Case Studies - August 2020

Case Studies - August 2020
City looks to oxygen for odor control

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Washing system helps eliminate FOG problem

Problem: A large north Florida regional wastewater system was battling FOG up to 4 feet thick that was blanketing lift station walls and equipment. Dry-weather spills exacerbated the problem and drove a search for solutions.

Solution: The agency selected the EP-1300 well-washing and pretreatment system from Anue Water Technologies. 

Result: The system eliminated the FOG in two hours. Spills were nonexistent, and confined-space entry for cleaning was no longer necessary. Expenses for a boom truck and two operators for two hours on each occasion were eliminated, reducing maintenance costs by up to 20% annually. The agency now operates 15 EP-1300s and plans to add more. 800-559-7159;

Screening system eliminates clogged pumps at pump station

Problem: The Drake Pump Station, located in Saginaw, Michigan, experienced chronic pump maintenance due to flushable wipes. Although the dry pit pump station represented only 0.1 mgd of flow in the city’s collection network, it required a substantial amount of servicing — up to three times a week. This consisted of two operators spending four hours manually removing rags in a confined space to clean out the clogged pump. It was a dirty, unplanned and time-consuming task.

Solution: In partnership with the city, Duperon adapted a proven screening system for a novel application. Deployed inside a 19-inch manhole, the system uses three existing technologies to screen, compact and transport collected debris 26 feet vertically without auger-assisted conveyance. Traditional solutions to handle flushable wipes require manual clean-outs or maintenance-intensive grinders that shred fibers to reconstitute, compromising downstream equipment. By removing nondissolvable solids at (or near) the point they enter the collections system, the Duperon system restores integrity and resiliency. 

Result: For the duration of the testing period, the city had zero instances of clogged pumps, resulting in a potential labor and maintenance savings of more than $41,000 annually. 800-383-8479;

Microturbine system helps plant save money

Problem: The aging internal combustion engines at York (Pennsylvania) Wastewater Treatment Plant caused energy bills to top $63,000 per month.

Solution: The city selected a Capstone microturbine combined heat and power system that promised lower life cycle costs, less maintenance and fewer emissions. A Capstone C1000 and C600 operate on natural gas and biogas.

Result: The units produce 40% more power using the same amount of natural gas as the former internal combustion engines. The plant also reduced operating costs by recovering the exhaust heat for digester heating. 818-734-5300;

Wastewater treatment facility finds efficient screening solution

Problem: In 2018, the Spencer (Wisconsin) Wastewater Treatment Plant launched a series of improvement projects and planned to invest $2.55 million. The first priority was replacing the headworks fine screen; options for a hauled-in waste receiving facility were also evaluated.

Solution: The plant conducted a successful one-week pilot test of a Septage BEAST in-tank screening system from Enviro-Care. However, the staff preferred to receive waste directly into the headworks channel. Instead of one screen for hauled waste and one for the headworks, the Enviro-Care representative suggested putting the dual drive screen from the BEAST directly into the channel. Spencer purchased a VFA800/6DM (BEAST) dual drive screen.

Result: The screen reduced maintenance at the headworks and downstream. The high capture rate keeps debris out of the plant even with the increase in hauled waste. Revenue from the hauled waste is paying for the screen. 815-636-8306;

Screw press provides Class A biosolids for coastal city

Problem: The City of Long Beach, Washington, faced challenges in managing biosolids due to increased regulations and loss of farmland for application.    

Solution: The city added an FKC screw press to dewater biosolids before composting. The biosolids are then blended with wood chips and yard waste for in-vessel composting. The resulting Class A compost provides a stable source of nitrogen, phosphorus and potassium where applied.

Result: The screw press provided a consistently dry cake, enabling a smooth composting process with easy-to-determine blending rates, composting times and temperatures. 360-452-9472;

Grinding at the headworks improves screens’ performance

Problem: Operated by Northern Ireland Water, the 25 mgd Moygashel Wastewater Treatment Plant in Dungannon faced operation and maintenance issues with its fine band screens and screenings compactors. Due to heavy rainfall, the flush surcharge from the gravity main flowed immediately onto the 6 mm headworks band screens, causing the screens to overload and blind three to four times a week. This resulted in screenings being forced into the treatment process; addressing the issues took about 16 labor hours per week.

Solution: JWC Environmental’s Channel Monster heavy-duty grinders were chosen to precondition the solids and debris and protect the screens from overload and damage. The units reduce solids to a smaller, uniform particle size, leveling the rate at which they hit the screen. The grinders also liquefy more of the solid fecal matter so that it remains in the flow and enters the treatment process, thereby reducing odors.

