Utility seeks to improve belt filter press performance

Problem

The Connellsville (Pennsylvania) Municipal Authority needed to overhaul the solids process for a new wastewater treatment plant built in 2020. Solids from various process stages were concentrated on a gravity belt thickener before anaerobic digestion. The biosolids were then dewatered on a belt filter press, dried in greenhouses and landfilled. The belt thickener was over 30 years old. The city sought an upgrade to handle more throughput with greater efficiency.

Solution

The authority chose an OMEGA gravity belt thickener. Supervisor Jerry Fox observes that the equipment from Aqualitec is made of high-quality stainless steel and is more durable than the previous system. “We’re using half the polymer versus before,” he says. The unit is designed to reduce volume by at least four times. The simple and sturdy design offers benefits including low energy consumption, low maintenance and low operation supervision.

RESULT:

Fox is fully satisfied with the thickener’s performance: “Now our maintenance is reduced significantly. It runs smoothly, the maintenance is super simple, and the starting and closing procedures are impressive.” 855-650-2214; www.aqualitec.com

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Upgraded technology extends life of screens at treatment plant

Problem

In 2011 and 2013, the Chelford City Municipal Utility District wastewater treatment plant in Texas, operated by Si Environmental, replaced two antiquated climbing screens with Duperon FlexRake screens. The improved performance was immediate and long-lasting, persevering even through Hurricane Harvey’s 53 inches of rainfall, but an upgrade was in the cards.

Solution

The plant decided to upgrade to Duperon’s FRO IQ rotational assembly to expand system capacity and capability and improve wear resistance without the financial or operational burdens of a new installation. Designed for existing Duperon screens, the FRO (FlexRake Only) utilizes a sequence technology that delivers four times more debris removal by sensing debris and flow conditions and automatically adjusting speed. When large debris is presented at the screen, the links can disengage scrapers as needed to remove it, while the leading and trailing scrapers return to the engaged position.

RESULT:

“Out of all the screens I’ve seen in my 39 years of being in this business, the Duperon screens are my favorite,” says Ramon Castillas of Si Environmental. “These screens have made our lives easy, because they are operator friendly, low-maintenance, and if you keep them washed down, they’ll work forever.” 800-383-8479; www.duperon.com

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Press leads to improved capacity and space savings

Problem

The 3.15 mgd (design) treatment plant in Marseilles, Illinois, averaged 1.25 mgd and produced 55 dry tons of biosolids per year. Increased solids production taxed the capacity of the drying beds, which took two to six months to dry in ideal conditions. Aerobic cake averaged 17 to 19% solids and anaerobic 20 to 24%. “The cake had to be stored for three years before land-applying it,” says Don Christensen, wastewater superintendent. “We were running out of storage options and needed more dewatering capacity, but had no extra space for it.”

Solution

The city installed a 2-900/2000CV two-channel expandable Fournier Rotary Press. Biosolids are fed at low pressure into a channel between two 36-inch parallel filters. As water drains out, solids collect against the outlet restrictor gate. Slow rotation of the filters produces enough backpressure to dewater the solids and extrude a dry cake. More dewatering channels can be added for future increase in sludge production. The press is low maintenance and energy efficient.

RESULT:

The plant now uses the drying beds for storage. “The press has improved our biosolids process by leaps and bounds,” says Christensen. “The best thing is, once we start the press, we can leave it unattended. It automatically adjusts to changes in the material.” 800-463-6328; www.fournierdewatering.com

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Receiving station helps ready plant for increased influent load 

Problem

Legislation for septic tanks in Florida may increase septage volume at Indian River County’s Residuals Dewatering Facility. Moves are afoot to require inspection and pumping of septic tanks every three to five years.

Solution

The county chose a fully automated and complete Raptor septage receiving station plant from Lakeside Equipment. The small-footprint, self-contained unit compacts and dewaters screenings to 40% solids. An overnight self-cleaning cycle stops the buildup of grit in the bottom of the unit. The system is pre-engineered, and all-stainless steel construction resists corrosion. 

RESULT:

Far more grit and rags are captured than anticipated. A 4-cubic-yard container is filled daily. There have been no equipment issues, and only basic daily maintenance is required. 630-837-5640; www.lakeside-equipment.com

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Large city undertakes sludge thickener improvement project

Problem

A large city in the Southwest U.S. wanted to replace aging infrastructure in dissolved air flotation units and the building that housed them. Plant managers researched simpler and cleaner options that would reduce their polymer usage when thickening waste activated sludge.

Solution

After pilot testing a variety of rotary drum thickeners, the team chose the Hycor ThickTech thickener (Parkson Corporation) based on its high capture rates and low polymer usage. Four units were installed in 2021.

RESULT:

The units exceed performance expectations. Space is open for additional units to be installed in the future. 888-727-5766; www.parkson.com

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Screw press chosen for dewatering at treatment facility

Problem

The wastewater treatment plant in Waianae, Hawaii (3 mgd) produces anaerobically digested biosolids mechanically dewatered for transport. The centrifuge dewatering system was approaching the end of its useful life.

Solution

The plant team selected screw press dewatering for its performance, ease of use, low maintenance and low energy requirements. Given the high electricity cost on the Islands, a system with the same throughput but requiring 10% of the horsepower was a welcome improvement. The team chose Schwing Bioset equipment as the best overall value. The FSP703 machine dewaters at a rate exceeding 1,000 dry pounds per hour, per unit while fitting within a footprint similar to that of the centrifuge.

RESULT:

Plant staff members were impressed with the machine’s construction quality and ease of use. The system consistently produced cake at 24% solids reducing labor and hauling costs. 715-247-3433; www.schwingbioset.com