Progress in mechanical installation in Hawaii

October 2023

After a long crossing by container ship from Hamburg to Hawaii, the mechanical assembly of all components of the two lines of the BD3000/8 belt dryer as well as its condensers, heating and conveyor technology takes place. SEVAR's experienced supervisor expertly supervises the team of locally hired fitters. They are doing a great job and making rapid progress.

In the coming months, the electrical installation, cold and hot commissioning will take place. The operating personnel will be trained and a performance test will be carried out.


May 2023

The Korean city of Yongin is modernizing the city’s waste water treatment system through the new construction of the Respia wastewater treatment plant with biosolids treatment to process 145,000 m3/d of wastewater. This plant, already under construction, will be built fully underground, enabling the creation of space for sport, leisure and park facilities and at the same time a more pleasant environment for its inhabitants. The conveying and ventilation technology of the sewage sludge drying plant is already designed for a future capacity increase of 30 %.

Everone Environment & Technology Co., Ltd. on behalf of POSCO Engineering & Construction, the general contractor of Yongin City, awarded SEVAR to design and manufacture two lines of belt dryers.

Two identical lines of the BD 3000/13 belt dryer, each with 13 modules, dry 9.2 tons of dewatered biosolids with 20 % DS to 90 % DS per hour. The dry biosolids are then mixed with coal and incinerated in a power plant. In a few years, both lines will be extended by 4 modules each. The annual throughput is 14,700 and will be in future 19,300 tons of dry material (100 % DS). Part of the biogas produced during the digestion of sludge is burned to generate heat for drying. In horizontal condensers, the humid exhaust air from the dryer is indirectly condensed with final effluent of WWTP as cooling water. The condensate is sent back to WWTP for biological treatment.

The belt dryers will be delivered and installed in 202. The drying plant shall go into operation in 2025.


December 2022

The Belt Dryer BD 3000/5 at KBA Hard in Schaffhausen, Switzerland, which has been operated since 2009 for drying externally delivered sewage sludge, has been dismantled and installed at the new Juracement site in Wildegg, Switzerland. The new application of the dryer, which will be extended by two modules to size BD 3000/7 in 2023, is the drying of shredded wood with a moisture content of 50 % at a throughput of 4.5 t/h. The material is distributed above the 3 m wide dryer belt by a pendulum screw.

Upon drying to 30 - 40 % residual moisture, the wood serves as a CO2-neutral substitute fuel for cement production. The Belt Dryer, which was previously heated with the cooling water of a biogas-fueled cogeneration plant, is now operated with hot gas. The hot gas generated in the flash cooler during cement production is passed through heat exchangers to produce the hot drying air at 130 °C. The hot air is then used as a substitute fuel. The humid exhaust air from the dryer is condensed in a biofilter and cleaned from odors.



December 2022

For the Stel II project, the French company NIJHUIS SAUR INDUSTRIE placed an order with SEVAR AG in March 2022 for a Belt Dryer BD 1500/2 including delivery, installation supervision and assistance with commissioning and automation. Due to its compact dimensions, the dryer was delivered fully assembled by heavy-duty truck from workshop in Karlsdorf-Neuthard to the installation site in Crolles near Grenoble in France. A second truck transported the feeding unit, discharge screw, elevator, dosing screw and fans.

Sludge from the biological treatment of wastewater, dewatered to 16 % DS by means of a chamber filter press, is dried to > 60 % DS at a throughput of 144 kg/hr [320 lb/hr] in the two modules of the Belt Dryer BD 1500/2. The feeding unit of the belt dryer consisting of distributor, dosing unit and roller press granulates the material upstream of the drying process. For efficient drying, an internal back-mixing system is installed. In this process, dried material is mixed with the dewatered sludge to approx. 30 % DS. The material to be dried is thus given a volume-surface ratio favorable for water transfer to the drying air. For the generation of the drying heat with minimum 56 °C [133 °F], a water circuit from a production process of the adjacent semiconductor industry with minimum 65 °C [150 °F] (nominally 90 °C [195 °F]) warm water is used. The water circuit heats the dryer air indirectly via heat exchangers installed in the mixing chamber of the dryer. During the drying process, 106 kg/h [233 lb/hr] of water are evaporated.


