Tools of the Trade
Look for more efficient, dollar-smart, multiple-application alternatives
- By L. K. Williams
- Jan 28, 2008
Are you keeping up with the Joneses? The plant down the street replaced its sequencing batch reactor with a membrane bioreactor. And the cross-town facility opted for ultraviolet (UV) over its chlorine disinfection program. What's the water industry coming to?
Maybe a realization that new technology can help treatment facilities, after all. Or, maybe not.
In today's water environment, the two most common reasons for facility expansion are an increased customer base and stricter regulations. Wherever people live, facilities are needed, but treatment capacity or acreage often is insufficient to accommodate conventional treatment systems. As water quality monitoring instruments have outgrown simple temperature and pH parameters, the U.S. Environmental Protection Agency's standards now include constituents that were unknown just a few years ago. Conventional treatment no longer meets the newer water quality standards as quickly or efficiently as it did in the 1990s.
But new technology often is more costly than conventional options. Expansion/upgrade pressures combine with the significant funding gap to create a sense of inertia. (The gap refers to the difference between how much money facilities need to distribute, collect and treat water over the next several years and how much they have. The U.S. EPA estimates the gap in the billions of dollars.) It is hard to know what to do to maintain water quality now and tomorrow. Some experts have a few ideas, though.
"The funding gap is going to force companies to look at innovative technologies," Robert Andoh, director of innovation at Hydro International, told WWN recently. He suggested that "end-of-point control and treatment is more expensive than decentralized treatment."
Industry leaders should be managing and controlling upstream to prevent downstream problems. Andoh said, "We need to manage and control our flows better."
For example, "There has been a tendency in the U.S. in the past to put in a pond to act as a stormwater storage device. With the increasing concern with climate change and West Nile virus, people are rethinking ponds," Andoh explained.
Technology can be a strong partner in the rethinking process. Take membranes, for example. First used in labs and industrial settings before the 1990s, membranes eventually became more economical to use in the water industry.
Today, membranes have been used to treat salt water, surface water, groundwater, and wastewater. In the very near future, membranes will not just filter out contaminants, but they will destroy chemical contaminants by converting them to harmless products.
Inventor Bruce E. Rittmann, while working at Northwestern University in Evanston, Ill., developed a hydrogen-based membrane biofilm reactor (H2-MBfR). The device uses microorganisms to reduce oxidized contaminants, including perchlorate, nitrate, selenate, chromate, and trichloroethene. Rittmann began working on the project in 1997 but got the first patent on the H2-MBfR in 2002. (He now is director of the Center for Environmental Biotechnology at Arizona State University in Tempe.)
The inventor explained that H2-MBfR supplies hydrogen gas to the hollow core of the membrane fibers. From there, the gas diffuses through the membrane wall to meet oxidized contaminants and the bacteria at the membrane's outer surface. The bacteria remove the electrons from the gas and add them to the perchlorate, for example, changing it into a chloride ion and water.
The key to the H2-MBfR is that it delivers hydrogen gas to bacteria efficiently and safely, Rittmann said.
Applied Process Technology, Inc. (APT) of Pleasant Hill, Calif., is field testing the technology, for which it holds an exclusive license from Northwestern.
David Friese, senior development engineer at APT, explained that two California facilities, one drinking water and the other wastewater, have been testing the H2-MBfR for nitrate reduction. In 2008, the company is planning additional drinking water testing on perchlorate and nitrate at California and Arizona sites.
"The chemical and biological side is working fine," Friese said. "The challenge is long-term stability of the biofilm and fluid flow."
The technology was being reviewed by the California Department of Public Health for drinking water treatment, and Friese said the company expects to have a large-scale system available for drinking water application by the end of 2008.
Like membrane technology, disinfection relies on physical-chemical properties to achieve its goal. Gary Hunter, senior wastewater process engineer at Black & Veatch, noted that while the trend in wastewater is away from chlorination to ozone and UV disinfection, these options use power and that costs more money.
