Wastewater Treatment Plant
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The City’s treatment plant treats 13 million gallons of water daily and serves 114,000 customers in the cities of Gresham, Fairview and Wood Village.
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Energy Net Zero
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How the Plant Works
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Educational Tours
In 2015, the treatment plant reached energy net zero. The plant now produces more energy than it uses, saving the city an estimated $500,000 a year in electricity costs.
Fats, oils and grease are trucked to the plant from local food service establishments. The City collects a tipping fee for receiving and recycling this waste.
Biogas is fed into two powerful cogen engines that converts biogas into heat and electricity.
- Primary treatment
Wastewater enters the treatment plant, flows through a screen, which removes large objects that could damage equipment. The remaining solids are minute particles that fall to the bottom of a sedimentation tank. The particles form a mass of solids called biosolids or sludge. This sludge is removed and converted to biogas to help create energy to power the treatment plant.
- Aeration
Aeration is an activated sludge process based on pumping air into a tank which promotes microbial growth in wastewater. The oxygen helps the bacteria break down organic matter and remove contaminants.
- Secondary
clarification
The wastewater from the aeration basin is slowed down and any remaining sludge is separated and removed from the wastewater.
- Disinfection
The wastewater is then disinfected with sodium hypochlorite to remove any disease-causing organisms and ensure that water leaving the plant meets the water quality standards set by the Environmental Protection Agency (EPA).
- Plant effluent
Following the treatment, the water is discharged to the Columbia River.
Schedule a tour of the Wastewater Treatment Plant
20015 NE Sandy Blvd.
503-618-3450
- Take a 45-minute guided tour through each step of the treatment process.
- Learn how the solar array and biogas generation allow the plant to be energy net-zero.
Tour the Columbia Slough Regional Stormwater Treatment Facilities
- Take a 45-minute self-guided tour through this restored parcel of land.
- School groups can check out a backpack of educational materials full of activities such as a scavenger hunt.
More information and educational resources
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