Explain the use of bacteria in the bioremediation of water.

a. example of where this has been used e.g. Exxon Valdez spill, Alaska / other correct example;

b. indigenous/existing bacteria can break down oil;

c. bioremediation is the use of nutrients to enhance the activity of existing organisms / the addition of non-indigenous microorganisms;

d. converts the toxic compounds of oil to non-toxic products;

e. bioremediation is used after other cleanup methods have been used;

f. bioaugmentation is when bacteria are added to supplement the existing microbial population;

g. biostimulation is when nutrients are added to stimulate the growth of the existing oil-degrading bacteria;

h. bacteria added seem to compete poorly with the indigenous population;

i. nutrient concentrations have to be sufficient to support the maximal growth rate of the bacteria throughout the clean-up operation;

Few candidates answered this question well. It is important to note that this option, in many cases, seemed to be answered by the occasional candidate within a school where the majority of candidates answered other options. Some understood that bacteria could decompose contaminants, but with no mention of oil, and certainly no differentiation between methods or details of any sort.