Crop Research Institute, v.v.i.
Prague – Ruzyne ecotoxicology Chomutov
Czech-Saxon project ZIEL in cooperation with VÚR V, v.v .i. Prague Department of Ecotoxicology, Chomutov and ENZYMIX s.r.o.
Ing. Roman Honzík a separate scientist and researcher of the RIFCH, v.v.i. Prague
Use of VERMAKTIV Stimul for decontamination of areas for subsequent economic use.
The principle of the method is based on the ability of certain strains of aerobic microorganisms to biochemically cleave unwanted organic compounds and use them as a source of carbon and energy for their metabolism. These microorganisms are able to degrade a wide range of hydrocarbons (alkanes, cycloalkanes, aromatics, polyaromatics), chlorinated biphenyl (via dioxins, furans and heavy metals), and other pollutants. Vermaktiv Stimul facilitates the absorption of heavy metals by the root system into plant tissue. Through a number of some intermediates, it will allow decomposition to final products – water and carbon dioxide.
To use VERMAKTIV Stimul:
Bioremediation is a set of technologies that utilize living organisms, such as bacteria, fungi or plants, to completely decompose or transform various undesirable substances into less dangerous substances, water and carbon dioxide.
Remediation approaches have found their application especially designed for environmental friendliness, ease of application, and low cost. They are used in the treatment of waste and ground water, sludge, gases, and soils. Bioremediation, however, also has disadvantages; the site must be closely monitored at all times, the process time is in many cases longer, and the decontamination of inorganic compounds is considerably limited.
The actual pollutant degradation is preceded by a lag phase of varying lengths. The lag phase can be defined as the time that elapses from the moment the substance enters the environment to the detectable drop in concentration. The lag phase may take several hours to several months. As the length of the adaptation phase increases, the risks associated with the presence of pollutants in the environment increase.
Bioremediation can be either anaerobic or aerobic. Aerobic processes releases energy, which can be utilized by microorganisms in metabolic degradation. Oxygen serves as an electron acceptor, which is converted to water. Anaerobic processes serve as an electron acceptor for nitrates, sulphates, or carbon dioxide.
Factors Influencing the Course of Bioremediation
Physical – Chemical Factors
The presence of organisms capable of degrading the respective pollutant and the ability to adapt and acclimatize
Relationships between organisms
Physical – Chemical Factors
Contaminant powers (structure, bioavailability, biodegradability)
In general, substances commonly found in nature are biodegradable. Similar substances can be degraded by the same metabolic pathways. A chemical is bioavailable when it can be absorbed from the environment by the organism. It is a function of the properties of the compound and the physical and chemical properties of the environment. It is difficult to decompose substances with low water solubility or to decompose substances that are strongly sorbed on the soil matrix. The bioavailability of persistent substances decreases over time. This phenomenon is called aging because the compound has enough time to interact with soil or sediments. The soil contains many pores of different sizes, which can be filled either with water or water and air. Another explanation for decreasing bioavailability over time is the formation of complexes with humic substances. Complexes are likely formed either by interaction of the substance with the reactive site of the organic colloid or by incorporating the substance into the structure of organic compounds.
The phytoremediation process is influenced by the following factors:
• the presence of surfactants
• contaminant concentration
• ambient temperature
• the presence of toxins
• the content of available nutrients
• soil structure
Decontamination of the environment will require the following steps:
• conducting a field survey
• choice of decontamination method
• in situ
• ex situ
Biostimulation (improved bioremediation)
This method, as the name suggests, is based on stimulating the number and activity of naturally occurring populations. The necessary condition is the presence of able organisms degrading a given pollutant. Biostimulation is to ensure the best possible conditions, e.g. by adding nutrients, adjusting the pH, etc. For growth, soil organisms need access to a carbon source, which, in most cases is a pollutant itself, as well as other elements. The lack of these elements can significantly slow the bioremediation process. The ratio between nitrogen, carbon, and phosphorus plays a major role. It is generally assumed that the C: N: P ratio should be 100: 5: 1. There is also the possibility that other N: P ratios can lead to stimulation of different kinds of microorganisms and therefore it should be different for the decomposition of different compounds. Biostimulation is a very cheap method.
It is also possible to stimulate the rate of biodegradation of a contaminant by adding microorganisms or enzyme preparations to the contaminated soil, if the naturally occurring organisms are not able to decompose the pollutant or there are too few of them. In order to maintain the natural environment, organisms must be genetically stable and able to adapt to the conditions. This is also the reason why bioaugmentation is not yet widely used. Although laboratory studies show good results, bioaugmentation does not appear to be very effective in comparison with other bioremediation methods. In practice, microbial cultures are often obtained by transferring a sample of contaminated water or soil into a solution containing all the necessary substances. When using isolated extracellular enzymes, the greatest advantages are the enzymes substrate specificity and catalytic activity. In addition, the enzymes are less sensitive to the presence of predators and fluctuations in contaminant concentration. On the other hand, the use of extracellular enzymes is more expensive because the cost is increased by the cost of insulation and cleaning. This is another reason why they are not yet widely used.
VERMAKTIV Stimul multiplies the intensity of biological activity by increasing the concentration and activity of microorganisms in contaminated material thereby multiplying metabolic activity and possibly enriching other specific bacterial strains, and thus extending the enzymatic spectrum.
On the basis of the observation, a decision on repeated spraying with VERMAKTIV Stimul, the number of bio replications, the necessity of aeration, which creates the necessary wetting of the material by spraying, can be made. During the biodegradation process on the decontamination area, samples of the treated area are continuously taken. The whole process is monitored by a number of chemical and microbiological analyses. After comparing these analyses, the dosage, the number of applications of the bioproduct, the necessity of further cultivation of soil bacteria, or the need for further cultivation are decided. For example, the use of minerals and organic fertilizers.