Bioremediation of soils contaminated by hydrocarbons

Reference image on the bioremediation of hydrocarbon contaminated soil. Soil in which a plant is starting to grow.

Since the beginning of the agrarian revolution and later the industrial revolution, continental soils have been the most damaged.

Industrial activity, being an activity of transformation of raw materials into manufactured materials, generates waste that can potentially harm nature.

Although industrial activity is not the only one responsible for soil degradation, it is the most important and we will deal with this in this publication.

Soil contamination can occur in any industry, in any commercial activity, or even in any human activity since soil contamination can occur due to any of the following aspects:

  • Incorrect storage of products and/or residues of human activity.
  • Uncontrolled dumping of waste.
  • Garbage derived from human activity.
  • Burying waste, directly or in containers.
  • Leaks in storage tanks or containers.
  • Incorrect use of pesticides, fertilizers, etc.
  • Deposition of atmospheric pollutants.
  • Due to the hydrocarbon spill.

Soil contamination by hydrocarbons

In this case, one of the most covered covers in the press worldwide, we want to talk about hydrocarbon pollution.

This is one of the industries that historically have had the most risks and challenges with soil contamination since the handling of large amounts of chemical compounds increases the risk of contamination due to their handling, storage, and transport.

Soil contamination, precisely, is understood as an increase in the concentration of chemical compounds in the ground that can cause changes that are detrimental to nature, which are widely spread.

Causes of soil contamination by hydrocarbons

The main causes of soil contamination by hydrocarbons are due to the difficult handling in the extraction and transport of fossil fuels, added to the little control that many of the producing countries have of accidents that occur in this industry.

In Europe, there are areas affected by accidental, illegal or even intentional discharges, in fact, there is a public register of contaminated soils.

In Spain, this record is made through potentially polluting activities of soils as established by Real Decreto 9/2005, de 14 de enero. The soils that are finally classified as contaminated, based on the criteria established in said Real Decreto, must be cleaned and recovered by the responsible party for possible subsequent use, whether industrial or otherwise.

It is also true that in recent decades investment in the development of innovative techniques for the recovery of contaminated soils has increased, as well as patents and projects dedicated to this issue at the European level.

The industry or trade related to hydrocarbons and fossil fuels (extraction, refining, transportation, wholesale, trading, etc.) is one of those activities that must periodically report their activity and status reports to the competent administration.

Bioremediation of hydrocarbon contaminated soil

As mentioned, contaminated soils must be recovered until the values ​​of the pollutants present are within the standards established in each case. There are different technologies for this, which may vary depending on the type of pollutant.

Leaving aside the techniques of containment or isolation of soils contaminated with physical barriers or confinement techniques, since they do not allow recovery, but rather the “non-expansion” of contamination, we can speak of in situ treatments or ex-situ treatments such as two large groups.

For obvious reasons, ex-situ treatments are usually more expensive, since they involve the removal of the entire amount of contaminated soil for treatment in suitable places.

Ex-situ treatment

This ex-situ method requires the stages of excavation, transportation, treatment in sewage plants, return and burial, making soil treatment more expensive and making it unfeasible for many companies that handle hydrocarbons.

In situ treatment

In situ treatments are, generally, the most used. Among them we can find a great variety, to mention a few:

  • Flushing, which consists of flooding the soil to drive pollutants to a place from which they can be easily extracted.
  • Physical-chemical treatments such as those that use columns of air to volatilize pollutants.
  • Phytoremediation uses plant elements that allow metabolization.
  • Biological treatments.

Biotechnology for soil recovery

Complex created in a former mining site with nature-based solutions, in which two forests were created, one tropical and the other Mediterranean.
Eden Project in Cornwall, UK. Complex created in a former mining operation. With materials from the area and positive environmental impact, two forests were created, one Mediterranean and the other tropical in the country of fog and frost. The area has resurfaced with tourism and generates millions of visits

In recent years, much progress has been made in terms of biological treatments for the recovery of soils, in addition to becoming the most innovative and with the best results, both in terms of treatment and cost.

Biotechnology has made it possible to take a great leap in this regard.

Bioremediation is one that uses Nature Based Solutions, or solutions based on nature, to naturally decontaminate the soil.

It has been known for decades that there are organisms capable of metabolizing certain organic and inorganic components that cause soil contamination, but due to the wide variety of known microorganisms and their special qualities, treatments were not always effective.

The great revolution in this area has come with the DNA sequencing of these microorganisms, among which we can find fungi, bacteria, microbes, etc. The sequencing of their DNA allows us to know their degradation capacities, each of them, of certain components and apply them with the prior knowledge that they are going to metabolize pollutants.

These types of systems are finally proven to be effective and also low cost and much more respectful of the environment in which they operate. It is about knowing which microorganisms is capable of metabolizing which pollutant and giving it the right conditions for it to reproduce in the contaminated environment.

Solutions based on Bio-augmentation and its application method

Amapex, in this area, has developed solutions based on the principle of bio-augmentation, so that the microbial population present in the soils to be treated is greater and has greater strength, by selecting the microorganisms with the best DNA for each specific case.

It is a formula developed to measure the soil and its pollutants.

The decontamination formula application process begins with an analysis of the contaminants present in the soil, which allows us to develop the specific formulation of the microorganisms.

Then the solution is implanted directly in the contaminated soil, using an intelligent dosing system: SDU, with which the dosing process is automated, avoiding overhead, removal and land transport.

After each application of this biological system, various measurements are carried out, until the complete elimination of contaminants in the soil, leaving it ready for reuse.

We are currently working on the decontamination of a large territory in central Italy, in which there was a hydrocarbon spill and which has been inoperative for decades. Soon we will be able to tell you the results of this application and the new use that is going to be given to that territory.

We invite you to keep an eye on our next publications and to learn more about our solution for the bioremediation of contaminated soils.