Section 5.6: Detox for Contaminated Land
Research This: Innovations in Bioremediation, page 221
A. Answers may vary. Sample answer: The purpose of this bioremediation project was to turn
mine tailings into crops that could be used as biofuels. The project involved depositing organic
waste from pulp and paper mills and corn and canola seeds onto tailings. The crops grown on the
tailings could be converted into biofuels, establishing a productive use for what was previously
unproductive land. Preliminary results in 2008 were encouraging because the test site produced
as much biomass as the nearby control site.
B. Answers may vary. Sample answer:
Bioremediation vs Physical or Chemical Remediation
Bioremediation
• It is less disruptive to the local environment.
• It is less expensive and more effective.
• It takes longer.
• It turns industrial waste into productive land.
Physical or chemical remediation technology
• It is more disruptive to the local environment.
• It is more expensive and not always effective.
• It takes less time, provided the technology is feasible.
• Contaminated land remains unproductive.
Based on the given information, bioremediation of the site is a more appropriate treatment
strategy than applying physical or chemical technologies.
Section 5.6 Questions, page 221
1. Answers may vary. Sample answer: The end-use of a contaminated site determines the extent
of remediation required. A contaminated site that is planned to become a parking lot, for
example, will require less cleanup than if it is intended to become a playground or schoolyard.
2. Answers may vary. Sample answer: To ensure the safety of the children at the school, a
complete excavation and replacement of the contaminated soil in the playground is necessary.
3. Most chemical reactions occur more quickly at higher temperatures. The release of thermal
energy reduces the energy required to decompose the contaminants.
4. Chemical reactions between oxygen and exposed minerals in a tailings pond can often make
the water draining from the pond acidic. Covering the pond with compostable material prevents
oxygen from reacting with the minerals. This should decrease the acidity of water draining from
the pond.
5. Fractured rock allows contaminated water to flow through it more readily, making it more
difficult to contain and treat a chemical spill.
6. (a) Answers may vary. Sample answer: Bioremediation is more desirable than physical or
chemical remediation technologies in some applications because it is less disruptive to the local
environment and provides a natural solution to an environmental problem.
(b) Answers may vary. Sample answer: One limitation of bioremediation is that it often takes a
long time to remediate a contaminated site.
(c) Bioremediation often has a smaller carbon footprint than other technologies because it is less
energy intensive. In fact, bioremediation that involves growing plants on a contaminated site
actually absorbs carbon dioxide from the atmosphere.
Copyright © 2011 Nelson Education Ltd.
Chapter 5: Chemical Processes
5.6-1
7. Answers may vary. Sample answer: Thermal technologies treat contaminated soil by heating
the soil to high temperatures which causes contaminants in the soil to burn or decompose. This
form of soil treatment is best suited for organic contaminants such as oil and organic solvents.
The contaminated soil can sometimes be treated on site by portable equipment. Otherwise, it
must be removed, transported to a treatment facility, treated, and then returned. The disadvantage
of thermal treatment is that it is costly and disruptive. Its advantage is that contaminated soil can
be treated relatively quickly compared to bioremediation methods.
Copyright © 2011 Nelson Education Ltd.
Chapter 5: Chemical Processes
5.6-2