Aerators and Mixers
WasteWater Aeration and Tank Mixing

Efficient aerators and mixers - jet ejectors

Discover the benefits of ejectors from us at Erivac – smart aerators and mixers without moving parts that provide maintenance-free and reliable operation. Fine bubbles provide high oxygen efficiency, while the powerful jet flow prevents deposits and keeps the bottom of the tank clean. The design is non-blocking, with no sealing problems, and makes it easy to control the oxygen supply. The systems are adapted to your pools and needs.

For cisterns and tanks where the medium does not need oxygenation, jet ejectors serve as highly energy-efficient mixers at, for example, cistern and tank depots; cisterns, tanks and basins in the process industry and sewage treatment, etc.

Want to know more? Contact us and we will help you!

Advantages of Körting Jet Aerators – Ejectors

maintenance-free- no moving elements
high oxygen efficiency- Fine bubbles create large contact surfaces between air and water and high turbulence renews these contact surfaces.
no deposits- The intensive jet flow directed toward the tank floor prevents deposits of biomass.
straightforward control of oxygen supply
non-clogging construction – The nozzle diameter defines the narrowest flow cross-section.
no sealing problems- When the plant is inactive, water can enter the air pipeline without negative effects and when re-started, the ejector’s entraining effect expels any liquid in the pipe.
design acc. to requirements- Various sizes can be designed and adapted to requirements.

Fields of application

Aeration and mixing of industrial or municipal wastewater
Air insertion, oxygenization, of industrial processes or fermentation
Activated sludge process wastewater aeration and mixing
Sequencial Batch Reactor (SBR), aeration and mixing
Membrane BioReactor (MBR) with high sludge content aeration and mixing
Moving Bed Biofilm Reactor (MBBR) aeration and mixing

Advantages of Körting mixing nozzles – eductors

complete mixing of the tank content
low investment costs
wear-resistant, long service life – no moving parts inside the tank
no sealing problems – no shaft ducts
no dead zones
no maintenance in the tank
low energy input

Mixing nozzles, eductors, are customized and designed for every application

Fields of application

mixing storage tanks, fuel oil tanks, wastewater treatment tanks, neutralization tanks, reactors, food storage tanks, stormwater tanks and others
complete homogenization of different liquids
preventing settlements and sedimentation
avoiding the formation of different temperature layers
as discharge support
for waste water treatment applications (ejectors in SBR-Plants operated with compressed air)

Jet Aeration - Ideal for plants with highly polluted waste water

In its construction form the ejector, jet aerator, for the aeration process corresponds to that of a jet ejector. Because organically polluted wastewater requires a high amount of oxygen and also because of the increasing height of modern biological wastewater cleaning plants it is energetically more efficient to pre-compress the air mechanically to the hydrostatic pressure prevailing at the installation point of the ejector, jet aerator, and to supply it so to the suction connection.

This waiving of an appreciable pressure in the ejector, jet aerator, reduces the necessary motive pressure. At the same time, more favourable mixing ratios (suction flow: motive flow) are achieved. Motive nozzles of Körting ejectors, jet aerators, are equipped with a non-clogging spiral. So the motive jet disperses the air already at a low motive pressure in a myriad of fine bubbles which are then mixed vigorously together with the motive flow in the mixing zone.

This air/water mixture is injected into the aeration tank with a high turbulence. In this way, the ejector, jet aerator, guarantees optimum oxygen supply and a total intermixing of the tank contents. Even with a high biomass concentration in the wastewater it is still possible to attain flow velocities that prevent deposits on the tank floor.

Multi-path ejectors, jet aerators, inside aeration tanks

Installation inside aeration tanks

Once the tank geometry, water depth and oxygen requirements have been determined then number, execution form and arrangement of the multi-path ejectors, jet aerators, can be adapted to the case in question. Their mounting can be effected quite simply by two flanges in the pipelines for motive flow and compressed air. Installation of compact units on the tank floor guarantees comprehensive jet aeration and complete intermixture of the waste water.

