Largest Biosolids Screw Presses in North America Aid Recycling Project

A $4.7 million biosolids dewatering facility, producing up to 20 tons of dewatered sludge per day, is in its final stages of construction at the regional treatment plant, located two miles north of Marina. The end product, known as “cake,” can be composted and used for fertilizer or other beneficial land applications.

Mechanically simple, the system utilizes two screw presses, each running at about 0.07 revolutions per minute, that slowly squeeze the liquid from the sludge. The process takes about four hours from start to finish. Methane gas reclaimed from the sludge will provide the required energy to operate the system.

“This facility is drawing much ’interest from other wastewater agencies across the country,” says MRWPCA Lead Engineer Ed Oyama. The screw presses are the largest biosolids dewatering screw presses operating in North America, each approximately 50 inches in diameter and 30 feet long. “Not only will the facility allow us to operate the treatment plant more efficiently, the cake it produces can be recycled. And that’s something we can all celebrate.”

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