Question

A 100-acre farmland contaminated by a massive diesel tanker spillage was subjected to the bioremediation using indigenous microbes in the soil as well as genetically modified Pseudomonas fluorescents over a 14-year period.

a) Briefly discuss any three factors that would have affected the bioremediation of the soil.

b) What bioremediation approach was used to tackle the problem and why?

c) What conditions would favor the approach used in question 2b above?

d) Highlight what outcomes of the process would indicate a successful remediation.

Answer 1

(a) Ans. Three factors that would have affected the bioremediation of the soil are -(1) Low nutrients - Low availability of nutrients such as phosphorus and potassium required for growth of oil removing bacteria in the contaminated soil will hinder the growth of oil (hydrocarbon) removing or degrading beneficial microbes. (2) Lack of oil degrading microorganisms - Lack of oil (hydrocarbon) degrading or removing microorganisms in the contaminated soil leads to non-degradation of oils. (3) Temperature of contaminated site - Microorganisms have specific optimum temperature for growth and hence effectiveness of external addition of beneficial microbes for removal of oils will depend on temperature of the contaminated site.

(b) Ans. Use of genetically modified Pseudomonas fluorescents would be adopted. Because the contaminated area is agricultural land and hence natural oil degrading microbes are generally not available in the such agricultural sites and hence external addition of oil degrading microbes need to be done for remediation.

(c) Ans. The site is agricultural land and hence soil would be nutrient rich. Hence, nutrients required for growth of beneficial bacteria are abundantly available and it would help in growth of beneficial microbes.

(d) Ans. Presence of beneficial bacteria at favourable density on soil analysis of the site on soil and reduction in amount of oil present in the site on chemical analysis would indicate successful remediation.