News this Week

Science  10 Aug 2012:
Vol. 337, Issue 6095, pp. 628
1. Around the World

1 - New Delhi
India Prepares Orbiting Mars Satellite
2 - Copenhagen
Squabble Over NEJM Paper Puts Spotlight on Antishock Drug
3 - Uganda
4 - Raleigh
Sea Level Rise Bill Becomes Law

New Delhi

India Prepares Orbiting Mars Satellite

India plans to send a small, crewless satellite to orbit Mars in what would be its first visit to the planet.

On 3 August, the Indian cabinet cleared a proposal from the Indian Space Research Organisation (ISRO) for a launch in November 2013. The agency will use its Polar Satellite Launch Vehicle, the same rocket that sent Chandrayaan-1 on a successful mission around the moon in 2008. The government has already allocated about $41 million for the Mars mission, which will cost an estimated$112 million.

The satellite will carry up to 25 kg of scientific instruments and track a highly elliptical orbit—500 km by 80,000 km—around the Red Planet. Although details are not available, ISRO officials said the mission's goal is to remotely assess “climate, geology, and the origin, evolution, and sustainability of life on the planet.”

No word on whether there will be opportunities for international collaboration. Chandrayaan-1 carried instruments from NASA, the European Space Agency, and Bulgaria.

Copenhagen

Squabble Over NEJM Paper Puts Spotlight on Antishock Drug

A seemingly small mistake in a paper in The New England Journal of Medicine (NEJM) landed a Danish physician-researcher in hot water last month after a German company threatened to sue him. The researcher, Anders Perner of Copenhagen University Hospital, corrected the error—but the episode sheds light on a widespread therapy that some scientists say may do more harm than good.

On 27 June, Perner published a clinical trial in NEJM that compared the effects of hydroxyethyl starch (HES), a synthetic derivative of starch that has been used globally for decades to treat sepsis, with treatment by an alternative called Ringer's acetate. The results were not good for HES: After 90 days, 201 of 398 patients in the HES group had died, compared with 172 of 400 patients in Ringer's acetate group.

Perner and NEJM amended the original paper after German pharma company Fresenius Kabi threatened legal action, stating that Perner had misidentified the HES compound used in the study as Fresenius's product.

But Perner says the data from his study are likely to apply to Fresenius's drug as well. He contends that the safety of HES compounds—first developed by Fresenius in 1974—has never been adequately assessed by modern standards. http://scim.ag/HESfight

Uganda

Ugandan health authorities are battling an outbreak of Ebola, an often fatal viral disease. On 6 August, the Ugandan government reported 59 suspected cases, including 16 deaths—but only 10 cases had been confirmed by tests at the Uganda Virus Research Institute in Entebbe. The outbreak started in early July in the western District of Kibaale, where the first cases may have been mistaken for cholera.

There are no drugs or vaccines that protect against Ebola, which is spread through direct contact with patients before or after they die. Outbreaks are usually stamped out in a few weeks by aggressively tracing patients' contacts and isolating them for 3 weeks. Early this week, more than 290 people were in isolation wards, according to the health ministry, which is supported by the World Health Organization and the U.S. Centers for Disease Control and Prevention (CDC). Two suspected cases in neighboring Kenya have both tested negative.

Uganda has seen Ebola outbreaks in 2000 and 2007 as well, with 425 and 149 cases respectively; in 2011 a 12-year-old girl died from the disease.

Raleigh

Sea Level Rise Bill Becomes Law

A controversial bill prescribing how North Carolina can forecast future sea level rise for planning became law on 2 August. Governor Beverly Perdue had until that date to act on the bill, known as House Bill 819, but she allowed it to become law by choosing to neither sign nor veto it.

Under the law, agencies are barred from considering accelerated sea level rise—such as might occur due to the melting of polar ice caps—in decision-making related to coastal development until 1 July 2016. Until then, the legislation requires state coastal planning agencies to base predictions of future sea level rise on a linear rate of increase as determined by “historical data.”

“House Bill 819 will become law because it allows local governments to use their own scientific studies to define rates of sea level change,” the governor wrote in a statement on 2 August. “I urge the General Assembly to revisit this issue and develop an approach that gives state agencies the flexibility to take appropriate action in response to sea level change within the next four years.” http://scim.ag/NCSLbill

4. Mycology

Attack of the Clones

1. Kai Kupferschmidt

Fungi have long been seen as the least interesting pathogens, but two catastrophes in the animal world have changed that view.

When Nature recently accepted a review co-authored by Sarah Gurr, the plant pathologist from the University of Oxford in the United Kingdom sent the journal a self-produced image to consider for its cover. It shows a fungus looking like one of those colossal, menacing tripods from H. G. Wells's War of the Worlds, stalking through a field, with bats, frogs, and toads fleeing before it in a crazed panic. “Fungal Wars of the World,” Gurr called it.

The picture didn't make it, but many scientists agree with its message: Fungi have now become a greater global threat to crops, forests, and wild animals than ever before. They have killed countless amphibians, pushing some species to extinction, and they're threatening the food supply for billions of people. More than 125 million tons of the top five food crops—rice, wheat, maize, potatoes, and soybeans—are destroyed by fungi every year.

Like other infectious agents, fungi benefit from a combination of trends, such as increased global travel and trade, new agricultural practices, and perhaps global warming. But they have several unique features, researchers say—including the way they can switch from asexual to sexual reproduction—that enable them to exploit these opportunities particularly effectively.

The Nature paper, published in April, was in part a cry for attention; its authors say the world isn't fully aware of the dangers and should invest more in countermeasures. For decades, fungal diseases have been overshadowed by bacteria and viruses. “There are probably 50 or 100 bacterial experts for every fungal expert,” says Bruce McDonald, a plant pathologist at the Swiss Federal Institute of Technology in Zurich. “There has always been a sense that fungi are not that important,” adds microbiologist Arturo Casadevall of Albert Einstein College of Medicine in New York City.

That has begun to change only very recently, thanks in part to some highly publicized animal die-offs. “A few years ago, people just scoffed when you thought a fungus had killed an animal such as a bat,” says Gudrun Wibbelt, a veterinary pathologist at the Leibniz Institute for Zoo and Wildlife Research in Berlin. “That is clearly changing.” In December 2010, the U.S. Institute of Medicine hosted its first-ever workshop focused exclusively on fungal diseases, which concluded that “threats posed by emerging fungal pathogens are often unappreciated and poorly understood.”

Interest in the Nature review has been “huge,” Gurr says. Scientists around the world have sent in articles describing other fungal diseases that could have bolstered the paper, says co-author Matthew Fisher, a molecular epidemiologist at Imperial College London. Among the wide variety of species under attack are crabs, corals, corn, and the Cavendish banana—and new fungal diseases are discovered every year. In June, Elsevier presented a new journal called Medical Mycology Case Reports, completely devoted to “unusual medical or veterinary fungal infections.”

Detective work

One of the issues that has held back research on fungi is that it's simply very hard. Fungi are more complex, have bigger genomes, and are more difficult to characterize than viruses or bacteria. In fact, most researchers find it hard to give a good definition of the whole group. (“That's tough. Let me have a quick look what Wikipedia says,” one of them says.)

Until the 1960s, fungi were considered to be closely related to plants, but scientists now know that they have a more recent common ancestor with animals—which means the mushroom in your salad is more closely related to you than to the lettuce. Like plants, animals, and bacteria, fungi comprise their own kingdom, which includes yeasts, molds, and mushrooms.

But the diversity is enormous—and most of it is uncharted territory. “We know the names of about 70,000 different fungi, but there are probably between 1.5 [million] and 5 million species out there,” Gurr says. Modern sequencing technology has multiplied the number of members in many fungal families. The number of known Phytophthora species, which include the cause of potato blight, has doubled since 2000, says David Rizzo, a plant pathologist at the University of California, Davis. Its size is what makes the fungal kingdom so scary, Casadevall says: “There is a lot of biological potential out there.”

The increased recognition of fungal threats was fueled by two major animal crises: the massive decline in amphibian species and an explosive disease outbreak among bats in North America.

Scientists had been observing declines in the numbers of frogs, toads, and salamanders since the 1970s. But it wasn't until 1997 that teams investigating simultaneous waves of population declines in Australia and Panama closely examined large numbers of animals and finally nailed the culprit: a fungus they named Batrachochytrium dendrobatidis, and which belonged to a clade not known to infect vertebrates. “It was an extraordinary piece of detective work,” says Fisher, who started working on B. dendrobatidis shortly after it was discovered. The fungus seems to have appeared at about the same time in Australia, Central and North America, and possibly Europe, and is spreading rapidly, Fisher says.

B. dendrobatidis's spores live in streams and ponds and have a flagellum that enables them to travel short distances; animals are thought to be infected by direct contact with the spores or with other infected animals. The fungus has caused the greatest disease-driven loss of biodiversity on record; some areas in Central America have lost more than 40% of their amphibian species.

