Reference letter – Operation of the Esmil Aeration System in Chernigiv, Ukraine during the war

During 2018 in tank №3 and in 2019  in tanks №2 and №4  an aeration system at the municipal wastewater treatment facilities of “Czernihivvodokanal” has been replaced into tube air diffusers from the APKV-120 series with a total length of about 1700 m.

This allowed to reduce significantly electricity consumption, as the operation of one TV-300 blower fully satisfied the technological needs (previously there were two blowers). Total savings amounted to about one million UAH per year.

In addition, these diffusers worked very well during the period of active hostilities in our region, when electricity supplies were unstable.

In the period from March 15 to April 1, 2022, due to continuous shelling and significant damage to power facilities, the wastewater treatment plant of the city of Chernihiv was cut off from electricity. All the sludge and water mixture that was in the aeration tanks at the time of shutdown, sank to the bottom. Activated sludge in this form remained in tanks for two weeks.

After the electricity supply was resumed, the tanks were gradually put into operation (they were not emptied). After half an hour of work, the sludge and water mixture was mixed homogeneously, air was supplied evenly, and the required intensity of aeration was restored in all corridors of the aeration tanks.

This proves that the dispersion layer of the diffusers was not clogged with organic matter and did not require additional rinsing and blowing in order to restore its properties.

The efficiency of the aeration system has not decreased.

During the period of operation, there were no failures in the operation of APKV series diffusers. Moreover, a fairly quick recovery period after operation in conditions of long-term power failure was noted.

Reference on the operation of APKV-120 aerators (Budapest, Hungary)

The Southern Wastewater Treatment Plant in Budapest, with a capacity of 80,000 m3 per day, operates on the basis of the technology of biological wastewater treatment using activated sludge and aeration system regulated by the content of dissolved oxygen in 8 cascade aeration tanks.

Until the end of 2018, we used exclusively membrane aerators in the aeration system, and aerators of this type required replacement due to aging. After studying the international market, we decided in favor of using APKV tube air diffusers developed by Esmil and having the best technical specifications.

In 2018, the Esmil aeration system with APKV air diffusers was installed in the L4 aeration tank as the first step, and then in 2019 and early 2020, the same air diffusers were installed in the remaining 5 sections (L1-L3 and L5-L6).

Our experience with membrane diffusers after several years of operation can be described as follows:

  • Stretching of membrane plates;
  • Loss of elasticity of membrane plates;
  • The size of the air bubble increases due to the increase in the size of the perforation, and as a result, the oxygen dissolution efficiency decreases;
  • Physical damage, rupture of membranes;
  • Lack of oxygen at high loads;
  • Physical cleaning of the contaminated surfaces of the membranes does not fully restore their performance.

In order to maintain the required level of dissolved oxygen in the membrane aeration system, we had to empty the aeration tanks to inspect the membranes, clean them, and, if necessary, replace damaged membranes every two years. The main goal of replacing membrane aerators was to reduce excess maintenance costs of the aeration system.

The original APKV Esmil air diffusers were installed in the L4 aeration tank, which was 1/6th of the capacity (13,333 m3/day) of the total activated sludge flow rate. This was done for the purpose of comparison with the existing membrane system.

APKV Esmil air diffusers showed stable operation, the required intensity of aeration, the required parameters for oxygen saturation were achieved at a lower air pressure. SSOTE was 5 – 6.3%/m depending on the current air flow rate. The overall air consumption was reduced.

An additional positive effect was the significantly higher adaptability of the APKV Esmil system in terms of air supply regulation. New aeration system made it possible to more precisely and flexibly follow the changing oxygen demand, which makes it much easier to control the process and provides the necessary air supply, even during peak load periods.

As a result of the positive experience of operating the aeration system in the L4 aeration tank in 2019, a complete replacement of the aeration system was carried out in the same year and in 2020; APKV Esmil air diffusers were installed in the entire activated sludge system.

Experience in operating the aeration system using Esmil air diffusers:

  • Constant oxygen supply in the required amount during peak loads, DO 3-4 mg/l (including the last 8. cascade);
  • working pressure 535 mbar;
  • Reduction of pressure losses;
  • The air diffusers retain their shape, they are resistant to mechanical damage and corrosion;
  • The air diffusers do not get clogged.

Summarizing the above, it can be affirmed that the use of APKV Esmil air diffusers significantly reduces the need of service, and also meets the requirement for dissolved oxygen in activated sludge aeration tanks while reducing energy costs.

