Aeration refers to the process of forcibly transferring oxygen in the air to the liquid, and its purpose is to obtain sufficient dissolved oxygen. In addition, there is also the purpose of preventing the sinking of the suspension in the stirred tank and strengthening the contact of the organic matter in the tank with microorganisms and dissolved oxygen. So as to ensure that the microorganisms in the pond oxidize and decompose the organic matter in the sewage under the condition of sufficient dissolved oxygen.

When using biochemical methods to treat sewage, aeration is usually the most expensive link, and the aeration equipment has been upgraded. Today we will talk about the advantages and disadvantages of various equipment.

Exposure, bào is the customary pronunciation used in engineering technology, originally pronounced pù, idiom: One exposure to ten cold, from "Mencius·Gaozishang": "Although there are things that are easy to grow in the world, they will be violent in one day ( "Storm" is the same as "exposure"), for ten days of cold, no one can survive. "Meaning: Although it is the easiest plant to grow, it is impossible to grow even if it is exposed to the sun for one day and frozen for ten days. "It is a metaphor for less time being diligent, more time being slack, no perseverance. English: aeration. The aerator should also pay more attention to its long-term performance rather than temporary working conditions.

Currently widely used aeration equipment types

There are: micro-hole (disc and tube), jet, swirl (single nozzle and double nozzle), diffuse flow, surface exposure.

The principle of the microporous aerator is to squeeze the air and escape from the micropores of the rubber diaphragm to form tiny bubbles and diffuse into the water. The oxygen utilization rate can reach more than 30% in 6 meters of clean water. But it is easy to be blocked and damaged, and its life is short. After the microporous aerator is used for a certain number of years, the wind pressure and energy consumption will increase due to fouling and blockage. After it is damaged, the oxygen utilization rate will drop sharply, and it needs to be replaced in time.

The principle of the jet aerator is that the circulating water entrains air, and after mixing in the cavity, it shoots out along the direction of the nozzle. It is an aeration process that was applied to industrial wastewater earlier, and has the advantages of large service area and not easy to block. The oxygen utilization rate in 6 meters of clean water is about 15%-21%. Because it needs to be equipped with an additional circulating water pump, it consumes a lot of energy. In calcium-containing wastewater, nozzles are prone to fouling and clogging.

The swirling flow aerator is based on the principle of high-speed jetting of airflow, which is mixed with sewage in the cylinder and cut by the mushroom head to form tiny bubbles and at the same time form a negative pressure to entrain the sludge at the bottom of the pool. Swirl is a new type of aeration process that has emerged in recent years. The oxygen utilization rate of 6 meters of clean water is about 18%-25%. Because it can be installed without stopping production, it is not easy to be blocked, the life span is more than ten years, and the energy consumption is moderate. In recent years, it has begun to be widely used in the field of industrial wastewater.

Diffuse aeration, inverted umbrella shape, oxygen utilization rate is about 8%-12%. The principle is similar to the swirling flow. The airflow hits the saw teeth for cutting, but because the airflow is dispersed, the impact force is weak, the cutting force is weak, the air bubbles are large, the oxygen utilization rate is low, the energy consumption is high, and there is no stirring effect, and the use is less and less.

Surface exposure, due to the centrifugal throwing and lifting effect of the impeller, the water is continuously thrown to the water surface in the form of a water curtain, thereby bringing in air; suitable for shallow oxidation ditch pond type, the oxygenation effect is not good at the depth of the water, and As the land is tight and the water depth increases, the use of surface exposure in new projects is becoming less and less.

Compare three common aeration forms in a list

Through the above comparison, the advantages and disadvantages and applicable scenarios of the three aeration processes are clear at a glance. The non-stop production installation of the cyclone is a big advantage, which not only avoids the loss of production shutdown, but also avoids the cost of dredging and the risk of safety accidents caused by replacement. The service life is more than ten years, maintenance-free, and the labor cost of the sewage station can be greatly reduced.

In terms of energy consumption. Although there is a big difference between the oxygen utilization rate of the swirling flow and the microporous oxygen, the utilization rate of the microporous oxygen is constantly attenuated, while the swirling flow is stable and unchanged. The degree of decline) is relatively small, and the long-term energy consumption of the two is basically the same. Through actual application case testing, the energy consumption of the imported microporous new product in the first year is about 15% lower than that of the dual-nozzle swirl, and it has remained flat since the second year. After the micropores are fouled, blocked, and damaged, the oxygen utilization rate will drop sharply if they are not replaced in time. Therefore, in some transformation cases, the phenomenon that swirling is more energy-saving than micropores.

The wind resistance of the swirling flow is low, and the wind pressure is stable without change, which is conducive to the smooth operation of the fan, especially when the fan is maglev or air floating. For example, a sewage plant in a park has a water depth of 7 meters. After using the micropores for 4 years, the wind pressure has risen to 90kpa. The energy consumption has risen severely, but the air output has dropped severely. The pressure can be stably maintained within 80kpa for a long time.

