Renewable & Nonrenewable Resources

Lesson 2.4: “Solid Waste Management”

1. Briefly explain the steps involved in steel making.• Iron ore is extracted & crushed, & the

iron is separated out. The ore is smelted to remove oxygen from the ore & leave the iron behind. The product of these processes is pig iron. Pig iron is converted into liquid steel by refining the pig iron in furnaces contain recycled iron & scraps of steel.

2. Explain some of the resource recovery & pollution control methods used in the steel manufacturing process.• Steel scraps are used to make new steel.• Some of the heat associated with emissions is

captured for reuse in other heating processes.• The water used to quench hot steel is often

recycled within the mill.• Much of the solid waste generated is recovered.

If the iron content of the dust is sufficient, the dust can be reused in the steel mill’s blast furnaces. If not high enough in iron, the dust can be sold for use as raw materials in bricks, cement, sandblasting, or fertilizers.

3. What makes up the bulk of municipal solid waste in the U.S.?

• Paper• Yard wastes• Food• Plastics

4. Contrast 3 methods of managing solid wastes.• A landfill is a regulated area where solid

wastes are placed in the land.• Some trash is disposed of by combustion.• Composting is a method of waste disposal

in which worms, bacteria, fungi, & other organisms decompose piles of fruit a vegetable food scraps, wood, & lawn clippings.

5. Explain various aspects of source reduction as it pertains to solid wastes.• Source reduction involves altering the

design, manufacture, or use of materials to reduce the amount & toxicity of the waste generated. Source reduction involves purchasing durable goods as well as products with little or no extra packaging & using environmentally friendly products to reduce toxic wastes.

6. List the steps involved in recycling metallic resources.

• Recyclable metals are collected, melted down, & reformed to produce new products. The recycling loop is complete when recycled products are purchased.

7. Explain the steps & processes involved in recycling aluminum cans.• The first step in aluminum can recycling is to collect the cans

& send them to a recycling center. At the recycling facility, the cans are cleaned, crushed, & baled. After they have been processed, the used cans are transported to the manufacturing plant where they are shredded, melted down, & mixed with raw aluminum. This mixture is then cast into ingots that are allowed to cool. The aluminum ingots are eventually rolled into long, thin sheets that are coiled & sent to can manufacturing plants. Aluminum beverage cans are fashioned from aluminum sheets. They are sent to soft drink companies for filling & sealing. When the cans are recycled by the consumer, the process starts again.