Treating wastewater wastes energy, but it doesn’t have to

Read the full story in GreenBiz.

Wastewater treatment plants are energy hogs. A 2013 study by the Electric Power Research Institute and Water Research Foundation reported that they consumed about 30 billion kilowatt-hours of electricity per year, or about 0.8 percent of the total electricity used in the United States.

Wastewater treatment’s high energy footprint is ironic because the organic matter in wastewater contains up to five times as much energy as the treatment plants use, according to the American Biogas Council (PDF). Reducing treatment plants’ energy footprints through energy efficiency and using the currently wasted energy could save money and reduce greenhouse gas emissions.

Despite all that energy seemingly there for the taking, reducing the fossil fuel demand of treatment plants is challenging and requires myriad approaches. Around the world, the industry is experimenting with new technologies, evaluating them for not just energy benefits but also cost and unintended consequences, such as additional waste streams to be managed.

The Metropolitan Water Reclamation District of Greater Chicago (MWRD) has set a target to be energy-neutral by 2023, following the lead of plants in the United Kingdom, Denmark and the East Bay Municipal Utility District in Oakland, California, which has moved beyond net-zero energy to actually selling energy back to the grid. These innovators are using a variety of technologies to reduce the electricity they use through energy efficiency and to generate electricity onsite to offset what they do use.

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