March 2009, Vol. 21, No.3

From Planes to WWTPs

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Often, a technology’s initial application is only the beginning of its usefulness. After a technology is proven in one industry, another may adapt it to suit its needs. As wastewater treatment professionals look to improve efficiencies, some are turning to technologies that originated far afield from wastewater treatment — in aerospace, for instance.

Airplanes and the activated sludge process might not seem to have much in common. But turbo blowers adapted from the aerospace and defense industries can help reduce the costs of supplying oxygen to biological reactors, which can use 50% to 90% of the energy consumed in an activated sludge treatment system.

“If you look at the layout of our blower, it has the same layout as a turbofan jet engine,” said Omar Hammoud, president of APG–Neuros (Montreal), a turbo blower manufacturer. The turbo blower lubricates impeller rotation with air instead of oil, according to Hammoud.

The key to oil-free lubrication is a technology application called an airfoil bearing. As a high-speed electric motor turns the impeller and pulls air through the blower, the airfoil bearing, relying on the principle of hydrodynamic pressure, creates a thin cushion of air between the shaft and bearing surfaces.

“There’s no friction,” said John Fountas, a principal engineer at CH2M Hill (Englewood, Colo.). The shaft holding the impeller has no contact with the volute, he said. Fountas worked on a project to install turbo blowers at the James River Wastewater Treatment Plant in Newport News, Va.

The advantages to frictionless operation include increased energy efficiency, low vibration and noise, greatly reduced maintenance needs, and a small footprint, Hammoud said.

A side-by-side comparison of a traditional blower and a turbo blower in Franklin, N.H., showed a 30% to 40% energy savings with the turbo blower, Hammoud said. In addition to reducing power consumption, turbo blowers also can reduce “installed power,”  he said.

For example, a 75-kW (100-hp) turbo blower can replace a 112-kW (150-hp) unit. In a plant with four such blowers, switching to turbo blowers reduces installed power from 450 kW (600 hp) to 300 kW (400 hp), Hammoud said, potentially resulting in credits from the electric utility.

Additionally, these blowers are “as quiet as a car,” Fountas said. They produce less than 80 decibels of noise without an optional inlet silencer, according to the Neuros Web site.

The units also are small, compared to their traditional counterparts. For example, a 225-kW (300-hp) turbo blower requires a 1.2-m × 1.8-m (4-ft × 6-ft) footprint, or one-half to one-quarter the amount of space needed by a traditional 225-kW blower, Fountas said.

For the James River plant, a life-cycle analysis of the turbo blower, single-stage blower, positive-displacement blower, and multistage centrifugal blower showed that the turbo blower came out far ahead, Fountas said. The capital cost for the turbo blowers will be a little more, but they will pay for themselves in a few years, he said.

Fountas said maintaining low costs is a driving factor for most wastewater treatment plant projects, but higher up-front capital costs are acceptable, within reason, for lower life-cycle costs.

“If you ask treatment plant operators, they’re also definitely looking for reliability and ease of maintenance,” Fountas said. “And this turbo blower is exactly that.”

A New Way To Mix
Another emerging technology focuses on improving the efficiency of a typical wastewater treatment process — mixing. Vertical linear motion (VLM) mixing is unique in that it reciprocates; it does not rotate in any way. VLM mixing works by raising and lowering a disc attached to a drive shaft.

This technology requires substantially less power to achieve the same degree of mixing as other technologies, according to Gary Haughton, president of Enersave Fluid Mixers Inc. (Oakville, Ontario). VLM mixing equipment also requires minimal maintenance, he said.

The VLM mixer originated in the mining and manufacturing industries, where it was used to maintain homogenous mixtures, Haughton said.

For example, the VLM technology was installed in the cyanide-dilution tanks at an aluminum-casting company to avoid any spikes in cyanide concentration in the effluent being discharged to the collection system, Haughton said.

When the factory used pressurized air to power its mixers, it could not achieve homogenous mixing and routinely ran short on compressed air for other factory uses. Haughton estimates that the factory was using a 75-kW (100-hp) compressor.

