Environmental ▼ News Quantifying industrial symbiosis
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HELGE BR AT TEBØ, NORWEGIAN UNIVERSIT Y OF SCIENCE AND TECHNOLOGY
ver the past decade, the trial ecology and especially to inshort tons per year (tpy) of SO2, notion that industries can 84.4 tpy of NOx, and 95.3 tpy of dustrial symbiosis,” says Robert function like biological particulate matter less than 10 miFrosch, senior research associate ecosystems has gained an increascrometers in diameter, according at Harvard University’s Kennedy ing amount of serious attention. to the researchers. However, the School of Government. “While it Central to the growing discipline net emissions of CO and CO2 from has also been assumed that sysof industrial ecology is the idea the linked facilities are higher than tems of waste reuse by interlinked that one business’s waste firms save money for can become another’s the participants, I have “food”—and that innot seen much direct creasing the cycling of evidence to this effect materials, water, and en[prior to this paper’s ergy puts businesses on publication].” the path to sustainable This is the “kind of development. But indusinformation that will astrial ecology suffers from sist in breaking down a lack of hard data on the the inertia that exists advantages of the mutuwhen industries and ally beneficial exchanges governments begin to that have become known consider exchanging or as industrial symbiosis. trading ‘wastes’,” adds For that reason, reRay Côté, director of the search published in this Industrial Ecology Reissue of ES&T (pp 6535– search and Development 6541) is significant beGroup at Dalhousie UniThis 454-MW coal-fired power plant is at the heart of a nascent cause it comprehensively versity (Canada). “If we documents both the envi- “industrial symbiosis” network in southeastern Puerto Rico, in are really serious about which participants share water, materials, and energy. ronmental and economsustainability, we have ic benefits of a nascent to begin using resourcfrom each alone, because of the insymbiotic network. For example, es more effectively and efficiently corresponding author Marian herent chemistry of switching from and taking systemic approaches.” Chertow and her colleague Raoil at the refinery to coal at the Unfortunately, all of the highly chel Lombardi of the Yale School power plant, the authors explain. planned approaches to industrial of Forestry and Environmental The price that the AES power symbioses in the U.S. have failed, Studies quantify the benefits that plant charges for its steam is not a says John Ehrenfeld, who directs accrue because a Chevron Philmatter of public record, but Cherthe International Society for Inlips Chemical Co. petrochemical tow and Lombardi estimate that dustrial Ecology. Even in Europe, refinery in Guayama, Puerto Rico, generating its own steam cost where the concept has taken hold purchases steam from a nearby Chevron Phillips $9.35 per 1000 more firmly, most successes have coal-fired power plant—rather lbs, which adds up to $11.7 milnot been the result of master planthan generating it via old oil-burnlion per year. They determined ning, Chertow says. ing boilers. This study also raises that AES could charge any amount The “waste-to-food” network questions about how governments over $2.75 per 1000 lbs of steam to that is developing in Guayama was can actively encourage industrial make a profit. And that bodes well inadvertently triggered by a shortsymbiosis. for both businesses, they say. age of water for cooling as well as By working together, the two By quantifying the economic by a requirement of the U.S. Public plants produce significantly lowadvantages being realized by the Utilities Regulatory Act (PURPA). er emissions of air pollutants. interlinked firms, the new reThe Puerto Rico Electric Power AuThrough the exchanges, the two search is making “an important thority (PREPA) follows the PURPA plants prevent the release of 99.5 contribution to the field of indusrequirement that companies bid354A ■ ENVIRONMENTAL SCIENCE & TECHNOLOGY / SEPTEMBER 1, 2005
© 2005 American Chemical Society
“What we need to do now is find [such instances of industrial symbiosis] and encourage them,” adds Chertow. “We need to determine what works and to analyze the successes as well as the failures—and move them along.” Chertow and her colleagues have helped encourage AES’s current negotiations to purchase wastewater from several companies located near Guayama. With PREPA charging AES $1 per 1000 gallons of fresh water, Chertow and Lombardi estimate that the value of additional wastewater reuse could save the power plant $63,000–314,000 per year. —KELLYN S. BETTS
Forget well-known toxics such as pesticides and industrial chemicals: Scientists are now focusing their energies on common household chemicals and medicines that are not regulated by the U.S. EPA but still come trickling out of kitchen taps. Americans consume thousands of pharmaceuticals and produce tons of chemicals to maintain their modern lifestyles, and new findings published in this issue of ES&T (pp 6649–6663) reveal that technologies to remove these products from drinking water have different levels of effectiveness. “I think the general overall pattern we are seeing is that ozone is better at removal of these compounds,” says Shane Snyder, a project manager with the Southern Nevada Water Authority and one of the authors of the study. The research evaluated several water treatments commonly used in the U.S., including chlorination, ozonation, and UV treatment. When researchers compared the effectiveness of ozone and chlorine in removing 31 chemicals
SHANE SNYDER
Removing emerging contaminants
News Briefs Carmakers falling behind on emissions cuts
Carmakers in Europe, Japan, and Korea are not on track to meet targets for cutting CO2 emissions, according to a European Commission report. In 1999, European carmakers agreed to reduce CO2 emissions from new passenger cars to an average of 140 grams per kilometer (g/km) by 2008; Asian carmakers agreed to 140 g/km by 2009. To meet this target, they need to reduce emissions by 2% a year. But, according to a report published in June, between 1995 and 2003, the yearly reduction was 1.2%, translating into a total cut of 11.8%. Road transport generates one-fifth of all CO2 emissions in the EU; passenger cars are responsible for more than half of these. For more information, go to http://europa.eu.int/ comm/environment/co2/report/ com_05_269.pdf.