Case Study: Esmil diffusers at Tesla (Shanghai, China)

SITE – Tube Air Diffusers
EQUIPMENT – Tesla (Shanghai) Co., Lingang Development Zone, Pudong New Area, Shanghai


On May 10th 2018 Tesla (Shanghai) Co., Ltd. was established in Lingang Development Zone, Pudong New Area, Shanghai. The company is engaged in technology development, technical services in the fields of electric vehicles and parts, batteries, energy storage equipment and photovoltaic products. Electric vehicles, technology, wholesale, consulting, commissioning as well as import and export business of the above-mentioned products and supporting services constitutes the business of the company.

Tesla Gigafactory is the largest foreign manufacturing project in Shanghai to date, and it is also Tesla’s first Gigafactory outside of the United States. Tesla has invested over 2 billion USD in the components plant in China in order to localize the supply chain and is preparing to expand the factory’s production capacity.

As Esmil diffusers has the advantages of stable performance, strong aeration capacity and low energy consumption, the owner decided to use Esmil tube air diffusers for the local WWTP.

Esmil diffuser parameters

Outer diameter120 mm (Threaded to DN100)
Total length1020/2025 mm
ModelAPKV-1 / APKV-2
Disperser length940/1945 mm
Dry weight4/8 kg
Design air flow8-25/16-50 Nm3/h


After detailed investigation of the on-site data, aeration tank conditions and blowers, we recommended arrangement of the diffusers accordingly. The installation of Esmil tube air diffusers was completed on the 30th of May 2019. The equipment operates smoothly since then.

Aeration system length64 r.m.
Air volume of the blowers1200 m3/h (2 blowers, each blower: 20m3/min)
Air volume per diffuser18.75 m3/h/m
Tank bottom coverage10.7% (percentage of the diffuser active area in relation to the bottom area of the tank)
SOTE0.6 m of aerator per 1 m2 of the tank bottom
Distribution of aerators33.5% (SSOTE 6.7% depth 5m)
Pressure loss140 mm H2O

Esmil tube air diffusers layout

Case Study: Esmil Tube Air Diffusers at Tianfu International Airport New City (Chengdu, China)

EQUIPMENT – Esmil Tube Air Diffusers
SITE – International Airport New City, Chengdu Tianfu


Chengdu Tianfu International Airport New City project is located in the Eastern New District of Chengdu, China. The Eastern New District was established on April 28, 2020. On March 4, 2020 Chengdu proposed 308.6 billion yuan (47.7 billion USD) to be invested in the construction of the Eastern New District of Chengdu within the next 10 years. Among them, the investment in 2020 will reach 28.9 billion yuan (4.4 billion USD).

By 2025 major infrastructure and public service facilities will cover the New District of Tianfu International Airport’s aviation hub is going to be completed by that time as well. Strategic emerging industries, modern service industries, legal governance will be established. The permanent population of the district is estimated to reach 800,000 and the regional GDP – 48 billion yuan.

Airport New City, relying on Chengdu Tianfu International Airport, gathers the functions of aviation economy, international finance, international trade, technological innovation, international education and cultural exchange. According to the development plan, 15 municipal WWTPs will be built in the Airport New City. Esmil  tube air diffusers are used at No. 6, No. 9 and No. 15 water plants.

Esmil Tube Air Diffusers Parameters

Outer Diameter120 mm (Threaded to DN100)
Total Length1020/2025 mm
Disperser Length940/1945 mm
Dry Weight4/8 kg
Design Air Flow8-25/16-50 Nm3/h

Project Overview

Chengdu Tianfu Airport New City WWTP no. 6 is located to the west of Jiangxi River and to the south of the New Airport Expressway. It’s estimated capacity is 40 000 m3/day. It is planned to serve mainly for innovative manufacturing, with the service area of about 1057 ha.

Aeration System Length1 550 r.m.
Air Volume of the Blowers14 040 m3/h (3 in use; 1 stand-by)
Air Volume per Diffuser12 m3/(m3/h/m)
Tank Bottom Coverage10.4%
Distribution of Aerators0.6 m of Aerator per 1 m2 of the Tank Bottom
SOTE47% (SSOTE 6.6% depth 7.2 m)
Pressure Loss80 mm H2O

The 9th WWTP’s capacity is 32 000 m3/day. It is located in the Jiangxi Henan Group West Area on the south side of the Jiangxi River in the Airport Industrial New City. It is planned for economics, high-end industries, hotel services, medical education, administrative offices and residences. The service area is about 1450 ha.

Aeration System Length1 190 r.m.
Air Volume of the Blowers9 000 m3/h (3 in use; 1 stand-by)
Air Volume per Diffuser9 m3/(m3/h/m)
Tank Bottom Coverage13.1%
Distribution of Aerators0.7 m of Aerator per 1 m2 of the Tank Bottom
SOTE49% (SSOTE 6.9% depth 7.2 m)
Pressure Loss75 mm H2O

The 15th WWTP has a design of 30,000 m3/day. It is located to the east of Jiangxi River in the starting area of the Airport Industrial New City, on both sides of the New Airport Expressway, and close to the new Chengdu Airport, which is currently under construction. It is planned for industrial and logistic purposes. The service area is about 581.6 ha.

