Industrial herb drying at the highest level
In the middle of the Negev Desert, just a few kilometers from Kibbutz Gvulot, one of Hans Binder’s most demanding drying systems of recent years is currently being built.
As part of the IL-Daya project in the Eshkol region, an approximately 50-meter-long belt drying system for digestate from the organic fraction of municipal solid waste is being implemented.
The particular challenge: The feed material has a solids content of only around 20%. Therefore, it cannot be processed directly in a belt dryer. An upstream back-mixing unit first brings the material to a consistency suitable for drying.
After around three weeks of mechanical and electrical installation on site, the system is now largely in place. The drying tunnel, back-mixing unit and parts of the peripheral equipment have already been installed. The next major step is commissioning.
Table of contents
- Drying and recovering digestate from municipal solid waste
- Why high-moisture digestate cannot be dried directly in a belt dryer
- The solution: modDryer-MRK-E-19-3 with back-mixing unit
- Technical data of the belt drying system in Israel
- Installing the belt dryer under extreme conditions in the Negev Desert
- How does digestate drying support the circular economy?
- Next step: Commissioning the drying system in Daya
- Conclusion: Belt drying of high-moisture digestate with back-mixing
Drying and recovering digestate from municipal solid waste
As part of the IL-Daya project, Hans Binder is constructing an industrial drying system together with a local partner. The Israeli partner company specializes in environmental technology and waste management.
The feed material is the organic fraction of municipal solid waste. After anaerobic digestion and processing through a screw press, a moist, nutrient-rich substrate remains.
Without further treatment, however, this material can neither be stored nor transported efficiently. The belt drying system therefore performs a crucial process step.
The liquid press-water fraction of the digestate is dried and thereby converted into a stable, storable and reusable product.
This project clearly demonstrates the role industrial drying technology can play in the circular economy. A difficult-to-handle residual material is transformed into a product that can subsequently be transported, stored and sent for further utilization.
Why high-moisture digestate cannot be dried directly in a belt dryer
The press-water fraction enters the system with a solids content of only around 20%. This makes the material too wet to be distributed evenly and directly onto the drying belt.
If fed directly into a conventional belt dryer, the material could smear across the belt. In addition, it could dry unevenly or cause the drying belt to become clogged.
The technical challenge was therefore not simply to design a suitable belt dryer. Instead, an overall process concept was required that takes the properties of the feed material into account while ensuring a stable and continuous drying process.
REQUIREMENTS FOR THE DRYING SYSTEM IN DAYA
- reliably handle large volumes of wet press water
- withstand the extreme climatic conditions of the Negev Desert
- enable continuous, low-maintenance operation over many years
- meet the requirements for emissions and operational safety
The solution: modDryer-MRK-E-19-3 with back-mixing unit
The system is based on a modDryer-MRK-E-19-3, a single-stage belt dryer with an upstream back-mixing unit.
Back-mixing is a central element of the overall system concept. Only through this process can the high-moisture feed material be prepared for subsequent belt drying.
HOW DOES BACK-MIXING WORK IN DIGESTATE DRYING?
Part of the already dried final product is continuously mixed back into the wet press water. As a result, the solids content increases. At the same time, the consistency changes sufficiently for the material to be distributed evenly onto the drying belt.
The process can be divided into three steps:
- First, the wet press water with around 20% solids content enters the back-mixing unit.
- Next, already dried material is continuously recirculated and mixed with the wet feed material.
- The prepared material is then distributed evenly onto the belt dryer and dried.
After back-mixing, the material passes through the drying tunnel. The required heat is supplied by hot-water heat exchangers.
At the end of the process, the product reaches a dry matter content of around 80%. It is therefore suitable for storage and transport and is prepared for further utilization.
Technical data of the belt drying system in Israel
The system designed for the IL-Daya project is intended for robust industrial continuous operation under the demanding climatic conditions of the Negev Desert.
SYSTEM OVERVIEW
- System type: modDryer-MRK-E-19-3
- Drying principle: single-stage belt dryer with upstream back-mixing unit
- Installation: outdoor belt dryer tunnel
- System length: approx. 50 meters
- Belt area: approx. 114 m²
- Water evaporation capacity: approx. 2.8 tonnes per hour
- Heating: hot-water heat exchangers with integrated heat recovery
- Control system: fully automated Siemens S7 process control with remote maintenance module
- Material: stainless steel design for robust continuous operation in desert conditions
- Dry matter content of the final product: approx. 80%
The combination of back-mixing, belt drying and heat recovery enables a continuous process.
