Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB
Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB

System Integration

In the treatment of process water, basically it is necessary to distinguish between the separation of substances, for example the extraction or recovery of materials, and the degradation of pollutants. Thus in many applications this means that processing has to be carried out in at least two process stages. However, it may also be necessary to include several subprocesses within one stage, for example in degradation.

The growing necessity for conserving resources means that the separation of substances, value preservation and in particular here selective separation, are becoming increasingly important.

Especially in the case of typical industrial wastewaters with a complex composition, efficient separation of substances is frequently not possible with just one single process stage. By combining and integrating various processes we are able to develop efficient and coordinated solutions, which are optimized in their overall impact as a process chain regarding selectivity and energy efficiency. In this way, results can be achieved that exceed the sum of the results of the individual process stages.

Water treatment with added value – combination of processes

A unique feature is our competence to integrate separate processes and components in system solutions. For this purpose we have at our disposal the very wide range of technologies established at the IGB. Further special competences and technologies can, if necessary, be made available through our network with other research establishments and industrial partners.

Membrane adsorbers, for example, can be used for concentrating solutions with a low pollutant concentration in order to treat the enriched solution energy-efficiently with AOP technologies and to destroy the pollutant. For a complete and also energy-optimized degradation of pollutants, physical-chemical and biological processes can be combined and be investigated at laboratory and pilot plant scale.

A further focus of research are the combination of adsorptive and electrophoretic processes and their integration in process chains. For example, capacitive deionization can be used advantageously for the preconcentration of substances in the water that are subsequently to be separated by means of free-flow electrophoresis. Another example is the selective separation of larger molecules before electrodialysis by means of electro-membrane filtration.

Automation and autonomous operation

As far as possible we develop process concepts that are flexible on the operational level. A further advantage of these processes is that they are suited to standby operation and can be switched on or off at any time. Integration in existing plants and automation including autonomous operation or remote control are feasible without any problems. For example, the continuous online logging of organic carbon (TOC, total organic carbon) can guarantee a requirement-based treatment that is therefore also energy-optimized.

AOP systems – more than hydroxyl radicals

Oxidative water treatment (AOP, advanced oxidation processes or AOT, advanced oxidation technologies) is understood as processes for chemical treatment in which highly reactive hydroxyl radicals are used for oxidation reactions of persistant substances in the water.

AOP processes are always used when a biological decomposition is not feasible or cannot be carried out efficiently, for example because the contaminations contain persistent substances. Also, AOP processes are the method of choice when the process wastewater has a toxic effect on the microorganisms of a biological purification stage or occurs extremely discontinuously.

In many cases a combination of processes is advisable with a reductive partial decomposition as the most energy-efficient variant. The possibility of testing an extremely wide range of combined treatments in the IGB laboratories and technical-scale facilities is one of our unique service features.

Formation of hydroxyl radicals without chemicals

In general, the formation of the reactive hydroxyl radicals can be achieved by metering oxidizing substances such as ozone and hydrogen peroxide, and also by introducing energy using plasma technology, UV radiation, ultrasound or electric current and by a combination of these methods. We investigate and also optimize the processes with hydrogen peroxide metering (Fenton reaction, UV/H2O2 and O3/H2O2) and ozone treatment as established reference processes. In the case of the electrolytic, photolytic and plasma-technological AOP processes developed at the IGB the reactive species are generated directly by the process itself, so that there is no need for the use of auxiliaries (gases, liquids) and for possible waste disposal.

Enrichment and fractionation systems

A further focus of research are the combination of adsorptive and electrophoretic processes and their integration in process chains. For example, capacitive deionization can be used advantageously for the preconcentration of substances in the water that are subsequently to be separated by means of free-flow electrophoresis. Another example is the selective separation of larger molecules before electrodialysis by means of electro-membrane filtration.

Reference projects

Related Links: