Experiment Demonstrating Oil Bioremediation

The best example for demonstrating oil bioremediation is one where you can see it visually and not have to do chemical analysis, i.e. use water rather than soil to demonstrate.

The experiment detailed below is very simple and costs very little to do.

In bioremediation you need: oil eating organisms (bugs), nutrients, oxygen, water and the food "oil".

There are plenty of natural organisms, bacteria, fungi etc in the air and water around us so there is no need to go searching for them.

Experiment details

• use a well stopped or screw top clear glass bottle or jar for the experiment
• half fill the bottle with pond water or sea water - try not to get any sand, dirt or clay in the water it will cloud the bottle and make it difficult to see what's happening (don't use domestic tap water - it may have chlorine to kill natural bugs)
• put a couple of pellets of fertiliser in the bottom for nutrients (slow release pellets are better- like osmocote used in gardens - only needs a little)- a drop of liquid fertiliser will also do but may cloud the water with brown/red colour.
• put a small amount of automotive diesel (not petrol) on top of water (get it from your local petrol station)
• put top on bottle, seal well
• shake the water/diesel mix for a couple of minutes - this gets oxygen into the water for the bacteria to use
• open the bottle and leave on shelf for a few days/week - not in direct light and keep away from any flames, heat or ignition sources
• each day put top on bottle and give shake for a few seconds
• after a few days the bacteria will start to eat (consume) the diesel and produce a film of waste products at the water/oil interface (sludge) - this is where the bugs are active, as they live mostly in the water and eat the oil touching the water surface.

This demonstration shows what goes on inside diesel fuel tanks of trucks and cars to cause sludge and blockage of fuel filters, the reason some home fuel oil heating systems stop working, and why power stations in remote settlements sometimes break down when bacterial sludge blocks injectors, pumps and fuel lines.

It is important in diesel storage to keep water out of the tanks to stop this biodegradation occurring.

In some long term diesel fuel storage, like in standby power stations, biocides (bug killing agents) are introduced into the diesel to stop this happening.

This also shows that oils like diesel can be easily broken down by bacteria at sea over time.