The huge amount of pollutants from industrial activities represents a threat to the ecological and environmental balance.
Chlorinated organic compounds, polycyclic aromatic hydrocarbons, pesticides, dioxins, industrial dyes, and other xenobiotics are among the most significant industrial pollutants.
A great variety of these xenobiotics are substrates for different types of enzymes, consequently, susceptible to enzymatic transformation.
Classification of enzymes
Enzymes are proteins specialized in the catalysis of biological reactions, this means that they accelerate the transformation of one organic compound into another, and are produced by a large number of microorganisms and plants.
Enzymes are classified into six groups based on the type of reaction they catalyze and, in practically all of them, there are enzymes that are currently used in industrial processes:
- Hydrolases
- Isomerases
- Liasas
- Garters
- Oxidoreductases
- Transferases
Wastewater treatment by the enzymatic method
The enzymatic method is a biological treatment that aims to improve the water effluent, through the supply of enzymes to reduce or eliminate the toxicity of the water through the transformation of pollutants.
It consists of obtaining, manipulating, and modifying enzymes for their application and use for industrial purposes in various fields.
These enzymes can be incorporated in the treatment and purification of water by use:
- Direct.
- Microbial cells.
- Whole plants or their tissues.
Many of these enzymes catalyze a wide variety of reactions. Before wanting to extract an enzyme from any source, one must take into account what this enzyme will be used for.
In addition, a certain method of obtaining will be needed, determining the concentration of the enzymes to establish if the source used is viable.
Each type of enzyme may be capable of degrading specific pollutants and catalyzing chemical reactions. Therefore, certain enzymes can treat only certain types of organic pollutants.
Substrates such as phenols, chlorophenols, methylated phenols, biphenols, anilines, benzidines and other heterocyclic aromatic compounds that are found under dilute conditions and are less sensitive to operational disturbances, can also be treated by enzymes.
Benefits of enzymatic wastewater treatment in the industry
Using enzymes in the treatment of industrial wastewater has multiple benefits:
- Biological transformation of pollutants present in wastewater.
- Reduction of the toxicity of water through the transformation of pollutants.
- They are part of a sustainable environment since they are naturally biodegradable substances.
- Its use does not require pressure, heat or corrosion-resistant equipment, saving money and energy.
- They can replace or reduce the use of polluting chemicals in different types of industries.
- They are produced ecologically from living organisms. Furthermore, modern techniques of molecular biology make it possible to improve production processes and develop new enzymes and new fields of application.
- They are very specific in terms of the substrate they are going to process.
Wastewater treatment in the textile industry
One of the biggest challenges that the textile industry has to face is the processing of its effluents with high loads of pollutants, which represent an environmental problem, because they contain, among other chemical substances, remnants of the dyes used in the dyeing of fabrics.
In the textile dyeing processes, we find organic compounds such as phenols, chlorinated phenols, aromatic compounds, and in certain colorants, peroxidase and lactase enzymes are used mainly.
This type of compound makes their removal difficult with conventional wastewater treatment methods since most systems based on physical-chemical treatments are expensive and require a large amount of energy and reagents.
In this line, biotechnology offers an alternative for the treatment and purification of wastewater.
These enzymes, due to their ability to catalyze reactions in the presence of peroxides, such as hydrogen peroxide and polymerize phenols and aromatic compounds, have been extracted by successful methods.
One of the advantages of the enzymatic method is that, in addition to catalyzing discoloration, complete mineralization of the dye can be achieved.
On the other hand, there are a large number of microorganisms that are capable of degrading and eliminating the color of wastewater through different mechanisms, such as bioabsorption, aerobic or anaerobic biodegradation, and production.
Enzymatic wastewater treatment with laccase
Laccases are enzymes with phenoloxidase activity, belonging to the group of multi-copper oxidoreductases, characterized by having copper atoms in their active center.
They present great specificity for a significant number of non-biodegradable compounds, present in the effluents of textile processes, for which reason they began to be used in industrial effluent treatments.
The enzymatic activity of laccase catalyzes the oxidation of various aromatic and inorganic substances (particularly phenols) with the concomitant reduction of oxygen to water. Also, it is capable of removing phenols through the polymerization process. Functions that corroborate its biotechnological interest.
Figure 1. Proposed mechanism of the indigo carmine bacterial degradation pathway.
A laboratory-scale example of this is the bacterial degradation of the indigo carmine dye, which can be transformed through the transfer of electrons from laccase and by decarboxylation to a metabolite, as a stable final oxidation product (Figure 2).
The function of laccase is to increase the dye’s susceptibility to hydrolytic attack by water.
Image 1. Effluent from EDARI from the textile industry (Tonella, Italy), the coloration product of the mixture of textile dyes present in the industrial process can be seen, a possible pilot for the Smart Doser Unit (SDU) of Amapex.
The SDU is an intelligent activator and dosing device for the active principle, in this case, enzymes for wastewater treatment, which has been designed and manufactured under the supervision of Amapex.
If you would like more information on the enzymatic treatment of industrial wastewater, you can contact us through the following web form.
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