ing and maintenance costs and the ease of repair. The technology shows great promise, according to EPA, because it attacks an array of microbial contaminants without the need for large doses of disinfectants, including chlorine, which may create harmful byproducts. "We are finding other organisms out there that are so small filtration can't find mem," Goodrich said. "This could be a gold mine." Several companies are experimenting with the use of electricity in drinking water to remove Cryptosporidium, but most consider building a unit for small systems unprofitable. Phoenix has developed a unit that processes just 10 gal/min, enough to serve 100 people a day.
Fuel cells turn landfill gas into electric power Methane from decaying garbage at a closed landfill in Groton, Conn., is powering a fuel cell that generates electricity and feeds it into a local power grid. In a field demonstration at the site, EPA and International Fuel Cells Corp. (IFC) are working out the bugs in a system that pulls methane from beneath the landfill's mounds, runs it through a cleaning process, then powers a fuel cell, which converts hydrogen and oxyinto electricity. Early test results from the year-long field demonstration which started last July indicate that the cleaning process works better than EPA scientists had anticipated IFC entered into a competitive procurement contract with EPA's Office of Research and Development in 1991 after the agency developed the idea for a landfill gas treatment system to help landfill operators cut greenhouse gases comply with lim-
Landfill methane is being turned into electricity by this 200-kilowatt fuel cell at a field demonstration in Groton, Conn. (Courtesy Northeast Utilities)
its for volatile organic compound (VOC) emissions, and generate power using fuel cells. The new technology provides an alternative to gas flaring, turbines, or internal combustion engines as methane and VOC controls. IFC and EPA jointly hold a patent on the system. "We overengineered the system," said EPA senior research engineer Ronald Spiegel, Research Triangle Park, N.C. "We've removed better than 99.9% of the sulfur and halide compounds from the gas." Spiegel is now looking at ways to cut the cost of the system by paring down the six-step cleaning process that removes sulfur in an impregnated carbon bed, dries and refrigerates the gas, and then takes out halides in an activated carbon bed. "We're hoping that if we drop out a lowtemperature cooler condenser dryer bed we C3.il still produce Scis clean enough the system " said Spiegel A concern is the $600,000 price tag for one 200-kilowatt fuel cell unit—enough to power 100 homes— said William Stillinger, director of research and environmental planning for Northeast Utilities, Berlin, Conn., which is running the field demonstration. "By 2000, the cost might go down to $1500 per kilowatt, which is still costly, but nonetheless desirable for sensitive urban environments," he said.
Thermophilic bacteria tackle nitroaromatic "pink water" Thermophilic bacteria, which function and reproduce at high temperatures, have provided molecular biologists and environmental chemists with numerous tools lately—from isolated enzymes that catalyze biochemical reactions at 60-95 °C to whole organisms that metabolize toxic wastes. Researchers at the nonprofit Center for Hazardous Materials Research (CHMR) in Pittsburgh are now exploiting thermophiles to remediate toxic nitroaromatic compounds Nitroaromatics, primarily the explosives TNT, RDX, and HMX, are a significant problem at military sites involved in weapons production and demilitarization operations. These operations contaminate soil and large volmes of wastewater, called "pink water" because of its distinctive color. Under a U.S. Army Environment
Center grant administered by Concurrent Technologies Corp., Johnstown, Pa., proposals from five commercial and academic research groups, including CHMR, were chosen from an original 21 for benchscale testing of various pink-water remediation technologies. On the basis of these results, some of these will undergo pilot-scale tests. CHMR researchers did their bacterial prospecting in soil already laden with the target compounds, in this case, at military bases. They isolated a mix of about 145 strains that have become acclimated to using the pink-water toxins as nutrients. According to Felicia Cianciarulo, CHMR's director of bioremediation, thermophiles were chosen because of their poor reproduction rates at ambient temperatures. This not only reduces the final biomass to be disposed of, but also helps sell the process to the public. Thermophiles' physiology prohibits rapid growth or high survival rates should any be accidentally released to the environment. The remediation procedure itself adsorbs nitroaromatics from pink water onto granular activated carbon (GAC), where they are digested by the thermophiles. GAC has been used before to adsorb nitroaromatics, but it has been either discarded or incinerated along with the toxins, rather than regenerated as in CHMR's process. In bench-scale experiments, wastewater samples from two military sites, containing 58-79 ppm TNT and 1-44 ppm RDX, were shipped to CHMR, where the contaminants were adsorbed onto GAC columns. A mix of bacterial strains was introduced to metabolize the nitroaromatics. Within hours, effluent TNT levels were < 0.1 ppm, and RDX levels were nondetectable (
