Case Study: Modernization of the sludge dewatering complex (Trzcianka, Poland)

CUSTOMER – Municipal Construction Department in Trzcianka
OBJECT – Municipal wastewater treatment plant in Trzcianka
MDQ 452-С
October 2022


The wastewater treatment facilities in Trzcianka were built in the 1980s and had a capacity of 2,400 m³/day. The wastewater treatment used the active sludge method, in which the sludge was sent to stabilization chambers and then to sludge clarifiers. The treated wastewater was discharged through a drainage ditch to the Trzcinica River. In 2006-2007, wastewater treatment facilities were modernized and expanded to include both the biological and sludge treatment stages. As a result of these measures, the capacity of wastewater treatment facilities increased to 4000 m³/day. The volume of wastewater received during the year is currently approximately 700,000 m³.

In 2022 Municipal Construction Department in Trzcianka invested significantly in the modernization of both the water supply and sewerage systems and the wastewater treatment facilities themselves. One of them was the modernization of the sludge treatment stage.

The sludge treatment technology at the Trzcianka wastewater treatment facility includes anaerobic stabilization of excess sludge in two separate fermentation chambers (WKF), followed by dewatering and hygienization with lime for agricultural use. Before the modernization, sludge from the WKF chambers with a dry matter content of 1.5-2.5% was sent to the belt filter press, and as a result of dewatering, it was possible to achieve approximately 16% DM in the dewatered sludge.

Due to rising energy prices, the frequency of equipment breakdowns and the high cost of transporting dewatered sludge, the company’s management decided to replace the equipment in the sludge dewatering building with more efficient and cost-effective equipment that provides an automated dewatering process. In search of an optimal solution, the Municipal Construction Department of Trzcianka ordered pilot tests in real conditions on a full-size Esmil MDQ-201 Multi-Disc Screw Dehydrator from PRODEKO-EŁK Sp. z o. o., which is part of the Esmil Group. The tests were positive and promising, and the dewatering technology based on Esmil MDQ Dehydrators convinced the management. In July 2022, a tender was held for the supply, installation and start-up of the Sludge Dewatering Complex based on a Screw Press, which was won by PRODEKO-EŁK, meeting all the Customer’s requirements.



As part of the modernization, PRODEKO-EŁK Sp. z o. o., a part of the international ESMIL group, supplied, installed and started up the Sludge Dewatering Complex in the autumn of 2022, which included the following equipment:

  • Mutli-Disc Screw Press Esmil MDQ-452 C
  • Horizontal Screw Conveyor approximately 2 m long
  • Inclined Screw Conveyor with a length of approx. 6 m, which partially extends outside the building
  • Pump for sludge feeding + flow meter
  • Polymer inlet pump + flow meter
  • Polymer make-down unit
  • Macerator pump
  • Control cabinet of the entire complex with a touch panel

Esmil PRODEKO-EŁK also carried out a comprehensive supply of pipelines and cables for the complex, as well as mechanical and electrical installation of the devices. After the complex start-up and adjusting the equipment’s
operating parameters, the treatment facility operators rated all the advantages of process automation and technology that requires virtually no operator intervention, especially compared to the previously used belt filter press. In addition, the absence of wearing parts, lower operating costs (electricity, washing water, etc.) and a much higher degree of dewatering result in significant savings. It is worth noting that despite the larger amount of sludge processed per day, the overall polymer consumption per month is comparable. The previously used belt press allowed for the processing of approximately 1,300 m3 of sludge per month on average, while the multi-disc screw press MDQ-452 C enabled the processing of approximately 1,700 m3 of sludge per month on average. In both cases, the monthly consumption of the flocculant in the form of an emulsion is approx. 1 m3. A detailed comparison of the operating parameters of both equipment is presented in Table 1.