The VLM mixer, on the other hand, achieved the job and operated at a fraction of the power costs, Haughton said. Now, the factory has a VLM mixer in each of its two cyanide-dilution tanks and uses only 2 kW (3 hp) per tank to achieve homogenous mixing.

In 2003, Haughton’s company approached the Ina Road Wastewater Treatment Plant in Pima County, Ariz., and convinced the plant to install a VLM mixer in its 5.7-million-L (1.5-million-gal) anaerobic digester, which was 27 m (90 ft) in diameter with an 8.5-m (28-ft) side wall, a cone bottom, and a floating roof.

The mixer had a disc with a 213-cm (84-in.) outer diameter and a 41-cm (16-in.) stroke; it operated on a single 7.5-kW (10-hp) motor, Haughton said. That mixer replaced four 15-kW (20-hp) peripheral and one 7.5-kW (10-hp) central draft-tube mixers, he said.

During the 16-month pilot, laboratory tests showed the digester was mixing completely. Afterward, the plant drained the digester to check for accumulated grit and entanglements on the disc, and none was found.

The plant then installed VLM mixers in each of its four digesters. The plant is saving about $40,000 to $50,000 per year on electricity, Haughton said. In addition, none of the mixers has needed repairs in 4 years, and all have required only minimal maintenance.

However, convincing people that such a different technology could work was a challenge, Haughton said. At first, treatment plant management and engineers were skeptical of the technology, he said. It wasn’t until they saw it in operation that they considered that it could work.

To secure concrete data, Enersave hired Black & Veatch (Kansas City, Mo.) to perform a tracer study in the digester, Haughton said. The side-by-side test compared the performance of the VLM mixer in the test digester to the draft-tube mixers in the other digesters. The study revealed that the VLM system operated comparably to impeller draft-tube mixers but required substantially less electrical power.

“It’s taken such a long time for this to be accepted,” Haughton said. “Finally, the consulting engineers are coming around.”

In addition to the Ina Road Plant, which is planning to use VLM mixers in its new upgraded plant, several treatment plants in Canada are using VLM systems, Haughton said.

Electric-Pulse Technology
On the solids side of the plant, a technology used to kill pathogens in food could help make wastewater solids more digestible. A device using pulsed electric fields could rupture the cells of microorganisms in thickened wastewater solids, said Jim Banaszak, chief technology officer at OpenCel (Glencoe, Ill.), which manufactures such a device. If more material is readily biodegradable, then solids production will be reduced, leading to less biosolids needing disposal, and, in an anaerobic system, more methane produced.

The fundamental theory is that because biological membranes are made of polar molecules, they are susceptible to electric fields.

“If you have the frequency right and the voltage right, and have the width of the pulses correct, you can open up pores in the side of the membrane,” Banaszak said. “And if you open up and hold open the pore long enough ... osmotic pressure causes cell lysis.”

During the past 30 to 40 years, there have been a few predecessor technologies to this product, Banaszak said. The first comes from research for the food industry at Ohio State University (Columbus), where pulsed electric fields were used as an alternative to pasteurization. Food technologists used the pulsed electric fields to kill pathogens in food without affecting taste, texture, or smell.

Another application of this technology is used by the biotechnology industry and is called “electroporation.” Electroporation is used to open pores in cells temporarily to transfer cellular material, such as DNA or RNA, into a cell. Basically, they don’t apply as much power and open only small pores, Banaszak said.

It took about 6 to 7 years to transfer a viable food-industry technology to a full-scale installation in the wastewater field, Banaszak said.

For wastewater use, Banaszak said the predecessor technology to what is used today was first installed in a pilot project 7 or 8 years ago at an aerobic wastewater treatment plant in Ohio. Waste activated sludge passed through the device and was returned to the aeration basin for digestion to reduce solids production. About one-third of the plant’s thickened waste activated sludge flow was treated and recycled to the aeration basins; this treatment led to a 24% decrease in the amount of solids sent to the landfill, according to the OpenCel Web site.

However, the real advantage to this technology is the ability to produce more methane from an anaerobic digester, Banaszak said. Research at Arizona State University (Tempe) has shown that focused pulse treatment makes more of the biosolids soluble and boosts conversion to methane.