As a result, a feed material that could not be dried directly in a belt dryer because of its high moisture content can still be processed reliably.
Installing the belt dryer under extreme conditions in the Negev Desert
After months of planning and prefabrication in Germany, the Hans Binder installation team traveled to Israel. There, the prefabricated modules were assembled into a complete drying system.
PREFABRICATED MODULES OF THE DRYING SYSTEM
- infeed module
- drying chambers
- discharge module
- back-mixing unit
- additional conveying equipment
Chamber by chamber, an almost 50-meter-long drying tunnel took shape in the Eshkol region.
Another challenge was the extreme heat in Israel in August 2026. Therefore, a large proportion of the installation work had to be carried out at night.
Nevertheless, shifting the work to the nighttime had no negative impact on the project schedule.
David Gollmann, Chief Service Technician at Hans Binder engineering GmbH: “Due to the extremely hot days in Israel in August 2026, a large part of the installation work was carried out at night. However, this had no negative impact on the schedule. Many thanks to my team and the local helpers for their remarkable commitment under these extreme conditions!”
The mechanical and electrical installation has taken around three weeks so far. During this work, the Hans Binder team was supported by local specialists.
The drying tunnel, back-mixing unit and parts of the peripheral equipment have now been installed. The control technology is the next step.
How does digestate drying support the circular economy?
In this project, drying does more than fulfill a process-engineering function. At the same time, it fundamentally changes the properties of the residual material.
Without further treatment, the initially very wet material is neither suitable for storage nor for transport. However, preparation and subsequent drying increase the dry matter content to around 80%.
This creates a product that:
- can be stored,
- can be transported,
- is prepared for further utilization.
In this way, drying creates an important prerequisite for returning organic residual materials from municipal solid waste to a further utilization cycle.
Next step: Commissioning the drying system in Daya
With installation largely completed, the foundation has been laid for the next phase of the project.
In the coming weeks, the Hans Binder commissioning team will travel to Daya again. The system will first be commissioned and then gradually adjusted to its target values during trial operation.
Commissioning will also include training the operating personnel and optimizing the process parameters for subsequent regular operation.
Hans Binder will continue to accompany the next project stages. In addition, the company will report on the initial commissioning and the subsequent stable operation of the belt drying system in the Negev Desert.
Conclusion: Belt drying of high-moisture digestate with back-mixing
The IL-Daya project demonstrates that even very wet digestate with an initial solids content of only around 20% can be processed industrially in a belt dryer.
However, this requires the preparation of the feed material to be integrated directly into the overall system concept.
The upstream back-mixing unit first brings the wet press water to a consistency suitable for belt drying. The modDryer-MRK-E-19-3 then performs the continuous drying process until a dry matter content of around 80% is reached.
With a water evaporation capacity of around 2.8 tonnes per hour, a belt area of approx. 114 m² and a system length of almost 50 meters, the plant is designed for continuous industrial operation.
Following installation in the Negev Desert, commissioning is now the next decisive project milestone.
Fresh herbs on the drying belt: Gentle processing of sensitive leafy products is crucial for the quality of the final product.
The solution: Multi-zone single-belt dryer with intelligent process control
A modern multi-zone belt dryer with intelligent process control was implemented – specifically a HBT EBT 3.0 / 9/6/3 single-belt dryer.
The basic principle: The product is evenly distributed at a defined layer height onto a permeable continuous belt and transported continuously through several consecutive drying zones.
Unlike batch processes, this creates a continuous and reproducible process in which all herbs undergo precisely controlled thermal treatment.
PERFORMANCE FEATURES OF THE SYSTEM
- Throughput capacity of up to 3,000 kg/h
- Multi-stage drying zones for optimal product handling
- TARGETED ZONE HEATING (TZH) for precise temperature control
- High-volume, controlled airflow of up to 100,000 m³/h
- Fully automated PLC process control
WHY A SINGLE-BELT DRYER?
With this design, the product rests in an even layer on a single continuous belt. It is not turned over, dropped or subjected to the mechanical stress associated with other types of dryers.
This is a decisive advantage when gently drying herbs: Sensitive leaves retain their structure, unnecessary breakage is avoided and their characteristic green color is preserved.
At the same time, the continuous belt system allows different products to be processed without complex modifications – changing from one herb to another can be managed via the process parameters.