Survey says Americans want new energy policy
These large generators are located at the River Mountains Water Treatment Facility in Las Vegas, Nev. Ozone disappears within seconds after disinfecting water.
from drinking water, they found that ozone successfully eliminated far more chemicals at much higher percentages. Of the 31, 26 were reduced to at least 30% of their original concentration by ozonation. These substances included testosterone, estrogen, naproxen, caffeine, and the mosquito repellent DEET. Only two chemicals seemed resistant to ozonation: the fragrance compound musk ketone and the flame retardant tri(2-chlo-
Nine out of 10 Americans worry about dependence on foreign oil, according to survey results released in June. Concern over this dependence outranked other issues such as the economy, global warming, air pollution, and contamination of water and soil. In addition, more than half of the Americans surveyed believe that the country’s environment is getting worse. Results also indicate that many consumers want the government to require the auto industry to make vehicles more fuel-efficient. They also support alternative energy sources such as wind and fuel cells. To view the key findings, survey questions, and full results, visit the Yale Center for Environmental Law and Policy website at www.yale.edu/envirocenter.
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RHONDA SAUNDERS
ding to build a new plant at Guayama use at least 5% of their energy output for products other than electricity—such as steam or desalinated water. This requirement ultimately led to the AES plant being sited in close proximity to the Chevron Phillips refinery. Although regulation can give industrial symbiosis a “push”, Chertow says she has come to believe that the most highly functioning examples of industrial symbiosis come about “organically”—based on mutually perceived need. “There’s some level of selforganization that needs to occur, and some proof in the market that [resource exchange] is desirable.”
Environmental▼ News roethyl) phosphate (TCEP). With chlorine, 15 of the chemicals remained at levels exceeding 70% of their original concentration. Like ozone, chlorine was ineffective at eliminating significant amounts of TCEP, but caffeine, progesterone, and the anticonvulsant drug carbamazine also resisted degradation. Snyder adds, “I don’t think it’s been recorded before, but chlorine was not effective at removing testosterone.” “Ozone has been around to help with taste and odor for some time,” says Craig Adams, a professor of environmental engineering at the University of Missouri– Rolla. “Ozone is also used for color removal if you have colored water. It’s really a holistic sort of treatment, and it works better for some of these chemicals such as endocrine disrupters.” Snyder has also compared ozone with UV treatment and found that the latter shows little effectiveness at destroying these chemicals. “At the dose used in
most plants for disinfection, there is essentially no removal of these types of compounds,” says Snyder. “That’s a real disappointment because UV is actually a more modern type of disinfectant.” But ozonation does have some drawbacks. Snyder points out that, like chlorination, ozone generates byproducts that can be harmful. For instance, ozone can generate bromate in water with high bromide levels. UV technology does not create these problems because most organics are not very photoreactive. Alan Roberson, the director of regulatory affairs with the American Water Works Association, says that many cities designing new drinking-water facilities are gravitating toward either UV or ozone because of EPA regulations aimed at controlling Cryptosporidium. “Generally, you’re seeing the middle to large cities moving in this direction because they have the financial resources and the skilled operators to run these plants,” he
says. He estimates that a switch to UV or ozone treatment might add about 10% to typical water treatment costs. Snyder agrees that the switch to UV and ozone has been spurred by EPA’s Surface Water Treatment Rule, a response to outbreaks of Cryptosporidium that hit the U.S. in the 1990s. Chlorination is not very effective at removing the protozoan, but ozone works by directly attacking the pathogenic cells, whereas UV “scrambles” the DNA inside. Adams says that research into which treatment proves more effective at destroying organic chemicals in the water is simply an added benefit for modern water treatment. Researchers are finding these contaminants at levels so low that they might not even be harmful. “The precautionary principle would say that if you can remove these substances in a reasonable manner, then that is probably a good thing.” —PAUL D. THACKER
No one disputes that Ronald Reagan was dead wrong when he said in 1981 that “trees cause more pollution than automobiles do.” However, scientists have known for nearly two decades that the biogenic emissions from certain trees can increase the levels of some pollutants, particularly ozone, in urban air. But until now, only scientists using sophisticated computers have had access to models for determining when the pros of planting different tree species outweigh the cons. In a paper published in this issue of ES&T (pp 6730–6738), researchers describe the first method for evaluating the impact that different tree species have on urban air quality that can run on a PC. Their Urban Tree Air Quality Score (UTAQS) should help urban planners in areas where air pollution is an issue to make the best decisions about which tree species to plant.
