RESEARCH ON THE INFLUENCE OF TEMPERATURE ON CAVITATIONAL TREATMENT OF WASTEWATER FROM CHEMICAL AND FOOD INDUSTRIES

The results of an experimental study of the influence of temperature and nature of the bubbled gas on the process of cavitation treatment of wastewater from chemical and food industries are presented. The main attention is focused on studying the patterns of destruction of organic compounds in wastewater from alcohol, pharmaceutical and paint and varnish plants under the influence of ultrasonic cavitation. To activate the process, gases of different nature were bubbled into the reaction medium: oxygen, nitrogen and air, which served as additional cavitation centers. The processes of cavitation destruction of organic substances were analyzed by the chemical oxygen demand (COD), which was determined before and after treatment. It was established that the highest cleaning efficiency is achieved when combining ultrasound with nitrogen bubbling in alcohol wastewater and oxygen in paint and varnish and pharmaceutical wastewater. It is shown that gas diffusion into the cavitation cavity depends on the solubility coefficient, which directly affects the course of the cavitation process. The effect of temperature in the range of 298–333 K on the efficiency of destruction of organic substances was studied. It was found that with increasing temperature, the rate of sonochemical reaction initially increases, but at temperatures above 324 K, cavitation processes stop, and the destruction of organic compounds occurs exclusively due to thermal action. The optimal temperature regime for the cavitation cleaning process of paint and varnish and pharmaceutical industries in an oxygen atmosphere was found to be the interval 322–324 K, in which the effective rate constants of destruction of organic substances were (3.8–4.0)∙10⁻⁴ s⁻¹, and for alcohol industries – 318K in a nitrogen atmosphere. The results obtained are important for the development of effective technologies for wastewater treatment of industrial enterprises, which allow reducing anthropogenic load on the environment and increasing the ecological safety of production. These results allow justifying wastewater treatment regimes and improving technological processes for different types of production. The feasibility of choosing the type of gas and temperature regime for each type of wastewater in order to increase the efficiency of their treatment by ultrasonic cavitation is shown.