Dual focus on wastewater

July 2011 » Products » ENGINEERED SOLUTIONS
Economics and the environment drive technology adoption.
Bob Drake

When asked about trends in the wastewater industry, the response from manufacturers of products and systems for collection and treatment can be summed up in two words: economics and environment. According to Daniel O'Connor, vice president of polyethylene sales, JM Eagle: "Increased environmental and economical concerns are clearly the main drivers (and rightly so), but those concerns are compounded by increasing evidence of our country's crumbling underground infrastructure. ... Civil engineers are looking for alternatives that are cheaper and easier to install, stronger, last longer, and are better for the environment."

Andrew M. Jenkins, national plastic products manager, Contech Construction Products Inc., noted an emphasis on designs that not only are cost effective, but also are capable of providing flexible, sustainable, environmentally friendly, and low-impact solutions. "There has been an increased demand for solutions involving combined sewer overflow (CSO) storage, package wastewater treatment systems, and large-diameter conveyance," he said.

Wastewater treatment plant (WWTP) projects often involve multiple objectives, such as upgrades, to meet regulations, capacity increases, improvement in energy efficiency, and reduction in biosolids volume, said Paul Rice, global market director, Municipal Water & Wastewater, Siemens Water Technologies Corp. "While there continues to be interest in new state-of-the-art facilities, particularly in growing regions, investment in existing WWTPs is increasing as a percentage of total investments," he said. "Over 40 percent of U.S. WWTPs are planning major upgrades in the next five years."

However, some WWTP capacity increases might be offset through use of decentralized treatment systems, according to Robert Rebori, president, Bio-Microbics Inc. "Water mining – using large, decentralized wastewater treatment systems to divert and pretreat influent for overloaded municipal plants – has been found to reduce costs and improve efficiencies," he said. Additionally, Rebori points to the effective use of onsite wastewater treatment systems to provide irrigation water.

Steve Kingsland, national sales, Marketing & Engineering Group, Oldcastle Precast, agreed: "There is a growing trend to redefine wastewater treatment as resource recovery. By finding ways to recover things like water for reuse, nutrients for fertilizer, and even energy, significant operating cost reductions or offsets are possible."

Jens Sonntag, vice president, Engineering, A3-USA Inc., also noted a trend toward smaller, decentralized wastewater treatment and collection systems. "In general, it is assumed that larger systems lower the cost per gallon of wastewater treated," Sonntag said. "However, once a certain size is reached – 1 to 2 million gallons per day – the treatment cost per gallon does not continue to decrease; in some cases [costs] actually increase during construction."

At the same time, capital budgets for many municipalities are down 50 percent or more as compared with pre-recession levels, according to Louis le Roux, president, BioAir Solutions, LLC. And municipalities also are cutting operational budgets, trying to achieve more with less. Some plant owners are doing more design work themselves – at least in the area of odor-control projects – which in the past might have been outsourced to third-party engineering firms.

Record rainfalls in 2011 have pushed many sewer systems beyond the point of typical repairs. ADS SaniTite HP pipe provides an easy, affordable, and readily available replacement option.
CONTECH's DuroMaxx SRPE provides wastewater storage and treatment.

According to Siemen's Rice, these economic factors are driving an interest in performance contracting, whereby capital investments can be made with little or no capital outlay. "In this type of approach, project investments are paid for directly by specified annual operating cost savings," he said. "Projects that reduce energy use or that lower biosolids disposal costs are two good candidates for this type of investment. Performance contracting is an opportunity for engineers to help a municipality kick-start a needed project."

On the wastewater collection side, David Martin, national sanitary market manager, ADS Inc., said that inflow and infiltration (I&I) reduction initiatives are being viewed as an investment, with a return on investment, rather than a cost to an agency. Additionally, "the record-setting rains experienced in early 2011 exposed the faulty condition of many wastewater lines across the United States," Martin said. "Due to the severity of the repairs required, we are seeing an increasing trend toward complete replacement of portions of the sewer line via open cut or slip line."

Environmental concerns
However, cost concerns are not totally overriding environmental concerns; even pipeline replacement is being evaluated from an environmental perspective. "Owners and engineers are paying more attention to the extraneous effects of a project, including social and environmental costs, for example, [in] the decision-making process for utilizing trenchless versus open-trenching methods in the installation of pipe," said Kimberly Paggioli, P.E., vice president, Marketing & Quality Control, HOBAS Pipe USA. "This could be social effects caused by traffic disruption in an already congested city, or effects to native habitats during construction."

Reduced construction impacts are a benefit of one technology that may be appropriate in some applications: vacuum sewer systems. Smaller-diameter pipe is installed in narrow, shallow trenches by smaller equipment, said Rich Naret, P.E., vice president, AIRVAC. In addition, vacuum sewers eliminate I&I, which reduces pollution and protects sensitive ecosystems, he said.