Sharif Fayez, a Persian literature scholar who helped launch AUAF as then–minister of higher education, says that a Western-style university is needed not just to attract the best students “but also the best faculty.” A typical public university professor earns less than $500 a month, while AUAF faculty salaries are competitive with those at Western universities. In return, all faculty members are expected to hold an advanced degree. (The figure is 40% for all Afghan universities, up from 30% in 2008.) “We've had a lot of success with this model over the course of USAID's history,” Shah says. “It was actually the American University [in] Cairo that brought a lot of technology industries to Egypt. And a lot of the people who led the efforts in Tahrir Square were graduates of a social mobilization and technology class taught at the American University [in] Cairo [for] 20 years.” That university had weaned itself from U.S. funding and was self-sustaining at that point, he adds. AUAF has similarly lofty aspirations, and it's moved with deliberate speed in building its capacity. It currently offers students three undergraduate degrees, with the vast majority choosing business and finance. (Computer science/information technology and political science/ public administration are the other two bachelor's-level programs.) There are seven faculty members in its science and mathematics department, which offers a variety of introductory and midlevel courses. Some 500 students are enrolled in its undergraduate degree programs, with a similar number pursuing English-language studies. Another 800 students are taking short courses in various fields offered by the university's professional development institute. Fazel says that chemistry and earth science degrees are next on his wish list. A history of violence But while AUAF may ultimately train the elites, the vast majority of Afghans seeking higher education will find it in the public university system. And that system is creaking. Only a 10-minute drive away, Kabul University represents the yin to AUAF's yang on the circle of Afghan higher education. Its leafy, walled-in campus serves as a quiet oasis in a city that struggles to provide even the most basic amenities—water, power, waste disposal—for its 5 million residents. Its 20,000 students make it by far the largest university in the country. Founded in 1931, Kabul University is also the country's most prestigious, and its science programs are bulging at the seams. “This is introductory physics,” says Mohammad Arif, a chemist and dean of the faculty of science, poking his head into a lecture hall. The sweltering, windowless hall, with hundreds of students crammed into every seat right up to the top wings, looks more like the setting for a rock concert than a physics class. “We are at double capacity,” Arif says. Some 1500 students are pursuing science and math degrees in the departments under his watch. The total does not include applied science majors in the university's schools of engineering, agriculture, and medicine. The current situation is a far cry from the recent past, says the 62-year-old Arif, who has taught at Kabul for 2 decades. “In the days of the Taliban, it was normal to have only one or two students in our classes,” says Arif, a cosmopolitan intellectual who was forced to wear a beard and turban during their reign. And that era was only the latest insult to the country's system of higher education. Arif had just finished his Ph.D. in chemistry in Moscow in 1979 when the Soviet Union invaded his homeland. “That's when everything fell apart,” he says. The departure of Soviet troops in 1989 led to a civil war that subsided when the Taliban took over. “We just never recovered.” The U.S. invasion in 2001 offered a ray of hope for Afghan academics. But so far job training has been the highest priority. “We actually put far more resources into vocational training in communities—essentially the Afghan version of community colleges,” says Shah about USAID's portfolio. The Afghan government spends about$35 million a year on higher education, most of it for administration, faculty salaries, and routine maintenance. Other requests wind up in the back of the queue. Two years ago, for example, Arif applied to the ministry for funds to update the chemistry labs. “I still have not heard back,” he says.

The other science disciplines are also languishing. “This is our physics lab,” he says, unlocking a tiny room. Old and battered oscilloscopes, scales, and voltmeters are laid out at a dozen stations along the walls. “They were donated by Germany probably 30 years ago. We don't have enough lab equipment to teach the basics, and our textbooks are completely outdated.”

It wasn't always so. During the Cold War, the United States and the Soviet Union competed with each other to invest in Afghan higher education. “The early 1960s was a golden age,” says AUAF's Fayez. There were academic exchanges and research collaborations with U.S. universities such as Purdue University, the University of Wyoming, and the University of Nebraska, Omaha. Columbia University went a step further, building an institute in Kabul to train future teachers. Fayez was one of many Afghans in the program, which included a year in New York City.

Not to be outdone, the Soviet Union invested heavily in science and engineering. It helped to build up Kabul's polytechnic universities, and by the 1970s Afghan academics were shuttling constantly between Moscow and Kabul. One reminder of that partnership is the fact that the older generation of Afghan scientists and engineers, like Arif, are just as likely to speak Russian as English. But the Soviet invasion soured that relationship.

Problems as opportunities

Getting accurate demographic statistics in Afghanistan is notoriously difficult. But 3 decades of war have certainly exerted a heavy toll on the country. When U.S.-led forces arrived in 2001, Afghanistan ranked near the bottom of every global index for wealth, public health, and education. Girls were forbidden from attending school. While neighboring Pakistan managed to double its literacy rate during that period, to 50%, fewer than 20% of Afghans were literate.

A decade later, Afghanistan's problems remain, but the trends are more encouraging. Literacy has reached 28% and is climbing. Only a third of students are female, but the gap is narrowing. “In primary education alone, we've gone from about 2 million kids in school, with almost no girls, to 8 million kids in school, more than 3 million of whom are girls,” says USAID's Shah. “I think those 3 million girls going to school every year is a huge accomplishment America should be proud of.”

Stroll through Kabul and its problems are all too clear. Packs of feral dogs compete with begging children for street corners. Some of the larger roads now have gutters, but elsewhere rubbish accumulates like snow drifts. Fewer than 10% of the city's roads are paved, and stinging red dust mingles with the smog. Traffic accidents are too common to attract notice, with cars navigating almost entirely without rules or street signs. And this is the capital city, the epicenter and criterion for international funding.

Then again, it is exactly these problems that appeal to scientifically trained Afghans like Muhammad Mujtaba, an engineering graduate student at the University of Missouri, Columbia. “I would like to bring a real change to the environmental situation in Kabul,” he says. He plans to return to Kabul next year to work as a civil engineer.

Agriculture is another area where, as Fazel says, “problems are also opportunities.” For most Afghans, modern agricultural techniques, especially irrigation systems adapted to the country's complex, water-deprived environment, have barely arrived. “Agricultural engineering can make a huge difference here,” Fazel says. There's also the challenge of finding a crop as profitable as poppy; Afghanistan is the largest producer of opium in the world.

And then there are the opportunities hidden underground. Foreign nations have been scrambling for the chance to share in the country's mineral wealth. The U.S. government announced in 2010 that geologic surveys had found that Afghanistan has enough iron and copper to make it one of the world's top producers. A Chinese mining company was the first to secure digging rights, and a Chinese-owned copper mine in southern Afghanistan is expected to become the largest foreign commercial investment in the country when it opens in 2014.

But those activities won't generate many well-paying jobs for Afghans unless the universities can provide the appropriate training. “[We] lack the skills and preparedness for such work,” says Nasir Shir, one of Afghanistan's leading geographers, who is based in Kabul and at the University of Maine, Portland. Afghan universities have embraced the challenge of generating the relevant expertise. Last year, for example, Kabul University began a master's degree program in physics, its first graduate program in the sciences.

Fazel says the Afghan government needs better scientific advice to take advantage of these opportunities. For the past several years, he and a small group of Afghan scientists have been pushing for a national science council that would report directly to the Afghan president, along with a national research center that would focus on the country's top priorities: “agriculture, healthcare, mining, and [information technologies].” In spite of the group's influence and energy, however, the government has shown little interest in either idea. Short-term security has trumped longer-term priorities such as science, he says, and security is likely to remain a priority after the 2014 troop withdrawal.

Back on the AUAF campus, the graduation goes off without a hitch. As the families head home, the guards look relieved. Fazel is bothered by the razor wire topping the high walls. “I look at this and I feel ashamed. A university should be an open place,” he says.

But the students take no notice. They gather on the lawn one last time for a celebration that would have been punishable by death only a decade ago: Pop music blares from a stereo and everyone dances. It's not rocket science, but it's a start.

• * With reporting by Jon Cohen in Washington, D.C.

6. Profile: João Zilhão

Neandertal Champion Defends the Reputation of Our Closest Cousins

1. Michael Balter

Archaeologist João Zilhão and his critics trade charges over who truly invented artifacts at European sites—and whether Neandertals were “modern.”

TORRES NOVAS, PORTUGAL—When João Zilhão was 14, he and other young spelunkers from Lisbon began exploring a labyrinth of caves in the cliffs overlooking this sprawling municipality in central Portugal. In those days, it took 5 hours by bus to get here, and there were few hotels in the area—certainly none that they could afford. So Zilhão and his comrades slept in the long, cool passageways of the Galeria da Cisterna.

