Resource recovery: Nutrients, metals, biogas

At Fraunhofer IGB, we develop processes to create an added value from waste or residual materials. Biotechnological processes can be established economically and ecologically advantageous for the substance recycling along with waste and wastewater treatment.

The best known substance recycling process of organic materials such as biowaste or sewage sludge is the recovery of biogas as a renewable energy source. Organic residues that cannot be recycled further are particularly suitable for conversion by means of digestion. In this process, anaerobic microorganisms break down organic carbon compounds via various intermediate stages to produce biogas, a mixture of methane and carbon dioxide.  

By integrating further appropriate process steps, additional value substances such as fertilizer salts (from nitrogen and phosphate ingredients of sludge, sludge water, digestion residues and other waste) can be recovered.

Biogas – renewable energy with multifaceted potential

Fraunhofer IGB has developed a particularly efficient high-load process for the digestion of sewage sludge, but also other organic materials such as biowaste, kitchen waste or agricultural residues into biogas.

The generation of electricity from biogas, which is produced in biogas plants primarily from ensiled renewable raw materials, is an important pillar of renewable energies. Biogas occupies a special position in this context: While the generation of electricity from sun and wind is highly dependent on the weather, biogas can in principle be produced continuously, stored for a certain period of time and converted into electricity and heat in the combined heat and power plant by means of combined heat and power generation.

If biogas is purified accordingly, high-purity biomethane can be fed into the natural gas grid, used as a fuel (for natural gas vehicles) or used as a basic chemical substance.

Recovery of nutrients from wastewater, manure and residues

Nutrients such as nitrogen, phosphorus, potassium, calcium and sulfur are essential components of fertilizers and thus indispensable for the world’s food supply. Nowadays, these nutrients are only partially recycled in agro-ecosystems, since human intervention has created a linear, dispersive system.

The key response to this lack of sustainability within agriculture and waste management is to recreate a cycle of nutrients. Not only liquid manure and digestion residues, but also municipal wastewater and residues from the food industry are rich in nitrogen, phosphorus, potassium or calcium. Fraunhofer IGB develops sustainable and cost-effective technologies and processes to recover the valuable nutrients and process them into plant-available fertilizers and soil conditioners.



Sludge management on wastewater treatment plants

Our services in the area of sludge management on municipal and industrial sewage treatment plants cover various aspects and range from solutions for filamentous bulking and foaming, to process adaptation from aerobic to anaerobic sludge stabilization, to digester design and optimization of digester operation.  


Nutrient recovery from sewage plants

For more than 25 years Fraunhofer IGB has been developing biotechnological processes for the treatment of water and waste. In addition to the organic load, wastewater also contains larger quantities of nutrients such as nitrogen, phosphorus, magnesium or potassium. Fraunhofer IGB is developing processes for the recovery of nutrients from wastewater streams.


Biogas from of organic waste and renewable raw materials

Organic substances rich in solid material with variable composition are found in several locations and processes. Fraunhofer IGB supplies customized, adapted solutions for the material and energetic use of by-products from the food industry and other organic material streams.


Digestate – raw material for nutrients and soil conditioner

In addition to valuable organic matter, digestate also contains important nutrients. At Fraunhofer IGB, methods are being developed to recover phosphorus and nitrogen. Furthermore, we develop soil improvers by processing the organic matter of the digestate.


Processing of liquid manure to mineral fertilizer and soil conditioner

Fraunhofer IGB develops technologies for the recovery of nutrients and other resources als well as organic components from agricultural waste such as manure to produce high-quality and compact organic and mineral fertilizers.


Nutrients from food and animal feed industry

In the food and animal feed industry, there is a great need for technologies for the sensible use of residues and waste. In this context, the researchers at Fraunhofer IGB develop methods for the preparation of production remains and the recovery of nutrients from these.


Plant and soil substrates

Due to intensive agriculture and the consequent soil contamination it is crucial to maintain the soil quality in arable areas. That is why there is a high demand for fertilizers. For this reason Fraunhofer IGB explores  sustainable production processes of fertilizers and soil conditioners, as well as of plant protection products on a biotechnological basis.



Two-stage high load digestion

Th IGB has developed a particularly efficient high-load process for the digestion of sewage sludge into biogas. It was first put into operation in 1994 and has since been successfully operated by other municipal wastewater treatment plants. The process has an improved efficiency, a short residence time and a high degree of degradation. It is also used for the anaerobic conversion of organic substrates such as liquid manure or biowaste.


ePhos®: Electrochemical phosphorus recovery of phosphorus

For the recovery of phosphorus from municipal wastewater, we have developed an electrochemical process that delivers the high-quality fertilizer struvite without added chemicals.


BioEcoSIM® – Multi-stage process for the treatment of manure and digestate

For the treatment of liquid manure or fermentation residues, different procedural steps are required, which have been integrated as separate modules in a plant. Thus phosphorus fertilizer, nitrogen fertilizer and soil conditioner can be obtained.


Nutrient removal or recovery from process water and fermentation residues

In anaerobic sludge treatment, nutrients often remain in the aqueous phase. These nutrients can be removed or recovered from the resulting process water through appropriate process steps, e. g. for cultivation of microalgae or fertilizing watering in agriculture.


Drying of solid biological residues and active substances

At the IGB, fermentation residues, the organic liquid manure fraction or cyanobacteria are dried with a new type of dryer using superheated steam dryer (SHSD). This dryer, developed at Fraunhofer IGB, offers significant advantages over conventional dryers using hot air.


Bioleaching and biomining

Bioleaching processes use bacteria to mobilize metals from spoil heaps or waste. The focus at the IGB is on the extraction and recovery of dissolved metals by biological processes such as biosorption, bioaccumulation or bioprecipitation.