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Exciting Environmental Technologies |
by Lee Thompson |
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A biodegradable plastic made from food waste. Compost used to treat soil
contaminated with chemicals from explosives at an army base. Sunflower plants
used to remove radioactive and other toxic metals from soil and water. Methane
extracted from garbage dumps and used as fuel.
Are you kidding me? No. If ever there was a time that we needed an open mind, it's now. Some of the most exciting new technologies now being researched and implemented are coming from none other than Mother Nature herself. It's almost humorous in a way. Trillions of dollars and decades of research later, natural alternatives now appear capable of performing the same tasks that many of our technological advances have often proved incapable of--providing solutions to environmental hazards in an inexpensive and comprehensive fashion. |
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In this article we'll look at several promising developments, and then ask you, our readers, to rate which is the most important. Your choice will be the subject of an in-depth feature in an upcoming issue of BWZ.
Biodegradable Plastics
More than 30 billion pounds of plastic wastes are generated by American consumers each year, clogging our landfills and polluting our beaches and oceans. Many of these plastics don't biodegrade for several hundred years.
After years of often-frustrating research into the concept of a biodegradable plastic, polylactic acid (PLA) plastic is one that shows promise. It has the desired properties of strength and flexibility, and is 100% degradable. The manufacturing process can also be altered, to give the plastic various physical properties and degradation rates, making it extremely versatile.
In the past, this form of plastic was too expensive to produce. The main component--lactic acid--is typically made from petroleum using a very costly synthesis process. But new research has found a more cost-effective way of making the environmentally-friendly plastic.
Lactic acid can be made from the carbohydrates found in food processing wastes--like potato wastes, cheese whey, and sorghum. The biological conversion process takes place in two main steps: conversion of starch to simple sugars, and fermentation of these sugars to lactic acids. The beauty of this process is that it will offer the food processing industry the opportunity to solve a combined economic/environmental problem by turning waste products into a desirable and salable product--high-quality, low-cost lactic acid.
Scientists have demonstrated the process for converting potato wastes to lactic acid. They are now refining the process at the laboratory scale and are beginning to design an industrial-scale system.
Bioremediation
Bioremediation is the science of using enzymes and bacteria to break down and biodegrade toxins and heavy metals in soil and water, turning the pollutants into harmless compounds. This occurs naturally in our ecosystem, but the results take time. By manipulating the environments in which these organisms live--altering the temperature, pH, moisture, oxygen, and nutrients--the process is dramatically quickened.
The contaminated soil and water are treated in-situ, meaning they need not be isolated, removed and transported to a clean-up facility. Many pollutants can be treated with bioremediation, including: pesticides, herbicides, aviation fuel, diesel oil, PCBs, gasoline, and many more.
In Hermiston, Oregon, compost bioremediation is being used to treat 14,000 tons of soil contaminated with explosive compounds at the Umatilla Army Depot. Bioremediation is expected to save $2.6 million for the clean up of the more than 14,000 tons of this waste, which would otherwise have to be incinerated, leaving behind toxic ash and emitting harmful gasses.
In a remarkable testament to the process's effectiveness, 2,700 cubic yard batches of compost was mixed with contaminated soil, and in less than 20 days the contaminants were decomposed to nondetectable levels.
Phytoremediation
Similar to bioremdiation, phytoremediation is the use of plants to clean-up contaminated environments. In natural ecosystems plants filter and recycle potentially toxic substances generated by nature herself. In phytoremediation, this process is extended to help clean up contaminants caused by man. Plants are effective at remediating soils contaminated with organic chemical wastes such as solvents, petrochemicals, wood preservatives, explosives, and herbicides, and pesticides.
In addition to cleaning up the soil and water in-situ, without having to remove it from the site of the contamination, planting vegetation on a site also reduces soil erosion by wind and water. This helps to prevent the spread of contaminants and reduces the exposure of these contaminants to humans and animals.
