Microbubbles are widely used in various fields including fishing industry, agriculture, chemical industry and light industry in the world and brisk researches have been conducted to improve their performance.
There are several methods for generating microbubbles, depending on their principles and applications. They are largely divided into two modes―one is liquid flow accompanying and the other is non-liquid flow accompanying. Liquid flow accompanying includes swirl jet, mechanical high-speed cutting, pressurized melting and Venturi, and non-liquid flow accompanying includes fluid oscillation, ultrasonic, electrolytic, etc.
Compared with the methods described above, the pressurized-dissolved microbubble generator has the advantage of high bubble generation and relatively small and uniform size distribution.
Han Il Song, a researcher at the Nano Science and Technology Institute, has manufactured a large microbubble generator that can be widely applied in various fields including wastewater treatment, sewage treatment and fishery by generating relatively small and uniform microbubbles at high density by means of a pressurized solution method.
The pressurized-dissolved microbubble generator used for pulp mill effluent treatment has the advantage of low cost and operating cost but very high efficiency of microbubble generation.
The new-type microbubble generator consists of a mixing tank, a circulating water pump, a Venturi air inlet, a pressurized tank, and a swirl jet nozzle.
The Venturi air intake unit, which is located at the inlet of the circulating water pump, is equipped with a flow control valve to provide a flow rate of 45-50L/min of air to be sucked.
The application of a pressurized-dissolved microbubble generator to pulp effluent treatment resulted in pulp recovery of more than 92% and the residual pulp content in the wastewater discharged after treatment of less than 0.002%.
At present, a large pressurized-dissolved microbubble generator has been introduced into pulp wastewater treatment to recover residual pulp in wastewater with higher efficiency than 92%, thus contributing greatly to recycling pulp and protecting the ecological environment.
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