December 2022

In drying 3.5 t/hr [7,700 lb/hr] of dewatered, biological raw sludge with 21 % DS to 90 % DS, a total of 2.7 t/h [6,000 lb/hr] of water is evaporated with two identical lines of the Belt Dryer BD 3000/6. The evaporated water containing dryer exhaust air is condensed in spray condensers operated with the effluent from the WWTP, and the resulting condensate is treated in theWWTP. Hot drying air is generated with diesel-fed burners and mixed with the condensed recycled exhaust air to approximately 130 °C drying [265 °F] temperature. Compliance with US EPA Class A requirements for pathogen elimination are met with treatment at this temperature and a residence time longer than 90 minutes.

Each line of belt dryers will be equipped with back-mixing, product crushing and screening, direct spray condenser and burner. Engineering, manufacturing, delivery, installation supervision, commissioning and performance test drive on site are part of the SEVAR AG contract.


September 2021

Drying plant for industrial sewage sludge from dairy wastewater is built in Grajewo, Poland.

The plant operator SM MLEKPOL is a Polish dairy cooperative and the largest dairy group in Poland. MLEKPOL is one of the twenty largest raw milk processing companies in Europe. Approximately 5 Million liters of milk from 9,000 milk producers are processed daily. The Polish engineering company SEEN Technologie is the general contractor.

The dairy wastewater is biologically treated in the plant's own wastewater treatment plant. The sewage sludge, which is dewatered to 16% DM, with a mass flow of 1.2 t/h [2,600 lb/h], will in future be dried to 90 % DM with a belt dryer size BD 3000/6 with a water evaporation capacity of 1 t/h. For optimum surface structuring, the wet sludge will be back-mixed to 30 % DM with sludge dried to 90% DM before it is fed onto the dryer belt.

The drying air is heated to approx. 80-85 °C [176 - 185 °F] in heat exchangers fed with the 90° warm cooling water (flow) of a CHP unit. The return flow of the cooling water to the CHP unit, cooled to 70 °C [158 °F] , is used to preheat the recycled drying air to 50 °C [122 °F] . The recycled drying air is previously dehumidified in a spray condenser and cooled to 30 °C [86 °F].

The special technical feature of this plant is the enhanced heat recovery with a heat exchanger using the warm, humid exhaust air downstream the drying process and in front of condensation to heat the thin sludge by a delta of 5 K for its anaerobic treatment in the digester at 36 °C [97 °F], to produce biogas for the CHP engine.

Commissioning of the drying plant is planned for the 3rd quarter of 2022.


April 2021

The American pharmaceutical company Merck Sharp & Dohme, Inc. (MSD) has awarded a contract to the general contractor Jacobs Engineering Group, Inc. for the design and construction of a drying plant for sewage sludge. The sewage sludge is produced during the biological treatment of industrial production wastewater at the Elkton production site in the state of Virginia, USA, at a rate of 2.6 t/h [5,700 lb/h] and 15 % DM.

The belt dryer BD 3000/8 from SEVAR AG is designed for a water evaporation capacity of 2.2 t/h [4,800 lb/h]. The drying air of the belt dryer is indirectly heated up to 130 °C [256 °F] with process steam generated in the production plant via heat exchangers. The sewage sludge, dried to 90 % DM at a rate of 0.4 t/h [880 lb/h], is conveyed by screw conveyors into containers, which are transported away by truck. The warm, humid exhaust air is dehumidified in a spray condenser operated indirectly with cooling water, also occurring in the production plant. Part of the exhaust air is recycled and the exceeding air is fed to the acid scrubber, for the removal of nitrogenous compounds. The condensate produced is treated in the company's own wastewater treatment plant.

Drying of digestate on a pilot scale

February 2021

Cométha is a joint innovation partnership project between SIAAP (French wastewater association) and Syctom (public operator for household waste recycling) in the Paris region, France. The companies take care of the wastewater management of 9 million citizens and the treatment of household waste of 6 million citizens. For Syctom's objective to turn waste into a resource with a sustainable circular economy, the recycling routes are constantly optimized.The Belgian mechanical engineering group John Cockerill has overall responsibility for the project as EPC contractor.

