In this first post, Carolina García, a collaborator of the Official University Master's Degree in Management of Occupational Risk Prevention, Excellence, the Environment and Corporate Responsibility of Bureau Veritas University Center , talks to us about the importance of physical-chemical water treatment.
Water represents approximately 70% of the Earth's surface, and is considered the basis of the origin and sustenance of life on the planet.
This is why the protection and conservation of water resources is one of the main social concerns today , since the problems of supply due to high consumption are compounded by the serious contamination of groundwater and surface water sources.
Thus, the European Union , in its Directive 2008/105/EC of the European Parliament and of the Council, modifies the previous Water Framework Directive 2000/60/EC and approves the list of priority pollutants in the field of water policy.
This list includes some 50 organic and inorganic substances part time data that can be found in various types of water and that are especially dangerous and resistant to elimination, such as benzene, heavy metals, pharmaceutical products and organic pesticides.
Among all the possible contaminants present in aquatic systems, the so-called "organic micropollutants" have gained great importance in recent years due to their high toxicity and their resistance to conventional water treatment methods.
It is therefore essential to select processes and methods that guarantee the elimination or recovery of contaminants present in various waters (both natural waters intended to be made potable for human consumption, and waste water to be discharged into public channels) until reaching the strictly authorized levels, thus guaranteeing healthiness in the case of waters intended for human consumption .
The purification of natural and waste waters containing organic micropollutants includes technologies such as physical separation, biodegradation and chemical treatments.
The choice of the most appropriate method will depend on the level of contamination and the desired degree of destruction of the contaminants , as well as the effectiveness of each treatment and the economic aspects.
Water treatment processes
Biological processes , both aerobic and anaerobic, are relatively inexpensive and are frequently used in wastewater treatment plants to degrade general organic compounds.
However, these biological methods are particularly sensitive to toxic compounds such as those mentioned above, which can inactivate the microorganisms responsible for carrying out the treatment of organic matter present in wastewater.
In these cases, it may be interesting to apply a pre-treatment of toxic water through chemical oxidation processes in order to generate reaction intermediates that are more biodegradable than the starting compounds.
The decomposition of organic compounds can be carried out directly on the water to be treated by chemical oxidation , using certain chemical agents that act as oxidants or as degradation catalysts.
They have the advantage of destroying organic contaminants and are also suitable for removing contaminants both in the production of drinking water and in the treatment of highly contaminated industrial effluents. However, the most important limitation is the speed of the process, which is often too slow.
To overcome this problem, the development of chemical oxidation technologies to eliminate organic contaminants in aqueous media is based on the introduction of one or more reaction activators that act by generating highly reactive radicals.
These combined treatments constitute the so-called Advanced Oxidation Processes (POAs) , which are mainly based on the generation of the hydroxyl radical (·OH) that reacts rapidly with most organic compounds, except for chlorinated alkanes.
The technical feasibility of these processes in water treatment is fundamentally determined by the pre- and post-treatments required, the design and optimization of the reactors, the oxidative capacity of the reagent chosen and the effectiveness of the oxidation process.
Likewise, economic viability will be determined mainly by the cost of the oxidant to be used and the necessary relationship between it and the pollutant to be degraded in order to obtain the desired results.