The HBT EBT 3.0 / 9/6/3 single-belt dryer implemented for the project: Stainless steel construction with multi-stage drying zones and robust drive technology.Der realisierte Einbandtrockner HBT EBT 3.0 / 9/6/3: Edelstahlbauweise mit mehrstufigen Trocknungszonen und robuster Antriebstechnik.
Technology in detail: TARGETED ZONE HEATING and precise airflow control
At the heart of the system is the interaction between zone-specific heat control and controlled airflow. TARGETED ZONE HEATING (TZH) allows an individual, precisely defined temperature to be set in each drying zone.
This is particularly valuable for industrial herb drying because the drying process does not proceed uniformly: At the beginning, large amounts of surface moisture must be removed quickly, while significantly gentler drying is required during the later stages to prevent damage to the product.
The multi-zone design with TZH reflects precisely this progression – each zone performs the task for which it is optimally suited.
PRECISE AIRFLOW OF UP TO 100,000 M³/H
The heat control is complemented by high-volume, controlled airflow of up to 100,000 m³/h. The air is directed specifically through the product layer, ensuring that moisture is removed evenly across the entire belt.
This precise airflow prevents both overdried areas and wet spots and is essential for achieving uniform residual moisture across the entire product width.
FULLY AUTOMATED PLC PROCESS CONTROL
The entire process is controlled by a fully automated PLC system. It monitors temperatures, airflow volumes and belt speed, keeps all parameters stable and makes the complete drying process easy to operate and reproduce – shift after shift, batch after batch.
The result: Consistent quality on an industrial scale
The system delivers consistently high product quality with maximum efficiency. In practice, the benefits of zone-specific control and precise airflow can be seen in measurable results:
THE RESULTS AT A GLANCE
- Uniform residual moisture of approx. 5%
- Significantly reduced product losses through gentle belt drying
- Stable process conditions across all batches
- High energy efficiency through zone-specific control
The uniform residual moisture of around 5% is a particularly important quality factor. It ensures a long shelf life, prevents mold formation during storage and provides the basis for consistent further processing.
Gentle belt drying also produces significantly less waste than more aggressive processes – every gram of raw material that is not lost directly improves economic efficiency.
And because each zone uses only as much energy as it actually requires, the system operates extremely efficiently even during energy-intensive continuous operation.
Industrial drying line in continuous operation: The multi-zone single-belt dryer enables reliable large-scale production with stable process conditions.
Added value for the operator
For the food producer, the technology translates into tangible economic benefits. Industrial herb drying is transformed from a quality-critical bottleneck into a predictable and scalable process.
OPERATIONAL BENEFITS AT A GLANCE
- Reliable large-scale industrial production of herbs
- Flexible processing of different products without modifications
- Consistent quality for the demanding food market
- Economical operation through optimized energy use
Conclusion
The solution sets new standards in industrial herb drying. The combination of intelligent zone technology, precise airflow control and automated process control creates a highly efficient drying process for maximum quality on an industrial scale.
The multi-zone single-belt dryer demonstrates that high throughput and gentle product treatment are not mutually exclusive but can be combined within a single system.
For producers looking to take herb drying to an industrial level with reliable, reproducible and economical processes, zone-controlled belt drying provides the ideal solution.
Industrial drying line in continuous operation: The multi-zone single-belt dryer enables reliable large-scale production with stable process conditions.
Frequently asked questions about industrial herb drying
A single-belt dryer continuously transports the product through the drying zones on a single continuous belt. The product rests in a uniform layer, is not turned over and is not subjected to mechanical stress. This is ideal for drying herbs because sensitive leaves retain their structure and color while achieving a uniform and reproducible drying result.
The multi-zone single-belt dryer used in this case study achieves a throughput capacity of up to 3,000 kg/h. This makes it suitable for large-scale industrial production and enables the economical processing of large quantities of herbs in continuous operation.
Very gentle. The stable belt transport combined with TARGETED ZONE HEATING (TZH) allows the temperature in each zone to be precisely adjusted. This means that only as much heat is applied as the product can tolerate during each stage of the drying process. This helps preserve color, aroma and valuable ingredients while significantly reducing product losses.
The system achieves a uniform residual moisture of approximately 5%. This low and, above all, consistent level ensures a long shelf life, prevents mold formation during storage and provides the basis for consistent further processing in the food industry.
Yes. One of the key advantages of industrial herb drying with a multi-zone single-belt dryer is its flexibility: Different herbs can be processed by adjusting the parameters of the PLC control system without requiring complex mechanical modifications. This enables fast product changeovers while maintaining consistently high quality.
