Operators of the water reclaim plant in a California prison devise a creative solution to provide denitrification and meet effluent standards for off-grounds discharge.
The four inmate operators of a water reclamation plant at the California Correctional Institution in Tehachapi faced a dilemma. Working with plant flows and influent BOD well below the original plant design levels, they could not denitrify well enough to meet a 10 mg/L total nitrogen permit limit for discharge to customers off the facility grounds.
Working together, and under the supervision of three state-employed operators and a contract chief plant operator, they developed a creative solution to the problem that enabled the facility to resume delivering reuse water to customers during a severe drought when demand for reclaimed water was high.
Decline in flow
“We operate a 1.1 mgd Class IV activated sludge water reclamation plant with extended aeration, tertiary treatment and UV disinfection,” reports Keith Fredrickson, lead inmate operator. “Our plant was designed and constructed in 2008, when the facility population was expected to increase over the years.”
However, the state’s initiatives to reduce prison overcrowding resulted in a drastic decline in the inmate population at Tehachapi. As a result, the influent flow dropped to 0.55 to 0.60 mgd, and the BOD loading averaged about 200 mg/L, just one-third of the average for which the plant was designed.
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