Design

The relatively short individual and detachable ejectors, jet aerators, are connected to a manifold casing and supplied with motive flow from below and with compressed air from above. The jet flow is inclined towards the floor and the angle of exit is adapted individually to the installation conditions. As material we use polypropylene which has excellent resistance to chemical attacks. For particularly demanding application conditions the motive nozzles as well as also the mixing zones can be made of chrome-nickel steel. When there are high calcium carbonate concentrations in the aeration tank the choice of materials must always be adapted to the operating conditions.

Oxygen efficiency

As oxygen transfer not only depends on bubble size (contact surface between gas and water) but to the same measure on the renewal of the gas bubble contact surfaces, ejectors – with their permanent circulation of the waste water – can so achieve a far larger oxygen efficiency than other aerators. With their inclined flow direction towards the floor Körting ejectors, jet aerators, utilise the respective tank depth completely as entrance depth. Extensive oxygen supply tests in pure water (ATV M-209) acc. to the oxygen adsorption method form the data basis for designing Körting ejectors, jet aerators. All measurements were executed on full-scale plants and confirmed in numerous inspection tests..

Control range and oxygen yield

Regulation of the oxygen supply is achieved solely by altering the air volume flow. A reduced air supply lowers the inlet pressure to the ejector thereby additionally reducing the power intake of the roots blower/compressor. At the same time the specific oxygen efficiency is increased. The result is a nearly constant high oxygen yield over the whole control range of the oxygen transfer system with its maximum value in partial load operation near the design point. Ejectors, jet aerators, are designed – depending on the rheological properties of the activated sludge (temperature, dry solids contents) – for a suitable air/water ratio. The improved performance of the oxygen transfer system by simply increasing the air supply as well as its optimal oxygen efficiency in partial load operation are so guaranteed at all times.

Installation from outside through the tank wall

The ejector, jet aerators, shown here is made of stainless steel and is mounted “through-the-wall“. Its connections for motive flow and compressed air are located outside the aeration tank. These comparatively large units are equipped with a second downstream mixing zone in which additional liquid is sucked in, thus intensifying the intermixing action in the tank.

If required, the ejector, jet aerator, can be equipped with a shut-off device downstream of the motive nozzle so that the motive nozzle can be checked at any time without having to empty the tank. This equipment option allows for a permanent application of the oxygen transfer system, even with extreme concentrations of calcium carbonate in the wastewater. Although the relatively large ejectors, jet aerators, are inferior regarding oxygen efficiency to our multi-path ejectors with finer air bubbles, their 100% availability is often the decisive criterion for our customers. It is therefore not remarkable that many plants have been realised in the paper industry – sometimes also as a retrofitting action to replace inadequate installations.

Oxygen efficiency

At the usual entrance depths of 5…8 m it is possible to achieve an oxygen efficiency OC₂₀in clean water of 11 g O₂/Nm³• m. In partial load operation – at a reduced air amount – the oxygen efficiency can be boosted above this value as far as 14 g O₂/Nm³• m. Depending on entrance depth and oxygen requirements approx. 400-500 Nm³/h of compressed air can be injected into the tank by one single ejector, jet aerator.

Ejectors in SBR plants

Ejectors, jet aerators, are exceptionally suited for the aeration and intermixing of so-called „SBR“ plants (Sequenced Batch Reactor). These aeration plants (with retaining operation) in which, amongst other things, the biological processes of nitrification and denitrification take place consecutively in the same tank, require a complete intermixing of the tank contents with and without an air supply. Through the installation and special arrangement of ejectors, jet aerators, patented for this process in the SBR reactor they can be utilized for the simultaneous aeration of wastewater and intermixing during the aeration phase as well as for a selective circulation – without air supply – during the mixing phase.

Recirculation of the wastewater through the ejectors takes place automatically at the end of the aeration phase. Both phases can be alternated as often as required so that the independence of the wastewater treatment process from feed conditions realised in the SBR process will be supported.

