From a King County press release:

Puget Sound Energy awarded King County’s Wastewater Treatment Division (WTD) an $894,970 grant for a project to replace aging pumps at South Treatment Plant with new energy efficient equipment saving sewer utility ratepayers an estimated $4 million over the next 20 years.

The new equipment replaces three of six raw sewage pumps in operation since South Plant came online 50 years ago. King County estimates the new pumps, which feature variable frequency drives that can adjust to flow rates, will reduce the plant’s energy consumption by 1.9 million kilowatt hours per year per year, equivalent to powering 212 homes annually.

The raw sewage pump replacement project is aligned with the ongoing strategic effort King County is taking to decrease energy consumption in all its facilities by 20 percent by 2020 while putting greater emphasis on using or generating renewable energy.

Although wastewater treatment delivers significant water quality benefits, the process is energy intensive. WTD established its Energy Program to prioritize energy efficiency in its facility upgrades and system expansions. In addition to the raw sewage pump replacement project, the program successfully guided several other energy-efficiency projects at South Plant that also received PSE grant funding, including the installation of LED lighting as well as new aeration equipment needed to break down pollutants during the treatment process.

Since 2007, PSE has awarded King County’s Wastewater Treatment Division more than $2.3 million in conservation grant funding to pursue innovative energy efficiency in its facility operations.

The division already harnesses waste gas from the treatment process to provide heat and power in its facilities. More information about WTD’s energy program is available online.