Cométha deals with the treatment of the solid and liquid fraction from biowaste generated during its treatment in the biogas plant. The methanization (anaerobic treatment) of organic material produces biomethane, which, purified, can be injected into the gas grid or used as fuel for vehicles. The digestate is the nutrient-rich residue left over from the fermentation process.

Cométha is investigating in a pilot plant (phase 2) the feasibility of joint treatment (new mixture) of the following solid and liquid biological materials with a high organic content: fats, sewage sludge, liquid fraction of garbage, household waste and horse manure. Energy recovery, optimized methanation and the production of nutrients are being investigated experimentally and in a forward-looking manner.

In the innovative pilot plant at the Seine Valenton site, France, the digestate produced during methanization, is dewatered in a screw press, dried with a SEVAR belt dryer (pilot scale) and fed to pyrolysis. From the liquid phase, ammonium sulfate is produced by stripping for use as fertilizer.

The pilot dryer of size BD 750/2 was ordered by John Cockerill in February 2021 for a throughput of 30 - 100 kg/h dewatered digestate with. approx. 25 - 50 % TR and a water evaporation capacity of 20 - 40 kg/h at SEVAR AG. The digestate is fed onto the dryer belt via a roller press, transported through the two electrically heated drying chambers and discharged via a water-cooled discharge screw. The external compact dimensions (LxWxH) are approximately 4200 x 3250 x 3000 mm.

The pilot plant will be operated for 3 years. The results from the operation will influence the design and construction of the industrial plant in phase 3.

Read more:


January 2021

Howard County’s Bureau of Utilities, the operator of the Little Patuxent Water Reclamation Plant (LPWRP) in the state of Maryland, USA has taken over the "Biosolids Belt Drying System" by signing of the Take Over Certificate. This initiates the 24-month warranty phase of the plant.

The contract for the drying facility executed by the contractor Clark Construction Group, LLC was awarded in February 2017. The engineering services of the "Biosolids Processing Facilities Improvement Project" were the responsibility of the renown American engineering firm HDR, Inc.

Two lines of the SEVAR belt dryer directly heated with natural gas or biogas and spray condensers as well as receiving wet cake bin including feed pumps and dry material silos were erected for a water evaporation capacity of 4,400 lb/hr per drying line. The operation of the turnkey plant for full drying started in January 2021.

The objective of the project was to modernize the current practice of stabilizing the undigested biosolids with advanced lime. The building of digesters and the following full drying of the digested sewage sludge meets the high standard of Class A in terms of elimination of pollutants and pathogens. The dried sewage sludge is available for sale to citizens for use as fertilizer or as a soil mix. The use in sod/turf production is another possible application for dry biosolids.

The project „Little Patuxent Water Reclamation Plant Biosolids Processing Facilities Improvements“ received the Envision Silver Award for Sustainability from the Institute for Sustainable Infrastructure (ISI) in September 2021.

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May 2020

In 2018, "The City and County of Honolulu" invited tenders for the modernization of its sewage sludge treatment system with the aim of processing the sludge into "Class A biosolids" by drying it, thus not only saving costs in disposal, but also producing valuable material that can be used for soil improvement.

After PARSONS was awarded the contract as general contractor, the company ordered the dryers (2 lines BD 3000/8) from SEVAR AG. With the active support of our local agent Promark Corp. SEVAR could secure the order.

The scope of supply includes the two dryer lines and the complete process air treatment line; heat generation by combustion of natural gas / biogas as well as the dryer exhaust air (condensation, recirculation and exhaust air treatment by chemical scrubbers).

Decisive for the customer was the flexibility of the SEVAR dryers to be supplied with different heat sources; thus the dryers are first heated directly by natural gas / biogas and later, according to the commissioning of the planned CHP, by the exhaust gases of the CHP. The dryers have an evaporation capacity of 2 t/h [4,400 lb/h] each, so that the plant can process over 5 tons of dewatered sludge per hour [11,000 lb/h].

Municipal sewage sludge with an initial solids content of 23 % TR dried to 92 % TR. By exposing the bacterial mass to drying temperatures of up to 130 °C [266 °F] the sludge is sanitized and all bacteria such as e.coli or salmonella are eliminated.

The engineering as well as the production takes place in Germany and is in full swing. The plant will be shipped by sea transport. The assembly and the commissioning is done by employees of SEVAR AG.