Municipality upgrades to decanter centrifuge with greased bearings

Problem

A southern wastewater treatment plant needed to upgrade its 25-year-old decanter centrifuges for efficiency and was leaning toward models with oil-lubricated bearings.

Solution

The plant selected the ALDEC G3 decanter centrifuge with greased bearings from Alfa Laval. The plant operators now prefer the technology. The centrifuge also provides long life, dependability and excellent process performance. 

Result:

The G3-125 decanter centrifuge can double the flow in the same footprint as the previous equipment, cut power consumption in half and reduce polymer use. Alfa Laval delivered the solution turnkey by partnering with an integrator, saving money on engineering and installations. The approach also enabled the installation of two units instead of one and reduced the project timeline by nearly one year. 866-253-2528; www.alfalaval.us

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Well-washers eliminate FOG and odor issues 

Problem

The growing city of Bonney Lake, Washington, (population 20,000) faced issues with FOG in its 25 lift stations, some processing 600,000 gpd. FOG issues were such that three crew members spent a full day every two weeks removing debris, including FOG.

Solution

The city installed Anue Water’s EnviroPrep Well-Washer Systems at eight lift stations and budgeted to install two to three more every year.

Result:

The city has written the systems into its specifications and standards. Now crew members clean the stations every six months. “We were sending three guys down there, so that’s costing me 18 man-hours twice a month,” says Curt Roundtree, sewer department lead. Now they can focus on other tasks and calls for health alarms or clogged pumps have been reduced. Many of the stations are near homes and, with less FOG, there are no more odor complaints. 760-727-2683; www.anuewater.com

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Screening system solves municipality’s ragging issues

Problem

The Coweta County Water Authority facility in Newnan, Georgia, serves 127,000 residents. The authority needed to resolve clogging issues that were reducing plant efficiency and damaging pumps. Operators had to derag the pumps every two weeks. The authority needed a solution that would not require additional construction or equipment. An existing manhole was upstream from the pumps, but due to site constraints, there was a need for a bar screen that would work without structural modifications.

Solution

The authority chose an Aqualitec Screentec unit for its ability to remove large amounts of rags and debris. The unit can retrofit to any manhole and provides a barrier against fouling, ragging, and debris buildup. It is flexible, durable and low-maintenance, and it frees operators from removing debris manually.

Result:

After nearly six months of service, the only maintenance needed was to spray oil onto the channel to allow for better travel. 310-703-2174; www.aqualitec.com

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Centrifuge helps municipality save on disposal costs

Problem

The 32 mgd treatment plant at the Lowell (Massachusetts) Regional Wastewater Utility faces extremely high biosolids costs. An older 30-inch-bowl-diameter centrifuge rental did not achieve consistent dry solids, and the plant was paying more for disposal and transportation.

Solution

The utility chose a Centrisys/CNP CS26-4 centrifuge for a three-year rental term.

Result:

After one year, the centrifuge improved the cake dryness by 4-5% total solids while using 30-40% less power than the previous rental. Despite a smaller bowl diameter, it consistently increased flow capacity. Operational savings have been significant. 262-654-6006; www.centrisys-cnp.com

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Receiving station helps ready plant for increased influent load 

Problem

Legislation for septic tanks in Florida may lead to higher septage volume at Indian River County’s biosolids dewatering facility. Regulations may 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 Equipment. The compact, self-contained unit compresses 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 maintenance is required. 630-837-5640; www.lakeside-equipment.com

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Screw press provides backup dewatering and lime stabilization 

Problem

The Little Blue Valley Sewer District wastewater treatment plant (25 mgd average) in Independence, Missouri, has a solids process that consists of centrifuges that feed a fluidized bed incinerator. During maintenance or when the centrifuges or incinerator were out of service, liquid or dewatered biosolids had to be landfilled, increasing operation costs.

Solution

The district chose Schwing Bioset’s 1203X screw press for its reliability and low maintenance and its capacity to handle the plant’s full solids load with a single unit within the available footprint. Lime stabilization was found to have the lowest capital cost versus other treatment options, such as digestion.

Result:

The screw press dewaters 4,700 dry pounds per hour to at least 24% solids. The material is fed to the incinerator or the new Class B Bioset process. During incinerator downtime, the process treats waste activated and primary sludge to Class B. The district has brokered off-take agreements with farmers and nurseries to receive the biosolids at a fraction of the cost of landfilling. 715-247-3433; www.schwingbioset.com

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Enhancing sludge dewaterability and phosphate removal 

Problem

The 30 mgd Lower Arkansas Water Quality Reclamation Facility in Wichita, Kansas, anaerobically digests biosolids and dewaters the materials on belt filter presses. The staff wanted to increase the solids content and reduce the biosolids phosphorous concentration.

Solution

The facility began using USP Technologies’ PRI-TECH process by adding hydrogen peroxide and ferric chloride at strategic locations in the collection system and plant. The hydrogen peroxide allows the spent iron to be reused, providing more process benefits at a low cost.

Result:

Cake solids content increased from 18% to 23%, soluble phosphorous levels in the filtrate decreased by 85%, polymer demand declined by 30% and throughput capacity increased by 85%. The cost savings met the 50% annual target of $150,000 per year. Mercaptan odor was reduced; while ferric chloride addition had no effect on purgeable mercaptans, hydrogen peroxide addition achieved more than 95% removal. Both chemicals effectively remove hydrogen sulfide. 877-346-4262; www.usptechnologies.com

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Dryer system enables municipality to produce Class A biosolids 

Problem

The Picnic Point Wastewater Treatment Facility in Edmonds, Washington, was reaching capacity, facing higher biosolids management costs. The staff sought to produce a Class A material that would be easier to land-apply.

Solution

Using Veolia’s BioCon dryer, dewatered cake is pumped into the drying system through oscillating depositors on top of the dryer cabinet. The depositors distribute the biosolids onto a slow-moving belt for drying; the material then falls to a second belt where the desired dryness is reached. The unit uses hot-air circulation to evaporate water. The temperature varies from 350 to 175 degrees F as the material completes the drying process. The air is recycled in a closed circuit under negative pressure, containing odors. The operation is fully automated.

Result:

The system produces Class A biosolids used by a third party as a farm fertilizer. The plant has doubled its wastewater treatment capacity to 4 mgd, expandable to 6 mgd. The project was completed in a small footprint and has allowed the city to create a valuable product, earning the community’s support. 800-337-0777; www.veoliawatertech.com