What are your views on the use of OUR (oxygen uptake rate), SOUR (specific oxygen uptake rate), BOD (Biological Oxygen Demand) and DO Dissolved Oxygen) in measuring biodegradation and bioremediation of crude oil?
Biodegradation of crude oil is a process that can be accelerated by living microorganisms such bacteria. These microorganisms consume oxygen in the process. Therefore, BOD and DO can be used for such monitoring, however, it is advisable to take into consideration how the two (BOD and DO) relate to each other.
All of these parameters you mentioned can be used to monitor biological activity. However, the best way to verify treatment of crude oil is to actually measure concentrations along time. SOUR, and OUR are good indicators, but remember that even though the crude oil is not being degraded, you can still get oxygen consumption due to degradation of other carbon sources, sometimes more readily available then crude oil. So my suggestion is that you could use it but not in a very accurate way.
David Olugbenga Adetitun: All the parameters you mention in your question could be used for monitoring and characterization of crude oil degradation. The problem is that commonly not only crude oil is biodegraded in contaminated soil, sludge or groundwater. It means that mentioned parameters are not specific for biodegradation of crude oil only.
Best regards
Vit
Not always, depending on the specifications of the crude oil, also I agreed with the answer of Dr.Fabio Kaczala .
You can use anaerobic treatment for PAHs and monitor the COD before and after treatment but the crude oil remediation maybe the BOD and DO measurement maybe helpful for aerobic one.
Crude oil components (mainly hydrocarbons C10-C40, plus other compounds, including IPA) have a very low solubility in water. You should clarify first if you are working on water contaminated by HC or soil contaminated by HC. In the second case, more frequent, the largest part of HC will be hanged to the soil (up to 10 g kg-1 soil) and in solution, you will have just the HC solubilized by bacteria. This means that BOD, OUR and COD of the aqueous phase are completely useless because not specific as other Colleagues pointed out. The best way to follow biodegradation in an oil contaminated soil, is measuring the HC left in the soil over time, preparing a series of bottles (5-10) , and utilizing one each time. The HC in the soil will be properly extracted by solvents, and after purification measured by GC-FID or GC-MS). The best would be also to determine the bacterial concentration either in the water phase or in the soil (by FISH after extraction): as long as the HC are biodegradeted the bacterial number increases. At the end you have to ascertain that no toxic compounds are left behind the acceptance limit (do not forget to look also for metals, such as vanadium).
Thanks for your comments and answers. Actually, the planned work is a bench test in the lab. Known and specific HC will be used as the only carbon and energy source. I agree that increase in cell numbers can be used to infer utilisation. Is it possible to send samples to some of you for FISH as I do not have it around me? is it also possible to visit some of your labs to do some work together?
Dear David if you can not do FISH /epifluorescence Microscopy)you should have access at least to a Optical Microscope, to count bacteria ( in phase contrast or after staining). Sending soil samples to our Lab is not permitted unless long burocratic procedures. Start determining the decrease of TH mass, and, if you can, counting bacteria. Good luck
David Olugbenga Adetitun: In your original question you are talking about "crude oil". Later you spoke about "...Known and specific HC will be used as the only carbon and energy source." So what are you going to evaluate?
Best regards
Vit
Thanks Vit. Will look at the rate at which the microbes are able to degrade the HC involved per time. For instance, phenol can be used as the only carbon source and monitored over time.
David Olugbenga Adetitun: I am affraid that phenol is not the best choice. There are more reasons for that. Phenol is toxic to bacteria in higher concentrations (approx. > 2.5 mg.L-1). Cometabolic degradation of phenol is much more efficient, etc. That is why I think that better choice woul be for example n-hexane or some opther aliphatic hydrocarbons.
Best regards Vit
I am not sure that countig of bacteria as recommended by VALTER TANDOI has any meaning for evaluation of biodegradation activity. Bacterial count has nothing to do with biodegradation activity at all. Biodegradation activity is determined by the presence of enzymes and their activity in the bacteria. It means the biodegradation activity (rate) could be much higher when bacterial count will be 105 bacteria per mg of soil in comparison to biodegradation activity with bacterial count 107 bacteria per mg of soil.
Best regards Vit
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