Zilhão credits those experiences for his success as an archaeologist, for he followed the inner maze of the caves to some of the most important finds of his career. He found 7500-year-old artifacts from Portugal's earliest known farming community in the Galeria. Then in 1989, he and a colleague climbed up a shaft in the Galeria's roof through 40 meters of vertical passageways and discovered a hidden back entrance to another cave, the Gruta da Oliveira. There, Zilhão unearthed extensive Neandertal bones and tools, and the cave is now an important example of late Neandertal survival.

Today, Zilhão, 55, is well-known as the Neandertals’ fiercest advocate, taking on any and all suggestions that their mental abilities might have been inferior to those of modern humans. His slender, soft-spoken presence often contrasts with his biting criticisms of others’ viewpoints, especially in print. “Where he passes, scorched earth follows,” says one archaeologist who asked not to be identified.

In June, Zilhão, now at the University of Barcelona in Spain, scored a key point in this debate: He and colleagues reported in Science that paintings from at least one Spanish cave might predate the modern human occupation of Europe, making Neandertals the possible artists (15 June, p. 1409). For Zilhão, however, “possible” is not enough. The new dating, he insists, “implies a strong probability of Neandertal authorship.”

Such strong statements have become Zilhão's trademark and make him a formidable foe in what some researchers call the “Neandertal wars,” the scientific debate over Neandertals’ intelligence and taxonomic status. Zilhão's dogged insistence on the logic of his case makes him “a tough person to argue with, … the kind of researcher that can be frustrating and even aggravating at times,” says fellow Neandertal defender, paleoanthropologist Erik Trinkaus of Washington University in St. Louis, Danforth.

Even Zilhão's opponents agree that he is a force to contend with. He is “a top-notch archaeologist,” says archaeologist Harold Dibble of the University of Pennsylvania. Zilhão's advocacy of close biological and cultural similarities between Neandertals and modern humans “has changed what we have to think about,” says archaeologist Iain Davidson of the University of New England in Armidale, Australia.

Into the caves

Zilhão was born in Lisbon, the son of an engineer father and a psychiatrist mother, and grew interested in history, archaeology, and politics early on. When he was young, Portugal was still in the grips of the fascist dictatorship of António de Oliveira Salazar, and like many of his peers, Zilhão spent his youth protesting against the regime, which ended in 1974. He traces his rebellious nature and his sympathy for the underdog to those turbulent days.

At 14, he began visiting caves with the spelunking club at his high school. Because Portugal had no undergraduate archaeology degrees at the time, he studied economics at the University of Lisbon, but soon switched to history and spent summers volunteering on archaeological digs in Portugal and France, biding his time until graduate school at the university. For his 1200-page archaeology Ph.D. thesis, Zilhão synthesized the little- known Upper Paleolithic of Portugal, the heyday of prehistoric modern humans.

Portugal was still “peripheral” to mainstream archaeology in those days, Zilhão says, which gave him independence: “I didn't have an old man telling me what I had to do and how I had to think.” Zilhão first worked as a professor at the University of Lisbon, where he successfully campaigned against a dam that would have flooded hundreds of rock art engravings in Portugal's Côa Valley.

Then his team found Neandertal tools, hearths, and fossils dating from 65,000 to 35,000 years ago at Oliviera, making them among the latest surviving Neandertals—consistent with other evidence that Portugal and Spain served as a “refugium” for the last Neandertals.

In 1996, Zilhão entered the Neandertal wars in earnest. For decades, researchers had argued about the authorship of an Upper Paleolithic culture called the Châtelperronian, found largely in France and characterized by personal ornaments made of animal teeth and ivory rings. That year, a team led by anthropologist Jean-Jacques Hublin, now at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, published a pivotal paper in Nature concluding that the Châtelperronian had been made by Neandertals. But Hublin's team concluded that the ornaments were the result of “acculturation” with modern humans, meaning that the Neandertals had either imitated modern human behavior or even gotten the ornaments through exchange or trade.

Zilhão was outraged. “This was an extraordinary conclusion,” he says. He saw it as a sign of bias against the Neandertals, an assumption that they were not capable of inventing the ornaments themselves. In 1998, Zilhão, archaeologist Francesco D’Errico of the University of Bordeaux in France, and others published a long paper in Current Anthropology challenging the acculturation model and arguing that Neandertals had invented the Châtelperronian independently.

The paper rekindled a fierce and longstanding controversy over just how different Neandertals and modern humans really are, a debate whose flame has not yet dimmed. “This is an old debate and quite cyclical,” Dibble says. “At times the Neandertals have been considered to be a branch of stupid, stoop-shouldered hominins. … Then the pendulum swings and they are considered to be exactly like us.”

Zilhão has continued to try to push the pendulum back, arguing vehemently against the acculturation model and insisting that Neandertals and modern humans are the same species and that they intermixed extensively. For example, in a 2010 paper in the Proceedings of the National Academy of Sciences, Zilhão and Trinkaus argued that the teeth of a child from the Lagar Velho rock shelter in Portugal show hybridization between moderns and Neandertals. Recently, the two have argued that the oldest undisputed modern human fossil in Europe, a roughly 40,000-year-old skull from Romania, bears some Neandertal features.

Zilhão sees the recent finding that many living people harbor between 1% and 4% of Neandertal DNA as vindication of this position. “That doesn't mean that there was only 1% to 4% admixture back then,” he argues, “but it's 1% to 4% of our genes today, 40,000 years after the fact.” He also argues that he already has produced the smoking gun on Neandertals’ symbolic abilities: jewelry, including ochre-painted shells, from sites in Spain dated as early as 45,000 to 50,000 years ago, earlier than the first accepted dates for modern humans in Europe (Science, 15 January 2010, p. 255).

Although some consider Zilhão biased, he accuses others of prejudice against Neandertals, recently commenting that some colleagues are on a “mission from God” to give modern humans credit for the Neandertals’ cultural accomplishments (Science, 1 June, p. 1086). And he insists that his viewpoint is gaining ground. “Twelve or 15 years ago, people like myself … were in the minority, but now … I don't know a single individual actually involved in [Neandertal] research in Spain, Portugal, or France who thinks Neandertals were dumb or had inferior cognition to modern humans.”

Straw man?

But Zilhão's critics are not swayed. They counter that Zilhão and his colleagues have created something of a straw man, because few serious researchers argue that the bigbrained Neandertals were stupid. Neandertal acculturation during the Châtelperronian had “nothing to do with inferiority,” Hublin says. Cultural diffusion between groups “is one of the most common and well-documented phenomena in the ethnographic and historical record.” He and others see key differences in the skeletons and archaeology of Neandertals and modern humans—for example, Hublin says, the claimed Neandertal jewelry is less sophisticated than that of moderns. He and others see Neandertals and moderns as distinct species that were separated for hundreds of thousands of years. “Denying any form of biological differences [between them] is a sort of creationism,” Hublin says, an argument that “rejects the very phenomenon of evolution.”

And Hublin insists that Zilhão is the one who seems to be on a mission. “Those who are on a mission from God … are those who try to deny any evidence not matching with their personal crusade,” Hublin says. “The latest debates on Neandertal abilities are one of the worst examples in which ideological issues have overshadowed scientific evidence.”

Dibble questions what he sees as an implicit tenet of Zilhão's position, “the belief that it would be somehow insulting to the Neandertals to conclude that their behavior is not like ours.” Rather, he says, they used different kinds of adaptations to survive. “Neandertals were around for 250,000 years. That's pretty successful, and better than we've done so far.”

Trinkaus says that both he and Zilhão have been “repeatedly accused” of being “politically correct” where Neandertals are concerned—treating them as a Stone Age minority group in need of affirmative action. But that's a charge he rejects. “João is, and will remain, controversial,” Trinkaus says. “But over the past decade he has contributed more of substance, and more ideas, to [Paleolithic] archaeology than any other active participant. His legacy is already being felt, and he has many years ahead of him.”

7. Infographic: World of Waste

In this four-page infographic, Science offers insights into where the world's waste is coming from, where it is going, and how waste streams are changing.

The scope and reliability of waste statistics vary widely around the world, and even wealthy, developed countries can have big data gaps. In the United States, for example, battles over waste policy have complicated government efforts to document some waste streams, and budget cuts threaten programs that try to calculate how materials flow through the economy. Further complicating matters, nations sometimes use different waste definitions, making meaningful comparisons difficult. Still, enough data exist to draw some insights into where the world's waste is coming from, where it is going, and how waste streams are changing. And the numbers suggest that local economic, social, and geographic factors can play a big role in waste management, leading nations to take often very different approaches.

Click the image for a larger version.

For more on waste, see the complete special section in this issue.

[CREDIT: G. Grullón/Science]

8. Garbology 101: Getting a Grip on Waste

1. Jeffrey Mervis

Most people choose to ignore it, but managing waste is a pressing and contentious issue that is prompting a closer look at what we throw away—and where it ends up.