Compared with jet flow, the required fan air volume is not much different between swirl flow and jet flow. Generally, the energy consumption of jet pump is the energy consumption saved by swirl flow compared with jet flow.

With the shortage of land, it is often necessary to increase the water depth and sludge concentration in order to increase the sewage treatment capacity without expansion. The requirements for non-clogging of aerators and stable wind resistance are becoming higher. The use of streams will increasingly become a trend. The following focuses on swirling aeration.

Oxygen utilization rate of cyclone aerator

Swirl aeration technology is introduced from Japan. At present, the swirl products are imported with original packaging, and some are produced and developed in China after purchasing Japanese patents. Most of them are imitations, and the quality is uneven.

Different brands of cyclone aerators have different oxygen utilization rates. Comparing with the oxygen utilization rate of 18% and 22%, it seems that the difference is only 4%. The actual difference in air demand is close to 20%, which means that the difference in energy consumption is close to 20% (the correct calculation formula should be 18/22=80% ). When the air volume of the fan is at a critical value, this difference will also directly lead to whether the dissolved oxygen meets the standard. When purchasing a cyclone aerator, the manufacturer can provide a test report from the National Water Supply and Drainage Equipment Testing Center to prove the oxygen utilization rate of the product.

The oxygen utilization rate of the dual-nozzle swirl aerator is usually about 15% higher than that of the single-nozzle. The difference in oxygen utilization of single and double nozzle swirl aerators is mainly due to the difference in the number of times the bubbles are cut and the time they stay in the water. Different brands of single-nozzle swirl aerators have different oxygen utilization rates. The main reason for the differences in oxygen utilization is whether the nozzles are reduced in diameter and whether the cutting heads are arranged in strict accordance with fluid mechanics.

Material of swirl aerator

The common materials of cyclone aerators are: ABS, PA66, polymer composite materials. In terms of performance, PA66 is better than ABS, and pure PA66 is better than "PA66 + glass fiber". In order to facilitate injection molding, some manufacturers add glass fiber to PA66, so that although the hardness increases, it will increase the surface friction coefficient and cause easy fouling. Polymer materials have a certain threshold for research and development, and the price of raw materials is relatively expensive, but they have the performance characteristics of self-lubricating, anti-scaling, abrasion resistance, impact resistance, acid washing resistance, and resistance to water absorption that are unmatched by other materials. In recent years, Shanghai Taiyu is the leader Some manufacturers have begun to apply polymer materials to cyclonic aerators.

Precautions for the selection of aerators for high-concentration wastewater and calcium-containing wastewater

For high-concentration wastewater and calcium-containing wastewater, if a single-nozzle cyclone aerator is used, fouling and clogging will occur after a long time, mainly because the cross-piece structure and material in the single-nozzle cylinder are easy to foul. This kind of waste water is suitable for double-nozzle swirl aerators made of polymer materials. One is that the polymer materials have self-lubricating and anti-scaling properties, and the other is that the double-nozzle swirl aerator has no cross-piece obstruction inside and has a large diameter. Not easy to block. Third, the cone of the double-nozzle swirling flow forms a Venturi effect, which has a stronger suction force for sludge and can prevent sludge deposition.

Precautions for installation of cyclone aerator

Improper installation method will seriously affect the service life of the cyclone. For aerators with side air intake, two straight rods must be used to fix the body and the vertical pipe to ensure that the air inlet pipe will not be individually stressed. It is best to choose an aerator whose air inlet pipe is formed at one time and thickened to prevent loose screws or breakage of the air inlet pipe under long-term high-frequency vibration. The aerator and pipeline are usually welded outside the pool in advance. During manual handling or lifting by crane, be careful not to let one end of the aerator touch the ground. For deeper pools, the vertical pipe must be thicker to prevent excessive disturbance. The connection between the vertical pipe and the horizontal pipe can be fixed with diagonal bracing to prevent breakage.

Recommended manufacturer of cyclone aerator: Shanghai Taiyu Energy Saving and Environmental Protection Technology Co., Ltd. Demonstration of the swirling principle and installation scenes can be viewed by clicking the video link below: Shanghai Taiyu swirling aerator promotional video.

If you need to design a cyclone aeration program, you can provide the following information and send it to WeChat or email. Data template (can be copied and pasted into the mobile phone memo or word to fill in one by one): company name, contact person, phone number. Industry. Project attributes: new construction/renovation. The original aerator type. Aeration tank water volume: original design daily treatment volume, current average water volume, current design water volume. Aeration tank water quality: COD index of influent and effluent, ammonia nitrogen index of in and out water, sludge concentration, chloric calcium and magnesium. Aeration tank conditions: length, width and height, effective water depth. It is best to attach a pool diagram (hand-drawn or CAD), indicating the size, direction of water flow, direction and diameter of the main air duct. With or without filler, with or without cover. For the aeration tank to be renovated, the current actual supply air volume and the original design air volume. Fan types and parameters: air volume, air pressure, power, several uses and several preparations.