Reuse, Recovery and Energy Management

Reuse, Recovery and Energy Management

Decanter effectively replaces belt press

Decanter effectively replaces belt press

Problem: For the West Central Conservancy District in Hendricks County, Indiana, the dry matter produced by its belt press was achieving mediocre results in terms of dry substance. They sought a better option.

Solution: The Flottweg Separation Technology C decanter series was designed to dewater and thicken the sewage slurry. The decanter centrifuge offers safe and fully automated operation and emits minimal odor because of a closed-system design.

Result: The previous system required 4.5 to 5 gph polymer feed to a belt press. Now, using two centrifuges, the facility feeds 1.75 gph. “Sometimes we can run as low as 1.25 gph,” says Bernard Brown, assistant superintendent. “This equates to a real savings because the polymer is roughly $16 per gallon. We can direct where we want the cake to go — to each of the three containers. We can change the feed rate and the polymer dosage rate from one control screen. The automation makes it extremely easy to use. It’s easy to train new operators. Generally, we just press the button and walk away.” 859-448-2331;

Treatment targets and controls filamentous organism growth

Problem: A large Midwest food and beverage facility needed to optimize sludge settling through better management of filamentous microbes in its biological treatment facility. The company uses an attached growth biological treatment process in addition to trickling filtration and secondary settling. While natural convection maintained adequate airflow in winter, sulfide toxicity in summer was causing overgrowth of filamentous organisms, leading to sludge bulking and higher effluent turbidity.

Solution: Water Warriors implemented a treatment using SETZYME, formulated to prevent filamentous growth in trickling filters and activated sludge treatment plants.

Result: After 21 days of treatment, effluent turbidity began to decline. Enzyme addition is being continued at a maintenance dosage to keep the filamentous organisms from establishing themselves in the biofilms on the rock media, especially during high influent BOD conditions. 859-629-2236;

Eco-friendly geotextile filtration unit reduces costs and environmental waste

Problem: Oulun Energia power plant in Finland was hauling its waste to a landfill using a vacuum truck at a cost of $400,000 a year. Operators wanted to reduce costs and the environmental footprint.

Solution: The Flowrox GeoBag offered an efficient solution. The container has a perforated bag inside. When waste is pumped in, the solids stay in the bag and the water drains to the bottom. The floor is watertight with a drain valve so that the filtered water can be pumped out. The unit can be heated for colder climates.

Result: The plant saved over $200,000 and none of its waste was sent to the landfill. At the end, the process left with a small amount of dried waste, which was reused as an energy source. The filtered water was discharged. 410-636-2250;

Hydrolysis enables plant to capture more biogas

Problem: The Kenosha (Wisconsin) Wastewater Treatment Plant was producing more biogas than it could use but not enough to justify installing another gas engine. The excess gas was being flared. 

Solution: The city installed the PONDUS hydrolysis process from Centrisys/CNP. It includes a tube-in-tube heat exchanger, a hydrolysis reactor, two progressive cavity pumps, and a sodium hydroxide dosing station. The system uses a thermo-chemical reaction at about 140 degrees F that changes the sludge viscosity for a trouble-free, easy flow. 

Result: By using the PONDUS process on waste activated sludge, the plant increased gas production by more than 20 percent, enabling installation of a combined heat and power unit. Heat from the engine is used to heat the waste activated sludge and operate the PONDUS system. The plant now produces about one-third of its electricity from biogas. 262-654-6006;

Repair-in-place turns five-week repair into five days

Problem: A pump drive at a wastewater treatment plant in Southern California showed significant wear in some critical rotating components, threatening a gearbox breakdown and a major disruption in operations. A complete overhaul would take four to five weeks in a repair center. The site did not have a spare and was running at peak capacity. 

Solution: Philadelphia Gear - A Timken Brand’s Onsite Technical Service team proposed to repair the drive in place. Instead of disconnecting the gearbox and shipping it to the shop, the team submitted an order to manufacture the damaged parts ahead of time. This included building up the bevel pinion shaft, bevel gear shaft and output shaft subassemblies at the shop. Each of these left Philadelphia Gear’s Western Region Service Center with new bearings mounted, and cartridges and spacers installed. The team then rebuilt the gearbox at the plant.

Result: The overhauled pump drive was in operation in just under five days. As the last phase of the job, the team shipped the damaged rotating elements back to the shop for evaluation. Some damaged components were overhauled and recertified to be used as spares, then long-term preserved and shipped back to the plant. 800-766-5120;

Drum skimmer effectively removes FOG from primary treatment cell

Problem: In early 2016, operators of a wastewater treatment facility in Carmi, Illinois, sought to reduce FOG in the primary treatment cell. Recovered material was being removed from the skimmer manually into a bucket. Material needed to be removed more efficiently. 

Solution: An Elastec TDS118 grooved drum skimmer was placed in the primary treatment cell.

Result: In five months, TSS was reduced by 66 percent. As the year progressed, a prototype skimmer and recovery tank system was developed with fully automated operation. On average, the system removed 473 pounds of FOG per month from the 1 mgd treatment plant. 618-382-2525;

Cloth media filters treat combined sewer overflows

Problem: The City of Rushville, Indiana, had to comply with a 2007 consent order for combined sewer overflows polluting the Flatrock River. The city planned to install a 1-million-gallon stormwater storage tank, but it was approached by Aqua-Aerobic Systems with a pilot test proposal using the AquaPrime cloth media filter.

Solution: The pilot study captured events from May to July 2015. The results prompted the city to request a design for an Aqua-Aerobic Systems AquaPrime filtration system that could treat both dry- and wet-weather flows. An alum coagulant was to be injected upstream of the filters to meet future effluent phosphorus limits and eliminate fine CSO particles.

Result: Two 14-disk AquaPrime systems started up in July 2017 with a design average flow of 1 mgd (dry) and 12.6 mgd (peak wet-weather). The filters were retrofitted to abandoned sand media filter structures, saving capital costs. The system cost $1 million less than the storage tank proposal. This was the nation’s first AquaPrime filter installation for dual tertiary/wet-weather treatment and will keep some 50 million gallons of raw sewage per year from entering the Flatrock River. 800-940-5008;   


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