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Jennings Secondary / Tertiary Treatment Facility

Treatment Facilities
In 1969, the City purchased property along the San Joaquin River and began developing what is now the largest pond system in the US. This new system is called the Jennings Secondary Treatment Facility.
The secondary treatment process biologically treats clarified water. The water is treated in facultative ponds and stored for irrigation. It is then blended with seasonal cannery waste and applied with biosolids from Sutter to the ranch at Jennings.
Tertiary Biological Nutrient Removal & Membrane System
The City of Modesto spent a decade and over $130 million on a state-of-the-art Tertiary Biological Nutrient Removal (BNR) and Membrane system to meet the stringent effluent limits required by the State of California.
The BNR river discharge and land application, including the irrigation fore bay, irrigation pump station and ranch reservoir, allows the City of Modesto to remove greater volumes of effluent than before. In order to do so, the City uses mechanical aerators, fixed film reactors, a chlorine contact tank, and a chlorination and dechlorination building.
As partners in the North Valley Regional Recycle Water Project, our tertiary effluent water supply provides a new source of water for agricultural customers in the Del Puerto Water District (DPWD). These customers have been severely impacted by drought and environmental restrictions on pumping water from the Delta.
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Wastewater pass through 1/4 inch screen filters to eliminate any remaining solid debris
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The solids are collected below and discarded
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An active Liquor containing micro organisms is used to fully break down all organic matter in the water
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during the first stage the micro organisms are kept in an oxygen deprived state where they must utilize elements in the waste to create their own air turning nitrates (NO3) into nitrogen (NO2)
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The wastewater is then aerated creating an oxygen rich environment increasing the activity of the micro organisms
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The heavily oxygenated wastewater is then transported slowly down the beds to a filtration system
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.08 micron filters remove all of the active liquor from the treated water
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The treated water is then moved through a series of pipes to the UV room for further processing
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A series of 6 banks of UV lights provide the final level of purification causing any resilient bacteria to die off leaving safe water