Reference no: EM131856219

ASSESSMENT OF A BIOREMEDIATION STRATEGY

Soil from a former timber treatment facility has been found to contain high levels of polycyclic aromatic hydrocarbons (PAHs). The Environmental Protection Agency has asked you to examine the application of a combination of aeration and fertiliser addition for the remediation of this soil.

This approach has been used in some instances to increase the rate and extent of degradation of a range of xenobiotics in soil. A fertiliser containing nitrogen, phosphate and potassium was added to the soil and it was aerated by tilling. Samples were removed (in triplicate) from the treated soil and from soil that was not treated (control) on days 0, 20, 50 and 100 and the level of total PAHs, the number of culturable bacteria (total and those that utilise PCP as sole carbon source) and microbial activity determined. Results from these analyses are attached below. Examine the data provided, answer the questions.

TASKS/QUESTIONS

1) Calculate the percentage degradation of PAHs in the treated soil and the untreated soil on each sampling day.

2) Display the results obtained in what you consider to be the most appropriate manner to allow the EPA assess the effect of the treatment (fertiliser addition and aeration) on PAH degradation compared to the untreated control.

3) Comment on the rates of PAH degradation in the soil that was fertilised and aerated. Compare these to the rate of PAH degradation observed in the untreated (control) soil.

4) Calculate the cfu g-1 soil of a) bacteria and b) bacteria capable of growing on a PAH as sole carbon source in the treated and control soil on each sampling day. Present the results in what you consider the most appropriate manner.

5) Do you think the numbers determined represent a true estimate of the number of bacteria present in a gram of soil? Explain your answer.

6) Plot the change in microbial activity in the treated soil and the control soil over time.

7) Using the results obtained for PAH concentration, bacterial counts and microbial activity in the treated and control soils comment on the effectiveness of fertilisation combined with aeration as a strategy for the remediation of this soil.

8) Are there any further tests you would recommend the EPA do before deciding on whether fertilisation combined with aeration would be an appropriate strategy for the bioremediation of this soil?

Attachment:- Analyses.rar