Tube Air Diffusers (Aerators) for Aeration Tanks
Air Diffusers for Aeration tanks
Esmil Tube Air Diffusers are designed to adapt to various size and design requirements for aeration tanks in municipal and industrial wastewater treatment applications.
The main purpose of the Air Diffuser is to deliver the necessary amount of oxygen to an aeration tank with the lowest possible energy consumption and provide the best possible air diffusion and sludge mixture during the treatment process.
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Esmil air diffuser consist of two pipes inserted one into another with the air gap between them.
The construction of the Esmil Tube Air Diffuser consists of two pipes inserted one into another with an air gap between them. The external air dispersing layer of the pipe is made of low-density polyethylene (LDPE) and is the “fibrous-porous” portion of the diffuser. During the pneumatic extrusion manufacturing process, melted polyethylene fibers are aerodynamically formed and applied to the mold of the outer pipe. The inner perforated pipe is made of durable PVC. The gap between the two pipes is divided with cross ring inserts which provide uniform air supply throughout the diffuser’s line.
The supply air enters the space between the outer and inner pipe through numerous openings in the inner PVC pipe. Fine bubbles of air are dispersed into the aeration tank through the “fibrous-porous” layer of the outer pipe. This process provides for consistent and uniform air distribution in the treated liquid and provides a very high aeration efficiency with minimal energy cost.
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Components and materials
Description Material 1. Perforated pipe PVC 2. Fibro-porous dispenser LDPE 3. Cross ring insertion PE Dimensions
Type Total leght (A), [in] Disperser leght (B), [in] External diameter (C), [in] Dispencer wall thickness, [in] Total weight, [lbs] APVK-1 41.0 37.0 4.72 0.39 8.8 APVK-2 80.5 76.5 4.72 0.39 17.6 -
- Low air headloss
Esmil Tube Air Diffusers head losses are 2-2.5 times lower than conventional membrane diffusers. This significantly reduces energy consumption and, therefore, the operational costs of aeration projects. - Effective Oxygen Transfer and Sludge Mixing
The air bubbles generated by the Esmil Tube Air Diffusers are in the range of .08-.12 inches in diameter which is ideal for sludge oxygen transfer and mixing. Air flow capacity of the Diffusers is some 2 times higher than in conventional air diffusers, which allows to decrease significantly capital costs of aeration projects with Esmil Air Diffusers - No need of air feed pipes on the aeration tank bottom
The air gap design between the two pipes provides the diffuser with equal air distribution throughout the entire aeration tank. Aeration line length can be up to 140 ft with just one air feed point. - The Esmil Tube Air Diffusers aeration system is simple to install and comes with threaded pipe in segment lengths up to 6’8” which are quick and easy to assemble on the tank floor.
In the result the capital costs of aeration projects are significantly lower comparing to conventional membrane diffusers systems. - High Reliability
Because of this durable construction, there is minimal risk of damage to the diffuser caused by pressure impact and other mechanical damage. The outer low-density polyethylene dispersion layer does not require routine flushing and cleaning maintenance. Esmil Tube Air Diffusers systems provide consistent, reliable and stable performance during their long installation life (8-12 years).
- Low air headloss
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Technical characteristics
Airflow rate, [sft3/h/ft] 100–250 Aerator diameter, [in] 4.72 Aerator length, [in] 41.0 or 80.5 Bubble diameter, [in] 0.04–0.12 Inlet air temperature, [°F] up to 212 °F 
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One of the most energy consuming processes in a sewage treatment plant is aeration. As an alternative to traditional aeration systems, modern solutions are constantly being sought to minimize energy consumption and maintenance while providing highly effective aeration results.
Oxidation of wastewater can take place in different ways and wastewater treatment systems commonly use compressed air to accomplish this aeration and mixing. Aeration operates on the principle of dispersing bubbles of air under a liquid surface through porous dispersion material using aeration blowers. Depending on the diameter of the air bubble produced, coarse and fine bubble systems are recommended. The most commonly used (and the most effective) is fine bubble aeration which produces bubbles less than .12” in diameter. Smaller bubbles make their way to the surface more gradually and this slow release in the wastewater increases oxygen transfer. Moreover, fine bubbles with the same amount of air flow will have a larger transfer surface area than coarse bubbles.
There are currently many types of air diffusers available on the market. They can vary in shape (disc, tube, plate) as well as material (ceramics, PVC, EPDM, polyurethane, silicone). Tubular diffusers are the most popular today. When compared to other types of diffusers, they have a larger active surface area and allow the aeration to spread to the bottom areas of the tank in addition to the wastewater above the air source. This helps to prevent the formation of “dead zones” in the aeration tank.
New to the North American market are air tube diffusers made of polyethylene. These new “Small Bubble” diffusers are manufactured by the Esmil Industrial Group and have been used worldwide for more than twenty years. The outer fibrous-porous dispersing layer of the tube has 35-50% porosity and is made of low density polyethylene LDPE by pneumatic extrusion. Fabrication is by applying aerodynamically shaped fibers of melted polyethylene on a molding machine. Inside the aerator tube is a perforated PVC or highdensity polyethylene (HDPE) pipe. Between the outer dispersion element and the inner pipe is an air space with ring inserts mounted transversally. These ring inserts provide uniform air distribution throughout the aeration pipe.
Effective oxygen transfer with low head loss is one of the most important requirements for aeration systems. Research results by independent Institutes confirm that Esmil polyethylene tube diffusers have very high SOTE (standard oxygen transfer efficiency) indicators and low head loss compared to the diffusers of other manufacturers.
In most applications, Esmil aerators do not require maintenance while other aeration systems need service and frequent cleaning. It is worth noting that with the Esmil diffusers, it is possible to adjust the structure during assembly in such a way that the air is delivered evenly over the entire length of the diffuser tubes with the least amount of pressure losses (head loss). The air gap design between the pipes helps to ensure a maximum transfer working surface.
Compared to the construction of elastic membrane diffusers, Esmil tube diffusers made of LDPE are strong and stiff. This provides resistance to hydro-impacts and other mechanical damage. In addition, polyethylene does not change its properties over time while the membrane diffusers can undergo aging. This wear can result in the cracking and enlargement of the aeration openings and consequently the generation of larger air bubbles with a decrease in oxygenation efficiency.
What sets apart the Esmil tube air diffusers from other diffusers on the market is primarily the efficient transfer of oxygen combined with the use of low density polyethylene which is durable and functions well in tough environments. The unique design allowing for flexible modifications to suit each plant aeration tank and an ease of installation.
Replacing the membrane diffusers with an Esmil polyethylene aeration system reduces energy costs, maintains the required oxygen levels in the aeration tank and reduces the risk of aerator damage and operation costs.