"In 2007, the technology that seemed to jump out is the introduction of the microwave UV system," said Hunter, who has more than 22 years in the industry and is responsible for all of his company's wastewater disinfection projects. "It is marketed by Siemens," Hunter said, explaining that the system can start without requiring any "warm-up time" and uses a lamp technology that doesn't use any electrodes. "They guarantee lamp life for three years," Hunter said, adding that this is "an attractive proposal to the alternatives that exist on the market."
The bad news, however, is that, as of December 2007, there were no operating units in the United States. "More manufacturer or vendor proposal information needs to be validated for this new approach," Hunter said.
Hunter said interest in disinfection technology was growing in the following areas:
• Onsite generation of hypochlorous, which seems to address some of the risks associated with liquid hypochlorite.
• Application of disinfection into wet weather techniques and the cost effectiveness for reuse.
• Simultaneous disinfection and emerging contaminants removal.
• A multibarrier disinfection approach (dry weather or wet weather, for example).
• Optimization of disinfection techniques through the more effective use and application of energy.
"What is finally happening is that people are waking up to reality: If I'm a plant manager, it is hard to budget the cost for hypochlorite. I can't get a long-term contract; in some instances, I can only get a four-month contract." Similarly, parts of the country still are going through energy deregulation and "power costs are jumping all over the place." Hunter said disinfection supply and power issues make budgeting "really challenging for operations staff."
He predicted that over the next five years, technology will be changing to make UV and ozone economically applicable in power-challenged parts of the country.
What about biology?
Julian Sandino, PhD., vice president, assistant director of technology, and wastewater treatment fellow of CH2M HILL's Water Business Group, suggested a broader view for the water sector.
The big challenge is how the world will get even close to meeting the U.N. Millenium Development Goals, Sandino said. The United Nations set 2015 as the deadline for accomplishing eight broad goals, including "Ensure environmental sustainability." Under that heading, the U.N. developed a three-pronged approach, and one of those actions is "Reduce by half the proportion of people without sustainable access to safe drinking water." Sandino noted that underserved large metropolitan areas present a huge demand but they often have very low financial, institutional, and operational capabilities.
"Mother Nature is a source of inspiration and implementation in the search for new water-sector solutions," Sandino explained, adding that the industry needs to consider the information it has and apply that knowledge and experience in new ways. He noted, for example, that nitrates have found their way into many water sources. The drinking water treatment industry has relied on physical-chemical methods to manage the problem, but more recently, it has discovered that microorganisms can take care of it. Wastewater treatment facilities have been using "bugs" for some years to convert nitrates into harmless nitrogen gas. "The premise and basis are well known," Sandino said, acknowledging that some retooling will need to be done. "Innovation is not just developing a new technology, it's taking existing stuff and reworking it for a new challenge."
Sandino explained that about 90 percent of wastewater treatment facilities in the United States use some variation of an aerobic biological process, which requires an external oxygen source, and thus, a considerable amount of energy. The advent of the anaerobic process, which does not require oxygen to stabilize organic matter, has reduced the need for energy and produces a biogas rich in methane. While anaerobic processes do not provide a treatment level equivalent to the aerobic process (70 percent to 90 percent reduction in organic content, respectively), treatment providers are adding a polishing step to make up the difference. Sandino added that Colombia, Brazil, and India are implementing larger scale systems using anaerobic systems. The energy savings reduces operating costs of the anaerobic systems, and their capital costs are roughly half that of aerobic systems.
Developing new technologies may take longer than it used to, Sandino suggested. The United States "went dormant" when the federal government stopped supporting technology research and encouraged the private sector to take over. According to Sandino, the private sector has not taken up the slack. "The new solutions will be coming from countries like Japan and the Netherlands where the government never stopped supporting R&D," he said.
L.K. Williams is editor of Water and Wastewater News.