People who work with waste for a living seem to have a special passion for their subject. And they aren't fazed by its complexity. Those traits help explain why Bill Davidson found himself tapping away at his home computer one Sunday morning more than a decade ago.

A consultant “got lost” trying to write a report on waste management in Montgomery County, Maryland, recalls Davidson, now section chief for strategic planning in the county's Division of Solid Waste Services. So the mechanical engineer, who once crunched numbers for the congressional Office of Technology Assessment, decided to try his hand at depicting what happens to all the waste generated each year by those who live, work, and play in these affluent suburbs of nearly 1 million people outside Washington, D.C.

His solution was an elegant flow chart that tracks 15 streams of the county's detritus, which last year totaled 1.34 million tons (see diagram, p. 669). It depicts the ultimate fate of every chicken bone, diaper, cereal box, beer can, plastic bag and bottle, broken toy, mattress, and grass clipping discarded by this racially mixed, highly educated, and relatively environmentally aware suburban community.

Davidson and his colleagues were able to devise such a flow chart because their employer takes waste management seriously. Recycling is mandatory in Montgomery County, for example, and haulers are required to submit reports on what they pick up and where they take it. “We were swimming in data,” he says. That's a relative rarity in the world of waste, where reliable statistics are often unavailable.

It may look convoluted, but Davidson's flow chart barely scratches the surface of the complexity, choices, and challenges that modern society faces in managing its waste. For example, it deals with only a slice of the pie known as municipal solid waste (MSW). That's the highly visible trash generated by residents, schools, and businesses and picked up at the curbside or in parking lots. But MSW makes up only a tiny fraction—3% to 5% by weight is a good estimate—of the total waste that humanity generates.

The United States, for example, produces roughly 12 billion tons of waste each year, of which only 350 million tons are classified as MSW. The rest, sometimes called invisible waste, comes from mining, farming, road building and other construction, and industrial activities. There's also the human waste flushed down toilets and the pollutants dumped into waterways or spewed into the air (see infographics spread, p. 664).

In addition, the diagram only hints at the myriad contentious issues surrounding how waste is collected, processed, and ultimately disposed of in developed nations. Experts have varying views, for instance, on the best way to economically sift recyclables out of the MSW stream, the pros and cons of burning trash to produce electricity, and how to account for the hidden costs to a society of managing waste. Meanwhile, the once-radical idea of generating zero waste has shifted from the streets to the corporate boardrooms, sparking further debate over the extent to which such approaches will actually reduce global demand for important raw materials such as aluminum. The good news: Such discussions are prompting a closer look at what we throw away—and where it ends up.

Bury, burn, and abandon

Trash wasn't always so complicated. “When I give talks on garbage, I start by saying our forefathers created waste with stone chips,” says Wilson Hughes, former co-director of the Garbage Project at the University of Arizona in Tucson, which from 1973 to 2001 pioneered the science of garbology under the direction of urban archaeologist William Rathje. “But it didn't become a problem until they settled down and began living in one place. That's when societies had to start thinking about what to do with it.”

Sitting around their fires at the end of the day, our ancestors had three choices for handling their waste, Hughes notes: “Bury it, burn it, or leave it on the floor.” Fast-forward a dozen millennia, and those three options still exist. The only new wrinkle is recycling. (Of course, the idea of throwing out something that still possessed value might have seemed bizarre to our resource-starved ancestors, who reused bones, hides, and tools until they wore out.)

The choices a jurisdiction makes about how it handles its waste can have a big impact on its bottom line. “When Montgomery County needs to float a general obligation bond for a new school or road,” Davidson says, “it goes to New York to get its bonds rated. And the first question the bond companies ask is, ‘Have you got your solid waste act together?’”

Getting that act together can take time, however. Montgomery County, for example, got into the trash business by happenstance in the early 1940s. “Before then, your garbage was picked up by a guy with a truck” who probably took it to a local landfill, Davidson says. “And then World War II happened, the guy got drafted, and a [public] scream went up.”

Since then, local officials have developed what is now a comprehensive, integrated system. To start, the county requires residents and businesses to separate their waste into four streams—paper; plastics, metals, and glass; yard waste; and garbage. Private haulers working under county contracts then bring everything to a centrally located, county-owned transfer station and recycling center that also composts the yard waste. The recyclable material is sorted and stored on site, sometimes for months, until an appropriate buyer is found. The garbage is shipped a short distance by rail to an incinerator in Dickerson, Maryland, where it is burned; metals are then removed from the ash and recycled, and the remaining residue winds up in a landfill in central Virginia. The county currently operates no landfills, although it has a permit for a site near the Dickerson plant.

Burning debate

Although waste experts applaud Montgomery County's overall approach, its reliance on incineration is more controversial. Landfills are the most common means of disposal for most of the United States outside the northeastern corridor and are especially popular in regions where land is relatively cheap and available.

Montgomery County's incinerator was built and is operated by Covanta Energy, a New Jersey–based company with dozens of waste-to-energy plants across the United States. It's called a resource-recovery facility because, unlike incinerators of the past, it operates with extensive pollution controls and separates and recycles metals after combustion. The 1800 tons of waste burned each day in its three boilers also generate 52 megawatts of electricity, which is sold to help off-set operating costs.

One of the big advantages of the Dickerson incinerator, Covanta officials say, is that it reduces the amount of waste Montgomery County must send to a landfill. Burning reduces the volume by 90%, they note. The sale of the power also helps offset the costs of the operation.

Environmental groups, however, have long opposed waste-to-energy plants, arguing that they have a negative net impact on the environment. A recent study by the Environmental Integrity Project, a Washington, D.C., non-profit organization, for example, concluded that the Dickerson incinerator produces more pollution per unit of power than Maryland's four largest coal-fired power plants. The study looked at emissions of carbon dioxide, nitrogen and sulfur oxides, mercury, and lead.

Covanta says its plants shouldn't be compared to coal-fired power stations because producing electricity is not their primary purpose. “Waste-to-energy plants are designed for sustainable waste management, and generating electricity is an added benefit,” says James Regan, a corporate communications officer. A more complete life-cycle analysis, he says, would show that waste-to-energy plants actually reduce overall greenhouse gas emissions. They do that by diverting waste from landfills, which generate methane, and by reducing the amount of fossil fuels that must be burned in other plants to generate the same amount of electricity.

Maryland legislators apparently agree. Last year, they put waste-to-energy plants in the same category as wind, water, and solar energy when providing special tax breaks for companies to develop renewable fuels. Most environmentalists oppose that classification, which more than a dozen states have adopted. But it's not just a semantic distinction. Such tax breaks can play a big role in determining whether it's cheaper for a local government to build a waste-to-energy plant or use a landfill.

A beer budget

The economics of waste handling also lie at the heart of another issue that is important to trash professionals: the scale, design, and business model used by recycling operations. Although almost anything can be recycled, experts note, market conditions often determine what is worth recycling.

Montgomery County, for instance, has opted to use public funds to support a mid-size recycling system that accepts waste only from its own jurisdiction. It also asks its residents and businesses to help sort recyclables into multiple “streams,” promoting the concept heavily to encourage compliance. A primary goal is to hold down the costs to taxpayers without skimping on quality. Or, as Davidson describes his employer's philosophy: “We try to provide champagne service on a beer budget.”

County officials pride themselves on the quality of their separation process, saying that a purer product can command a higher resale price. Toward that end, workers on the high-speed conveyor lines at the county's recycing center separate and bale more than a dozen different types of metals and plastics (glass is sorted into four categories but not baled), and the material may be kept for months until the county can find a buyer willing to pay a reasonable price. Montgomery County recycles 44% of its MSW, well above the national average of 24% but short of the county's own target, which it is in the process of raising from 50% to 70%. And what can't be sold must be disposed of.

Not far away, however, the behemoth of the trash industry, Waste Management Inc., operates a different model: It pays communities millions of dollars to bring their waste to its regional materials-recovery facility, and it doesn't demand that users sort their recyclables. For the company, economies of scale are the key to profitability.

During the week, a 24-hour stream of trucks arrives at the company's Kit Kat plant, which sits just off a major highway not far from the Baltimore/Washington International Airport. The trucks are delivering unsorted recyclable waste from customers throughout the mid-Atlantic region, including communities that, unlike Montgomery County, lack their own waste-handling facilities.

Kit Kat, which opened in 2007, can sort and process 75 tons of recyclable material an hour. (By comparison, Montgomery County's recycling facility handles 12 tons an hour and operates many fewer hours a week.) In 2010, Kit Kat processed 230,000 tons, 70% of it paper and cardboard.

