Simple package improves dewatering

Problem

An upgrade to the Groton (N.Y.) Wastewater Treatment Plant from 0.35 to 0.5 mgd included sequencing batch reactors followed by tertiary treatment. The Public Works Department also wanted to replace the aged and undersized drying beds with a more efficient dewatering system. In summer, the beds averaged cake at 12 percent solids. In winter, they became storage ponds with insufficient capacity.

 

Solution

Engineers selected the 3012 DSP screw press from BDP Industries for its compact footprint and ability to dewater tramp material. A positive displacement pump transfers feed slurry from the aerobic digester to the rotary drum thickener. Thickening the slurry before dewatering increases throughput capacity. The slow-turning dewatering mechanism and few moving parts reduce maintenance costs.

 

Result

Dewatering results exceeded the department’s expectations of 12 percent solids. The press turned feed sludge at 0.5 to 0.7 percent solids into cake at 15 to 17 percent solids. 518/527-5417; www.bdpindustries.com.

 

Bar screens simplify maintenance

Problem

Weekly greasing of the climber screens at the 80 mgd Donald C. Tillman Water Reclamation Plant in Van Nuys, Calif., was tedious and hazardous. Operators set up fans and put on hazmat gear before climbing down into a 9.5- by 5-foot-wide confined channel with poor air quality and working conditions. Other maintenance included replacing broken misaligned rakes, freeing clogs, and dealing with corrosion on carbon steel components.

 

Solution

Maintenance supervisor Pritpal Jhaj reviewed alternatives and selected 46 mgd stainless steel Mahr bar screens from Headworks. Multiple rakes keep debris flowing from the screen troughs and drain lines to prevent clogging, while the self-reversing feature automatically dislodges material. The variable drive maintains the appropriate water level.

 

Result

“Inspection and maintenance are completed at ground level,” Jhaj says. “Operators can walk up to the observation doors and see the equipment working.” The channels also are covered to prevent accidental falls. The custom-fit bar screens installed smoothly into the existing space. The operators have since recommended the equipment to sister facilities. 877/674-6667; www.headworksusa.com.

 

New filter belts restore efficiency

Problem

Operators at the Franklin Regional Wastewater Plant in Murrysville, Pa., struggled with belt blinding and sludge throughput on the belt filter press. Although they used a polymer belt cleaner and power washed the belt daily, the press failed to reach design capacity. Plant superintendent Gene Greco tried different polymers, cleaning methods, and increasing the washwater pressure, but saw no improvement.

 

Solution

Greco decided the press needed a new cloth and ordered Nano Green belts from National Filter Media. Molecular changes in the fiber decrease blinding, increase throughput, and heighten resistance to abrasion.

 

Result

After installing the belts, dewatered biosolids were 2 percent drier, throughput was back to design levels, and the belts required little maintenance. “This is the greatest belt life that we have ever experienced,” says Greco. 800/321-5223; www.nfm-filter.com.

 

Membrane process pre-thickens biosolids

Problem

Suffolk County, N.Y., paid more than $100,000 annually to haul 1.1 million gallons of liquid biosolids from the Woodside Wastewater Treatment Plant to the Bergen Point wastewater treatment facility. Officials looked for a solids handling process to minimize hauling expenses.

 

Solution

Operators retrofitted a membrane thickening process from Ovivo into two sludge holding tanks. The Kubota flat-plate membrane pre-thickened the material to 3.5 percent solids.

 

Result

The process reduced hauling by more than 57 percent, saving the county $60,000 annually and achieving a return of investment in 2.5 years. 801/931-3000; www.ovivowater.com.

 

Screening protects membranes

Problem

The wastewater treatment plant in Lancaster, Ohio, was unable to meet the expected growth in waste loading from industrial customers, so officials decided to build a new facility. Consulting engineers proposed using membrane bioreactors, but needed to protect the highly sensitive membranes from stringy materials.

 

Solution

Engineers chose two Rotomesh pre-membrane screens from Parkson Corp. The rotating drum screens with perforated plate media have a high capture rate for stringy materials.

 

Result

The plant has been operating successfully for several months without a membrane failure caused by solids bypass. 888/727-5766; www.parkson.com.

 

Drying facility increases process efficiency

Problem

Emission and odor issues at a 52 mgd wastewater treatment plant caused the Greater Lawrence Sanitary District in North Andover, Mass., to shut down the biosolids incinerators. Officials then used costly private contracts to transport the material to distant incinerators and landfills. The district hired a consultant to identify the best biosolids management options.

 

Solution

The plant upgrade included anaerobic digesters to thicken the material and a centrifuge to dewater it. Officials selected NEFCO to design, build, and operate a drying facility using digester gas and convert sludge cake into biosolids suitable for fertilizer.

 

Result

Two drying trains are designed to process more than 76 wet tons each per day at 25 percent solids. Dryer exhaust is treated by scrubbing, condensing, exhaust recirculation, and thermal oxidation. 617/773-3131; www.nefcobiosolids.com.

 

Facility upgrade adds dewatering efficiency

Problem

The Biosolids Recycling Center at the Philadelphia (Pa.) Water Department processed 30 percent of the city’s biosolids into Class A product. They transported the remaining material to a landfill or land-applied it. Increased tipping fees, escalating fuel costs, and stricter regulations added to issues of odor control and insufficient capacity.

 

Solution

Officials decided to upgrade the plant to process 100 percent of the biosolids into Class A product. The department selected Synagro Technologies and partners Andritz Separation, King Engineering Associates, and TN Ward Co. for the work. During the interim operations phase, Synagro assumed operations of the dewatering facility.

 

Result

The new facility uses thermal drying or pelletizer technology. It processes up to 65,000 dry tons per year of biosolids and meets Class A requirements. 800/370-0035; www.synagro.com.

 

Cleaning tool saves $11,000 for treatment plant

Problem

The 84 mgd (average) Metro Wastewater Treatment Plant in Syracuse, N.Y., serves 270,000 people. The plant staff was facing high labor costs for cleaning sludge and grit from 22 tank floors, cleaning the outfall troughs, and handling spills.

 

Solution

The plant’s mechanical maintenance coordinator tried the Waste Blaster hybrid hand tool for annual cleaning and maintenance inspections of the tanks. Workers found them efficient, durable, and easy to use. During cleaning, they push and pull the tool with its aluminum rubber-edged blade. Personnel report that the tool speeded up jobs and reduced worker stress and strain. The 24-inch-wide version worked well in tight places and for clearing the outfall troughs. The handles quickly disconnect from the blade for cleaning and storage.

 

Result

Using the tools, the plant cut tank cleaning time by one-third, saving an estimated $11,000 ($500 per day times 22 tanks) and cutting out squeegee costs. The staff also reported using one-third less water. The plant owns 11 of the tools and expected to purchase more in 2012. 315/569-9974; www.waycoolproduct.com.