Recovering essential raw materials from wastewater to bring them back into the value chain

The consumption of natural resources by modern industrial societies is leading to a shortage of essential raw materials. This includes phosphorus, for which there are hardly any geogenic sources in the European Union.

In order to conserve resources and become independent of imports, a research team at the University of Kaiserslautern-Landau is developing the basic processes for recover phosphorus and other raw materials from wastewater streams and sewage sludge and making them usable for industry.

Phosphorus is an important raw material for fertiliser production and therefore also for food production. It is included by the European Commission in a list of 30 critical raw materials with a high supply risk and high economic importance.

Municipal wastewater, into which large quantities of phosphorus from private households and industry are discharged, offers potential for recovery. This is motivation for research within the research training group "WERA" (Wertstoff Abwasser - valuable wastewater) at the University of Kaiserslautern-Landau, which is funded by the German Research Foundation.

WERA focuses on several goals: "We are working on possible solutions to reduce the phosphorus concentration in municipal wastewater from the inlet to the outlet by a factor of around 100," explains Professor Dr Sergiy Antonyuk, spokesperson for the research training group and head of the Institute of Particle Process Engineering at the University of Kaiserslautern-Landau. "At the same time, our aim is to process the removed phosphorus in in such a way that it can be made available again as a resource for industry in line with the recycling principle."

A third aspect concerns the environment. Professor Dr Heidrun Steinmetz, deputy spokesperson of the research training group and head of the Department Resource Efficient Wastewater Technologies at University Kaiserslautern-Landau, explains: "The phosphorus concentration in the outlet of wastewater treatment plants also needs to be further reduced in order to protect our waters from algae formation. There are already pilot projects implementing this idea for individual sewage treatment plants but not in combination with P recovery. However, there are considerable gaps in our knowledge. which processes are promising under which conditions. This is what we hope to find a solution for."

As part of the research programme, the University of Kaiserslautern-Landau combines expertise from the natural sciences and engineering. Among other things, the programme involves the investigation of tailor-made adsorber materials on which phosphorus compounds can accumulate. Another research task consists of investigating basic mechanisms of crystallisation and precipitation. These are separation processes that can be used to recover phosphorus from sewage sludge in the form of plant-available fertilisers.

"In addition, we will use and further develop innovative methods of characterisation, measurement techniques and simulation methods to describe the influences of boundary conditions in the real wastewater system on the efficiency of phosphorus recovery with crystallisation and adsorption processes and the product quality," Steinmetz and Antonyuk add.

"We perform the investigation using an experimental wastewater treatment and recycling plant installed as a pilot project on the University of Kaiserslautern-Landau in Kaiserslautern. Our ultimate goal is to transfer the developed materials and processes to other raw materials and adapt them to recover nitrogen, potassium or organic carbons, for example."

» More about WERA

Source: University of Kaiserslautern-Landau (RPTU)