Filtering Through the Options

Aug. 6, 2003
Watsonville, Calif. incorporates automatic filter to recycle treated wastewater

About the author: Elaine Floyd is a freelance writer based in Bellingham, Wash. For further information, phone 310/839-2828.

Situated in the heart of California's Monterey Bay area in the lush Pajaro Valley, the city of Watsonville lies 95 miles south of San Francisco at the southern end of beautiful Santa Cruz County.

Long before the federal government dedicated the pristine Monterey Bay as a National Marine Sanctuary, the Watsonville Wastewater Treatment Facility was serving as a first line of defense in protecting the Bay's precious water quality.

First constructed during the 1920s, the Watsonville Wastewater Treatment Facility has seen its mission grow from servicing a small agricultural community to treating wastewater for as many as 50,000 residents. An average daily flow of seven million gallons of wastewater originates from residential, commercial and industrial sources.

Always a friend of the environment, the Watsonville Wastewater Treatment Facility makes a conscious effort to conserve natural resources.

Accordingly, the treatment facility uses its own treated wastewater for general plant purposes such as washing and cooling rather than consuming fresh water from the city.

Although Watsonville's wastewater is treated to the advanced secondary treatment level, and undergoes extensive monitoring and testing to ensure compliance with all state and federal pollution prevention laws prior to being discharged to the Monterey Bay over a mile off shore, it must be filtered before it can be used for plant washdowns and cooling.

Otherwise, the accumulation of solids such as algae would clog machinery and make such recycling impossible.

Principle of conservation

When the plant's 20-year-old filter needed replacing last year, one major concern was that the new filter operate on a small amount of electricity.

"We try to conserve as much electricity as we can in addition to conserving the amount of potable city water that we're using," said Mike Wagner, operations manager.

Wagner's search for the filter led him to two choices, after which a cost comparison narrowed it down to the Tekleen water filter manufactured by Automatic Filters in Los Angeles.

"The Tekleen filter uses 110 current for the control box and no motorized parts, so we cut down our electrical usage from before," said Wagner.

Although the actual dollar savings may amount to only about $50 per year, "it's the principle of conservation that counts," he said.

According to the manufacturer, the Tekleen continuous-cleaning filters require very little maintenance.

As particles collect on the screen, the line pressure at the filter outlet drops. When the pressure reaches a preset differential, the backwash cycle begins. Within seconds and without interrupting the main flow, vacuum nozzles aggressively suction the dirt from the inside of the screen.

The Watsonville Wastewater Treatment Facility currently pumps 400 gallons per minute through the filter installed with a 200-micron screen.

"The filter is working very well," said Wagner, "and we've received very good service from the company."

About the Author

Elaine Floyd

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