Ecosystem protection also is the goal of more stringent limits on nutrients, which according to Mark Boner, vice president, WWETCO, requires additional biological treatment or chemical precipitation and filtration. However, nutrient removal technologies are more sensitive to wet weather peaks, Boner said, so there is a need for new technologies and more flexible solutions to manage and protect WWTPs.

Wastewater technology
With a dual emphasis on economic and environmental issues, civil engineers need to stay current on new and emerging technologies to evaluate design options effectively.

Slip lining or trenchless installation of HOBAS pipe can decrease environmental impacts of wastewater collection system projects.
JM Eagle's Eagle Corr PE is available in 4-inch to 60-inch diameters and is suitable for use in gravity flow applications. It features a corrugated exterior for structural strength and smooth interior for maximum hydraulic efficiency.

A3-USA (www.a3-usa.com) launched a membrane bioreactor module designed for small-scale, on-lot systems. Most equipment, including tanks, piping, and controls, is manufactured in its shop in Irwin, Pa., to minimize costs. A3-USA also developed low-cost membrane sludge dewatering equipment that has been installed in existing plants and has reduced sludge disposal costs by 85 percent, the company said.

ADS (www.ads-pipe.com) developed the SaniTite HP pipe product line made from polypropylene resins. SaniTite HP pipe can be specified along with traditional materials including ductile iron and fiber-reinforced and solid-wall PVC in most gravity applications. SaniTite HP includes a dual-gasket spigot with an "in-line," fiberglass-reinforced bell for enhanced joint performance.

AIRVAC (www.airvac.com) is in the advanced stages of developing a valve monitoring system for its vacuum sewer systems that will notify operators in real time of any problem at any given valve pit. The monitoring system also will provide key system-wide data 24/7, allowing operators to fine tune their system to optimize performance.

BioAir Solutions (www.bioairsolutions.com) developed small-scale biological odor-control systems for pump stations and collection systems. Its EcoPure Mini provides vapor phase odor control that, according to the company, is less expensive and more efficient than liquid phase technologies.

Bio-Microbics (www.biomicrobics.com) said its decentralized wastewater treatment products are designed for low cost and maintenance while maintaining a wide variety of flexible options for simplicity. Its advanced treatment units, membrane bioreactors, and other appurtenances offer options for retrofit, upgrade, or new construction.

An AlgaePac decentralized wastewater treatment system from Oldcastle Precast is under construction at the Cincinnati Nature Center, Rowe Woods in Milford, Ohio.
Retrofitting existing secondary clarifiers with Siemens Rim-Flo technology increases capacity in the same footprint.

CONTECH's (www.contech-cpi.com) steel reinforced polyethylene (SRPE) pipe technology in diameters as large as 120 inches combines pressure-rated polyethylene with high-strength steel reinforcing members. Additionally, the company said, advancements in ElectroFusion technology create bottle-tight system connections.

HOBAS's (www.hobaspipe.com) commitment to environmental stewardship was reaffirmed through a rigorous environmental analysis of its internal environmental management system, the company said. Through these efforts, HOBAS pursued and subsequently was awarded ISO 14001 certification.

JM Eagle (www.jmeagle.com) has expanded production of low-impact development products such as solid-wall HDPE for slip lining pipelines. JM Eagle also has developed directional drilling products, such as its new Eagle Loc PVC product line, that reduce the need for exterior joints – a common source of leaks.

Oldcastle Precast (www.oldcastleprecast.com/wastewater) offers the AlgaePac system, a modular, packaged wastewater treatment system. AlgaePac uses photosynthetic algal contactor wheels rotated by a low-energy air drive method to provide an optimum environment for algae and bacteria to thrive. Solar energy is used by the algae to convert nutrients from the wastewater and provide oxygen for use by bacteria, while bacteria convert organics to CO2 for use by the algae.

The Heard County Water Reclamation facility in Heard County, Ga., uses a WWETCO FlexFilter for tertiary treatment.

Siemens Water Technologies (www.siemens.com/water) provides expertise, experience, and high-performance technologies to increase capacity of existing clarifiers. Siemens also offers the Forty-X disc filter with 40 percent more filter area in a given footprint compared with other disc filters. These tertiary filters can be retrofitted into plants that have traditional sand or multimedia filtration.

WWETCO (www.wwetco.com), a WesTech subsidiary, has developed the FlexFilter, which uses a synthetic fiber media that is compressed laterally to form a porosity gradient to remove large and small particles from the top to the bottom of the media bed. FlexFilter versatility includes tertiary filtration with metal salts; high-rate biological filtration; CSO filtration; bio-filtration of sewage; and remote CSO treatment.

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