Classification and characteristics of aeration blowers in sewage treatment!

Aeration is an important process link in wastewater biological treatment system, and it is also the process link with the highest operation cost in wastewater biological treatment system. The power consumption of aeration and oxygenation generally accounts for 60% - 70% of the total power consumption. At present, the problems of low efficiency, high cost and energy consumption are common in aerobic aeration blowers. In recent years, there are many kinds of new aeration blowers which are widely used in the field of sewage treatment at home and abroad. We collected and integrated the current information about aeration blowers, and sorted out their types and functions, hoping to further understand aeration blowers and play a role in practice.

Aeration is an important process in wastewater biological treatment system. Its main function is to aerate the reaction tank, ensure the dissolved oxygen needed for aerobic metabolism of microorganisms, and maintain the mixing and material transfer in the reactor, so as to provide the necessary conditions for microbial culture.

1、 Aeration principle

Aeration is a means to make the air strongly contact with water. Its purpose is to dissolve the oxygen in the air into water, or to expel the unnecessary gases and volatile substances into the air. Aeration blower is widely used in wastewater treatment for this purpose.

2、 Aeration type and function of aeration equipment

All aeration equipment should meet the following three functions:

First, to produce and maintain effective gas water contact, and to maintain a certain dissolved oxygen concentration in the water under the condition of continuous consumption of oxygen by biological oxidation;

Secondly, sufficient mixing and water circulation are generated in the aeration zone;

Third, maintain the liquid at a sufficient speed to suspend the biosolids in the water.

There are two types of aeration, one is blast aeration, the other is mechanical aeration.

The following focuses on: blast aeration equipment

Blast aeration is an aeration method in which air bubbles are introduced into water by an aerator (diffusion plate or diffusion tube).

The blast aeration system consists of blower, aerator and a series of connected pipelines. The blower delivers the air to the aerator installed at the bottom of the tank through a series of pipes. Through the aerator, the air forms bubbles of different sizes. Bubbles are formed at the outlet of the aerator, and their size depends on the form of the aerator. After rising and circulating with the water, the bubbles finally break at the liquid level, which produces the role of oxygen transfer to the sewage.

The blowers of the blast system are mainly divided into:

Roots blower, multistage centrifugal blower, single-stage high-speed centrifugal blower, air / magnetic suspension centrifugal blower and screw blower, etc. The characteristics of various blowers are as follows.

Roots blower

    This kind of blower is cheap, simple in structure, mature in product and stable in performance. Its characteristic is that in the range of the highest design pressure, when the pipe network resistance changes, the air flow changes very little. At high aeration pressure, roots blower has low efficiency, high energy consumption and high noise. Now it has been phased out as an aeration blower in sewage treatment plant.

Multistage centrifugal blower

  Centrifugal blower is a motor driven blower impeller rotation, so that the gas between the blades is thrown out under the action of centrifugal force, and the external gas is inhaled through the negative pressure formed in the middle of the impeller, so as to achieve the purpose of continuous blowing. The multistage centrifugal blower adopts the way of connecting multistage impeller in series to meet the pressure increasing requirements. The flow of multistage centrifugal blower changes greatly when the wind pressure changes. Compared with Roots blower, the efficiency of multistage centrifugal blower is higher, and the requirements for the use environment are not high. It is widely used as the aeration blower in the sewage treatment plant.

Screw blower

  Belongs to the positive displacement blower, is based on the principle of screw air compressor improved from a blower, is in recent years with the technical progress and appear. Its characteristic is that the flow changes little with the change of outlet pressure. It is suitable to be used under the condition of high aeration pressure.

Single stage high speed centrifugal blower

  It means that the wind pressure requirement of sewage treatment process can be achieved by increasing the blower speed and single-stage centrifugation. The single-stage high-speed centrifugal blower is accelerated by gears, and the impeller speed is high, which can reach more than 20000 R / min, with large air volume, high efficiency and high requirements for manufacturing level. This kind of blower technology causes low market share.

Air / magnetic suspension turbo blower

    It is also a high-speed turbo blower, which cancels the traditional gear transmission and mechanical bearing, and makes the rotating shaft form a suspended state through the action of magnetic or air, with small friction resistance and high efficiency. The air volume regulation is realized by adjusting the impeller speed by frequency conversion, which is convenient to use, low cost and little daily maintenance. However, the air / magnetic bearing has high requirements for the use environment, and is generally used in large state-owned sewage treatment plants.

Sewage treatment is an important part of environmental engineering, and aeration is the key equipment in water treatment. It is an urgent and important task to study new aeration equipment and improve environment to improve aeration capacity and reduce energy consumption of aeration blower. Aeration equipment in wastewater treatment is gradually developed with the in-depth study and wide application of wastewater treatment technology. In recent years, there are many kinds of new aeration equipment which are widely used in the field of sewage treatment at home and abroad, and after continuous updating and development, its structure and performance are changing with each passing day. We briefly introduce the characteristics of commonly used aeration equipment based on the existing data, and welcome to put forward opinions and exchange.