Wastewater plant upgrades earn two achievement awards

Updated November 03, 2020
Wastewater plant upgrades earn two achievement awards
Our wastewater utility picked up two awards for two large upgrades – valued at $19 million -- at our Dry Creek Wastewater Treatment Plant (DCWWTP), including improvements to reduce nitrates as well as add in a cogeneration process to generate electricity.

The awards come from the local Northern California Chapter of the Construction Management Association of America (CMAA) as well as the national award from the same organization.

Nitrate reduction

The nitrate reduction project added significant aeration (adding air into the wastewater process) control and flexibility to our secondary treatment process.

With new instrumentation and innovative process equipment, operators can now further fine-tune the aeration process to more effectively monitor and significantly lower the discharge of nitrate and other constituents to meet newly imposed permit limits.

While nitrogen is an important nutrient in the environment, its natural cycle has been altered for a number of reasons. In the end, too much nitrogen is a bad thing. This project helps with reduction of nitrates found in wastewater, and contributes to the overall goal of maintaining a clean and healthy watershed.

The cost of this project was $10.9 million.

Energy generation

Last year, we constructed a new energy producing facility at DCWWTP where we operate two anaerobic digesters as part of the treatment plant process.

We take biogas generated by the wastewater process and maximize its use. Before this project, we used biogas in a limited scope – to fuel an engine-driven blower at our plant. The balance of the gas was flared (combusted) and simply wasted. We did not harvest it for heat or energy.

Now complete, we have a cogeneration facility, where gas from the plant fuels a generator that produces about 400kw of electricity for plant use. We also take Fats, Oils, and Grease from local restaurants and process it at the plant for energy generation.

If you can imagine, energy usage at a wastewater plant is typically one of the top three expenses annually since it is an extensive process to purify, treat, and discharge the water back into the environment.

What is cogeneration? It is an effective means of achieving cost savings for wastewater treatment plants. Cogeneration, also known as combined heat and power, is the concurrent production of electricity and heat from a single source of energy.

The cost of the Cogeneration Project was $8.2 million. We were able to obtain nearly $700,000 in grand funding from the PG&E Self-Generation Incentive Program. Energy offsets and other funding expected from energy generation credits will reduce annual operating costs by $300,000.

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