An easier-to-use scoring system shows that willows, such as one shown here, can worsen urban air quality if planted in large numbers. Oak and poplar trees are also problems. On the other hand, the model finds that pine, larch, and silver birch have the greatest potential to improve urban air quality.
“Trees do benefit air quality if you plant the right kind,” Hewitt explains. The procedure, which was developed by a team of researchers he co-led with his Lancaster University (U.K.) colleague Robert MacKenzie, can be tailored to provide appropriate recommendations for cities in any ecosystem.
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WESTMINSTER INTERNATIONAL CANOE MAR ATHON
Choosing the right trees to improve urban air
“This work goes beyond previous efforts to ‘rank’ the potential contribution of various tree species by considering the impact of the emissions using an air quality model,” says Alex Guenther, a senior scientist at the National Center for Atmospheric Research. State and local governments around the world are beginning to consider tree planting to address a variety of environmental issues, including air quality, says Lisa Tilney, Trees and Air Quality project coordinator for the nonprofit National Tree Trust. For example, the Kyoto Protocol allows countries to meet their carbon emission targets by planting forests to soak up carbon instead of making emission cuts. Regions out of compliance with the U.S. EPA’s ozone standards may also be able to obtain partial credit for planting trees, according to guidance that the agency released last September. However, the guidance doesn’t specify which species to plant but instead
quality standards because 1 ppb of ozone is not equivalent to 1 ppb of NO2 in health terms,” explains MacKenzie. For the UTAQS to work, a user must know the VOC emission rates of trees in their city. This emission information is widely available for trees growing in temperate regions but is lacking for trees found in tropical regions, MacKenzie adds. Because the nine genera of deciduous trees known to produce the highest levels of isoprene include the varieties that UTAQS has found to increase air pollution, Nowak says that the results are no surprise. However, MacKenzie stresses that “our score [also] incorporates effects on NO2 and particulates.” Nowak contends that the UTAQS results would improve if temperature effects were included. “The transpiration, cooling, and shading provided by the trees can cause the air temperature to drop, which in turn can reduce the levels of air pollutants by altering emission rates and changing the photochemistry of ozone formation,” he explains. Unfortunately, temperature data are beyond the scope of UTAQS because such data require more computing power than is possible with a PC, MacKenzie says. “City authorities in the U.K. are already applying what we’ve done,” Hewitt says. “But we hope and expect that this ES&T paper will generate interest around the world,” he adds. —KELLYN S. BETTS
Natural oceanic source for fluorinated tracer Strong evidence that trifluoroacetate (TFA), a breakdown product of hydrofluorocarbons and perfluoronated chemicals, also has a natural source in the ocean will complicate proposals to use the compound as an atmospheric tracer of certain emerging contaminants. In research published in this issue of ES&T (pp 6555– 6560), researchers report finding high and unexpectedly different
levels of TFA in deep ocean waters. Environmental scientists have known for some time that hydrofluorocarbons, which are used as ozone-safe refrigerants, ultimately degrade to TFA. Recently, Trent University (Canada) chemist David Ellis and colleagues reported that fluorinated polymers, including Teflon (polytetrafluoroethylene), also emit TFA when heated (Nature 2001, 412, 321–324). These ob-
News Briefs EPA drops sewage bypass option
After receiving more than 98,000 comments, the U.S. EPA has abandoned its plan to allow sewage treatment plant operators to skip one of the steps required by federal law before discharging into waterways. The policy, proposed in 2003, was an attempt to clarify when the widespread practice of blending would be allowed—namely, only during periods of heavy rainfall or snowmelt. Under these conditions, some plants divert excess stormwater flows around the system’s biological treatment units to prevent the microorganisms that provide secondary treatment from being washed out. Environmentalists have contended that the practice is illegal and contributes to beach closures nationwide every year. EPA is now looking at other options to address contaminant discharges during heavy rain conditions, according to the agency.
