What is Ultrasound
Ultrasonic waves refer to ultra-high frequency sound waves with frequencies exceeding the normal range of human hearing. It is a mechanical wave with an extremely short wavelength, which is generally shorter than 2 cm in the air. It must rely on a medium to propagate and cannot exist in a vacuum (such as space). It propagates farther in water than in air, but because of its short wavelength, it is very easy to lose and scatter in the air, and is not as far-reaching as audible sound and infrasound.
Surface waves
Ultrasonic applications in the metal industry
Ultrasonics can predict the service life of industrial parts. The importance of predicting the service life of parts of industrial equipment cannot be overstated. This prediction process is tiring, complex and difficult. Research reports in the literature show that micro-damage gradually occurs in different metal parts of fatigue machines, followed by a gradual increase in fatigue-induced cracks, leading to the catastrophic growth of the main damaging macro-crack. The existence of this long preparatory stage suggests that suitable measures can help prevent changes in the next stage of the process.
Ultrasonic technology in the food industry
In high-energy ultrasound applications, more than 1 W/cm² intensity and 100 kHz frequency are used. High-energy ultrasound removes gases from liquid foods, crystallization, induces redox reactions, extraction and purification of proteins and enzymes, for the initiation of nucleation as well as enzyme inactivation. Studies comparing the requirements for the inactivation of plant microorganisms show that thermal treatment of liquid foods can also be achieved at lower temperatures with the help of ultrasound. For ultrasonic treatment, additional energy is required, which leads to an increase in the overall energy demand of the integrated process. But in areas where cheap electricity supply or alternative energy sources are not available, ultrasound-assisted treatment is an interesting alternative to currently popular thermal treatments. Among the treatments, gases can be removed from liquid products relatively easily using ultrasound.
Application of Ultrasound in Agricultural Industry
In the Mediterranean region, wastewater from olive mills pollutes the environment. Moreover, olive mills are used to irrigate fields and farms, and wastewater discharges waste into waterbeds, which seriously pollutes water sources because it contains stubborn biological properties. Therefore, there is a need to use ultrasound to remove pollutants from agricultural wastewater. The primary treatment of this wastewater includes photon activation of catalysts by light irradiation, while the secondary treatment includes ultrasound-induced power ultrasonic cavitation.
Application of Ultrasound in Leather Industry
The pollutants discharged from the leather industry contain different chemicals that are used during leather processing and ultimately produce solid waste. Enzyme treatment can be a beneficial alternative to chemical treatment in the leather industry. It is also very helpful in terms of environmental safety. In addition, enzyme treatment is low in cost and can be performed at low temperatures without the use of additional chemicals. The simultaneous application of ultrasound and enzyme treatment helps to improve the enzymatic hydrolysis of tannery waste and leads to an increase in digestibility and the yield of chips and shavings.
Hides are mainly composed of insoluble fibrous proteins called collagen, which may be degraded under the action of proteases. By applying ultrasound, the fiber network of the hide loses its function and its rate decreases. The fiber network of the hide disappears and the diffusion rate of the protease in the skin pores increases. In a research report, a neutral protease (Bacillus subtilis, Bacillus subtilis) and an alkaline protease (Bacillus licheniformis) were applied. The results showed that the protease (alkaline) of Bacillus licheniformis was almost unaffected by ultrasound. Therefore, it was selected as a raw material for the degradation of solid waste.
The utility of power ultrasound has now increased significantly, especially in industrial applications, and scientists have conducted in-depth research on this. It is known that the energy input through ultrasound can significantly increase the yield and product quality and can facilitate the recycling and purification processes of products in many different industries. Ultrasonic technology is a clean and efficient technology that is widely used in food processing, freezing and preservation. It can also be used to predict the service life of industrial processes and machine parts, as well as the treatment of waste generated by different industries such as textiles, agriculture, tanneries, etc.
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