Different energy saving tips at wastewater treatment plants are discussed here as energy saving becomes crucial at the current situation. In general, wastewater treatment process is an energy intensive process specially the conventional aerobic wastewater treatment or activated sludge process. As per United States Environmental Protection Agency (USEPA); with pumps, motors, and other equipment operating 24 hours a day, seven days a week, water and wastewater facilities can be among the largest consumers of energy in a community. Electricity use accounts for 25 to 40 percent of the operating cost for wastewater utilities (NYSERDA, 2008). Also, drinking water and wastewater systems are responsible for approximately 3 to 4 percent of energy use in the United States that contributes in the greenhouse gas emission of more than 45 million tons annually (U.S. EPA, 2012b).
In this scenario saving energy can not only translate into saving operating budget but also other economic and environmental benefits such as
Reduce air Pollution and Green House Gas Emission:
Current energy generation technologies are mostly fossil fuel based. Burning of fossil fuel release various greenhouse gases (GHGs) to the environment like carbon dioxide (CO2), sulfur dioxide (SO2) and nitrogen oxide (NOx) etc. These GHGs are responsible for different detrimental effects to the environment like chronic to acute health issues, smog, acid rain, global temperature rise, polar ice melting, sea level rise etc. By saving energy, it will be possible to cut down fossil fuel usage and release of GHGs to the climate.
Help to create a more stable energy supply: by saving energy there will be more energy available at peak hour, so there will be less chance of blackouts.
Longer life for the plants and the Equipment: More energy efficient technologies/ equipment are usually advanced one with longer life and less maintenance requirements. As a result, treatment plants not only have a longer life but also less maintenance cost.
Install plant-wide high efficiency motors - The cost of running electric motors can be the largest fraction of a plant’s total operating costs. Water Environment Federation estimates that electric motors make up 90 percent of the electric energy consumption of a typical wastewater treatment plant (WEF 2009). Energy saving by replacing low efficiency old motors should be minimally 5% to 10% (Focus on Energy, 2006).
Adopting Variable Frequency Drive (VFD) - VFD is a motor control technology that control the speed of a motor by varying the frequency of the power delivered to the motor. The objective of the variable speed technology is to match motor output speeds to system demand/ load requirement and thus prevent it from running at a constant full power. That how a VFD saves energy.
Recycle final effluent - Recycling final effluent to replace potable water for wash down of tanks and other process related applications can save money as well as reduce energy use.
Electric Peak Reduction - Shifting to off-peak or shaving peak power usage) can substantially lower energy costs.
Idle or turn off non-essential equipment - When feasible, especially during periods of peak power demand turning off non-essential equipment can save energy.
Adopted efficient lighting systems - Advances in lighting systems provides the WWTF with opportunities to reduce energy consumption (Installing compact fluorescent lamps, occupancy sensor, Scheduling controls etc.)
Renewable Energy Options - assess the feasibility of installing renewable energy resources (wind, solar, biogas or hydro) etc. at the facility to meet part or all of the facility’s electric and heating needs.
Energy Education for
Facility Personnel – Operators should be trained and educate with various energy saving tips. Then they can contribute effectively
in energy conservation.