Aug 06, 2003

Filtering Through the Options

Watsonville, Calif. incorporates automatic filter to recycle treated wastewater

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

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

"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

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

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

About the author

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