Waste Management's business model depends on getting the best price possible for those bales of materials from buyers as close as Baltimore or as far away as Beijing. And unlike at a landfill or most transfer stations where the hauler pays a tipping fee to dump its load, Waste Management pays for what comes across its scales. “We do a sort test for each community,” explains Jim Marcinko, head of the company's recycling operations for the Delmarva (Delaware, Maryland, and Virginia) area. “We'll analyze a whole day's worth of material. Then we'll deduct our processing fees and send them a big check.” For Howard County, where Kit Kat is located, that check totaled $3 million last year. Waste Management's high-volume approach also gives the company a good reason to invest in potentially game-changing—and lucrative—new technologies. Currently, for example, most waste-to-energy facilities burn plastic to produce steam, which can be used to turn turbines to generate electricity. But that electricity has to compete in the market against relatively cheap sources of power such as coal and natural gas. In contrast, converting the plastic to higher-value transportation fuel could be a bigger moneymaker—if researchers can figure out a practical way to do it. That's why Waste Management is exploring the feasibility of using a high-tech version of pyrolysis, in which waste is heated to 2000°C in the absence of oxygen, to transform plastic into a substance that can be used as liquid transportation fuel. Getting to zero waste As Montgomery County and other municipalities grapple with the materials that end up in their recycling centers and transfer stations, some waste professionals would like researchers and companies to spend more time thinking about the front end of the waste stream, in other words, reducing how much trash we generate in the first place. That's the concept represented in a widely used “waste hierarchy,” issued by the European Union in 2008, which depicts five options for dealing with trash (see graphic, p. 668). In descending order of preference, they are reduce, reuse, recycle, recover, and dispose. Many in the “zero-waste” movement, in fact, see waste as the product of poor planning. “Waste is just a design flaw,” asserts Montgomery County's Davidson. “If materials are created in such a way that they can't be recycled, then they need to be redesigned. And that's what we need to work on.” Garbologist Hughes, who spent a decade managing waste-reduction efforts for the city of Tucson after leaving the university, says the real payoff from the zero-waste movement will be when companies begin “manufacturing things that can be taken apart and recycled. Stuff that has to be dumped won't be made any more.” General Motors (GM), the mammoth global carmaker, is one of many Fortune 500 companies that have embraced the concept of zero waste. In 2008, GM announced a goal of achieving “zero waste to landfill” at half of its 145 plants, a phrase that includes sending some of the company's waste to incinerators but that doesn't count the burial of ash residue. Two years later, it also promised to reduce the total waste generated at its facilities by 10% over the next decade. But what exactly do those targets mean for an automaker? John Bradburn, an environmental engineer who has spent his entire 34-year career with GM and who now manages its waste-reduction efforts, says it means finding productive uses for material that GM would have previously discarded. That includes making air-inlet panels from recycled bumpers, turning used packaging into sound-absorbing components within vehicles, and converting plastic waste into shipping containers. Bradburn says the initiative extends beyond the factory gates: The air deflectors on the Chevy Volt, GM's electric-gas hybrid car, were once oil-soaked plastic booms used to contain the 2010 Deepwater Horizon oil spill in the Gulf of Mexico. At the same time, GM faces some constraints in reducing waste on the plant floor. “Vehicle parts must come to us in the best possible shape,” he says, “and to do that you need robust packaging” that creates additional waste and can be difficult to recycle. GM says the zero-waste-to-landfill campaign is going smoothly, and an independent auditor recently verified its claims. As of June 2012, GM said 100 facilities—nearly 70%—have already achieved that goal. It hasn't yet reported on progress toward its second goal—to reduce overall waste by 10% in the next decade—but GM says it did cut the amount of waste per vehicle manufactured by 28%, to 304 kilograms, in the 5 years prior to 2010. Raw facts? For advocates of sustainability, however, the real question is not what GM or any particular company is doing to reduce its waste. Instead, they want to know whether those steps are helping make significant progress toward a bigger goal: reducing the world's demand for raw materials. For one particularly valuable material, aluminum, a 2010 forecasting study by the U.S. Geological Survey (USGS) suggests that recycling is having less of an impact than might be expected. The issue involves how much of the projected rise in demand for aluminum—from 46 to 120 million metric tons—can be met with metal from so-called secondary sources, which includes recycled material. That estimate, in turn, rests on some fundamental assumptions about how aluminum is used. The heaviest demand in the next 2 decades will come from developing nations, the USGS report concludes. But those countries will tend to use aluminum mostly to construct long-lasting infrastructure such as buildings, bridges, and power lines. As a consequence, the aluminum probably won't be available for reuse for many decades, according to the report. In contrast, advanced economies tend to use aluminum in products with shorter lives, such as cars, trucks, and jets. Although most of that aluminum will be recycled, it won't be enough to meet the global demand. Based on that analysis, the USGS report concludes that “the proportion of aluminum generated from old scrap may decrease” between now and 2025. The industry disagrees, saying that there will be 50% more recycled metal available over the next 2 decades than the USGS has projected. The dispute demonstrates just how hard it can be to measure the extent to which recycling helps conserve Earth's resources. Some waste-management scholars worry that recycling has become a feel-good activity that diverts the public—and government agencies—from the need to find the most effective strategies to reduce waste and limit the nonsustainable extraction of raw materials. A new book by Samantha MacBride, an adjunct professor at Columbia University's School of International and Public Affairs, argues that the primary burden of reducing waste should fall on the shoulders of manufacturers rather than on the public. “Recycling only affects 80 million tons of MSW a year [in the United States],” she notes. “It's really only the tip of the iceberg.” Even so, the title of her book makes clear that she hasn't abandoned all hope: Recycling Reconsidered: The Present Failure and Future Promise of Environmental Action in the United States. Making the case for changing how the world perceives and handles waste, however, will require solid statistics. Without them, “trash talk” is too often simply that: uninformed opinions. But in the United States, at least, long-ago political decisions about how to regulate waste are limiting the flow of data. In particular, twice within a decade Congress amended a potentially powerful tool to manage materials flow: the 1976 Resource Conservation and Recovery Act. The changes limited the U.S. Environmental Protection Agency's ability to monitor and regulate large chunks of the U.S. waste stream. As a result, it now has responsibility for just two of the smaller pieces of the pie: municipal and hazardous waste. The outcome was predictable, says Sue Briggum, a longtime observer of federal environmental policy as vice president for federal public affairs at Waste Management. “If you only measure hazardous and municipal waste, that's what will get managed and that's what will get recycled. And what you don't measure becomes invisible.” Last year, EPA put out a notice asking for comments on whether it should expand the definition of MSW and look more broadly at what's called “sustainable materials management.” Sensing a business opportunity, Waste Management told EPA that it welcomed the invitation to shift the discussion from “how to dispose of waste safely” to “the safe recovery of used materials.” But observers say federal legislators have little appetite for increasing the agency's regulatory powers and, specifically, the scope of the law. USGS, meanwhile, has proposed wiping out the small team of analysts who produce the federal government's only comprehensive and authoritative studies on materials flows, including the report on aluminum. Agency officials admit that the$5 million cut to the team's parent office, part of a broader belt-tightening for 2013, “would reduce its ability to assist other federal agencies who rely on timely, accurate, and unbiased mineral resource data for decision making.”

In other words, eliminating the effort would make the government less able to manage its material resources wisely. Now that sounds like a real waste.

9. Modern-Day Waste Pickers

1. Jeffrey Mervis

People have been sifting through trash for as long as society has been producing waste. But to most people, it's all just trash.

With 12 tons of trash whizzing past her every hour, Norma Garcia has only a few seconds to spot the diaphanous plastic bags that can foul the machinery at the Montgomery County, Maryland, recycling center where she works as a lead sorter.

But the trim mother of two is good at her job. Within seconds she's plucked another bag from the stream of detritus on the conveyor belt and deftly tossed it into a trash can in the noisy, malodorous—but orderly—three-story concrete building where she's worked for 8 years. Garcia is a traffic cop for waste, directing the recyclable paper, plastic, metal, and glass to its proper destination while barring entry to the plastic bags, medical needles, batteries, pesticides, diapers, and everything else that can't be recycled—and shouldn't be there in the first place.

People have been sifting through trash for as long as society has been producing waste. But compared with those who toil in the steaming, vermin-infested mounds of garbage on the outskirts of Rio de Janeiro or Manila, Garcia and her crew work in relative comfort. They are provided with safety equipment, get regular breaks, earn well above minimum wage, and—although contract workers rather than regular county employees—receive the same health insurance. In fact, the regular hours and indoor venue make working the line a plum assignment and translate into very low employee turnover rates.

Still, working with waste brings with it some unavoidable risks. On Garcia's conveyor line, the work screeches to a halt “anytime we see something toxic,” she explains through a translator. “We push the button to turn off the line, and people have to leave until they make sure the fumes are gone.” The stench is the worst part of the job, she says. “The spoiled milk in a carton … sometimes it's so bad it can make you sick.”

