Biodiesel: what’s in your tank? 20% biodiesel (termed B20) can be used in most diesel engines. Blends containing more than 20% biodiesel can damage hoses and gaskets in cars manufactured before 1993 and also can freeze in cold temperatures. “This could cause fuel filter plugging, or in the worst case, the fuel solidifies in the EMILY PE ACOCK
Some biodiesel blends for sale in the U.S. do not contain the amount of biodiesel advertised, according to new research published in ES&T (pp 2476–2482). Chemist Christopher Reddy of Woods Hole Oceanographic Institution and colleagues analyzed both pure biodiesel and blends from more than 20
Biodiesel is becoming more popular as an environmentally friendly fuel and is cheaper than petroleum diesel in some places.
distributors and small U.S. retailers. They found that blends sold as 20% biodiesel contained as little as 10% or as much as 74% biodiesel. “It’s a huge problem for the industry,” says Teresa Alleman of the National Renewable Energy Laboratory, who recently completed a study showing that biodiesel manufacturers have improved the overall quality of pure biodiesel over the past year. If consumers pay a premium for biodiesel that they aren’t getting, she says, public confidence could be shaken. Also, blenders receive a tax credit based on the amount of biodiesel used, which could mean some sellers have received larger credits than they merit. Biodiesel is sold today mainly as a blend with petroleum diesel, because blends containing less than
tank,” says Gerhard Knothe, a biofuel researcher at the U.S. Department of Agriculture. Concerned consumers can ask retailers how they are blending fuel and whether they participate in the voluntary BQ-9000 biodiesel certification program, Knothe says. The federal Renewable Fuels Standard and tax incentives are helping the biodiesel industry grow at a breakneck pace. “There’s been a bit of dot-com mentality, with a lot of people getting into the business,” Knothe says. The industry has been left scrambling to set standards and ensure reliability. Many states adopt and enforce fuel standards set by ASTM International for chemical and physical properties; these currently are designed for pure biodiesel. “It’s mostly the smaller mom-
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and-pop retailers that are mixing it themselves” that have problems, Reddy says. These operations often use a simple method called splash blending, in which biodiesel is poured into regular diesel in a tank or truck. Improper measurement or mixing can lead to incorrect blends. In areas where the biodiesel industry is more developed, such as Minnesota where all diesel sold must contain at least 2% biodiesel by law, more sophisticated mixing equipment heads off problems. For example, tanker trucks in some places can drive up to a “rack” with computer-controlled blending done to order. The research is the first to apply highly precise radiocarbon measurements to biodiesel mixtures. Radiocarbon is also used to determine the ages of fossils, because this form of carbon decays predictably over time. In this case, the team measured the radiocarbon content of retail mixes and calculated biodiesel content by using the fact that petroleum diesel, as an ancient fossil fuel, no longer contains any radiocarbon. Biodiesel, derived from plants grown recently, does contain radiocarbon. Radiocarbon testing is more expensive than other methods for testing biodiesel blends, such as infrared spectroscopy. However, radiocarbon is more accurate across all of the plant sources of biodiesel, Reddy says, and is the only method that directly measures the content of renewable carbon in a fuel mixture. That measure could be used to certify fuel in states that require a given percentage of fuel to be made from renewable resources. The biodiesel industry is trying to rein in the problem, says Amber Pearson, a spokesperson for the National Biodiesel Board, by working with ASTM on standards that will include biodiesel blends. States will then have to adjust their own regulations to include blend verification. —ERIKA ENGELHAUPT © 2008 American Chemical Society
Bird die-offs in the Great Lakes taminants, and introducing the anaerobic bacterium Clostridium botulinum to the food chain. Birds may be infected directly by feeding on the infected mussels or indirectly by eating tainted gobies or other quagga-eating fish. “Gobies change color after ingesting the MARK BREEDERL AND, MICHIGAN SE A GR ANT
