WASTE NOT, WANT NOT
Danny Cunningham, Kristi Slaby, Susan Talkmitt
The BREAKTHROUGH is a lesson model aimed at helping students to evaluate the impact of technology on society. Using a discussion outline, students brainstorm to find the pros and cons of a current breakthrough in technology. (Examples: in vitro fertilization, transgenic animals, organ donors, animal rights, nuclear waste, or recycling.)
To relate a technological issue to society and to derive a view of its impact on society as a whole.
Intended Audience: Grades 9 - 12
Objectives: The students will be able to:
It is suggested that the class be broken up into groups of 4-5 students to brainstorm the breakthrough. This could also be done individually or with the class as a whole.
Assign a role to each group and have them work through the model using their role. Examples could be environmental activist, city or county council, concerned citizens, political groups, or other special interest groups.
The students will:
America's trash heaps are generating 180 million tons of solid waste per year. Recycling efforts are generally aimed at inorganic waste including metals, plastics, and glass. Yet these components constitute only 24% of the total weight of a landfill . Organic components comprise the bulk of landfill weight. Paper products alone account for nearly 40% of the weight, while food and yard waste add another 25%. According to the Environmental Protection Agency (EPA), 65% of the solid waste is reusable organic material. The Solid Waste Composting Council (SWCC) is urging municipalities to produce salable compost to utilize these reusable organics.
Biotechnology is taking the idea of composting beyond the backyard pile to a national composting effort. Compost produced from the landfill components can be sold for land modification. The adding of sludge from the sewage treatment plants to the solid landfill waste speeds the decomposition efforts of the landfills and produces a compost richer in nutrients. Compost is produced from organic materials when microorganisms feed on the carbon, nitrogen, and water found in the waste. The microorganisms respire and produce carbon dioxide and heat as byproducts; as a result, the organic material shrinks into small bits and pieces. Sludge increases the nitrogen (nutrient) content of the waste and thereby increases the rate of decomposition. The heat produced in the reaction destroys pathogens. In addition, companies heat the products to 55 degrees Celsius, destroying human pathogens.
Preliminary studies in which solid waste compost was used as a soil modification prove to be promising. In a seven year study, pine trees growing in a forest were treated with 200 tons of compost/acre/year. They grew at a faster rate, and the density of the wood increased. No harmful effects were observed in the plants. Additional studies proved the usefulness of compost soil modifications. Papaya groves produced more fruit when treated with solid waste compost. The addition of sludge to solid waste compost produced an even higher yield. This can be seen in studies dealing with tomato fruit yields. Sludge alone, due to the high nitrogen content, encouraged the growth of the plant and not its fruiting. Lower amounts of sludge with solid waste compost increased the yield of the tomato beyond the expected yield of untreated plants. An additional benefit of the compost/ sludge was observed in green beans. The beans grown in the modified soil did not develop fungal diseases as readily as beans grown in untreated soil. In fact, diseases were almost eliminated with the compost/sludge applications. Besides lowering the fertilizer demands, the modifications increased the water holding capacity, thus lowering the rate of pesticide contaminated water runoff into underground aquifers. Although these studies with municipal compost/sludge applications are in the preliminary stages, the data offer a hopeful utilization of municipal waste products.
The yields of edible crops have increased with waste-derived products, but the consumer has a problem with fertilizing edibles with compost/sludge byproducts. "Waste-derived products have a stigma attached to them." Taste tests showed that consumers said they disliked the tomatoes grown in sludge. But in blind taste tests, consumers preferred the sludge tomatoes over all other tomatoes.
Another consumer concern, heavy metals in edibles, has sent up "a red flag." Current research is checking the heavy metal amounts in municipal solid waste. Nickel, zinc, and copper kill plants when present in high levels, plus, cadmium and lead cause health problems in humans. Metals can only be taken up by the plant in the ionic state . Studies show most metals in solid waste are in the combined state. Scientists are hopeful that continued research will lower consumer concerns.
If testing shows the use of municipal waste is economical and safe, recycling from our landfills and sewage plants will be promising. Recycling must include organics since targeting only inorganics will not adequately reduce the rate at which America is generating trash for landfills.
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