Sludge for energy

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Sludge—a goopy, mudlike mix of organic matter and dead microorganisms—is a byproduct created at almost every step of the treatment process. When sewage flows into Blue Plains and most other treatment plants, for example, it first goes through a settling stage called primary treatment that allows suspended solids to sink to the bottom of large tanks. Then, the water undergoes secondary treatment, in which microbes process food and fecal waste, creating more sludge. At many plants, the liquid effluent is returned to a local river or ocean after secondary treatment. But at Blue Plains and other plants that discharge into sensitive waterways, a third tertiary treatment is added to remove nitrogen and phosphorus compounds. All told, Blue Plains' three-step process produces some 1200 tons of sludge, or “biosolids,” every day, enough to fill 50 tractor-trailers.

Historically, treatment plants simply dumped their sludge into landfills or treated it with lime and spread it on farm fields. Such practices have drawn criticism, however, because transporting sludge is expensive and dumping it wastes a potential source of energy. In response to such concerns, Blue Plains is installing technologies that will enable it to convert one-half of its sludge into methane for use as fuel, with the remainder processed into a high-quality, pathogen-free material that could be used like compost in landscaping.

The heart of that new system is currently a construction site for a new building where biosolids will be subjected to high pressure and heat—150°C for 30 minutes. During this pasteurizing process, known as thermal hydrolysis, bacterial cells in the sludge will burst, making them more amenable to being eaten by methanogens, microbes that produce methane gas that can be used for fuel. The fuelmaking process will occur in huge new tanks called digesters, and the methane in turn will be used to fuel a turbine that will produce electricity and heat that will power the thermal hydrolysis system and net enough extra electricity to power 8000 homes. The remaining pasteurized biosolids, meanwhile, will be available for use as fertilizer. Adding thermal hydrolysis to the system saved about $200 million in digester construction costs because the process concentrates the cells and less space is needed for methane conversion, Peot says. “Without that [amount of savings] we would not have been able to afford the digesters,” he says. Waste streamlined A second Blue Plains project, being undertaken in conjunction with two other treatment plants in Austria and Virginia, is coming up with a better way to remove nitrogen compounds from wastewater. Ironically, part of the nitrogen problem is created by the methane-producing digesters; the microbes release a lot of ammonia into the wastewater stream. At first, Peot and his colleagues considered taking that water and putting it through the entire treatment process again to remove the ammonia. But that multistep process, which involves aerobic bacteria and methanol, is costly, in part because sustaining the bacteria requires aerating, or adding oxygen, to the water, which accounts for almost one-quarter of the Blue Plains plant's power use. The process also yields carbon dioxide, increasing the plant's carbon footprint. Instead, they decided to use an increasingly popular bacterial process, called anammox or deammonification, to get rid of the nitrogen compounds (Science, 7 May 2010, p. 702). To start with, Blue Plains will use anammox on only the ammonia-rich water coming out of the digesters. But if the process works as advertised, Peot envisions using it for the entire waste stream. And “if we are successful,” he says, Blue Plains will cut its power use for aeration by two-thirds and, together with other energy-saving measures, almost get by on just the power generated using its own methane. “Our goal is to investigate ways to become energy neutral or even energy positive,” he says. Other plants are finding that reaching that goal is possible. In 2004, for example, anammox combined with other measures enabled a plant in Strass, Austria, to become energy self-sufficient. A similar multifaceted approach is enabling the East Bay Municipal Utility District, which serves part of the greater San Francisco area in California, to use various types of organic waste, including chicken blood and cheese waste, to generate enough power to run its treatment process as well as 13,000 homes. As the East Bay's director of wastewater, David Williams, puts it, “We've turned wastes into commodities.” It's an achievement Blue Plains and other waste-treatment plants hope to emulate. 12. A Better Way to Denitrify Wastewater 1. Elizabeth Pennisi Anammox bacteria, which convert ammonia into nitrogen gas in the absence of oxygen, could dramatically improve methods of removing ammonia from wastewater streams. Call it the case of the missing nitrogen. Forty years ago, wastewater treatment engineers noticed that a common process used to convert ammonia into nitrate sometimes failed to produce as much nitrate as expected. The nitrogen “must have gone somewhere,” says Mark van Loosdrecht, an environmental engineer at the Delft University of Technology in the Netherlands. Fermentation engineers determined that the process was producing nitrogen gas, but nobody knew how. Then, in the early 1990s, microbiologist Gijs Kuenen of Delft University and his colleagues discovered a new microbe in wastewater that helped solve the mystery—and turned existing dogma about ammonia's conversion to nitrogen compounds on its ear. Called anammox (for anaerobic ammonium oxidation), the microbe was converting ammonia into nitrogen gas in the absence of oxygen, a reaction previously thought impossible. It took several years to convince the skeptics. One problem was that the bacterium—which is in the phylum Planctomycetes—grows slowly. It divides every 2 weeks, rather than in just half an hour like some bacteria; that means it can take months and sometimes years to get a culture up and running reliably in the laboratory. Another challenge was that the bacteria had never been found in the wild. Once researchers knew what to look for, however, they found it and its relatives living in many places—in oxygen-poor waters of the Black Sea, Lake Tanganyika, and off the coast of Namibia, for example. Now, researchers consider anammox bacteria to be essential components of the global nitrogen cycle and estimate that they account for 50% of the world's nitrogen turnover. And they believe the microbes could dramatically improve methods of removing ammonia from wastewater streams at large municipal plants like the Blue Plains treatment facility in Washington, D.C. (see main text). “It's possibly going to be a game-changer in the U.S.,” says Kartik Chandran, an environmental engineer at Columbia University. Harnessing anammox's potential, however, requires a mastery of microbial ecology. The microbe must be grown in conjunction with a second bacterium that converts ammonia to nitrite; anammox converts the nitrite into water and nitrogen gas. But to operate efficiently, the system must also exclude bacteria that make nitrate. That's proven relatively easy in industrial processes that operate at high temperatures and produce relatively warm, ammonia-rich wastewater streams; several companies have already commercialized anammox systems for use in such environments. But excluding nitrate producers has proved harder in lower-temperature municipal wastewater treatment plants, where the concentration of ammonia can also be low, says van Loosdrecht. Under those conditions, it's been tricky to create a stable anammox community, although a number of plants have installed pilot anammox, also called deammonification, systems. To solve that problem, van Loosdrecht has been experimenting with very slow-growing anammox microbes. Typically, dividing bacteria form suspended particles called floc. But these slow-growers form a much larger, denser particle called a granule. The larger granules somehow tend to exclude the nitrate-producing bacteria. To take advantage of that characteristic, he's engineering a reactor that retains larger granules but excludes smaller floc; he predicts the reactors will enable treatment plants to “do the same process [with] 25% of the space” used by current systems, and cut energy and other costs by about one-third. Columbia's Chandran, who once isolated a strain of anammox bacteria from a Brooklyn, New York, treatment plant and now has it happily growing in his lab, is also perfecting ways to keep the microbe happy and healthy in wastewater treatment plants. Since 2010, treatment plants developing anammox systems have been sending him samples weekly, or more often if they suspect problems. Drawing on findings from his research, he tests the health of a plant's anammox community by sequencing the DNA that covers the microbes' 16S ribosomal subunits. Each type of microbe has a unique 16S fingerprint, and he can tell what kind and how many anammox organisms are present by the number of copies of the 16S genes. His team also looks at the expression of the microbe's key ammonia-fixing genes by monitoring messenger RNA. If Chandran sees 16S numbers and gene activity dropping, he knows the system needs tweaking—there might be too much oxygen, for example. If gene activity is dropping, but the population is stable, it's likely to be a transient phenomenon that should right itself, he says. Such efforts are nudging deammonification into more widespread use. “There's no scientific limitation,” van Loosdrecht says. “It's purely an engineering question.” 13. Save Pave the World 1. Robert F. Service Carbon dioxide may be the ultimate industrial waste product. Could tropical corals provide a trick for locking it away in our highways? Researchers who think about how best to stave off the worst impacts of climate change often have their favorite way of disposing of one prominent industrial waste product: carbon dioxide (CO2). Some urge planting trees to soak up the greenhouse gas; others say capture it and pump it underground. For Brent Constantz, the solution is pavement, and lots of it. Drawing on the chemistry that corals use to build their rock-hard shells, the California entrepreneur and biomineralization expert hopes to combine simple seawater with CO2 to manufacture cement and concrete that would devour vast amounts of the greenhouse gas. “I honestly don't think we can address the carbon problem any other way,” says Constantz, a consulting associate professor at Stanford University in Palo Alto, California. It's an audacious idea he's already tried to commercialize once—with mixed results and plenty of criticism. And his peers are divided on the prospects for seawater cement. “Brent has been too optimistic about these kinds of processes in the past and too glib about the challenges,” says Roger Aines, a geochemist at Lawrence Livermore National Laboratory in California. But Constantz is “a brilliant man” with “a very interesting idea,” says Barry Blackwell, president and CEO of Akermin, a start-up in St. Louis, Missouri, that also works with CO2. Abundant waste There is certainly plenty of work needed to deal with humanity's most abundant waste product. In simple numbers, burning fossil fuels generates nearly 35 billion metric tons of CO2 per year. Roughly 40% of that CO2 comes from some 5000 power plants that burn coal and natural gas to produce electricity. The likely impact of that waste is well known. Since 1750, the amount of CO2 in the atmosphere has risen from 280 to nearly 400 parts per million (ppm) today. By 2100 it's expected to reach 500 to 1000 ppm, depending on progress in cutting emissions. That's expected to lock in a global average temperature increase of up to 5.2°C, trigger sea-level rise, and boost ocean acidity by as much as 150%. The world won't have a prayer of limiting the CO2 buildup unless nations find ways to either prevent or lock up billions of tons of CO2 emissions per year. Constantz, for one, doesn't see many ways to prevent emissions quickly at that large of a scale. Although he says it is critical to improve energy efficiency and develop low-carbon energy sources—such as wind and solar—he doesn't think that will be enough. And he believes that carbon capture and storage technologies—separating carbon dioxide from industrial emissions, liquefying it, and injecting it underground—will be too costly to be widely adopted. If researchers can develop a valuable product that gobbles up CO2 during manufacture, however, that would dramatically lower the cost barrier to megascale carbon capture, he says. And for Constantz, the most obvious candidates are cement, concrete, and the mix of sand and gravel known as aggregate, all of which are used to build infrastructure, from bridges to buildings. The world today produces some 2.5 billion tons of Portland cement annually, for example, as well as 12.5 billion tons of concrete and 32 billion tons of aggregate. Using those mountains of material to trap carbon is “a properly scaled solution to the problem,” Constantz says. To achieve that solution, however, Constantz needs to turn the current concretemaking process upside-down. Today, manufacturing the materials actually produces—rather than traps—huge quantities of CO2. Making a ton of concrete, for example, generates a ton of CO2. Overall, in fact, concrete production accounts for about 5% of all carbon emissions globally. Tropical inspiration Constantz, 53, says the idea of transforming concrete from a carbon source into a carbon sink came from his early academic work studying how tropical corals make their shells. But he quickly turned to the corporate world. When he was 27, he used his experience studying marine calcification to come up with and commercialize a novel cement that revolutionized the repair of bone fractures in hospitals around the globe. In 2002, he revised his recipes to develop a stronger and faster-setting cement. He now holds nearly 100 patents in cement-making technology. As he mixed his boutique medical cements, however, Constantz began to wonder whether it might be possible to turn waste CO2 into the minerals that form the basis of structural cement and concrete. In principle, the idea is straightforward. When dissolved in water, CO2 reacts with water to make bicarbonate ions, which under the right circumstances are transformed into carbonate ions. When carbonate meets up with calcium and magnesium ions present in seawater, they readily combine to form calcium and magnesium carbonates; those form the same minerals used by many marine organisms to build their shells, as well as what is found in standard industrial Portland cement. In 2007, Constantz got the chance to turn his idea into a company called Calera. Backed by Khosla Ventures, a Silicon Valley venture-capital firm, it raised$182 million to build a pilot cement plant next to a power station in Moss Landing, on the California coast. A pipe from the plant carried CO2-rich flue gas into the base of a 33.5-meter-high tower. The gas then streamed up through the tower, where it met droplets of seawater raining down. Calcium and magnesium carbonates formed as the gas and water collided and then sifted down in a fine white powder that was dried and used to make cement. Instead of producing CO2, however, the company said the process actually sequestered one-half ton of CO2 per ton of concrete. The upshot, they argued, was that humanity could solve its CO2 problem by using seawater cement to build more roads and buildings.

