Fraunhofer with wastewater project in Bitterfeld-Wolfen

The quality requirements for water are increasing and the water industry is facing new challenges. On the one hand, this is due to the scarcity of water as a resource: the supply is decreasing due to climate change, but at the same time demand is growing, for example in agriculture or due to the widespread switch to a hydrogen economy. In addition, modern methods of analysis are now detecting previously unnoticed pollutants in water, even in the smallest concentrations, including pharmaceutical and chemical residues, so-called micropollutants. "We have to prepare ourselves for the challenges of the future," explains Dr Burkhardt Faüauer, head of the Circular Technologies and Water department at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS.

Research platform directly on the factory site

The project in Bitterfeld-Wolfen, which the Fraunhofer researchers launched in autumn 2022, aims to enable even more efficient protection of water and drinking water. Another goal is to extract recyclable materials from wastewater. „Some residues or process chemicals in industrial wastewater can be reused as raw materials for industry. This applies, for example, to various salts or metals. We are developing processes with which these raw materials can be recovered from the wastewater," explains Mr Faäauer. In addition to Fraunhofer IKTS, the Fraunhofer Institutes for Solar Energy Systems ISE, for Microstructure of Materials and Systems IMWS and for Molecular Biology and Applied Ecology IME are also involved as project partners.

The special thing is that the Fraunhofer researchers have not installed their technology platform in the laboratory. Rather, they have set up a series of test containers on the site of the Bitterfeld-Wolfen joint venture plant. According to the operator, the wastewater treatment plant is one of the most modern in central Germany. In addition to municipal wastewater, it primarily treats industrial wastewater from the almost 300 companies in the Bitterfeld-Wolfen Chemical Park, one of the largest in Europe.

„Here we are directly on site and can access specific wastewater in a targeted, continuous manner and in relevant quantities. This enables us to carry out the experiments close to the industrial scale and under real conditions," says André Wufka, Head of the Water and Wastewater Systems Technology Group. A key advantage of the technology platform is the basic concept of its modular design. Units and systems can be replaced at any time or moved to a different position in the process flow. This allows the expert teams to simulate, analyse, convert and optimise technical processes in the wastewater treatment plant almost at will.

Combine and further develop processes

In order to achieve their project goals, the experts are taking several approaches. They develop existing processes further, they combine conventional methods to create new processes and they work on innovative and ideally disruptive technologies. One example is intelligent, switchable membranes that recognise certain micropollutants and then separate them. Fraunhofer IKTS is contributing its experience and expertise in this area.

In addition to membranes, biological and electrochemical methods, the researchers also use modern sensor technology. For example, we are testing the performance of novel sensor systems that work on the basis of surface plasmon resonance spectroscopy. The pollutant molecules to be detected, which adhere to a nanostructured sensor substrate, change the refraction of light. The sensor registers the altered refractive index of the light, thus measuring the concentration of pollutants in the water and could be used to control a cleaning process," explains Wufka.

Remove harmful salts

In addition to testing new technologies for the treatment of industrial wastewater, the Fraunhofer experts are also focussing on another problem: the residues such as salts that are produced during the cleaning process. They are often a component of production wastewater, and even the purified water still contains some salts. If these salts get into rivers in large quantities, this can lead to problems. During a hot spell, such as in the summer of 2022, the river level drops and the concentrations of substances contained in the river water rise accordingly. This can have significant consequences for the underwater flora and fauna," says Wufka. The researchers at Fraunhofer IKTS are therefore working together with partner institutes not only on solutions to reuse the salts obtained in production, but also on how to remove them even more effectively from wastewater.

Use directly in production

The filter and cleaning technologies developed in the project benefit the sewage treatment plants, but can also be used directly in industrial production. Here, the Fraunhofer researchers can utilise the flexibility of their technology platform by testing suitable cleaning strategies for individual problems or requirements of an industrial customer.

Companies in the chemical industry, for example, can install a system developed by us for the recovery of raw materials in wastewater directly in the production hall,

says Faßauer.

Article from " Chemie Technik" from 15 March 2023