A system installed at an Arizona wastewater treatment plant in April 2007 showed a 41% reduction in biosolids requiring disposal and a corresponding 60% increase in biogas generation, according to the OpenCel Web site.

However, adapting the technology is only the first step. Perhaps the biggest challenge is overcoming skepticism and gaining acceptance. It takes time and results to gain an audience, Banaszak said.

“People want to see some track record or history,” Banaszak said.

— Steve Spicer, WE&T


 

 

 

 

 

Gaining Voter Support for Clean Water Initiatives
U.S. taxpayers are increasingly willing to pay for clean water and needed infrastructure projects, but water quality professionals say more funding is needed

In November, despite an increasingly negative outlook for the U.S. economy, voters in several states approved billions of dollars in state bond issues for infrastructure improvements. Measures also were passed that increase property and sales taxes to pay for clean water programs. However, in addition to these earmarks, more money is needed — specifically for the Clean Water State Revolving Fund, which industry professionals say would stimulate new economic growth while addressing the nation’s immediate infrastructure needs.

With a long, steady stream of bad news related to older infrastructure breakages, as well as overflow failures and sewer spills, people are now more supportive of allocating taxpayer money toward clean water programs and infrastructure projects, according to Greg Chung, an associate wastewater engineer in the Palo Alto, Calif., office of Kennedy/Jenks Consultants (San Francisco).

“People are realizing that money needs to be spent on water quality initiatives or we simply won’t have clean water to drink,” Chung said. “Infrastructure is equally important. ... Here in California, the last infrastructure bond measures passed, which shows that residents are ready to pay for these necessities. Without dedicating funding in this area, we could lose our advantage and fall behind in being a leader as an industrialized nation.”

According to Susan Bruninga, director of public affairs at the National Association of Clean Water Agencies (Washington, D.C.), polls show that the public overwhelmingly cares about the environment and water and that they are ready to pay for it. “The majority of people interviewed overwhelmingly support this issue,” she said. “They want clean water.”

Conservation Funding in Minnesota
Minnesota voters in November approved the Clean Water, Land and Legacy Amendment, the largest conservation ballot measure in U.S. history, which dedicates unprecedented funding to protecting water resources, water quality, and natural lands in Minnesota, as well as preserving the state’s arts and cultural heritage.

The amendment, which passed with a net 56% of the vote, effectively raises the state’s general sales and use tax rate by 0.375% to generate an estimated $7.25 billion during the next 25 years. Of the total proceeds, 33% will be dedicated to a clean water fund to protect, restore, and preserve Minnesota’s water quality, in addition to protecting drinking water sources. Another 33% goes to an outdoor heritage fund, which also can help improve water quality. The balance is dedicated to supporting parks and trails, and preserving arts and cultural heritage.

Cordelia Pierson, program director in the Minnesota office (Minneapolis) of the Trust for Public Land (TPL; San Francisco), a national conservation organization that advocated for the amendment, said approval of the measure reflects a historic commitment to preserving water and natural areas. “The results of public opinion surveys conducted in Minnesota over several years show that a large majority of the population — around 90% — supports taxation for water quality and habitat,” Pierson said. “While the support nationally for water quality purposes is strong, Minnesota’s support has been exceptional. And now Minnesotans are dedicating funding to show that support.”

TPL provided expertise from other successful state and local ballot measures. TPL’s Minnesota and national staffs worked with legislators and a broad coalition to propose ballot language that voters would understand clearly and also served on the campaign’s steering committee. TPL helped lead an education initiative to raise awareness and worked closely with public agencies to provide information for them, rather than advocacy. The campaign and education initiatives were effective in getting the most appropriate messages out to specific audiences and demographics using direct mail, broadcast media, earned media, grass-roots field organizing, YouTube, a speakers bureau, and even Google pop-up ads, Pierson said.

“The campaign effectively learned what voters’ interests were, what messages would best resonate with different groups, and where they get information,” Pierson said. “Raising general public awareness about the state’s surface water quality was extremely effective, as was using a targeted communications strategy in which key messages were relayed to key voters.”