Field tests have confirmed that a phytoremediation using sunflower plants can be used on a commercial scale to remove radioactive and other toxic metals from soil and water. Special strains of the plant have been developed that remove as much as 95 percent of some of the most toxic contaminants (including radioactive uranium) within 24 hours. The method costs between $2 and $6 to clean a thousand gallons of contaminated water, while conventional dredging and filtration techniques would cost $80 to clean the same amount. Plants at a research greenhouse at a Department of Energy (DOE) facility in Ohio cleaned water that had been severely contaminated with uranium to levels less than half that of EPA's groundwater standard. Plants grown on a raft on a lake near Chernobyl absorbed strontium and cesium to concentrations 2,000 and 8,000 times less, respectively, of those previously found in the water.
Solar Detoxification
Potable water is becoming a more and more serious problem in the world today. In the US alone, nearly 40% of our surveyed lakes, rivers, and estuaries have been designated as unfit for basic use. In fact, one-quarter of all large US drinking water systems shows traces of toxic chemicals, including chlorinated solvents, pesticides, and fuels. Hazardous wastes have leaked, been dumped, or accidentally spilled onto the ground and have contaminated water for years.
A promising technology is being researched that uses solar energy to destroy a wide range of the contaminants in our water. The new technology, solar detoxification, can be used to treat both contaminated groundwater and industrial wastewater. More than 80 toxic chemicals including industrial solvents, pesticides, wood preservatives, dyes, and various types of fuels can be treated effectively with solar detoxification.
Sunlight destroys many toxic chemicals in water, but the process takes time. Solar detoxification--a procedure that destroys contaminants by using the ultraviolet energy in sunlight--can speed this process dramatically. In this process, sunlight illuminates a reactor through which contaminated water and a catalyst--such as titanium dioxide--are flowing. Ultraviolet light activates the catalyst, which results in the formation of reactive chemicals known as "radicals". These radicals are powerful oxidizers that break down the contaminants into non-toxic by-products such as carbon dioxide and water.
A big advantage of solar detoxification over conventional treatment processes--such as those using granular activated carbon or air stripping--is that it completely destroys the toxic compounds in the water instead of simply removing or displacing them. The solar process also has no atmospheric emissions.
The process has been successfully tested, decontaminating groundwater at a former naval air facility. A 4-month field test was conducted on the grounds of Lawrence Livermore National Laboratory (LLNL). The groundwater contamination there dates back to World War II, when the facility was a naval air base. Trichloroethylene (TCE) and other volatile organic compounds that were used to clean engine parts now contaminate the groundwater.
The LLNL field test was a huge success, proving the detoxification process works. The process brought the contaminants to levels well below the 5 parts per billion (ppb) EPA standard.
The detoxification process doesn't require highly concentrated sunlight to successfully destroy contaminants. In fact, reactions were actually more efficient at normal sunlight intensity. This means that the process can even be used on cloudy days.
Landfill Gas
Not only does is smell bad, it's also bad for the environment. Methane, the most dominant gas in a landfill, is a potent "greenhouse" gas which has nearly 21 times the global warming effects of carbon dioxide. Methane is also highly flammable, and has been responsible for over 40 landfill fires and explosions that have resulted in nearly a dozen deaths in the United States.
What on Earth should we do about this growing problem?
Turn it into a solution. We now have the technology available to profitably capture and use the gas generated by degrading garbage in our landfills to generate not only electricity, but heat, steam, and even as a fuel source for vehicles, while at the same time reducing this serious threat to the environment.
Gas is collected by a series of wells placed throughout the landfill. Wells are constructed by drilling large holes into the landfill, to within about 10 feet of the bottom. Perforated plastic pipes are inserted into the wells, and the area around the pipes is filled with large gravel to keep the garbage from plugging the holes in the pipes.
The wells are joined by a series of pipes that lead to the large header pipes that deliver the gas to the processing and conversion stations. Once the gas reaches the processing and conversion station, the gas is then filtered to remove any particles and moisture that remain in the gas stream.
Once filtered, it is ready for use and is converted to another energy form. Either internal combustion engines or turbines are then used to power on-site generators, which convert the gas into electricity. The electricity is used for powering the landfill's operations, and the excess is sold to local utilities.
which new technology is most significant to you?
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