Resource recovery: Nutrients, metals, biogas

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.  

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.

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.

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.

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.

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.

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.

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

To recover ammonium from municipal wastewater, we have developed a process that uses the principle of gas absorption with membrane contactors. Gaseous ammonia diffuses across a hydrophobic membrane and is directly bound in an absorbent solution as ammonium sulfate.

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.

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.