Question

During a bioremediation process, nitrates and phosphates are added to soil contaminated with petroleum oil. Explain why chemicals such as nitrates and phosphates are added to the soil instead of adding additional bacteria.

Answer 1

During a bioremediation process, nitrates and phosphates are added to soil contaminated with petroleum oil. These act as terminal electron acceptors which enhances the bioremediation.

The main primary requirements of bioremediation are

a) Contaminates like petroleum oil or petroleum hydrocarbons etc

b) an electron acceptor like nitrates , phosphates, sulfates, iron etc. The use of addition of nitrate and phosphates to the soil contaminated with petroleum hydrocarbons or petroleum oil is to increase the cell growth rate and decrease microbial lag phase. This helps the microbial population at high activity levels which increases the rate of hydrocarbon degradation. Whereas addition of extra bacteria does not increase the rate of hydrocarbon degradation to an optimum level and after certain time they also reach to lag phase. Hence instead nitrates, phosphates are added.

c) presence of microorganisms like bacteria that can degrade the contaminate.