient removal, excluding pumping and other peripherals is less than 0.1% of all energy use and that overall reduction in water consumption is much more important in terms of energy savings and reduction of GHG emissions.