Biosolids Management and Headworks

Biosolids Management and Headworks
Temporary belt press provides relief

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Temporary belt press provides relief

Problem

The dewatering equipment at the Grand Chute-Menasha West Wastewater Treatment Facility in Neenah, Wis., had to be offline during construction. Operators believed a 2-meter mobile belt press could process 150 gpm or more of autothermal thermophilic aerobic digested biosolids at 3.2 percent solids, but the unit was unavailable.

Solution

A demonstration of the 1.7-meter extended length (XL) mobile belt press from Bright Technologies proved the unit was adequate. Company representatives tested the biosolids before recommending a polymer, then suggested where to place the press for maximum efficiency and minimal labor. They also trained the operators.

Over 16 weeks, the press processed 2,526,000 gallons at 200 gpm, producing 30 percent solids cake and operating at a 2,000 pounds per hour per meter loading rate. Dewatering occurred two days per week and less than 8 hours per day, thereby minimizing labor. 800/253-0532; www.brightbeltpress.com.

Cake pump increases efficiency, saves energy

Problem

Dewatered biosolids fell onto a conveyor at the Delaware (Ohio) Wastewater Treatment Plant, then into dump containers needing frequent relocation by a front-loader to maintain even distribution. Spillage caused odors and required constant cleanup. Breakdowns were common.

Solution

The plant installed a load-cell-controlled, open-hopper, progressive-cavity BTE 17-12 cake pump from seepex. It conveys 14 to 18 gpm at 35 percent solids. The pitch, diameter and speed of the auger can be adjusted to match the application, while load cells automate the process. Sensors on the hopper detect the increase in weight and adjust the speed of the pump accordingly. Valves allow even distribution in the containers. The cake transfer piping also has a pressure sensor and dry run protection.

The pump has run without problems for two years, resulting in a $1,500 per square foot mean capital cost savings. 937/864-7150; www.seepex.com.

Bar screen decreases plugging and matting

Problem

The Rittman (Ohio) Wastewater Treatment Plant averages 1.6 mgd with peak flows of 10 mgd. The manual bar screen with 1-inch bar spacings was in a chamber 30 feet below grade. Operators cleaned the rack using a rake and hoisted the debris out, but rags, fibrous material and plastics still entered the plant, plugging lines and pumps and settling in tanks.

Solution

Scott Ellsworth, an engineer with Environmental Design Group, selected a Blue Whale micro bar screen with compactor washer and touch-screen control panel from OR-TEC. Bogner Construction installed it. The 1/8-inch bar spacings capture 95 percent of debris. Screen rake teeth elevate screenings to grade, and a simple scraper mechanism sends them to the washer. Organics flow to the inlet waste stream, while screenings, compacted to 60 to 70 percent dry, are stored for disposal.

Operators are freed from pulling pumps to clear rags, unwrapping fibrous material from rotating equipment, or manually cleaning the bar screen. "We are very happy with the performance of the bar screen and washer, and I'm a skeptic," says operator Rick Horton. 216/475-5225; www.or-tec.com.

Filtration system saves $12.6 million

Problem

A city in Morehouse Parish, La., needed to replace the primary clarifiers and upgrade the grit removal system at its 2 mgd, 80-year-old wastewater treatment plant. One option was building a new facility for a proposed $14 million. The plant superintendent sought a more affordable alternative.

Solution

M2 Renewables scheduled a pilot test of two M2R MicroScreens. The filtration system captured 96 percent of 100 and larger mesh grit. After a week, it reduced influent BOD by 44 percent and TSS by 61 percent.

The process enabled the plant to eliminate the clarifiers and grit removal system, and to remain where it was. It also saved the city $15,000 annually in sludge hauling and $12.6 million in capital, achieving a return on investment in less than one year. 816/824-9879; www.m2renewables.com.

Upgrade reduces polymer usage

Problem

The polymer system at the Woodstock (Ill.) Wastewater Treatment Plant was no longer economical. It used 7.8 pounds of polymer per ton of dry solids, producing cake at 14 percent solids. The 2-meter belt filter press dewatered 175 gpm at 2 percent solids. Plant superintendent Anne George looked for a cost-effective solution.

Solution

The city purchased the ParaDyne system from EnPro Technologies. After operators installed it, Energenecs personnel trained them to use it.

