Biosolids Management And Headworks

Biosolids Management And Headworks
Mobile dewatering truck saves on handling, disposal costs

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Mobile dewatering truck saves on handling, disposal costs

Problem: Antigonish County in Nova Scotia faced escalating costs for handling septage and wastewater treatment plant biosolids.

Solution: ABCO Industries Limited offered its Mobile Dewatering Truck (MDT), essentially a vacuum truck that dewaters biosolids. In most cases, about 85 percent of biosolids volume is returned as a clear filtrate to the source. The dewatered solids are mixed with wood chips and composted. Once stabilized, the compost is applied as landfill capping material.

Result: The county achieved cost savings and no longer needed its lagoon system. The results showed savings in mileage and fuel consumption, vehicle wear, travel time and volume transferred. “The truck has performed as we had hoped for and has allowed us to greatly reduce our costs,” says Darrell Myers, an operator for Antigonish County. 866/634-8821; www.abco.ca.

Ferric chloride helps control phosphorus, reduce polymer demand

Problem: The Southwest Wastewater Treatment Plant in Springfield, Mo., had high polymer demand, using 100 pounds per dry ton of solids. The plant also had issues with controlling effluent phosphorus and struvite in the centrate lines. Operators needed to lower overall operations and maintenance costs while addressing the phosphorus issue.

Solution: After lab and full-scale testing, Kemira installed a 5,000-gallon tank for ferric chloride with containment and spill safety protocol. The company installed and calibrated two pumps and trained the staff to operate the equipment safely, calibrate the equipment and make process calculations required to monitor the trial performance. Kemira also designed and installed a system that allows operators to adjust the ferric chloride/biosolids ratio while the automated valve fills the holding tank. This includes a specially designed static mixer to blend the ferric chloride with the incoming biosolids.

Result: Polymer dosing dropped 33 percent, cake solids content increased 1.5 percent, alum dosing costing $170,000 per year was eliminated, phosphorus removal increased 93 percent and the total process cost decreased by 9.15 percent for annual total savings of $311,165. 800/533-5990; www.kemira.com

Double-tube heat exchangers rectify blockages

Problem: The Severn Trent Water facility in Leicestershire, United Kingdom, faced spiral heat exchanger blockages, resulting in low efficiency and high maintenance costs. The problem led to replacement of the heat exchangers in the digesters. Replacement units had to fit the space available, and both sides had to produce pressures to suit existing equipment. The design also needed to have minimal impact on existing site piping. The exchangers had to resist clogging with raggy biosolids and meet thermal requirements efficiently, reliably and with minimal maintenance.

Solution: HRS Heat Exchangers recommended DTI Series industrial double-tube heat exchangers, a tube-in-tube design with tubes sized to allow large particles and raggy biosolids to pass through. The internal tube is corrugated, creating turbulence that improves heat transfer and reduces the risk of fouling.

Result: The heat exchangers ended the blocking problems and increased digester efficiency. 623/915-4328; www.hrs-heatexchangers.com.

Screw press helps utility meet biosolids goal

Problem: Faced with aging infrastructure and equipment, Daphne (Ala.) Utilities needed technology to help fulfill the goal of producing Class A Biosolids. A crucial element was a reliable dewatering process that would meet performance goals and be harmonious with the neighborhood.

Solution: The utility ultimately chose the RoS3Q screw press from Huber Technology. The press can achieve up to 27 percent cake solids, has a low power requirement with a 5 hp motor, has an automatic cleaning function and leaves no watery mess around the unit.

Result: “Before choosing the Huber screw press, we examined several other technologies,” says Jim Caudle, manager of the Daphne Utilities Water Reclamation Facility. “After using the press for more than two years, we have found it to be efficient and reliable. It’s a selection we’d make again.” 704/949-1010; www.huber-technology.com.

Cake bin systems provide material handling for thermal hydrolysis

Problem: The DC Water Blue Plains Advanced Wastewater Treatment Plant in Washington, D.C., needed a supplier to provide the material-handling component for the first-ever CAMBI thermal hydrolysis process system in the U.S.

Solution: Jim Myers & Sons worked with PC Construction and the CDM engineering firm to provide four large T-316 stainless steel cake bin systems. Each receives dewatered biosolids from three centrifuges through chutes with electric-actuated diverter gates. Each bin is 28 feet long, 35 feet tall and 18 feet wide, and tapers to 9 feet wide at the live bottom pan. Each live bottom pan houses four 20-inch-diameter shafted T-316 stainless steel screws. Each bin was provided in four pieces with stiffeners, assembled completely and provided separately. Other features include local control stations, electric-actuated slide gates, load cells, level sensors, and 10 chutes with sampling ports and spray-water nozzles.

Result: The systems offer a separate control point to adjust the thermal hydrolysis process throughput independently from upstream processes. They provide capacity to store sufficient biosolids to be able to maintain operation of the process for about 12 hours at the design average throughput rate. 704/554-8397; www.myersequipment.com.

Screw press replaces dewatering system destroyed in fire

Problem: Tim Frank Septic Tank Cleaning Co. in northern Ohio began a dewatering operation in 1994, but a fire in 2007 destroyed the company’s dewatering building and press.

Solution: Having hosted a National Association of Wastewater Technicians waste treatment symposium before the fire, Tim and Tom Frank saw various dewatering technologies in operation. They installed a screw press from FKC Co. in the new dewatering facility.

Result: The screw press dewaters a mixture of septage and biosolids from small commercial treatment plants to about 30 percent solids. The solids are landfilled or land-applied. Filtrate from the screw press is treated in lagoons and manmade wetlands before being spray-irrigated onto farmland growing giant miscanthus, which will be used as a renewable fuel. 360/452-9472; www.fkcscrewpress.com.

Digester system produces biogas for large poultry processing plant

Problem: Mironovsky Hleboproduct in the Ukraine is one of Europe’s largest sustainable poultry product producers. The company sought to install a digester to use chicken manure, wastewater treatment plant biosolids, sorghum and wastewater to produce biogas.

Solution: Nijhuis Water Technology installed digester tanks 30 meters in diameter, mixed and heated to allow anaerobic digestion. A two-step system increases biogas production. The digestate is separated in a solid and liquid fertilizer. The biogas is used to heat the digesters during the year, to heat buildings and stables in winter and to produce electricity year-round.

Result: The system treats more than 700 tons of substrates each day, generating up to 5 MW. Exhaust heat feeds boilers for the slaughterhouse. The heat is also used in the processing plant and in winter to heat the chicken houses. The power is used at the slaughterhouse year-round, and excess power is sold to the commercial grid. 312/300-4101; www.nijhuis-water.com.   



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