 |  Environmental Science: A Global Concern, 7/e William P. Cunningham,
University of Minnesota
Mary Ann Cunningham,
Vassar College
Barbara Woodworth Saigo,
St. Cloud State University
Solid, Toxic, and Hazardous Waste
Be Alert BoxesBE ALERT FOR: Nature’s Solution to Waste
Interesting comparisons can be made between how human societies confront waste disposal and how it is handled in natural ecosystems. Both must live by the conservation of matter principle studied in Chapter 3.
Although things may be slowly changing, our society's basic resource use patterns are not designed to facilitate recycling. Given that state of affairs, the conservation of matter principle makes it inevitable that we will eventually run out of nonrenewable resources at the input end (can't create matter) and face a growing disposal problem at the output end (can't destroy it either).
Natural ecosystems have neither problem. Material cycling is a fundamental process centrally embedded in ecosystem dynamics where waste automatically becomes resource.
Chapter 25 explores the concept of sustainability and its importance to our futures. We need look no further than the natural ecosystems for a useful model.
BE ALERT FOR: Meaning of Organic
You frequently encounter reference to organic waste in this chapter. A refresher on its meaning is in order. Recall from earlier chapters that organic compounds are carbon compounds. These substances are the central ingredients of living things. These bio-organic compounds are lipids, carbohydrates, proteins, and nucleic acids. So, organic waste can be thought of as materials produced by living processes. Food wastes, tree and lawn trimmings, leaves, and manure are examples.
These materials are easily decomposed back to the original chemical substances from which they were made. Depending on the circumstances of decomposition, methane gas, a valuable energy source, can also be collected.
BE ALERT FOR: Hazardous Waste Treatments
The highest priority approach to our hazardous waste dilemma will always be to produce less. Some toxic waste production, however, does seem inevitable. An important section of this chapter describes surprisingly varied ways to detoxify many wastes in order to minimize the amount in need of final disposal. These methods include the use of physical treatments to physically isolate the substances. Many hazardous substances are dangerous only when dissolved. For these kinds of substances, converting them in a solid form away from potential solvents should render them harmless.
Another approach is to mix them with other substances to chemically change them into less dangerous forms. Both of these methods would obviously be more expensive than options that are less protective of the environment.
The third approach generating lots of research interest is the use of biological organisms to detoxify these materials. As surprising as it may sound, there are bacteria and other life forms that can make some of these chemicals benign.
These methods have not yet been fully put to use. The expanded use of these approaches gives real hope that we can effectively defang much of the hazardous waste monster if we are determined to do so.
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2003 McGraw-Hill Higher Education