Operators decreased the polymer feed rate from 1.9 to 1.4 gph and set the water flow rate at 480 gph, producing a polymer solution concentration of 0.3 percent by volume. This decreased polymer usage by 25 percent. 800/343-6337; www.energenecs.com.

Bar screens prevent flooding

Problem

The two manual bar screens and pump station at the Sudbury (Ont.) Wastewater Treatment Plant are 90 feet underground. Two workers cleaned the screens three times per day, loading debris into a wheelbarrow and transporting it topside by elevator. During some high-flow events, debris plugged the screens, allowing water to rise 65 feet. A watertight door separated the screen room from the pump station.

Solution

As part of the station upgrade, consulting engineer R.V. Anderson Associates chose two Mahr bar screens with submersible motors from Headworks. Each screen handles 54 mgd with 1.18-inch bar spacing. Both units pivot out of the channel for easy maintenance.

The screens require minimal attention. They improved operator safety during high-flow events, allowing them to focus on operating the plant. They also enhanced the pump station's efficiency and dependability. 713/647-6667; www.headworksusa.com.

Hybrid squeegees are cost effective and ergonomic

Problem

The Metropolitan Syracuse (N.Y.) Wastewater Treatment Plant treats an average of 84 mgd. Cleaning sludge and grit from 22 tank floors and outfall troughs was a physical strain for operators, and their squeegees didn't last long.

Solution

The mechanical maintenance coordinator purchased Waste Blaster heavy-duty hybrid pusher-puller squeegees from Way Cool Product Co. The ergonomic tools have stainless steel hardware with 24- or 36-inch-wide 12-gauge aluminum frames and 1/4-inch reinforced replaceable rubber blades. Fiberglass handles disconnect easily for disinfection and storage.

Operators reported that the tools made cleaning easier and faster, reducing labor by one-third and saving the city $11,000. The plant has 11 of the tools. 315/569-9974; www.waycoolproduct.com.

Pulsed hydraulic mixing system homogenizes sludge

Problem

The London (Ohio) Wastewater Treatment Plant pumped waste activated sludge to a gravity belt thickener before pumping it from a holding tank to the anaerobic digesters. Thickened sludge at 2.5 percent solids remained in the tank until 15,000 to 25,000 gallons accumulated, allowing solids and grease to float to the surface. The mixer in the holding tank failed to homogenize the batch. During pumping, water emptied first, causing problems in the digesters, while thicker sludge overwhelmed the pumps.

Solution

Operators installed a PHi-300 controller and three Hydro-Pulse large-bubble forming plates from Pulsed Hydraulics. They used an existing 7 hp compressor to deliver air at 50 psi to the controller, and set the forming plates on the tank floor.

The system homogenized the batch in minutes and was more affordable than other solutions. Pumping and digester problems disappeared. 800/641-1726; www.phiwater.com.

Reactor reduces ammonia levels

Problem

On race weekends, more than 250,000 fans converge on the Indianapolis (Ind.) Motor Speedway. Filtrate from anaerobically digested solids had ammonia concentrations of 800 to 1,200 mg/L with spikes to 2,000 mg/L, often causing exceedances of the wastewater treatment plant's effluent permit.

Solution

In April 2012, the facility started the storage nitrification denitrification reactor with BiofiltAer from Thermal Process Systems.

The reactor achieved a 98 percent reduction in ammonia, destroyed volatile and total solids, and eliminated odors in the dewatering building and biosolids storage area. The process also reduced the volume of biosolids by 33 percent. 219/663-1034; www.thermalprocess.com.

Bar screen improves efficiency

Problem

Sand and rags frequently clogged the bar screen at the Havre (Mont.) Wastewater Treatment Plant, and grit flowing downstream reduced plant efficiency. The city wanted to replace the unit and implement odor reduction.

Solution

Officials chose the RakeMax Multi-Rake bar screen from Huber Technology. The system's configuration uses top and bottom covers to practically eliminate odors.

The unit removed a high percentage of inorganics and grit, improving downstream processing and reducing stress on components. "The system works very well and requires such minimal attention that we almost forget about it," says plant superintendent Bill Dean. "We wish we had installed it 30 years ago." 704/949-1010; www.huberforum.net/TPO.



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