Result: The grinders resolved the peaking factor at the headworks and solved problems with the compactors. Previously, the compactors could not process heavier plugs of screened rags and solids. Now the compactors can process all the material coming off the screens. 800-331-2277;

Rotary press used to replace outdated press system

Problem: The Town of Lewiston (New York) Water Pollution Control Center needed to replace a 35-year-old belt press.

Solution: After full-scale pilot testing, the town chose a Fournier Industries rotary press. GHD Group engineers were assigned to get the press to the second floor where the existing belt press was. Fournier shipped the unit with the channels separate from the gearbox, allowing the drive to fit through the floor opening.   

Result: “In the short time that the press has been in operation, staff has been very pleased with the quality of the biosolids produced, the ease of operation and how quiet the equipment is,” says Jeff Ritter, wastewater administrator/chief operator. “The low water usage is an added benefit. This has reduced the humidity in the pressroom, which was contributing to problems with electrical and HVAC equipment.” 418-423-4241;

Receiving station helps ready plant for increased influent load

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

Solution: The county chose a fully automated Raptor septage complete plant from Lakeside. The compact, 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 preengineered, 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;

Mixer reduces grease buildup and high solid slug loading

Problem: The Random Farms wastewater treatment facility, located in Chappaqua, New York, has faced various issues related to pump station grease build up, solids settling and pump clogging.

Solution: C3ND Environmental Consulting installed the PHi-Constant Air (PHi-CA) from Pulsed Hydraulics within 2 inches from the bottom of the pump station to provide a full mix of the pump station wet well to eliminate sedimentation buildup and removal of residual grease at the surface and accumulated on floats. 

Result: Within 10 minutes, the residual grease at the surface was removed, while also generating a complete mix to transfer sedimentation through the station to be treated appropriately within the wastewater treatment plant. Within one week, residual grease accumulated on the station’s pump floats were removed, helping consistent operation of the pump station pumps. It has also been reported that the pump station now experiences reduced odors and reduced maintenance associated with “ragging” of the pump impellers. 800-641-1726;

Aeration tank organic overload resolved by mixers

Problem: The 29 mgd Little Patuxent Water Reclamation Plant in Howard County, Maryland, is an enhanced nutrient removal facility. A planned upgrade to the biosolids management facilities included high-rate anaerobic digestion, rebuilt centrifuges, phosphorus recovery and sidestream deammonification to reduce nitrogen loading in the return to the main treatment process, helping to meet a 3 mg/L total nitrogen limit.

Solution: The county chose Veolia Water Technologies’ ANITA Mox moving bed biofilm reactor sidestream deammonification process, which uses K5 biofilm carriers and media-retaining screens, eliminating anammox washout. Biomass remains attached to the carriers as high TSS passes through. The system was retrofitted to existing tanks and includes media, media-retaining screens and medium-bubble aeration diffusers designed to be maintenance-free. The media fill volume of the two reactors leaves room for expansion by adding more media if ammonia loading increases. The process control strategy has flexibility to be controlled by DO, pH or ammonia for optimal energy savings.

Result: The reactors reached the design loading and removal rates despite high influent TSS. Since startup, the system continues to meet the design nitrogen removal rates. 800-337-0777;  

Screw press used to effectively dewater while saving time, money

Problem: The 2 mgd Upper Sandusky (Ohio) Wastewater Treatment Plant aerobically digested its biosolids and dewatered them to 10% solids on drying beds. Due to the age of the beds, hauling costs were increasing and personnel spent more time keeping the beds functioning.

Solution: The city successfully tested a Schwing Bioset screw press. It delivered cake at more than 20% solids, and plant staff found it well constructed and easy to use.

Result: The Schwing Bioset equipment became the basis of the design for a new dewatering building. The FSP 603 screw press reduced hauling costs substantially because of the higher solids content and a reduction in labor. 715-247-3433;

City saves on polymer expense by implementing two-zone polymer activation system

Problem: The original wastewater treatment plant in Fort Atkinson, Wisconsin, was built in 1972, and a large portion of the operating budget is spent on polymer, primarily to dewater aerobically digested sludge. The system was effective, but the operators sensed it required too much polymer and started to investigate efficiency opportunities.

Solution: UGSI Chemical Feed, working with its local Wisconsin representative, Energenecs, offered a free demonstration of the Polyblend-Magnum skid-mounted polymer system. Polyblend systems are designed to use an optimized energy sequence in the mixing chamber. By immediately subjecting the polymer to a high level of energy and then tapering the amount of energy in a second stage in the mix chamber, the system is able to activate polymer without subsequently “chopping it up” once the polymer starts to increase in viscosity.

Result: The system was able to decrease polymer usage by 25-30% and enabled the dewatering equipment to operate more efficiently. The city projects an annual savings of $20,000. Staff also found the system to be much more space efficient versus the older mix-tank system. 855-669-3845; 


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