Outsiders, however, were far from convinced. Some critics argued that the company was too secretive about its process, and that something else must be going on for the chemistry to work. One outspoken critic was Ken Caldeira, a climate scientist at the Carnegie Institution for Science at Stanford University. Caldeira argued that getting calcium and magnesium ions to bind with CO2 to precipitate out of water isn't easy. That's because carbonate ions are stable in water only if the pH is above 9.5 (far more alkaline than the 8.1 pH value of seawater). In natural seawater, the lower pH causes carbonate ions to pick up an extra H+ to become bicarbonate. Many shell-building organisms get around this by creating microenvironments with high pH to precipitate out their needed minerals.

Caldeira was right. It turned out Calera engineers were adding sodium hydroxide or other strong bases to their seawater to make it more alkaline, driving the pH as high as 12 or 13. The higher pH allows more CO2 to dissolve into the water and then speeds the precipitation of calcium and magnesium carbonates. The problem is that alkalinity isn't free. And although the Moss Landing site had a ready source of alkalinity—piles of magnesium hydroxide left over from the plant's former life of making metal for World War II bombs—most power plants do not (although Constantz estimates that 10% of coal and natural gas power plants worldwide are located next to plentiful sources of alkalinity).

In the end, despite early demonstration successes, Calera's cementmaking process turned out to be too expensive to be broadly applicable. And last year, the company replaced Constantz as president, shifting its focus to using the process to make other, higher-value chemicals. “That's not why I founded Calera,” Constantz says of the specialty chemicals business. “I founded it to sequester gigaton levels of CO2.”

A second try

Now, Constantz is back at Stanford University, working on what he calls his generation-2 approach. Like the earlier effort, Constantz envisions bubbling CO2 into seawater to bind it into solid minerals. But this time he hopes to run the process with a gentler and, he hopes, cheaper chemistry.

The key, Constantz now believes, is carbonic anhydrase (CA), an enzyme that whisks CO2 out of our blood and into our lungs to be exhaled. Corals use their own version of CA to pull CO2 out of seawater to build their shells. This process happens slowly without the enzyme. But CA speeds it up as much as 1 million–fold. And speed is the key for industrial reactions. A fast reaction, for instance, could dramatically reduce the size of the tower used to mix water and CO2. Instead of a 33.5-meter tower, for example, the process might need one just 3.5 meters high. That, Constantz hopes, will significantly reduce the capital costs of setting up seawater cement plants.

Speeding up the reaction might also help reduce the need to add so much alkalinity. Even at a pH of 9.5 without CA, few bicarbonate ions turn into carbonate and become available to bind with calcium and magnesium to form calcium and magnesium carbonates. That's why Calera was forced to add powerful bases, to pump the pH up above 12 and accelerate the reaction. The addition of CA could change all that.

Most CAs have a zinc atom at their core surrounded by four amino acids called histidines. The histidines help zinc bind to a water molecule. Once it does, the protein's core essentially splits water (H2O) into a hydroxyl group (OH−) and a proton (H+). The hydroxyl quickly binds with CO2, forming bicarbonate (HCO3−), and the H+ floats off into solution. The fastest CAs can perform this little molecular dance 1 million times a second, fast enough to turn lots of CO2 into bicarbonate, which then goes on to form carbonate if the pH is 9.5 or higher.

But there's a catch. “For this reaction to continue, you need to maintain this pH,” says Alex Zaks, a biochemist and Akermin's chief technology officer. But if H+ ions continue to stream into the seawater, they will steadily drive down the pH, increasing the water's acidity (pH is the measure of available H+ ions in solution). And if the pH drops too low, only bicarbonate will be stable in solution, not carbonate. That means even with CA, engineers will still have to add chemical bases continually. But Constantz says he's hopeful that CA will enable them to use less strong, and less expensive, bases such as coal ash, a waste product from coal-fired electric plants. “The logic does make sense,” Zaks says. However, until he sees a working demonstration plant and the numbers to go with it, he's remaining noncommittal.

Constantz and others will also need to make other improvements to CA to enable it to work in an industrial setting. For starters, CAs are fragile proteins that fall apart in hours to days at about 40°C, well below the temperature of a normal power plant flue gas. Some companies have already taken steps to make them hardier. Researchers at Akermin, for example, have shown that by encapsulating a CA variant in a CO2-permeable polymer, they can keep their enzyme stable and highly active for at least 90 days even above 40°C. Aines and his colleagues, meanwhile, reported online 6 June in Inorganic Chemistry that they've made a synthetic CA mimic that withstands temperatures up to 100°C. Although the catalytic activity of the mimic is more than 10-fold slower than natural CA, Aines says his team is now working on versions that are faster. Finally, Codexis, a Redwood City, California–based company, reported last month that one of their engineered CAs remained stable during a field test at a coal plant in which temperatures reached as high as 82°C.