Tens of thousands of birds have perished from botulism poisoning around the Great Lakes in less than a decade. Evidence points strongly to two culprits: the quagga mussel (Dreissena bugensis) and the round goby (Neogobius melanostomus), both aggressive invasive species that were presumably introduced to the region via ships’ ballast water. Researchers say that environmental changes brought about by the invaders are likely to worsen the situation. Bird carcasses infected with the type-E strain of botulism first washed ashore around Lake Erie in 1999. Since then, mass bird mortalities have occurred annually, and the problem has spread to Lakes Ontario, Huron, and Michigan. Of the more than 50 avian species affected, diving birds such as loons, grebes, and many ducks—migrating southward from central Canada through the Great Lakes—have been hardest hit. But large numbers of shorebirds, songbirds, and raptors also have fallen prey. Rough estimates by the U.S. Geological Survey’s National Wildlife Health Center, based only on opportunistic collections of bird remains, peg the avian death toll at close to 70,000 from 1999 to 2006; no systematic surveys of bird mortalities on the Canadian side of the lakes have been conducted. Probably thousands more birds have expired on the water and have sunk, says Helen Domske of New York Sea Grant. Quagga mussels and round gobies are commonly found in the stomachs of botulism-infected birds and fish. Because the quagga can flourish under a wide range of conditions, it is now displacing its invasive cousin, the zebra mussel (Dreissena polymorpha). The quagga wreaks havoc on lake food webs by consuming vast quantities of plankton, accumulating con-
More than 1300 loons died during 2006–2007 from type-E botulism poisoning along the shores of northern Lake Michigan.
botulism toxin,” Domske says, “and this may act as a visual cue for birds, attracting them to the weakened fish.” When scavengers feed on contaminated fish and birds that land on coastlines, they can pick up the toxin. The round goby has multiplied ferociously since its debut in the lakes in the early 1990s. “They’re like ants on the lake bottom,” says Mark Breederland of Michigan Sea Grant. “They breed four to five times a year and have voracious appetites for the eggs of our native fish.” Scientists recently discovered that newly hatched round gobies swim from lake-floor breeding sites to the surface; this enhances their chances of getting sucked into ballast tanks and transported by ships. Despite the evidence implicating the goby and quagga in the massive bird die-offs, vexing questions remain. For one thing, type-E
C. botulinum is ubiquitous in the lakes’ environment, and outbreaks did occur periodically before the current vectors arrived. However, it has proven difficult to show spores germinating in lake sediments. Alicia Perez-Fuentetaja of Buffalo State College recently measured significant levels of the genetic material coding for toxin production in lake sediments and in several invertebrates, including mussels, aquatic worms, and even fly larvae. Her work suggests that spore germination happens in localized, low-oxygen hot spots in the sediments that meet bacterial requirements for growth. More research is needed to better understand processes at the water–sediment interface, she says, “but it appears there are potentially many routes of toxin transmission.” Altered ecosystems have clearly augmented conditions favorable to botulism, says Breederland. The filtering action of zebra and quagga mussels has turned waters crystal clear in many areas of the lakes, allowing sunlight to penetrate deeper waters and significantly boost temperatures. In addition, an excess of phosphorus, which leads to more pervasive anaerobic conditions ideal for bacterial growth, may be responsible for a resurgence in the growth of the macroalga Cladophora. “We are seeing the long-term consequences of synergistic responses between multiple invasive species,” Breederland says. Efforts are under way to tighten up restrictions on ballast-water discharge, curtail phosphorus runoff, and develop pheromones to disrupt goby reproduction, but researchers say no simple answer exists for realigning the food chain now dominated by the invaders. Still, Breederland says, “if dead birds lined up on beaches don’t get us passionate about addressing these problems, it’s hard to see what will.” —NOREEN PARKS
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Just add (gray) water resulting in pure water that exceeds government drinking-water standards, according to Xia. Such easy-to-assemble treatment plants can be quickly rep licated and can help in waterstressed regions, says Xia. He can deliver a 10,000 L/day facility for less than $14,000.