Table 1: Comparison of the previous belt filter press and the Multi-Disc Screw Dehydrator Esmil MDQ-452 C

Belt Filter Press

Multi-Disc Screw Dehydrator Esmil MDQ-452 C

DM content in the incoming sludge
1,5 – 2,5 %

Hydraulic flow capacity
~ 6,5 – 8 m3/h

8 – 15 m3/h
Dewatering performance
~ 97,5 – 200 kg DM/h

120 – 375 kg DM/h

DM content in dewatered sludge
~ 16 %

18 – 22 %

Reduction of sludge volume
6-10 times

9-14 times

Polymer dosage
15-19 kg/t DM
12-15 kg/t DM
Amount of polymer used in emulsion form per 1 m3 of sludge
≈ 0,8 l
≈ 0,6 l
Sludge processing per month
1200 - 1400 m3
1700 - 1800 m3
Electricity consumption
8,7 kW

4,2 kW

Washing water consumption

10 m3/h

0,2 m3/h

The advantages of using the Sludge Dewatering Complex based on Esmil Multi-Disc Screw Press MDQ:

  • better sludge dewatering, due to the reduced volume of sludge, which means less storage space is required and transportation costs are reduced;
  • more dewatered sludge per day;
  • less use of polymer, washing water and electricity;
  • no parts that wear out quickly;
  • does not require maintenance;
  • automated process.

sludge dewatering complex

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.

Case Study: Reconstruction and modernization of the mechanical treatment system at the wastewater treatment plant (Ostrów-Mazowiecka, Poland)

PROJECT: Reconstruction and modernization of the mechanical treatment system at the wastewater treatment plant located on Olszynowa Str. 16 in Ostrów Mazowiecka
CUSTOMER: Public utility company in Ostrów Mazowiecka Sp. z o.o.
SITE: Wastewater treatment facilities on Olszynowa Str. 16
COMMISSIONING: February – March 2021

Project Objectives

The objective of the project was to update and reconstruct the system of removing and collecting waste extracted from wastewater at the wastewater treatment plant in Ostrów Mazowiecka.

According to the modernization plan, the following equipment was delivered, installed and commissioned in February 2021:

  • Esmil RSK0815 step screen with 3 mm gaps
  • SGSM 0.9×2.6 (1.2) penstocks – 2 pcs.
  • Screenings compactor

Until recently, the wastewater treatment plant had been experiencing difficulties with overflowing the channel with wastewater, so it was decided to widen the channel and install a wider screen with a higher capacity.

Project Implementation

The equipment for the project was manufactured at the Esmil plant. The existing inlet channel was enlarged to properly position the screen according to the project requirements. After the completion of the construction work, the Esmil professionals proceeded to the installation and commissioning of the unit. The screen was commissioned in March 2021.


Thanks to the use of the Esmil RSK0815 step screen, the problem of overflowing the channel with wastewater was completely eliminated. The screen selected and supplied by Esmil not only keeps the mechanical treatment facility clean, but also, thanks to its reliable operation, protects the equipment on the further stages of the wastewater treatment process.

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: Brown’s Bay Packing Company (Campbell River, BC, Canada)

TYPE OF INDUSTRY – Fish processing
MODEL OF DAF-UNIT – FT-20Z with static mixer


The customer was looking for the solution to reduce pollutants in wastewater from the fish processing plant, after the FBR advanced oxidation process. Moreover, they were looking for the compact and easy to operate system, with low operating costs.


Based on initial information and theoretical calculations, Esmil in cooperation with our representative in Canada Archer Separation Inc. offered DAF-unit FT-20Z.

Wastewater Sourceseawater with fish farm byproducts
Operating Time16-20 h/day, 3-4 days/week
Flow Rate20-40 m3/h
Feed TSS Concentration800-1200 ppm
Effluent TSS Concentration80-100 ppm

Case Study: Municipal Wastewater Treatment Plant (Bridge City, TX, USA)



In the plant sludge drying beds for sludge dewatering were used. This method required lots of labor and constant maintenance. Due to this reason, the customer was looking for the efficient and minimal maintenance solution.


On-site pilot tests were carried out, using mobile dewatering unit MDQ-201, to find the best dewatering technology. According to the test results Esmil offered sludge dewatering complex based on Multidisc Screw Press Dehydrator MDQ-354(2) CL. The complex includes – influent sludge feed pump, polymer feeder, three screw conveyors and service platform.

Type of sludgeaerobically digested excess sludge
Operating timeup to 8 h/day, 3 days/week
Unit sludge capacityup to 9 (18*) m3/h
up to 320 (400*) kg DS/h
Inlet sludge DS content3.5 %
Cake DS contentapprox. 22-23 %
Polymer consumption14.6 l/tonDS
TSS concentration in filtrate200 ppm
DS capture rate99.4 %
*in case of adding two additional dewatering drums.



