The environmental protection measures include saving the planet’s water resources and management of used resources which occupy large areas. Especially important is the treatment or industrial wastewater, among which the wastewater of chemical, engineering, food, instrument, petrochemical and other industries poses the greatest danger to the environment.
Wastewater of these industries varies in amounts, composition and concentration of contaminants and thus requires the application of reliable and efficient cleaning methods and appropriate equipment. The problem of wastewater purification is caused by the complexity of physical and chemical processes involved.
Existing methods of industrial wastewater treatment. Their advantages and disadvantages
The methods of industrial wastewater treatment applied today are ion exchange, reagent and electrocoagulation. They treat wastewater, removing chromium and other heavy metals. In spite of the existing achievements, they are not fully efficient and economical and do not provide rational management of water resources. These methods also produce large quantities of waste requiring disposal. In most cases, the resulting sediment is dried and stored on the premises or in places specially designed for waste disposal at extra cost. In recent years, much attention is paid to no-waste or low-waste technologies. But, as practice shows, they require large investments.
The main drawbacks of ion exchange and reagent methods of wastewater treatment with traditional equipment are the process duration and the large consumption of reagents, significant operating costs, high metal consumption and bulky equipment with large footprint.
Electrocoagulation process leads to a higher content of iron and aluminum in the treated water and a high electric bill. It is significantly affected by the flow fluctuations, temperature, salt content and concentration of pollutants. This method requires a feasibility test in each particular case. In addition, the electrocoagulation process often does not ensure the necessary water quality to return to the production facilities and its subsequent use in manufacturing processes
What is an electromagnetic nano-mill (AVS)?
The first electromagnetic mill (AVS) was constructed in the 1960’s. The principle of this device is very simple. It is a hollow cylinder made of nonmagnetic material. Inside this cylinder are ferromagnetic particles (the so-called “needles” with magnetic properties, with a ratio of length to diameter of at least 20).
Outside the cylinder is wound with inductor coils that create a rotating magnetic field. When voltage is applied to the coil, the magnetic particles come into a complex oscillatory motion, forming electromagnetic field in the operating space. Each particle moves in the direction of the rotating field at high velocity, colliding with each other.
The interaction of the rotating electromagnetic field produced by the inductor and the ferromagnetic needles create a number of effects, which together with mechanical and thermal effects change the physicochemical properties of the substance. The effects in the operating chamber of the AVS are highly energetic.
Today, the AVS are successfully used in many process lines, improving productivity by tens and thousands of times.
Possibility of AVS application to improve industrial wastewater treatment
The analysis of the intensifying factors which take place in the AVS shows the processes that influence industrial wastewater treatment:
- Intensive dispersion and mixing of the components;
- High local pressure;
- Acoustic effects;
- Electromagnetic effects, etc.
Kinetic intensification of the processes instead of diffusion completely overcomes the disadvantages of the existing methods of wastewater treatment.
Until recently, the performance of one unit was relatively low to provide, for example, a large company or a city with wastewater treatment. However, the company has created units with 100-1000 m3/h capacity. Therefore, there are no performance issues today.
We tested the AVS (based on the AVS-100 commercial sample) for purification of chromium-containing acid-alkali wastewater with different compositions of chromium, iron, nickel, zinc, copper, cadmium and other contaminants.
The results of the tests were as follows. The AVS achieved a high degree of decontamination (below allowable limits) of chromium and heavy metals (Fe, Ni, Zn, Cu, Cd). Reagent consumption was 90-100% and the operation of treatment plants was greatly simplified. The conventional methods use 115-120% Ca (OH) 2, Na2CO3 and 150-175% of the reduction agent (FeSO4).
Using the AVS system for simultaneous cleaning of chromium and acid-alkaline wastewater ensures water quality standards marginally below allowable concentrationы, reduce reagent consumption by 1.5-2 times, half the power consumption, and reduce water treatment plant footprint by 10-15%.
AVS can be retrofitted into the existing line easily and cheaply and can be efficiently used in any industrial wastewater treatment plants.