Cross-linked polyethylene tanks resolve safety issue

Problem

Sodium hypochlorite began weeping from three 7,000-gallon high-density linear-polyethylene tanks at the Neenah (Wis.) Wastewater Treatment Plant after a year of use. The facility treats 10 mgd and uses 400 to 500 gallons of chemicals daily. Maintenance manager Jim Peichl tried different repair options before replacing the tanks.

Solution

Peichl ordered three 5,200-gallon cross-linked polyethylene tanks from Assmann Corp. of America. Cross-linked bonds in the polymer structure better withstand impacts and chemical attack.

Assmann delivered the tanks in four weeks, resolving the plant's safety issue. 888/357-3181; www.assmann-usa.com

Density current baffle reduces TSS

Problem

In 2007, the Monclova (Mexico) Wastewater Treatment Plant was upgraded from 11.5 mgd to 15.5 mgd. As the flow reached the three 112-foot-diameter clarifiers, effluent TSS rose to more than double the 5 ppm limit. To remain compliant, the facility considered a fourth secondary clarifier at more than $560,000, or some way to improve the operation of the existing units.

Solution

Before ordering the additional clarifier, plant officials contacted NEFCO to see if the Stamford Baffle 2.0 could help reduce TSS. They bought one for $22,000 and installed it on a clarifier. The density current baffle features a 30-degree inclination angle and an increased horizontal projection. Tests during summer 2009 showed a 78 percent reduction in TSS.

The municipality installed baffles on the other clarifiers, saved more than $500,000, and remained in compliance. 561/775-9303; www.nefcoinnovations.com

Process thickens waste activated sludge

Problem

The 0.5 mgd (design) Patchogue Wastewater Treatment Plant on Long Island, N.Y., upgraded its biological process to a 1.2 mgd integrated fixed film aeration system, increasing biosolids production and raising hauling costs to more than $27,000 a month.

Solution

Operators retrofitted a membrane thickening process from Ovivo into two existing tanks. A Kubota flat-plate membrane prethickens waste activated sludge to 3 percent solids.

The village saved more than $327,000 in annual hauling fees. Based on those savings, officials will see a payback on their $1.5 million investment in 4.5 years. 801/931-3000; www.ovivowater.com

Custom building protects equipment

Problem

The Williamsburg (Ohio) Waste Water Treatment Plant needed fiberglass shelters to protect a grit washer and a mechanical bar screen. The bar screen enclosure had to sit on an existing concrete slab poured at two different elevations with an 18 inch difference in height. Roughly half the building would sit up on the higher portion. The grit washer enclosure was installed on a new concrete foundation with two elevations. The doorway dropped down below the bottom of the walls into a 10-inch-deep notch in the concrete.

Solution

Engineers at Burgess & Niple specified field equipment shelters from Shelter Works. Project manager Chuck Berry from Layne Heavy Civil worked with the engineers and village representatives through the shop drawing phase. The custom-made structure with an explosion-proof electrical package had some tall walls, some shorter walls, some standard-sized doors, and some short doors for access to both sides.

"Installation was quick and we were done in a matter of hours," says Berry. 800/794-8037; www.shelter works.com

Storage tank enables water conservation

Problem

An irrigation expansion project by the City of Antioch and Delta Diablo (Calif.) Sanitation District included six miles of conveyance and distribution piping, a pump station, and a 1.1-million-gallon recycled water storage tank to be buried beneath the 14th tee at the Lone Tree Golf Course.

Solution

The district hired Psomas, a local engineering firm, to design the project. Engineers specified a prestressed concrete tank to withstand the weight of the concrete masonry station built on top of it. JMB Construction won the contract and subcontractor DYK, a division of DN Tanks, cast the tank.

The city converted the golf course, four municipal parks, medians, and other green spaces along the pipeline from irrigation with potable water to recycled water. 855/368-2657; www.dntanks.com

Cleaning tool saves $11,000 for treatment plant

Problem

The 84 mgd (average) Metro Wastewater Treatment Plant in Syracuse, N.Y., faced high labor costs for cleaning sludge and grit from 22 tanks and outfall troughs, and handling spills.

Solution

The plant's mechanical maintenance coordinator tried Waste Blasters heavy-duty squeegees from Way Cool Product Co. During annual cleaning and maintenance inspections of the tanks, workers found the hybrid pusher-puller hand tool efficient, durable and easy to use. Aluminum rubber-edged blades sped up jobs and reduced physical effort. For cleaning outfall troughs and working in tight places, workers used units with 24-inch-wide blades.

Tank-cleaning time was reduced by one-third, saving an estimated $11,000 ($500 times 22 tanks), and workers used one-third less water. The plant owns 11 of the tools and expects to purchase more. 315/569-9974; www.waycoolproduct.com

Treatment packages increase capacity

Problem

The 0.5 mgd (design) Patchogue (N.Y.) Wastewater Treatment Plant was running out of capacity. To meet new discharge regulations, village officials hired an engineering firm to design a 1.2 mgd plant expansion and upgrade.

Solution

Engineers chose two STM-Aerotor biological nutrient removal systems and two clarifier optimization packages from WesTech Engineering for the 55-foot-diameter secondary clarifiers. Their addition increased capacity to 0.8 mgd.

The technologies reduced CBOD, TSS and total nitrogen to well below the mandated levels, making the plant one of the most efficient in the state. 801/265-1000; www.westech-inc.com

Insulated cover controls algae and TSS

Problem

The Sanford (Fla.) Utilities Plant Division wanted to control algae and TSS solids in the chlorine contact chamber at one of its wastewater treatment plants.

Solution

Engineers at Lemna Technologies recommended a floating LemTec modular cover with R-10 insulation value and greater than 10-year UV stability.

When installed, the cover immediately controlled algae, reduced TSS, and produced satisfactory effluent for private and commercial irrigation. 612/253-2000; www.lemnatechnologies.com

Modular building solves multiple challenges

Problem

Operators at the Wadena (Minn.) Wastewater Treatment Plant wanted to remove the rotten wooden frame building covering the primary clarifier and replace it with a fiberglass structure. Enclosed secondary clarifiers on either side of the basin limited space and made it challenging to locate access points, stairs, doors and exhaust systems.

Solution

Engineers at RM Products designed a custom industrial straight-wall modular fiberglass building to fit the allocated space. Magney Construction in Chanhassen assembled the unit.

The building fulfilled the needs of the site. 800/363-0867; www.rmfiberglass.com