Sign in

Environmental Science

Unit 9

Waste and Sustainability

5 topics · 21 practice questions · Free responseNot yet reviewed

Take the unit testFlashcards

Notes

Solid waste

  • MSW goes to landfills, incinerators, recycling, or compost. Sanitary landfills have liners and leachate collection and release methane. Leachate can contaminate groundwater.
  • The waste hierarchy: reduce, reuse, recycle, recover energy, dispose. Source reduction is the best option. Recycling saves energy; contamination limits it.

Hazardous waste

  • Hazardous waste is toxic, corrosive, flammable, or reactive. RCRA tracks it cradle-to-grave; Superfund (CERCLA) cleans up abandoned sites. Brownfields can be redeveloped. Bioremediation and phytoremediation use living things to clean sites.

Laws and policy

  • Key US laws: NEPA (1969), Clean Air Act (1970), Clean Water Act (1972), Endangered Species Act (1973), Safe Drinking Water Act (1974), RCRA (1976), CERCLA (1980). The EPA enforces them.
  • Policy tools: regulation, taxes, subsidies, and market-based approaches like cap-and-trade. People differ on how to weigh costs and benefits.

Sustainable solutions

  • A circular economy, life cycle analysis, extended producer responsibility, deposit-refund programs, and renewable energy support sustainability. Environmental justice calls for fair treatment in environmental decisions.

Topics in this unit

Each topic has its own short notes and practice.

Practice

Which is the best first choice in the waste hierarchy?
Why does a sanitary landfill have a liner and leachate collection system?
Recycling an aluminum can uses about 95% less energy than making a new can from ore. If making a new can takes 200 units of energy, about how much does recycling take?
Which law created a program to clean up abandoned hazardous waste sites?
A company proposes a cap-and-trade system. Supporters say it lets firms cut pollution at the lowest cost, while critics worry it may not cut enough or may leave local hot spots. This is best described as:
Plants such as sunflowers are used to absorb heavy metals from contaminated soil. This is called:

Free response

Write your answer first, then open the scoring guide.

Free-response question

A town of 50,000 people produces 4.6 pounds of municipal solid waste per person per day. The town currently sends all of it to a landfill and is considering a recycling and composting program.

(a) Calculate the total waste the town produces per day in pounds, and per year (365 days) in tons (2,000 lb = 1 ton).

Show the answer and scoring guide

Per day: $50{,}000 \times 4.6 = 230{,}000$ lb. Per year: $230{,}000 \times 365 = 83{,}950{,}000$ lb, which is $83{,}950{,}000 \div 2{,}000 = 41{,}975$ tons.

Check off the points you earned:

(b) If the new program diverts 35% of the waste from the landfill, how many pounds per day will still go to the landfill?

Show the answer and scoring guide

Remaining is 65%: $230{,}000 \times 0.65 = 149{,}500$ lb per day.

Check off the points you earned:

(c) Describe two environmental benefits of composting and recycling, and one challenge.

Show the answer and scoring guide

Benefits: less methane and leachate from the landfill, saving of energy and raw materials, and compost improves soil. Challenge: contamination of recycling streams with food or non-recyclable items, or the cost of collection and processing.

Check off the points you earned:

Previous unitUnit 8: Energy Resources