Aeration System Length1 250 r.m.
Air Volume of the Blowers10 800 m3/h (3 in use; 1 stand-by)
Air Volume per Diffuser10 m3/(m3/h/m)
Tank Bottom Coverage12.7%
Distribution of Aerators0.7 m of Aerator per 1 m2 of the Tank Bottom
SOTE50% (SSOTE 7% depth 7.2 m)
Pressure Loss76 mm H2O

Case Study: Herzliya WWTP, Israel

SIZE OF WWTP 22 000 m3/d (5 812 000 GPD)


Soon after the reconstruction of WWTP and launching a new biological reactor with EPDM membrane disc diffusers in 2009, the aeration system appeared to be highly uneconomical. In order to keep the constant dissolved oxygen DO concentration of 1.5-2.0 mg O2/l in the reactor, three blowers with capacity of 4500 m3/h each had to work continuously almost all the time.


Because of its low economic efficiency and tearing of some diffusers noticed at the beginning of 2013, it was decided to replace the existing aeration system. Esmil company installed 600 m (1970 ft) of highly efficient PE tube air diffusers with high mechanical strength and longevity. Previously installed air diffusers were replaced gradually section by section.


Bioreactor Size3 sections, 6000 m3 (1,6 MG) each
with an operating height
approx. 6 m
Type of biological treatment processAerobic suspended growth
DO concentration2.0 mg O2/l
Supply air flow rate4500-9000 m3/h (2650-5300 cfm)

End User’s Comment

After we launched the first section of the reactor with Esmil tube air diffusers, the quantity of consumed air as well as the energy was significantly reduced. Wastewater saturation with oxygen became more stable and uniform throughout the whole basin. After the old aeration system in all reactor sections was replaced with Esmil air diffusers, the quantity of consumed air was reduced up to 3
times. From November 2013 so far there has been no diffuser breaking detected or any other problems occurred.


Reference of WWTP, Herzliya, Israel

During reconstruction of sewage treatment facilities in Herzliya in 2009 a new biological reactor, consisting of three sections of 6000 cubic meters each with an operating height about 6 m, was installed. Air is pumped by means of three air blowers of 6000 cubic meters each through disc diffusers.

Soon after launching it was obvious that all system is highly uneconomical. In order to keep oxygen concentration at 1.5/2 mg/l we had to continuously work with two-three air blowers (9000-13000 cubic meters) for the whole reactor and it was not always possible. After in the beginning of 2013 rupture marks were detected on some diffusers we decided that it is time to replace them by somewhat more effective. We issued a tender, and one of many offers we have received for consideration contained information about aerators of Esmil Company.

There were a lot of cons: unknown company, lack of experience of work in Israel, disagreement of designers and technical advisors.

However, despite of some concerns and doubts we decided to install these particular aerators. This product attracted us by its simple and reliable design, price, mechanical strength, longevity, 8-year warranty, no need for service checks, easy and quick installation, and also a very tempting offer of company management: possibility to pay the most part of the amount only in case if we are fully satisfied by their operation, which can be done even in six months.

In November 2013 we launched the first section of the reactor with Esmil tubular aerators.

Reality has exceeded our most optimistic expectations. Quantity of used air has significantly reduced as well as quantity of consumed energy.

Saturation of liquid with oxygen has become more stable and homogenous in the whole basin. In 2 months instead of previously agreed 6 months of observation of aerator performance it was decided to replace diffusers installed in two remaining sections by Esmil aerators, which was done in stairstep order.

Today the whole reactor (3 sections) is functioning with installed Esmil aerators, and we are extremely satisfied with obtained results. Required oxygen concentration (about 2 mg/l) is kept in all sections with much less energy consumption. The most part of a day (14-16 hours) we use one air blower (4500 cubic meters) and during peak hours (8-10 hours) two air blowers (instead of 2-3 air blowers used previously, before replacement of aerators). I send you the reactor operation schemes made before and after replacement of aerators.

Esmil tube air diffusers israel

Esmil Group

Esmil Group stands as a premier global manufacturer, crafting cutting-edge equipment for wastewater treatment and sludge dewatering. Additionally, we specialize in delivering advanced membrane systems tailored to various industries.

EU Flag Esmil Group

Equipment for Wastewater Treatment & Sludge Dewatering.

EU Flag Esmil USA

Equipment for Sludge Dewatering in the USA.

EU Flag Esmil Process Systems

Membrane Systems.