Courtesy of SIQING XIA
2010 will be the year China embraces “toilet-to-tap” water treat ment technology, predicts envi ronmental engineering professor Siqing Xia. Until then, he continues to educate the public about the technology’s benefits through a unique demonstration project at Tongji University in Shanghai. His small-scale, 400 liter per day (L/day) treatment plant on the Tongji University campus turns wastewater from the College of Environmental Science and Engineering’s lab building into pure water for scientific procedures and irrigation of the surrounding landscape. The end product is so pure it could be used for kidney dialysis, carbon-chip washing, or to replenish drinking-water supplies, according to Xia, who is also head of the State Key Laboratory of Pollution Control and Resource Reuse. Although using recycled or gray water for agriculture and industrial applications is common in many parts of the world, direct consumption is still frowned upon, and the water at Tongji University does not end up in drinking glasses. In 2010, Xia will set up another demonstration project, this one for the Shanghai World Expo, and he expects broad interest in, and even acceptance of, so-called toilet-to-tap, or direct potable reuse, technologies. At Tongji University, wastewater from lab-building toilets and rainwater collected in tanks on campus are eventually funneled into a membrane bioreactor, which uses membrane technology and traditional biological treatment with bacteria to remove nutrients. The membrane component filters out silt, pollen, colloids, bacteria, protozoa cysts, and large viruses, among other things. Most of the water leaving the membrane bioreactor is disinfected and reused as gray water in the lab-building toilets or for landscaping. The rest is treated with reverse osmosis and ion exchange,
of environmental groups and local officials, but state laws prevented direct reuse. “Perception is a big issue, but permitting is also a big issue,” says John Petersen, a professor of environmental studies and biology at Oberlin College. Oberlin pioneered on-site water reuse when its “living machine” went on-line nearly a decade ago to recycle gray water at the Adam Joseph Lewis Center for Environmental Studies. The living machine does not use membrane filtration, and effluent is used solely for toilet reuse and landscaping. A handful of larger-scale projects exist around the world, but only one, according to experts, uses direct toiletto-tap—a municipal facility in the Namibian capital, Windhoek. The U.S. EPA is also beginning to embrace water reuse. “We are moving towards a more integrated approach to water resources management, and we know that water reuse and recycling will play a greater role,” says agency spokeswoman Shakeba Carter-Jenkins. A $480 million treatment plant, like the one in California, may not be feasible in other parts of the world, including rural China, but smaller-scale projects like the one at Tongji University present another option. “It shows that local users and citizens can make a difference and take a part in improving the environmental quality of their own habitat,” says University of Iowa hydrology professor Youkuan Zhang, who visited Tongji University last year. “Education is one of the important measures to effectively deal with environment problems.” Petersen agrees: “I think the key value of the technology right now is probably as a tool to transform people’s perception of what is waste and what is resource.” —TASHA EICHENSEHER
Siqing Xia has developed a small-scale water treatment plant on the Tongji Univer sity campus in Shanghai. Wastewater is treated in a membrane bioreactor (shown here behind Xia) and is then disinfected and reused as gray water in the lab-building toilets or for landscaping. The rest is treated with reverse osmosis and ion exchange (photo on right), resulting in exceptionally pure water.
So why aren’t we seeing them everywhere? Negative public perception presents an enormous stumbling block. Even in a country that suffers from severe drought and pollution, people are not ready to drink water that is directly derived from the toilet bowl. Nevertheless, says Xia, the Chinese government encourages such projects, and Tongji University is a step closer to making toilet-totap technology a viable solution to China’s water woes. At the end of last year, Orange County, Calif., christened a largescale, 266 million L/day plant that treats sewage and uses the effluent to fill drinking-water aquifers relied on by some 2.3 million people. Orange County staged a sophisticated marketing and education campaign and earned the support
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