SBR process will be supported.

The ejectors, eductors, responsible for completely intermixing the tank contents during the mixing phase, are operated with the same circulation pumps used during the aeration phase. When the ejectors convey liquids, the power intake of the circulation pumps is utilized to an optimum – even during the mixing phase..

Design according to requirements

The numerous layout and arrangement possibilities of ejectors and their differing operating methods with atmospheric air intake or compressed air provide ideal basic conditions for their application in large and small water treatment plants.

Aerators and mixers for energy-efficient wastewater treatment plants and tank deposits in the industry

We offer a wide range of aerators and mixers for wastewater treatment plants, tank farms and various industrial process operations in the Nordic region and Latin America. Whether it is biological treatment steps or flotation plants, there are solutions that create the right oxygenation and good circulation in the process.

Aeration is one of the most energy-intensive parts of a wastewater treatment plant. The biological steps can account for 30–50 percent of the total electricity consumption. By choosing the right aeration system and adapted aerators, it is often possible to reduce energy consumption significantly.

Jet mixers are also very energy-efficient for stirring contents in cisterns, tanks and basins. They are also completely static equipment that requires minimal maintenance over its lifetime.

With modern technology and smartly designed mixers, we help businesses streamline their processes, reduce operating costs and at the same time ensure stable and reliable operations. Good for both the environment and the budget.

Different types of aerators and mixers

Fine bubble aerators. Jet aerators create fine bubbles that provide high oxygen transfer and energy-efficient operation. The mass transport of oxygen begins already in the ejector, the aerator. Oxygen transfer is then enhanced by turbulence from the jet, which is directed roughly parallel to the bottom, and drag effects. Jet aerators are ideal for activeted sludge basins, SBR, MBR and MBBR processes and can be adapted with various piping and distribution solutions.
Jet mixers can be used in virtually all types of vessels and tanks for all types of liquids that can be pumped. The mixers are placed in the tank, where the cistern contents are pumped around as motive media. The medium in the tank, adjacent to the mixer, is sucked in and mixed with the circulating motive media. At the outlet of the mixer, a jet is formed that mixes the contents of the cistern. The mixing effect is enhanced by drag effects.

Questions and answers about aerators and mixers

Why is aeration needed in wastewater?

Aeration gives the aerobic bacteria the oxygen they need to break down organic matter into carbon dioxide and water. It is one of the largest energy items in a treatment plant – but with the right dimensioning, you can save a lot of money.

What are the benefits of effective aeration?

Faster purification, less odour and lower energy costs.

How are aerators maintained?

Jet aerators are essentially maintenance-free for their entire lifetime, which can be over 20 years. This is a huge advantage over conventional diffusers, which need to be cleaned or replaced regularly to avoid clogging of sludge and limescale.

What is an ejector and how does it work as an aerator and agitator?

An ejector, also called a jet aerator, is an effective solution for aerating wastewater.

It sucks in air and mixes it with water at high speed. The result is small bubbles that provide high oxygen efficiency. At the same time, it acts as a stirrer and keeps the whole tank moving.

Why Do Ejectors Provide High Oxygen Efficiency?

The small bubbles create a large contact area between air and water. The strong turbulence constantly renews the contact surface, which increases oxygen uptake and improves the purification process.

Does a jet aerator and jet mixer need a lot of maintenance?

No. It is virtually maintenance-free, has no moving parts and is not at risk of clogging under normal operating conditions.

Do jet aerators in all types of tanks and basins?

Yes. They can be adapted to the size, depth and oxygen demand of the tank. They are also suitable for SBR systems where both aeration and agitation are required. Jet aerators are particularly effective for MBR processes with high sludge contents. Even MBBR processes work very well with these jet aerators.

Are jet mixers suitable for all types of cisterns and applications?

Yes. They can be adapted to the size, depth of the tank, and the physical properties of the thought content. They work just as well for tanks in industrial processes as cisterns at depots and basins at wastewater treatment plants.