Other companies are also exploring CA to make seawater cement. Last year, for example, Quebec City, Canada–based CO2 Solutions teamed up with Codexis and aluminum maker Alcoa to pursue a similar strategy. However, last month the companies announced that they put their pilot project on hold because they couldn't meet their timeline from the U.S. Department of Energy, which was funding much of the work.

That means, for now, most companies working on CA are looking at using it to develop a cheaper method of purifying CO2 from flue gases. Their hope is either to pump the purified CO2 into old oil wells to push out additional oil, or to feed it to algae to produce plant oils that can be converted into transportation fuel.

Such work underscores that Constantz is not alone in his hope to use CA to convert billions of tons a year of CO2 waste into something valuable. And for now, Constantz's dream of using CA to pave his way to saving the world remains just that. But geologist Gordon Brown, a Stanford colleague, says people would be premature to dismiss Constantz. “He's often prescient and sees things before others do,” he says. And anyone hoping to curb climate change is probably hoping Constantz's dream comes true.

14. Getting Minds Out of the Sewer

1. Greg Miller

The aversion to excrement, which is deeply rooted in the human psyche, gets in the way of sensible solutions to recycling wastewater.

In water-starved Orange County, California, engineers take treated wastewater from sewage processing plants and put it through a battery of filters and purifiers that produce a fluid that is more than clean enough to drink, according to government standards. A county facility opened in 2008 churns out 70 million gallons of this recycled water a day, enough to meet the needs of 600,000 residents. But instead of piping the ultrapure water to people's kitchen sinks, the county pumps it into the ground.

The reason has more to do with psychology than with engineering. The public was too squeamish about drinking recycled wastewater straight from the tap, local officials say; the “yuck factor” was just too great. So they came up with an alternative: About half of the reclaimed water is injected into wells to prevent seawater from seeping into local aquifers; the other half goes into basins, where it filters through sand and gravel to replenish the aquifers that supply drinking water. “This perception of a natural barrier where it's blending and mixing with all of our other water supplies … helps people make the leap,” says Eleanor Torres, director of public affairs for the Orange County Water District and its euphemistically named Groundwater Replenishment System.

Technologically speaking, it's no huge feat to turn water contaminated with human waste into a usable resource. A report earlier this year by the National Research Council of the U.S. National Academies found that wastewater reuse could provide up to 27% of the public water supply in coastal communities in the United States. But getting communities to accept such projects often isn't easy. That's because—whatever the science says—winning people over involves the delicate work of overcoming deep-seated psychological barriers and cultural taboos surrounding human waste.

Cognitive sewage

The aversion to excrement is deeply rooted in the human psyche, and for the most part it serves us well, says Valerie Curtis, an evolutionary psychologist at the London School of Hygiene and Tropical Medicine. For our human and prehuman ancestors, pathogens were probably a greater overall threat than predators, Curtis says. That's why we have a strong, intuitive sense of disgust, she says: “Pretty much all the things we find disgusting have some kind of connection to infectious disease.”

Those intuitions can easily trump reason, says Paul Rozin, a psychologist at the University of Pennsylvania and a pioneer of research on disgust. In one classic experiment in the 1980s, Rozin gave college students a piece of fudge shaped like a dog turd. “They know it's chocolate, okay, and they like chocolate, but most of them won't eat it,” he says.

In fact, disgust can evoke what Rozin and colleagues call “magical” thinking. In one demonstration of this, they presented undergraduate students with a glass of juice. Then, using forceps, a researcher dipped a dead, sterilized cockroach into the glass. Despite assurances that the juice was perfectly clean and safe (which it was), the students had a strong aversion to taking a sip. And it didn't stop there. Even when the researchers provided new glasses filled with juice, students still didn't want to drink. It was as if people believed that the newly poured juice had somehow been contaminated by the roach, says Rozin's then–graduate student, Carol Nemeroff, who is now at the University of Southern Maine, Portland. Nemeroff thinks the same logic-defying thought process comes into play in getting people to accept recycled wastewater, especially for drinking. The question, she says is: “How do you get the cognitive sewage out, after the actual sewage is gone?”

Sometimes you can't. The yuck factor has scuttled proposed wastewater recycling projects in San Diego, Los Angeles, and elsewhere. Opponents of these projects effectively used slogans like “toilet to tap” to create a stigma that's hard to overcome, says Paul Slovic, a psychologist at the University of Oregon, Eugene, and president of Decision Research, a nonprofit research organization. Since the 1990s, Slovic has studied the mental shortcuts people use to assess risk. In work on attitudes toward nuclear and chemical waste disposal, for example, he found that whereas experts methodically tote up risks and benefits, laypeople tend to decide intuitively whether a given material or technology is either good or bad. And once they decide a technology is bad, they tend to overestimate the risks and downplay the benefits. “For most of us, risk perception is not the output of a scientific, mathematical calculation, but of a gut feeling,” Slovic says.

Let's be reasonable

Water agencies have taken note of this research, and in some cases they're commissioning studies of their own. Slovic, Rozin, and Nemeroff collaborated on a 2008 survey of public attitudes sponsored by WateReuse, a nonprofit organization in Alexandria, Virginia. That study, led by Brent Haddad, a social scientist at the University of California, Santa Cruz, found that educating consumers about the water cycle can help increase acceptance of recycled water. Most people have no clue what happens when they flush the toilet, Haddad says. In most of the developed world, what happens is this: Collected wastewater is treated to remove solids and pathogens and then pumped into the nearest natural body of water, where it can enter the water supply of the next community downstream. “Any city that's at the bottom of a river is drinking the recycled wastewater of cities upstream,” he says. His survey found that when people realize they've been drinking unintentionally recycled water, they're more willing to accept intentionally recycled water.

A more recent study sponsored by WateReuse expands on this idea, suggesting that framing reuse projects in the context of the urban water cycle—in which all water is essentially recycled—can help make them more acceptable. The focus should be on what the water is now (clean and safe) rather than where it came from in the recent past (a sewage treatment plant), says Linda Macpherson, a co-author of the recent study and a reuse technologist at CH2M Hill, an engineering and consulting firm that works with water agencies around the world. “We've got to get people to start thinking of water as a reusable resource,” Macpherson says.

Borrowing a few lessons from psychology might help water-reuse projects gain traction, but it takes old-fashioned politicking too. In Orange County, the water district made sure key politicians were onboard from the beginning, and they reached out to various communities they knew were likely to be wary of the project, including mothers' groups and the region's Vietnamese and Latino immigrant communities, which have tended to be suspicious of the government, Torres says. The district tried to build trust in those communities by sending local doctors and engineers to answer their concerns. And they're doing it again now to pave the way for an expansion of the Groundwater Replenishment System that will increase its capacity to 100 million gallons a day by 2014. Torres thinks acceptance is growing and will eventually lead to direct potable reuse. “The younger generation, I think they get it more,” she says.

The poo taboo

Disgust for feces is universal, but it varies in degree in different cultures, says Sarah Jewitt, a geographer at the University of Nottingham, University Park, in the United Kingdom. In China and other parts of Southeast Asia, for example, people have used human manure to fertilize crops for centuries, Jewitt says. China is also a leader in biogas production from human and animal feces. “I would describe them as a more fecophilic society,” Jewitt says. “They have fewer taboos.” Indian society, in contrast, is one of the more fecophobic. That manifests in a number of ways, including the stigma faced by the workers who clean toilets and remove waste from community latrines, Jewitt says.

Attitudes also tend to fluctuate with time. Jewitt notes that the editorial pages of British newspapers in the 1840s and 1850s endorsed collecting London's sewage to fertilize nearby farms. By the end of the Victorian era a few decades later, however, enthusiasm for such endeavors dimmed and the flush-it-and-forget-it mentality became predominant, Jewitt says.

But in some European circles, the pendulum is swinging back. Composting toilets and diversion toilets that collect urine for use as fertilizer (see p. 673) have been widely adopted by some communities in Germany and Sweden. These so-called ecological sanitation (“ecosan”) technologies could be especially beneficial in parts of the developing world where water is scarce and no sewage infrastructure exists, says Elisabeth von Muench, who oversees ecosan efforts for the German Agency for International Cooperation. Ecosan advocates would like to see people in developing countries leapfrog flush toilets, just as they've gone straight to mobile phones without a landline stage. But composting toilets haven't yet taken off on a global scale—at least partly, experts believe, because the small amount of hands-on upkeep required can run headlong into taboos about handling excrement.

In general, the places where ecological sanitation, wastewater recycling, and other alternative strategies for handling human waste have taken root are those where the waste can be used to fulfill an urgent local need: for fertilizer, energy, sanitation, or clean water. In other words, these projects tend to have the best chance of success in places where intuitive disgust can be overcome by other powerful forces of human psychology—such as the desire to live a healthier, wealthier, and more comfortable life.