Headworks and Biosolids Management

Headworks and Biosolids Management
Unit provides aeration and mixing to equalization basin

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Unit provides aeration and mixing to equalization basin

Problem: Big Park Domestic Wastewater Improvements District in Arizona built a 500,000 gpd biological wastewater treatment system in 1997. In 2012, the district hired Sunrise Engineering to upgrade the equalization basin and digester/thickener.

Solution: The district installed AIRE-O2 Triton equalization basin and digester systems from Aeration Industries International. They enable aeration and mixing in one piece of equipment that can be easily accessed from the surface. The process achieves significant volatile solids destruction and consistent treatment. To decant, the equipment is turned off and the solids settle to the bottom, allowing the supernatant to be removed.

Result: The operators saw a significant decrease in biosolids volume. The facility had run the belt press three times a week but now does so once every two weeks. Lower volume means less biosolids to land-apply biosolids. The system has reduced maintenance and freed time to optimize the treatment process. 800/328-8287; www.aireo2.com

Adsorption system helps community meet arsenic level standard

Problem: With arsenic at 13.25 and 13.5 ppb in its two wells, the Crescent Valley Water System in Nevada needed to meet the U.S. EPA drinking water standard of 10 ppb.

Solution: The district chose De Nora’s SORB 33 arsenic removal system after a successful pilot test. The fixed-bed adsorption system uses a simple pump-and-treat process that flows pressurized water through a fixed-bed pressure vessel containing iron oxide media.

Result: Two 8-foot-diameter SORB 33 adsorption vessels, each containing 169 cubic feet of SORB 33 and with 175 gpm capacity, run in parallel. The district blends the treated 13 ppm Well 5 water with untreated 8 ppm Well 4, maintaining an average result of 5 ppb. “Everything is working excellently,” says Bruce Harland system operator. “I haven’t had to backwash the system for a month because the differential pressures haven’t approached 10 psi.” 412/788-8300; www.denora.com

Continuously cleaned bar screen solves ragging downstream

Problem: The perforated fine screen at the Bell County (Texas) WCID South Wastewater Treatment Plant was not performing and needed significant maintenance. Grease and rags passing through created issues downstream. At the headworks, the screen “moved debris around, back and forth, rather than removing it,” says Bruce Sorenson, chief operator.

Solution: Facility management chose the FlexRake FPFS-M screen with 1/8-inch openings from Duperon. It captures up to 37 percent more debris than 1/4-inch screening.

Result: “We were surprised that we could see the difference right at startup,” says Sorenson. “The back side of the screen cleared up immediately; we could always see debris coming through before, but once the FlexRake was installed, we haven’t seen anything. We’re seeing clear water. It really catches everything.” 800/383-8479; www.duperon.com

Submicron filtration system allows brewery to expand water reuse

Problem: A large brewery in the northeast U.S. sought to expand water reuse, but the application required a reduction of TSS load in water reclaimed from processes and evaporator condensate. A filtration system needed to handle each stream independently or combined. The differing TSS loads of the two streams required the system to be flexible.

Solution: A laser particle analysis demonstrated that a Vortisand submicron filtration system from Evoqua Water Technologies would deliver. The flexible system can handle flows from two water sources. The system was designed to handle 80 to 350 gpm.

Result: Submicron high-efficiency filtration helped reduce TSS by 98 percent. Fine filtration reduced the requirement for chemicals. The system also helped eliminate the purchase and maintenance cost of replacing cartridge filters. The system’s small footprint enabled low construction costs. 888/876-9655; www.evoqua.com

Rotary press ideal in retrofit situation

Problem: The city of Becker, Minnesota, needed to replace two belt presses but wanted to use the existing building and existing conveyors.

Solution: Fournier Industries used an eight-channel rotary press. Skid mounting enabled the presses to be installed without reworking the concrete floor where the old presses stood. It also expedited installation and commissioning. New conveyors receiving the cake solids feed the existing conveyor system, saving money.

