MICROBIOLOGICAL AND BIOLOGICAL TECHNIQUES (BIORREMEDIATION)
In the application of bioremediation as a technique for the recovery of contaminated soils and waters, processes are used in accordance with biomimicry principles. For this reason, with good reason, Microbiological and Biological Techniques can be considered the most sustainable in the short, medium and long term. These techniques are the most used in in-situ decontamination projects, although ex-situ treatments are also carried out when there are no structural risks derived from the excavation of the soil (dynamic or static biopiles).
The objective of these processes is the transformation of hazardous substances, in biomass, water and CO2, through the application of microorganisms, fungi, plants or enzymes.
IN SITU AND EX SITU BIORREMEDIATION STRATEGIES:
NATURAL ATTENUATION (in-situ): site monitoring to control the natural degradation of the pollutant.
BIOSTIMULATION (in-situ y ex-situ): by the addition of a co-substrate (e. g. injection of methane during the degradation of trichlorethylene), nutrients (mainly nitrogen and phosphorus) or gaseous stimulants (O2 o CH4).
- Injection of electron acceptors (NO3–) /electron donors (halogenated hydrocarbons or metals)
- Air sparging
- Diffusion of oxygen
- Methane injection
- Bio-oxidation walls
BIOAUMMENTATION (in-situ y ex-situ): inoculation of microorganisms, fungi and / or their enzymes to accelerate the degradation of the contaminant at the site.
PHYTO-MEDITATION (in-situ y ex-situ): use of certain plants for the recovery of contaminated sites. There are different mechanisms:
- Phytoextraction (heavy metals)
- Phytodegradation (organic compounds)
- Rizofiltration (organic compounds)
- Phytostabilization (soil stabilization, reduction of erosion)
PROJECTS OR SERVICES LINKED TO THE MICROBIOLOGICAL TECHNIQUES:
Among the projects in which microbiological techniques are applied, the following stand out:
- Laboratory tests for the determination of biological degradation capacity
- Monitoring of recovery processes in soil and water
- Monitoring of recovery and decontamination processes in soil and water
- Monitoring of Natural Attenuation Projects (MNA)
- Design, assembly and monitoring of dynamic and static biopiles
- Bio-transformation of heavy metals
- Monitoring of the Biogeochemical Baseline
During the monitoring of the bioremediation processes it is necessary to control a series of key parameters in order to evaluate the microbiological performance, directly linked to the elimination rate of the contaminant. The analytical battery can be classified in two blocks:
Microbiologic analysis:
CFU counting to measure abundance and / or specificity
- Total Heterotrophs
- Specific degradation
Molecular biology techniques
- DNA extraction (PCR / qPCR): presence and / or abundance of genetic diversity
- RNA extraction (RT-qPCR): genetic expression
- Enzymes: microbiological activity
- Phospholipids (AGF): active microbial biomass
Ecotoxicity tests (calculation of the LD50 and / or germination index)
Physicochemical analysis:
- Soil characterization: granulometry, texture, porosity, Koc
- Environmental conditions: Temperature, pH, ORP, Conductivity, and Humidity
- Nutrients (NH4+, PO4-3, K, etc.)
- Electron acceptors(O2, NO3, Fe+3, etc.)
- Polluting concentration