Along with strategic targeting, Pierson said having clear and compelling ballot language was one of the most important elements of the campaign. “After all the work in raising awareness through the campaign and education initiative, when it came time for people to actually vote, it was absolutely critical that they specifically recognized the question on the ballot as a vote for clean water,” she said.

For a constitutional amendment to pass in Minnesota, the question must receive a majority of all those voting, and nonvotes on the ballot are counted as “no” votes. Targeting outreach to those most likely to skip voting — such as young voters — was vital, and proved successful. “Young voters were a key demographic and were anticipated to turn out in record numbers for the presidential election,” Pierson said. “To reach this segment, the campaign promoted campus organizing and utilized the Internet wherever possible. Social networking tools, such as Facebook, were also important.”

TPL and its partners relied upon their strong relationships with Minnesota’s clean water agencies during this effort. “We provided the agencies with information and material, such as educational direct mail and literature, that they, in turn, could use to reach voters,” Pierson said. “The agencies were able to educate the public about the measure without advocating. That is because the facts about Minnesota’s water situation are very compelling. Fewer than one out of every five lakes and streams in the state have been tested in accordance with the Clean Water Act, and of those tested, 40% failed water quality standards and were confirmed as impaired waters. Minnesota is known as the land of 10,000 lakes. People identify with water here. So learning that the state’s waters are not clean was very powerful and motivating.”

Coastal Community Backs Higher Taxes
Another clean water ballot that passed in November, Measure E in Santa Cruz, Calif., raises annual property taxes to help fund clean storm-water projects. Voters overwhelmingly approved the measure with more than 75% of the vote — a showing that emphasizes how high the community regards the quality of its waters.

“Santa Cruz is a very environmentally conscious community, and the people who live there are very concerned with clean water issues,” said Chung, who works with Santa Cruz residents. He said the reason for this strong view toward water stems from the fact that Santa Cruz is a coastal community — just as Minnesotans are also closely tied to water because of the state’s many lakes.
 
“Santa Cruz residents recreate in the coastal waters and are therefore probably more sensitive towards clean water issues, as compared to people living in metro areas,” Chung said. “The level of education in Santa Cruz is also very high, and Santa Cruz County was one of the first municipalities in the U.S. to push global warming issues. The community is ahead of the curve in these kinds of issues.”

Measure E will generate about $700,000 annually and can only be spent on stormwater cleanup projects. “The money may be spent on projects related to mitigating stormwater runoff and could include advanced designs, such as pervious pavements and detention basins,” Chung said.

Stimulus Funding
At press time, President Obama had signed a $787 billion economic stimulus bill that includes $6 billion for the Clean Water State Revolving Fund. The Water Environment Federation (WEF; Alexandria, Va.) and other groups have been working to call attention to the crisis of the nation’s ailing water infrastructure systems.

According to Robert Matthews, senior vice president at CDM (Cambridge, Mass.) and chair of the WEF Government Affairs Committee, an economic stimulus bill with dedicating funding to the Drinking Water and Clean Water State Revolving Fund would bring positive momentum to the water quality industry.

“Hopefully, this will help many communities move forward with water and wastewater projects that need to get completed,” Matthews said. “Although some municipalities have been able to do portions of projects, most have been forced to defer their improvements because of a lack of financing.”

Matthews said an infrastructure-based economic stimulus package would spur new construction jobs, but more importantly, it would drive utilities to spend their own money to initiate more projects independent of government assistance.

“The government does not want to be a permanent source of money for the clean water industry,” Matthews said. “The goal is for municipalities to eventually get back to being able to do their own bonding and capital spending to keep their infrastructure projects moving forward.”

— Jeff Gunderson, WE&T


©2009 Water Environment Federation. All rights reserved

©2009 Water Environment Federation. All rights reserved

©2009 Water Environment Federation. All rights reserved

 

©2009 Water Environment Federation. All rights reserved

 

©2009 Water Environment Federation. All rights reserved

 

©2009 Water Environment Federation. All rights reserved

 

©2009 Water Environment Federation. All rights reserved

 

©2009 Water Environment Federation. All rights reserved