Biological In-Situ Remediation Methods

A microbial community has often developed at contaminated sites that has adapted exceptionally well to the presence of specific contaminants and can even degrade them under adverse conditions. In such cases, experience has shown that it is sufficient to supply these site-native (autochthonous) microorganisms with appropriate substances, such as oxygen and/or nutrients, so that they can carry out their degradation activity with greater efficiency. Drawing on our many years of experience and using specific analytical tools, we are able to determine which specific active agent will most effectively stimulate the degradation-active microorganisms at your site for your remediation project.

There are sites where an insufficient number of degradation-active microorganisms have been able to develop. This is particularly common in reductive VOC degradation processes, where the natural biological degradation of PCE and TCE often comes to a halt at the cis-dichloroethene stage. In such cases, the additional introduction of anaerobic microorganisms capable of degradation can extremely effectively support the site’s natural self-purification processes.

In addition, mixed cultures of aerobic bacteria that specifically break down pollutants in our tests can be propagated on a long-term basis and incorporated into our strain collection. This means that specialized cultures are available for many groups of pollutants, which can be used specifically for remediation as needed.

Sensatec GmbH offers bioaugmentation cultures and the technology for their application to treat a wide variety of biodegradable contaminants. If needed, we can cultivate site-specific microbial communities on a large scale for your remediation project.

Many polychlorinated pollutants, including low-volatility chlorinated hydrocarbons (LCHs), can be biodegraded only under strongly reducing environmental conditions and in the presence of specialized dechlorinating microorganisms.

Sensatec has a broad portfolio and the expertise to supply the appropriate reagents. We are the only company in Germany that cultivates the necessary specialized dechlorinating cultures in our own production facility, and we have the molecular biology tools to detect these degradation specialists. This allows us to offer you the greatest possible assurance of success in implementing your remediation project.

Biological degradation processes in the subsurface can also be stimulated by introducing air into the groundwater. Some of the oxygen introduced via the air dissolves in the groundwater and can then be consumed by the microorganisms that break down pollutants. Since relatively large amounts of air must be introduced into the subsurface to ensure an adequate oxygen supply, it is essential to ensure that the air can escape from the subsurface. This requires well-permeable, non-layered subsurface materials. In the case of highly volatile contaminants, biosparging quickly causes the contaminants to migrate into the unsaturated soil zone, which must then also be treated.

We design and deliver the technical specifications as well as turnkey systems for implementing biosparging processes for groundwater treatment, in combination with a soil air extraction system if required.

Incomplex, potentially stratified aquifers and in structures that consume large amounts of oxygen,direct oxygen gas injection is a viable alternative to biosparging.

We hold an exclusive license for the construction and implementation of the Bioxwand process (a gas storage method). In this process, an oxygen gas reservoir is created in the aquifer in the form of a fine-bubble gas distribution system, through which oxygen is continuously dissolved into the flowing groundwater. This method has proven highly effective for treating a wide range of contaminants, such as BTEX, vinyl chloride, chlorobenzenes, PAHs, MKW, and ammonium compounds. We have already applied it with great success in a wide variety of geological formations. (For reference) In cases where contaminated sites are completely built over or inaccessible, direct gas injections can also be carried out via horizontal boreholes using a method patented by Sensatec GmbH.

Aerobic methane stimulation offers an alternative to reductive dechlorination for the degradation of volatile chlorinated hydrocarbons (VCHs), particularly the more difficult-to-degrade byproducts such as vinyl chloride. In this process, methane is specifically introduced into the subsurface to activate methanotrophic microorganisms, which use methane as an energy source. This metabolic process produces the enzyme methane monooxygenase, which also co-metabolically oxidizes the pollutants dissolved in the groundwater into harmless compounds.

This process is particularly suitable in cases where reductive dechlorination reaches its limits or comes to a halt at the cis-dichloroethene stage, and it can be combined very effectively with other in-situ processes. We handle the technical design and implementation of the methane injection for you, using either gaseous or dissolved forms of application depending on site conditions.