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Removing oil from soil

We are concerned here with microbes capable of degrading petroleum derivatives (diesel, furnace fuel, etc.) commonly referred to as 'hydrocarbons'.

The scenario

A road tanker rig is accidentally involved in an incident and loses its load on the side of the road. After the vehicle has been removed, what invariably remains is a stain of oil soaked (and still soaking) into the soil called a 'plume'. Usually the oil penetration is shallow in hard ground such as a road reserve or hard shoulder, but contamination can be far deeper in agricultural land alongside the highway.

What happens next?

A specialist 'spill response' contractor is appointed. First the excess oil is absorbed using the highly absorbent, non-leaching Spill-Sorb™ fibre product (obtainable from BIO-SYSTEMS SA). Next, we spread a mixture of BIO-SYSTEMS B350, Spill-Sorb™ and/or Fungi-Carb™, which is tilled into the contaminated surface, watered and covered to break down and degrade the oil that has seeped below the soil surface. Water is then added to the spread.

As soon as water penetrates the dried out cell wall of every microbe in the B350 product, the microbes rehydrate and resume their interrupted metabolic cycles. Like a dried prune dropped into a cup of water, the water swells the fruit back to its original size. However, unlike the 'dead' prune, the microbes are released from their suspended animation and carry on living and multiplying.

Bioremediation begins…

Each unicellular bug finds itself lying next to a molecule of oil stuck between minute grains of soil. When the ambient temperature, atmospheric pressure, soil pH, availability of trace nutrients and other factors are to their liking, the bugs ingest life-restoring water into their cellular structures and 'wake u' and feed on the oil molecules. What follows is a truly remarkable phenomenon. Stimulated by its proximity to the oil molecules (food), each bug secretes an enzyme that breaks down part of the complex hydrocarbon. The oil is thus sequentially degraded as the fractions are taken up by the microbes and further digested as a food source inside their cells.

As the bugs reach contented maturity they reproduce (roughly every 30 minutes) by dividing in half. The new identical bug grows, forcing itself against its 'mother cell' and deeper into the mass of oil molecules. This happens simultaneously and spherically in biochemical balance with the entire 'biomass' and to the gastronomic satisfaction of all varieties in the complex bug population. As a result, the biomass, depleted of its substrate (food) becomes democratically self-regulating, expanding irrevocably into the oil plume all the time.

The microbes that started the process end up at the centre of the biomass. Having completed their job they starve and die leaving behind nothing but a harmless organic residue. Budding bugs that are pressed (by 'parental' pressure) against unpolluted soil with no oil (food) to degrade will also recess. As a result, the buggy biomass expands to follow the food into the interstices between soil grains, rock strata, or concrete. The process continues until the bugs break down every inch of the remaining molecular residue of the contaminant into natural gasses, inorganic radicals and water. These products of biodegradation are then metabolized back into the natural food chain and used by other life forms.

Spill-Sorb boom used to treat oil spill  Spill-SorbTM boom used to clean up oil spill

Spill-Sorb boom after treatment  Close-up view of Spill-SorbTM boom

Note how boom has 'sucked up' all the oil.

As well as oils in soils, microbial degradation applies to sewage in septic tanks and pit latrines; FOG in grease interceptors, pump stations and sewers; and all types of biologically degradable effluent.

For more information about how BIO-SYSTEMS bugs can assist you, click on our Municipal, Domestic, Industrial and Agricultural links.

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