Resource Recovery in Action: City of Coeur d’Alene’s Coeur d’Green^TM Composting Facility turns municipal biosolids into nutrient-rich soil amendment.

The City of Coeur d’Alene has been a pioneer in the wastewater treatment industry since 1939, when it’s 10,000 residents passed a bond to build one of the first secondary wastewater treatment plants in the Northwest (for a whopping $140,000!). Then, in 1989, the City again demonstrated its pioneering efforts in resource recovery with the construction of a composting facility that converts biosolids from the City’s wastewater treatment facility into a high-quality soil amendment using the aerated static pile composting method. The Class A Exceptional Quality product has been affectionately coined Coeur d’Green^TM compost and is unrestricted for horticultural uses. Since 1989, the composting facility has gone through many upgrades to improve operations and the quality of the end product, including covered wood chip storage, added bays for aerated curing, and upgraded conveying, mixing, and screening equipment. Figure 1 below is a schematic of the current composting process.

In the 1970s, Spokane County noticed that septic tanks in the area posed a threat to the Spokane Valley Rathdrum Prairie Aquifer, especially as urban growth increased in the Spokane Valley. This aquifer is the primary source of drinking water for Spokane County, Washington and Kootenai County, Idaho. So, in the 1980s, the County led an effort to install sewers throughout urbanized areas of Spokane County, eliminate septic systems, and connect homes and businesses to a centralized sewer system. During that effort, all regional wastewater was treated at the City of Spokane’s Riverside Park Water Reclamation Facility.

Congratulations to the City of Boise for being awarded the 2021 PNCWA Excellence in Resource Recovery Award! As one of the fastest-growing cities in the country, the City of Boise knows that protecting natural resources is vital to maintaining livability. The City has embarked on the following efforts that demonstrate their commitment to resource recovery in the Pacific Northwest.

The City of Sequim Reclaimed Water Facility is a pioneer in the field of resource recovery with programs for both production of Reclaimed Water and Beneficial use of Biosolids. The plant, which is located on the North Olympic Peninsula, was originally constructed in 1966 as a conventional Secondary wastewater treatment plant with an outfall into the Strait of Juan De Fuca. In 1997, the treatment plant was upgraded to produce 100% of flow to Class “A” Reclaimed Water, and the Outfall was extended 1,900 feet into the Straits of Juan de Fuca. The plant was further expanded in 2010 to have a maximum month design flow of 1.67 MGD. As currently constructed, the plant consists of mechanical fine screening, influent flow measurement, grit removal, equalization basin (for daily and storm flows), aeration basins configured to perform biological nitrogen and biochemical oxygen demand removal, and secondary clarifiers. The secondary treated effluent is then coagulated and filtered either by anthracite coal media filters or a cloth media disk filter prior to UV disinfection.

The City of Gresham was recently awarded the 2020 PNCWA Excellence in Resource Recovery Award, which recognizes programs (nutrient, energy, water, or carbon recovery) that demonstrate outstanding performance in moving the concept of resource recovery forward in the Pacific Northwest region.