Applications of Energy Efficiency Technologies in Wastewater Treatment Facilities

Abstract

"Depending on the level and type of treatment, municipal wastewater treatment (WWT) can be an energy intensive process, constituting a major cost for the municipal governments. According to a 1993 study wastewater treatment plants consume close to 1% of the electrical power in Northern and Central California. Activated sludge is the most common method for wastewater treatment, and at the same time the most energy intensive process. New energy efficient technologies can help reduce energy consumption of these processes, while improving the treatment effectiveness. Energy efficient technologies can be implemented in retrofit, expansion as well as new construction. This paper details the application of energy efficient technologies in retrofit as well as new construction projects, outlining significant opportunities for energy efficiency and conservation as well as demand response in various types of WWT facilities. This is based on detailed assessments of over 10 wastewater treatment plants in Northern California. The results show that energy savings in the range of 15,000 kWh per year to over 3.2 million kWh per year with paybacks in the range of 1.7 years to 8.9 years are readily achievable in retrofit projects. Application of energy efficient technologies in new construction can be most beneficial in the lifetime of the plant, which usually exceeds 30 years. Based on our experience in evaluation of design by others in energy efficiency design assistance of 7 plants, energy efficiency opportunities in new construction will be elaborated. This paper will discuss common energy efficient practices in new construction and outline additional opportunities that can help further improve energy efficiency of new construction projects. Finally, based on a recent survey, wastewater treatment plants have excellent opportunities for demand response. In Northern California, several WWT plants have participated and greatly benefited from demand response opportunities. Opportunities for demand response based on detailed assessment of 10 plants will be discussed."