ecoFertiliser Factory

The SWISS COMBI ecoFertiliser Factory (eFF) processes liquid and solid digestate from biogas plants or manure into marketable fertilizer granules or pellets. In doing so, we address various environmental issues and make a significant contribution to a circular economy.

Biogas is a CO2-neutral substitute for natural gas. There is a high demand for biogas, and the trend is towards larger and more biogas plants. During the production of biogas, liquid digestate is generated, which is commonly used as fertilizer on fields, similar to manure.

However, an excess of liquid digestate poses a significant environmental burden, such as nitrate pollution in groundwater, ammonia and nitrous oxide emissions, as well as “manure tourism.” The SWISS COMBI ecoFertiliser Factory can help address these issues by processing the liquid digestate or manure into fertilizer granules or pellets.

This process involves two main steps. In the first step, the liquid digestate or manure is treated in a vacuum evaporator to obtain a creamy concentrate. In the second step, this concentrate is dried into solid fertilizer using the SWISS COMBI ecoDry.

Concept SWISS COMBI ecoFertiliser Factory

Application areas of the ecoFertiliser Factory

Biogas Plants: Dry Fermentation

Pressed water from dry fermentation is processed into fertilizer pellets.

Biogas Plants: Wet Fermentation

Liquid residues from wet fermentation are processed into fertilizer granules or pellets.

Manure

Farm animals (e.g. pigs or cows) produce large amounts of manure, which can be processed into fertilizer pellets.

Advantages of an ecoFertiliser factory

Reduction of energy demand by

67%

Reduction weight and volume by

85%

Reduction of redistribution transportation by

75%

High energy efficiency
High environmental benefit
Application of nutrients when the plants need them
Good storability and easy handling
Accurate dosage
Production of plant specific fertilizers
Organic fertilizer
Possibility of organic certification

High energy efficiency

By using the waste heat from the ecoDry dryer for the vacuum evaporator, the energy can be used twice: First in the dryer, then in the evaporator. This enables us to achieve very high energy efficiency. In the eFF process, we typically need only 330 kWth to remove one ton of water. That is only one-third of the energy that would typically be needed for pure drying.

High environmental benefit

Too much liquid digestate or manure on the fields leads to high environmental pollution: Groundwater is polluted with nitrate, ammonia outgasses and threatens biodiversity, nitrous oxide increases global warming (nitrous oxide is 298x more harmful to the climate than CO2). Since the liquid fermentation residues/slurry can only be brought to fields in the surrounding area to a limited extent, they often have to be transported to distant fields by truck. This slurry transportation causes corresponding CO2 emissions. Our solution helps with all these points.

Application of nutrients when the plants need them

Plants typically require nutrients in spring and summer during the growth phase, but hardly ever in fall and winter. Nevertheless, slurry stores are often emptied again in the fall to have sufficient storage capacity over the winter when slurry application is prohibited. Since the plants cannot fully utilize the nutrients in the fall, these end up in the groundwater, for example, and thus pollute the environment.

Good storability and easy handling

Fertilizer granules and pellets are easy to store, they only need to be protected from moisture. This is possible in most on-farm buildings. In addition, fertilizer granules and pellets can be stored for several years. If they are not used in one year, they can readily be used the following year or even later. The fertilizer granules and pellets have a low odor level, can be spread and are dust-free.

Accurate dosage

When liquid digestate or manure is applied to the fields, the exact composition is not known. Therefore, too much is often applied rather than too little. The composition of the fertilizer granules/pellets in terms of nitrogen, phosphorus and potassium (NPK) is regularly analyzed and monitored during production. This means that the nutrients are known, and accurate dosing is possible. This is beneficial for both the plants and the environment.

Production of plant specific fertilizers

Plants have different needs regarding their nutrient supply. In pelleting, it is possible to change the NPK composition of the fertilizer by admixing additional fertilizer materials. For example, a fertilizer with NPK 12-2-3 can be created from the starting material NPK 5-1-3.
Switching between two different end products can be done easily and quickly.

Organic fertilizer

Fertilizers produced from press water, liquid digestate or manure are an excellent organic alternative or supplement to synthetic mineral fertilizers. The latter are expensive, often have to be imported leading to criticism for their environmental impact. The raw material for our fertilizers is already available. Therefore, fewer imports are needed, resulting in lower costs and greater independence from the global market.

Possibility of organic certification

Under certain conditions, fertilizers produced in the eFF can be approved for organic farming. For pressed water, the criteria of the Research Institute of Organic Agriculture FiBL can be met quite well. For liquid digestate and slurry, attention must be paid to the amount of ammonium-N and urea-N. The ammonia in the condensate must be removed with a stripper. However, the requirements for approval as a biofertilizer often vary from country to country.

Raw materials suitable for the ecoFertiliser factory

- Digestate
- Press water
- Liquid manure
Find the right dryer

When it comes to drying, there are often more possibilities than you might think. We specialize in designing and constructing drying systems for various types of raw materials. If you have a new task or project for us, please get in touch.

We would be happy to discuss the possibilities and find the right drying solution for your specific needs.

Call us or send an email to learn more about our products and services

The SWISS COMBI ecoFertiliser factory produces a spreadable fertilizer granulate or fertilizer pellets from solid and/or liquid fermentation residues from biogas plants or from liquid manure, and does so in an extremely energy-efficient manner.