Consultant earns the A. P. Black award
David Cornwell, best known for his research on sludge treatment, received the A. P. Black award for research from the industry trade group the American Water Works Association (AWWA) in June. As president of Environmental Engineering & Technology, Inc. (EE&T), the consulting firm he founded in 1985, he is the first consultant in many years to receive the award. AWWA chose Cornwell because his work has helped bridge the gap between cutting-edge technological research and its application as well as for his 30-plus years of volunteer work with AWWA. Cornwell says that his philosophy has been to “bring stateof-the-art techniques into practice,” adding that his most recognized research is in the sludge treatment field, in which he has worked on characterization of residuals, beneficial use methods, and treatment technologies.
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EE&T, INC.
“encourages general strategic tree planting as a means to potentially reduce ozone levels,” says David Nowak, a project leader at the U.S. Department of Agriculture’s Northeastern Research Station in Syracuse, N.Y. The main reason that trees are able to help clean pollutants, such as ozone and NOx, out of the air during the day is a side effect of having their stomates open to expel oxygen and water as part of photosynthesis, explains Nowak. At the same time, high levels of ozone, for example, diffuse into the leaf, where the compound reacts and is removed from the atmosphere. However, trees also emit volatile organic compounds (VOCs), particularly isoprene from deciduous trees, which react to increase levels of ground-level ozone in urban areas. The new study focused on Birmingham, an industrial city with air pollution levels on a par with other large U.K. cities, as a case study. The researchers painstakingly identified the city’s tree population and fed the data into CiTTyCAT—a well-known atmospheric chemistry model developed at Cambridge University (U.K.) and “widely used throughout the U.K. for air quality research work,” MacKenzie says. “The score weights the impact of a tree species on different pollutants by comparing tree-induced changes in model pollutant concentrations to air quality standards. The score is compiled relative to air
Environmental▼ News
R. W. MACDONALD, CANADIAN INSTITUTE OF OCE AN SCIENCES
servations suggest that TFA could has no known way of partitioning Because deep ocean waters have be used to track anthropogenic been sequestered from surface inout of the ocean. Therefore, the sources of perfluoroalkyls, which fluence for centuries, only a natuTFA observed in precipitation and are emerging chemicals of concern ral underwater source can explain inland waters must, at present, that are found throughout the enthe high values, says correspondwith current understanding, origivironment. Currently, the sources nate from anthropogenic sources.” ing author Brian Scott, also with and sinks of these alkyls are the The study in ES&T reports on a Environment Canada. The differsubject of heated deent concentrations in bate; a reliable tracer various oceans also would help to resolve suggest the presence this controversy. of active sources and However, the finding sinks, he adds. Underthat TFA has a natural sea vents seem to be the source makes it hardlikely source, especially er to use it as a global because fluorinated tracer for perfluoroalchemicals have been kyl chemical sources or reported to spew out of to generate time trends, volcanoes. says Derek Muir, a seThe team also renior research scientist ports data from the viwith Environment Cancinity of three undersea ada and a co-author of vents, but these are not the ES&T paper. “These conclusive. In some results suggest that to measurements, TFA track the longer-chain concentrations increase fluorinated polymers close to the vent, but at it will be necessary to others they do not. Measurements by researchers on board this icebreaker show that trifluoroacetate concentrations are higher in the Arctic look for longer-chainThe scientists hope Ocean than in the Pacific. length degradation to obtain better meaproducts,” he says. Ensurements near the volseries of 22 depth profiles, which vironmental scientists currently canic vents, says Scott. He is also show that TFA values are higher believe that the long-chain commeasuring longer-chain perfluoin the Atlantic and Arctic Oceans pounds lack a natural source. rocarboxylic acids in rain to see (150 nanograms per liter [ng/L]) Ellis welcomes the new study whether these can be used to track than in the Pacific (
