Brewing beer generates more than the finished beverage. One of its main solid byproducts is brewer’s spent grain, a material that leaves the brewing process carrying a substantial amount of water.

Fresh spent grain commonly contains around 80–85% moisture. At this level, the material becomes heavy and bulky, increasing the demands placed on storage, conveying and transportation. More importantly, when the final product needs to reach a much lower moisture level, removing all that water through thermal drying can require considerable energy.

This makes the initial dewatering stage an important part of the overall processing strategy.

A Practical Pilot Project: From 100 kg of Wet Grain to a Dry Product

A recent pilot application highlights the challenge clearly.

The project is designed to handle approximately 100 kg of wet spent grain per day. After processing, the target is around 20 kg of finished dried material per day, with the final moisture controlled at approximately 8–12%.

The dried product will then undergo screening and milling before being developed for two potential markets:

Food ingredients and animal feed.

For this type of application, sending high-moisture spent grain directly into a thermal dryer is not necessarily the most efficient approach. Introducing mechanical dewatering first can remove a significant portion of the free water and reduce the amount of moisture that must later be evaporated by heat.

This creates a more efficient connection between the wet raw material and the final low-moisture product.

How Does a Spent Grain Screw Press Work?

The HUATAO screw press uses continuous mechanical compression to separate liquid from solid spent grain.

Wet material enters the feeding hopper and is gradually transported forward by a rotating screw. As the material advances through the pressing chamber, the available space decreases and compression progressively increases.

Under this mechanical pressure, free liquid is released from the spent grain and passes through the machine’s specially designed wedge-wire screen.

Meanwhile, the dewatered solid fraction continues toward the discharge end.

An adjustable back-pressure system at the outlet helps control the resistance inside the pressing zone, allowing the machine to maintain consistent operating conditions. The separated liquid is collected through the drainage system, while the partially dewatered spent grain is discharged continuously for subsequent processing.

The principle is simple:

Wet Spent Grain → Mechanical Pressing → Liquid Separation → Dewatered Grain → Thermal Drying

Why Dewater Before Thermal Drying?

1. Reduce the Water Entering the Dryer

Thermal drying becomes much more demanding when the feed contains excessive free water.

Mechanical dewatering removes part of this water before the material reaches the dryer, reducing the amount of moisture that needs to be evaporated during the thermal stage.

2. Lower the Thermal Drying Burden

Producing dried spent grain with a final moisture of 8–12% requires substantial moisture removal.

Using a screw press as a pre-treatment step can reduce the thermal load placed on the dryer. Instead of relying entirely on heat, the process combines mechanical water removal with thermal drying, allowing each technology to perform the task it is best suited for.

3. Improve Material Handling

Once excess free water has been removed, spent grain becomes easier to convey, transfer and temporarily store.

The reduced moisture content can also provide a more suitable feed condition for downstream equipment such as dryers, screens and mills.

4. Support Continuous Processing

Mechanical screw pressing provides continuous solid-liquid separation rather than relying on intermittent manual pressing or batch-based operations.

This makes the technology suitable for pilot-scale trials while also offering a processing principle that can be adapted to larger production systems.

5. Prepare Spent Grain for Further Utilization

Dewatering is only one stage of the complete process.

After mechanical pressing and final drying, the material can be screened and milled according to the requirements of the intended application. Depending on product specifications and local regulations, dried spent grain may be further processed for animal feed, food ingredients, functional products, composting or other resource recovery applications.

A Two-Stage Processing Route for Dried Spent Grain

For pilot projects targeting low final moisture, a practical process configuration is:

Wet Spent Grain → Screw Press Dewatering → Thermal Drying → Screening & Impurity Removal → Hammer Milling → Finished Product

Each stage has a specific role.

The screw press focuses on removing free water mechanically.

The thermal dryer then reduces the remaining moisture to the required final level.

Finally, screening and milling help prepare the dried material for its intended application.

This separation of duties can make the overall process more manageable and can help avoid using thermal energy to remove water that could first be separated mechanically.

Mechanical Dewatering Is a Pre-Treatment — Not a Replacement for Drying

For applications requiring a final moisture content of 8–12%, a screw press should not be considered a substitute for the dryer.

Its role is different.

The screw press acts as a mechanical pre-dewatering stage, reducing the amount of water entering the thermal drying system. The dryer then completes the final moisture adjustment.

This combined approach can help improve the overall energy efficiency and economics of spent grain processing, with actual performance depending on feed characteristics, equipment configuration and operating conditions.

Customized Spent Grain Dewatering Solutions from HUATAO

Every spent grain project has different requirements.

Feed moisture, particle structure, fiber content, processing capacity, desired dewatering level and downstream drying technology can all influence equipment selection and process design.

At HUATAO, we provide screw press dewatering solutions for brewer’s spent grain and other high-moisture organic materials. For pilot applications, we can develop the equipment configuration around the actual material and production requirements, helping integrate mechanical dewatering into the complete processing line.

If your project involves wet spent grain, thermal drying and a low-moisture final product, mechanical dewatering can be an important first step toward a more efficient process.

Email: team2@huataogroup.com
Phone / WhatsApp: +86 177 3285 2676
Website: huataofilter.com

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