Energy consumption reduction in a waste water treatment plant

Against the background of energy transition, the operators of large municipal WWTPs have come to understand the importance of issues related to energy use. Since about 2000, one such operator in the Paris conurbation, Syndicat Interdépartemental pour l'Assainissement de l'Agglomération Parisienne, has set up actions enabling energy consumption optimization, to reduce both its costs and the associated environmental impacts. Using energy (electricity, gas, fuel, and biogas) meters for sectorial recording, consumption has been mapped at various scales (macroscopic, plant, process). Electric power has emerged as the leading energy source in WWTPs and biological treatment processes (aeration) as the main consumers. On this basis, energy use optimization paths have been described, needing action at three levels. First, operating cost optimization should involve the full treatment chain, including all costs (reagents, etc.), to make the best operating choices. Two further levels, comprising process and equipment, should then be considered to determine suitable action sets.