Applications
Soil Remediation
Main subjects of this page:
- Biological degradation contaminations – even chemical
- Treatment with windrow turners
- Treatment with lane turners
Applications
Main subjects of this page:
Soil contamination with substances that are harmful to health and environment has become a mass phenomenon worldwide since the industrialisation.
Soil remediation is the targeted treatment of soil to removecontamination with a specific substance.
The contamination of soils with substances that are harmful to health and environment has become a mass phenomenon worldwide since the industrialisation. Depending on the type of contamination, these pollutants can escape as gases, be washed into the groundwater by rain or enter the food cycle through uptake by plants. The affected areas can only be used to a limited extent or not at all. In addition, local residents are endangered and the neighbourhood may even become uninhabitable.
The possible soil remediation processes are often very complex, but are the only truly sustainable solution.
A basic distinction is made between on-site and off-site treatment. Both of them require the soil to be excavated first. In an on-site process, it is then treated on site, while in an off-site process it is first transported to an appropriate facility.
The aim of soil remediation is to free contaminated soil from contamination. The best possible remediation method is determined by means of a laboratory soil analysis. The method to be selected depends heavily on the type of contamination. In the case of contamination with harmful organic substances, for example, thermal treatment of the soil in rotary kilns is possible. Other soils can even be remediated by using certain plant species that absorb and bind the pollutants through their roots (phytoremediation). Another alternative is chemical treatment of the contamination. Here, chemicals are used to bring about a reaction with the pollutants, whereby they can be bound, neutralised or broken down. Biological treatment with microorganisms is also possible.
Bioremediation is the biological treatment of contaminated soil by microorganisms. There are "extremophilic" microorganisms that are particularly well adapted to certain hostile conditions and can break down pollutants.
If the necessary organisms are already present in the soil, they are cultivated through biostimulation. This involves deliberately adding nutrients and creating favourable living conditions for the growth of the population of those microorganisms. If the desired microorganisms are not yet present in the soil, they can be introduced in a targeted manner. In this case, we speak of "inoculation of the material"; the process itself is called "bioaugmentation".
As a rule, the soil must first be suitably prepared for the actual remediation process. This is because impurities such as stones or roots can hinder the respective process. In these cases, pre-treatment with a shredder and a screening machine should be carried out. Depending on the type of impurities to be expected, we offer our TEUTON and FORUS shredders as well as our TERRA SELECT and STAR SELECT screening machines for this purpose.
Our BACKHUS windrow turners are suitable for both bioaugmentation and biostimulation of contaminated soils. They create the optimum conditions for the necessary microorganisms, homogenise the material and provide sufficient oxygen. They can also additionally moisten it via an irrigation system or supply it with nutrients in a targeted manner via the concentrate spraying system.
To protect the drivers from toxic vapours, it is possible to equip the cabs of our turners with a particularly powerful air filter and an overpressure system. By generating positive pressure, air can no longer enter the cab, but can only escape.
If there is an increased risk of re-infection of the material or if you are dealing with a particularly hazardous contamination, it is advisable to turn it inside of lanes. Our automated LANE TURNERS are the perfect solution for this.
Our BACKHUS windrow turners were actively involved in the biological treatment of kerosene-contaminated material in East Germany, for example. This involved the soil of a former Soviet military base where the fuel had been improperly stored. Even in the case of paraffin, the cleaning was carried out completely biologically using microorganisms, for which our BACKHUS turners create the right conditions.
Our BACKHUS were also used in Rammstein for ground remediation. A Lockheed Galaxy C-5A crashed there on 29 August 1990 immediately after take-off, killing 13 passengers. The ground at the crash site was contaminated with paraffin during the accident. The clean-up has been carried out using BACKHUS turning technology and has long since been completed.
Image source: U.S. Air Force photo from the National Museum of the United States Air Force.
Firstly, the excavated material should be suitably prepared using a crusher and a screening machine so that it no longer contains any impurities. It can then be placed in a suitably secured location to form a windrow. If the microorganisms required for decomposition are not already present in the excavated material, it should be inoculated with an appropriate culture. By regularly moving the pile, optimum environmental conditions are then created for the microorganisms so that decomposition can be reduced from over a year to up to two months.
During treatment, a separate strain of microorganisms is formed that is precisely adapted to the specific oil in the soil. Due to its customisation, it proves to be particularly efficient during decomposition. After setting up a first windrow and starting the process, the following windrows should therefore be inoculated with approx. 20 litres of material from the first windrow in order to achieve maximum process speed immediately.
It is also interesting to note that the level of contamination is only an insignificant factor for the duration of the degradation process. For example, there will hardly be any difference between a contamination level of 10 or 40 % in the reduction to approx. 1 %.
However, this last per cent is always the most difficult, as the population of microorganisms now begins to die due to a lack of food. The process therefore takes the longest here, but even this last per cent will still be reduced.