Thermodynamics are hot in the 21st century, and submerged combustion evaporation technology could change the world. In China, New Zealand, Brazil, Venezuela and the United States, undesirable landfill leachate is being evaporated and neutralized by a patented process designed to combat environmental problems caused by prolific amounts of human waste. Leachate, an unsavory liquid that can leak from municipal garbage sites, has the potential to contaminate aquifers and soil that could be used to grow crops.

There are ways to dispose of this stream and to achieve zero liquid discharge status, making landfills much more environmentally friendly. In submerged combustion evaporation, landfill gas is collected, combusted and saturated with the liquid, or feed stream in a low-temperature, low-pressure treatment process. Volatile compounds found in the leachate are subsequently stripped and thermally oxidized before being released into the atmosphere.

Because of scientific breakthroughs and industrial applications like these achieved by GEI Development subsidiary Liquid Solutions LLC (LS), a St. Louis-based waste management and renewable fuels company, global recycling powers are being significantly amplified. LS's patented E-VAP technology can neutralize aqueous salt solutions, oily wastewaters and spent caustics in a sealed system that vents contaminants through thermal oxidizers, controlling emissions, leachate and odors. In the ownership and operation of LS, GEI Development is partnered with the Shaw Group Inc., a mega-conglomerate with dozens of offices around the world. The company was named contractor of the year by the Associated Builders and Contractors Association and is building waste management systems all over the world. Since 1991, E-VAP has been installed in about 24 landfill applications using landfill gas for power, and simultaneously managing leachate through evaporation.

Bernie Duesel, whose name is pronounced like the diesel fuel, is director of business development at LS and has been involved with the E-VAP technology since its inception, he says. The chemical engineer recalls during his formative years in Massachusetts when towns used to set their dump grounds on fire. "That wasn't that long ago," Duesel says. "It's amazing how far we've come."

Eliminating Exchangers
The U.S. EPA classifies leachate as a fairly benign material. "Still, you wouldn't want to drink it or be near an open container of it for too long," Duesel says, adding that most applications of LS's technologies do not deal with hazardous, corrosive materials and/or waste-streams. Often leachate is collected and hauled to a sewage treatment plant, but there are obvious inefficiencies in managing a landfill this way. Sewage treatment plants, however, can still compete economically with E-VAP technology, which is why more E-VAP systems are not in operation, Duesel says. On the other hand, hauling leachate to a sewage treatment plant doesn't simultaneously burn landfill gas or generate electricity, the way the E-VAP system does.

This is a low-temperature, low-pressure technology for managing landfill waste streams. While the combustion gases generated in the burner section are relatively hot, through a thermodynamic principle called adiabatic saturation, the E-VAP process uses low pressure and the liquid being treated never reaches the boiling point. A process is said to be adiabatic if the system doesn't exchange heat with its surroundings. This rather innocuous operation is safer, and more reliable and durable than other systems. The sheer heat that characterizes alternative technologies, and the volatility that goes along with them, can lead to more breakdowns and shorter equipment life spans, and can be potentially dangerous for operators.

Ultimately, many things are different about the E-VAP process when compared with conventional methods of waste stream management, Duesel says. Where there is a high precipitation of solids from solution in systems that employ exchange methods for instance, the efficiency of the heat transfer drops. "If you attempt to limit the precipitation of the solids, then you're defeating the purpose, so what we've done with the E-VAP system is eliminate the heat exchangers all together," he says. Conversely, LS places the combusted landfill gas in direct contact with the leachate, therefore dispersing the gas uniformly, and bypassing surface exchange.

"When you take wastewater and concentrate it [through heat transfer], it becomes high in solids," Duesel says. "Heat exchangers can be troublesome because the solids build up and there is a loss of heat transfer efficiency." Also, the buildup of residues can lead to operation downtime as the machines need to be cleaned to prevent fouling. One common example of a heat exchanger is the radiator in a car, in which an engine-cooling fluid, like antifreeze, transfers heat to the air flowing through the radiator. The direct nature of the E-VAP process, however, allows heat transfer to occur "at the dynamic and continually renewable interface" formed by the gas bubbles and evaporation of the leachate or other wastewater stream. "We have a way of dispersing the gas very uniformly through the liquid," Duesel says. "Very fine bubbles throughout the leachate provide excellent mixing and vigorous agitation."

The most significant aspect of the E-VAP system is that LS has been able to make several technologies compatible such as electrical generation, landfill gas combustion and leachate treatment. "We can reduce the volume of the leachate by 97 percent or more," Duesel says.

Biofuels Sector
GEI Development and LS are also entering the renewable fuels sector by building a biodiesel plant in Buffalo, Ind. Groundbreaking for a 5 MMgy facility was scheduled for this fall. With the development of biodiesel plants, GEI has the opportunity to integrate all three of its divisions-waste management, liquid solutions and fuels. GEI's biodiesel operations will be combined-heat-and-power (CHP) facilities, using energy generated by the landfill to run the methyl ester refinery. "I'm very impressed by landfills today," Duesel says. "These are self-sufficient, well-managed operations that control leachate and emissions, and are becoming a robust source of power for biodiesel plants."

According to the U.S. EPA, the building of biodiesel refineries on or near landfills in order to capitalize on the synergistic qualities of a CHP operation is becoming a trend. Just to name a few, Texas-based Biodiesel Industries Inc., is building a 3 MMgy plant at the Denton Sanitary Landfill in Denton, Texas. The Pacific Biodiesel Inc. refinery in Maui, Hawaii, which according to the company is the oldest continuously operating biodiesel refinery in the United States, was built at the Central Maui Landfill more than 10 years ago. Smoky Mountain Biofuels Inc. in Cullowhee, N.C., also uses methane gas generated by the landfill in Jackson County, N.C., to power its process as part of a green energy park.

"The latent energy of these landfills is now being captured to produce renewable fuels," Duesel says. Also, the energy for the E-VAP system can come from the landfill gas or can "be derived from previously considered waste heat from engine exhausts, flares or other combustion gases," he says. Ultimately, this means that the E-VAP process can operate in either direct-fired or indirect-fired modes. In addition to the energy harnessed by the combustion of landfill gas or other fuel sources, LS can also capture exhaust heat from the reciprocating engines used to drive the electrical generators. This is heat that would otherwise be wasted. A single E-VAP system that harnesses waste heat to evaporate 30,000 gallons of water per day saves the equivalent of more than 1.1 MMgy of fuel oil, Duesel says.

For more information on the E-VAP system visit GEI Development's Web site at www.geidevelopment.com.

Nicholas Zeman is a Biomass Magazine staff writer. Reach him at nzeman@bbibiofuels.com or (701) 746-8385.