For many municipal governments, water and wastewater treatment plants are their largest energy consumers, often accounting for 20 to 40 per cent of their total operation and maintenance (O&M) costs. On the other hand, energy costs represent the most controllable costs and the biggest opportunities in providing water and wastewater services. Incorporating energy efficiency practices into water and wastewater plants typically has payback periods of only a few months to a few years. The early savings can be reinvested in other sustainable solutions.
Energy-efficient equipment, systems, and components, such as variable speed pump drives, can be easily implemented to save energy. Smart controls can improve water and sewage operations in real time, optimizing energy consumption without the need for major capital investment. Renewable and clean energy sources, like solar and wind, can be explored as potential power sources.
The anaerobic digestion of the biosolids produced in wastewater treatment generates green energy, which can potentially offset the electricity consumption of the entire plant. In the most simplistic scenario, biogas can be used to feed boilers and provide hot water heating to the plant; however, it can also be used in combined heat and power (CHP) engines to produce electricity and thermal energy on-site. It can even be refined, then injected in the natural gas network or to produce biofuels for transport vehicles.
Moving away from the conventional biological treatment of sewage can also help the wastewater treatment plant achieve net-zero energy. Implementing ceramic filter membranes in place of active sludge reduces the energy needed for aeration and drastically reduces greenhouse gas (GHG) emissions. This established technology has lower sensitivity to incoming quality variations, is not easily fouled, is averse to abrasion, and allows the installation of pressure recovery devices. You can learn more in our “Re-Thinking the Treatment of Sewage” for additional insight.
Understanding how a system uses energy is essential to better manage costs and identify the opportunities in energy efficiency. The Barrie Wastewater Treatment Facility, located in Barrie, Ontario, is an example of identifying opportunities to reduce energy and operational costs.