THE SUPERCHARGED FUTURE OF WASTEWATER TREATMENT PLANTS
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released into the atmosphere, while nitrate—an breaks down food and keeps us healthy in astewater treatment plants have important plant nutrient—stays in the treated many other ways. This community was the a PR problem: People don’t like water. Regulations on the amount of nitrate subject of the new study. to think about what happens to that may be released vary by state, but excess “We knew very little about the role of the the waste they flush down their toilets. But for amounts contribute to algal blooms in natural bacteria that co-exist in anammox granules,” many engineers and microbiologists, these bodies of water, which may deplete oxygen Noguera says. “For the first time, our study plants have been a hotbed of scientific levels for aquatic organisms. identified detailed gene expression levels in advances, which has even prompted their An additional advantage of anammox these granules. This provides important clues on trade organization to propose a name change bacteria, compared to conventional wastewhat the anammox bacteria and their partners to “water resource recovery facility.” water treatment, is that they convert a larger might actually be doing and how they interact.” That’s because wastewater from our sinks, amount of ammonium to nitrogen gas. These partners are called heterotrophs since toilets, showers and washing machines can be Treatment plant operators now have to they rely on the anammox bacteria—which turned into valuable products with the help of weigh the advantages of these new microbes are autotrophs (primary producers), like plants scientists and unique bacteria, some of which against their implementation challenges. capable of photosynthesis—to turn atmospheric weren’t even discovered—by pure chance—until Anammox the mid-1990s. bacteria grow These very slowly, latecomers to taking about the research seven days scene—anammox to double in bacteria—are number, and the subject of a require closely new study led monitored by Professors oxygen and Daniel Noguera temperature and Katherine cycles, which McMahon, which increases was published in operational May 2017 in the complexity. journal Nature But anammox Communications. Left: Graduate student Christopher Lawson samples biomass at an anammox bioreactor at Radboud University in reactors are The bacteria’s Nijmegen, The Netherlands. (Photo courtesy of Christopher Lawson) Right: Daniel Noguera and Trina McMahon study how not the only name reflects anammox bacteria may improve conventional wastewater treatment methods. (Photo: Stephanie Precourt) option for the their function: treatment plant They turn of the future to extract valuable resources carbon dioxide into organic carbon. Among ammonium into nitrogen gas under anaerobic from wastewater. In fact, some plants already the most intriguing results of the new study (oxygen-free) conditions. Researchers and produce more energy than they need to are novel hypotheses for the exchange of treatment plant operators alike have been operate from the biogas that forms during biochemical material between these two excited about these microbes because they have the breakdown of organic material. groups of microbes. the potential to save a great deal of money. “Ten years from now, the typical treatment The heterotrophs receive the organic carbon “Being able to remove ammonium plant will probably look pretty different from they need to grow from the anammox bacteria, anaerobically is pretty important because about today,” Noguera says. “Recovered resources in the form of several specific molecules the 50 percent of a sewage plant’s operating cost is may not only include clean water and energy, researchers discovered in the study. In return, pumping oxygen into the water,” Noguera says. but also a variety of chemicals, such as the heterotrophs convert nitrogen into a form “Some of this oxygen is needed to remove fertilizers and precursors of plastics and fibers. that anammox bacteria require for growth. ammonium with the conventional method.” As part of this evolution, I believe anammox A conventional wastewater treatment plant But anammox bacteria don’t tackle their reactors will soon become conventional.” converts ammonium, which is toxic to fish, job in isolation. They are part of a community into nitrogen gas and nitrate. Nitrogen gas is as complex as the microbiome in our gut that 5