Result: “In the short time the presses have been in operation, staff has been very pleased with the quality of biosolids produced, the ease of operation, and how quiet the equipment is,” says Dave Pesola, water/wastewater supervisor. “The low water usage is also an added benefit. It has reduced humidity in the press room that was contributing to problems with electrical and HVAC equipment.” 418/423-4241; www.rotary-press.com

Fine screen saves wear on membrane bioreactor

Problem: Idaho’s Star Water and Sewer District had obsolete in-channel grinder technology. The needed repairs could force two weeks of downtime. It could not compete with newer screening technology.

Solution: On the advice of consultant, the district chose the RPPS fine screen from Huber Technology to prevent harmful screenings from reaching the membrane bioreactor.

Result: With the previous unit in place, the screenings dump container had to be emptied every two weeks. The new unit requires emptying weekly and protects the MBR. A STAR basket with a zigzag folded surface allows for a compact design. 704/949-1010; www.huberforum.net

Receiving station stops pump clogs at private treatment plant

Problem: In the town of Haverhill, Massachusetts, John DiVicenzo and his crew at Stewart’s Septic Service handle 60,000 to 100,000 gpd in the company’s own wastewater treatment plant. Constant problems occurred because of the high volume of solids in the wastewater. “The pumps were clogging with all sorts of stuff, 20 times a day,” DiVicenzo reports.

Solution: The company installed a Honey Monster septage receiving system from JWC Environmental that grinds, screens and washes the flow and sends the liquid into the treatment plant and its settling tanks. The facility serves seven trucks a day, 10 hours a day. A 2-cubic-yard dump container of screened solids is emptied several times a week. Inside the Honey Monster, the Muffin Monster grinder and Auger Monster work together to grind and remove tough solids, which are then washed, dewatered and ground to reduce volume.

Result: “The Honey Monster processes the sludge easily, and my guys don’t need to unclog the pumps,” says DiVecenzo. 800/331-2277; www.jwce.com

Mixers used to process wastewater in gold mining area

Problem: In northeastern Nevada, the city of Elko wastewater treatment facility contends with more suspended solids and gold mining waste in its influent than is typical.

Solution: At the facility’s activated sludge process, Model POP-I mixers from Landia are used to suspend solids, homogenizing the sludge in the anoxic tanks without issues. This proved valuable during severe floods that saw flows up to 12 mgd from infiltration into the collections system.

Result: “The mixers do a very good job and are extremely reliable,” says Mike Haddenham, wastewater superintendent. “Landia’s Ken Jacobs worked out a maintenance program and trained up our team on how best to service the mixers. We know that help is always at hand if we need it.” 919/466-0603; www.landiainc.com

Push-floor bin and biosolids pumps help plant stabilize operations

Problem: The city of High Point, North Carolina, was pumping biosolids to an incinerator using hydraulically actuated piston pumps. The pumps were aging and spare parts were difficult to obtain. The plant also lacked buffering capacity for dewatered biosolids ahead of the pumps.

Solution: The city purchased a push-floor storage bin and piston pump arrangement offered by Schwing Bioset. A new push-floor bunker with 60 cubic yards of storage capacity handles the centrifuge-dewatered biosolids. Directly coupled to the bottom of the push-floor bunker are two SD 350 screw feeders and KSP 17 piston pumps.

Result: The piston pumps have dual discharges that allow the biosolids flow to be split and fed into the incinerator at four injection points for more efficient incinerator operations. If the incinerator goes down, biosolids can discharge to a new truck loading facility. The system has operated effectively. 715/247-3433; www.schwingbioset.com

Process helps facility harvest struvite from wastewater

Problem: The South Durham Water Reclamation Facility in Chapel Hill, North Carolina, uses biological phosphorus removal, but a sizable fraction of phosphorus removed in the secondary process is resolubilized during anaerobic digestion and returned to the secondary treatment train via centrate from biosolids dewatering. This means the plant must remove the recycled phosphorus a second time and deal with struvite in piping and equipment.

Solution: The facility installed the Struvia process from Veolia, a compact precipitation system that uses magnesium chloride solution and sodium hydroxide where required to precipitate phosphorus from filtrate, creating a clean struvite-based product.

Result: The process consistently reduced orthophosphate from 180 mg/L down to 30 mg/L. 919/653-4574; www.veoliawatertech.com


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