The application of ultrasonic technology in water treatment​

The application of ultrasonic technology in water treatment

Ultrasound is a kind of high frequency mechanical wave which can effectively improve mass transfer and heat transfer, change physical-chemistry phase equilibrium, fasten chemistry reaction rate. Ultrasonic technology is simple, efficient, pollution-free or less polluting.It is a new water treatment technology developed in recent years. It has significant advantages in treating difficult biodegradable organic pollutants.

Ultrasonic degradation is the ultrasonic degradation of molecule.What are the main factors that affect ultrasonic degradation.Ultrasonic frequency, ultrasonic power intensity, dissolved gas, PH , temperature, reactor structure.

What is the key to improve the reactor ? The key is to improve sound intensity and energy utilization effect .At present, there are mainly the following types of reactors .Ultrasonic cleaning tank reactor;Sound amplitude transformer bar immersion sonochemical reactor;Parallel board near-field sound processor (NAP, developed by Lewis, USA).The NAP reactor uses the dual ultrasonic frequencies.It reduces the generation of standing waves and increases the number of cavitation bubbles.

If the frequencies are different, the effects of ultrasound will be different . The ultrasonic field produced by transducers in the MHz range can effectively transfer mass.Ultrasonic fields generated by transducers in the kHz range can increase the mechanical and power cavitation effects of ultrasonic waves. If the reactor can make good use of the synergy between two or more different frequencies of ultrasound,it will increase the area of ultrasonic radiation in the reactor.Of course, it can also increases the efficiency of the reactor.

The application of ultrasonic technology in water treatment

The wastewater treatment

Ultrasonic technology can be used in all kinds of refractory wastewater . At present, it has been used in the study of monocyclic aromatic compounds, polycyclic aromatic hydrocarbons, phenols, chlorinated hydrocarbons, chlorinated hydrocarbons, organic acids, dyes, alcohols, ketones and other substances . And it has achieved good results .

The sludge treatment 

Activated sludge is a suspended agglomerate of particles . It contains different microbial communities embedded in a macromolecule network . Ultrasonic can promote coagulation . When the ultrasonic waves pass through a fluid medium with tiny flocs, the particles begin to vibrate with the medium . However, the particles of different sizes have different vibration speeds, particles will collide and bond with each other, increasing both volume and mass . When the particle is too large to vibrate with ultrasonic, it can only do random motion. Then going to collide and bond, get larger, and eventually precipitate . The sludge can be decomposed by high intensity ultrasonic waves .

Ultrasonic processing is an extremely complex process . Due to the different degradation mechanism of pollutants with different physical and chemical properties, the ultrasonic degradation effect is also different.