Case Study: Municipal Wastewater Treatment Plant (Webster, Texas, USA)



The customer had an interest in reducing sludge disposal costs in their municipal wastewater treatment plant by obtaining lower maintenance costs and lower energy consumption. The plant treats wastewater from nearby residential areas and numerous local restaurants and generates about 120 gallons of aerobically digested sludge from their digesters per minute.


On-site pilot tests were carried out, using mobile dewatering unit MDQ-201, to find the best dewatering technology. According to the test results Esmil offered sludge dewatering complex based on Multidisc Screw Press Dehydrator MDQ-354 C. The complex includes – macerator, polymer feeder and service platform.

Type of sludgeaerobically stabilized excess sludge
Operating time9-10 h/day, daily
Initial sludge capacity20 m3/h
310 kg DS/h
Inlet sludge DS content1.3-1.5 %
Cake DS content16-18 %
Polymer powder consumption8.8 g/kgDS
TSS concentration in filtrate70 ppm
DS capture rateup to 99.7 %



Case Study: Soapberry WWTP (Kingston, Jamaica)

START OF OPERATION – 2020 February


Soapberry WWTP located near Kingston Harbour has been operated since 2004. Biological wastewater treatment process is based on wetland lagoons. The WWTP has not previously had any sludge processing equipment, therefore since the start-up of the plant lagoons have been gradually filled with dry solid particles. As a result, sludge accumulation had impact on biological process efficiency, because of the reduced effective volume of the lagoons. For this reason, customer was looking for the solution to clean the bottom of the lagoons and process the sludge.


The lagoons cover an area of nearly 6 km2. Bottom sludge from the lagoons is removed by remote controlled dredger supplied by Dragflow. For this reason, Esmil offered Mobile dewatering complex based on Multi-disc Screw Press Dehydrator MDQ-353 C. The complex includes mechanical screen, sludge tank, influent sludge feed pump, polymer solution preparation unit, polymer dosing pump, water tank, water pump and screw conveyors. All the equipment is mounted on the common platform. The complex can be fitted in a standard 40’ container or on a trailer, which allows an easy relocation.

Type of sludgebiologically digested lagoon sludge
Operating timeup to 23 h/day
Initial sludge capacity10-15 m3/h
Inlet sludge DS content2-3 %
Cake DS contentapprox. 23-26 %
Polymer powder consumption1-2 kg/tonDS
TSS concentration in filtrate100 ppm
DS capture ratemore than 99 %

Case Study: Municipal Wastewater Treatment Plant (Argentia, Newfoundland, Canada)

START OF OPERATION – 2019 November


The customer was looking for a low-cost, yet reliable and easy to operate solution for sewage from a construction site of an offshore platform treatment.


Project was carried together with our partner MABAREX. Esmil offered Multi-disc Screw Press Dehydrator MDQ-102 C, which is the part of the containerized wastewater treatment plant.


Type of sludgeexcess activated sludge from MBR
Operating time6-10 h/d
Unit sludge supply0.5-1 m3/h
Inlet sludge ds content0.5-1 %
Cake DS content15-17 %
Polymer consumption5 kg/ton DS
TSS concentration in filtrate20-100 ppm
DS capture ratemore than 98 %

Case Study: KB Bioenergy, inc. (Akron, OH, USA)

TYPE OF INDUSTRY – Renewable energy


The customer was looking for a solution to replace one of the three existing centrifuges as well as to increase dry solid content, reduce energy consumption and improve operation.


On-site pilot tests were carried out, using mobile dewatering unit MDQ-201, to find the best dewatering technology. According to the test results Esmil offered sludge dewatering technology based on Multi-disc Screw Press Dehydrator MDQ-354 CL together with service platform.


Type of sludgeanaerobically digested sludge
Operating time23 h/day, 6 days/week
Unit sludge supplyup to 78 gpm
up to 3,276 lbDS/h
Inlet sludge ds content8.4 %
Cake ds content26.5 %
Polymer consumption16.5 lb/ton DS
Tss concentration in filtrate350-500 ppm
Ds capture rateup to 99.4 %

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