Production and treatment of drinking water

Water vapor in the atmosphere is a source of high-quality drinking or process water. Current research at Fraunhofer IGB is focusing on the use of efficient adsorption systems that capture atmospheric water and, when required, release this as drinking water and other purposes.

We have many years of expertise in the investigation of bacterial contamination and in the determination of the efficacy of individual disinfection approaches. We specialize in the identification of bacteria, viruses and fungi as well as in the analysis of biofilms and how to reduce or avoid them in technical systems.

Further developments focus on the removal of micropollutants by means of advanced oxidation processes (AOP) and membrane adsorbers.

Thermal processes for drinking water production and water treatment

Heat dehumidification. — Water from air humidity.

In many regions of the world, climate change, high water consumption and a growing world population have led to a shortage of natural drinking water resources. In coastal areas, for example in southern Europe and on many islands in the Mediterranean, groundwater is already salinated by the infiltration of seawater.

However, common technologies for water desalination, such as reverse osmosis and conventional thermal processes, are energy-intensive and consume large amounts of fossil fuels, directly or indirectly, with significant CO₂ emissions. Fraunhofer IGB is developing an energy-efficient and low-cost alternative that allows thermal energy to be used for multi-stage vacuum evaporation of water even at comparatively low temperatures. The negative pressure required for evaporation is generated and maintained by an innovative solution using gravity alone.

Another resource for obtaining drinking or process water of the highest quality is air humidity. Current research work concentrates on the implementation of concepts that enable the air humidity to be bound in a hygroscopic salt solution and released as usable water.

Disinfection

UV light source — Disinfection of water using UV light

A disinfection step is of the utmost importance to supply the population with safe, high-quality drinking water. Also high-quality, hygienically safe water is required as process water in the pharmaceutical and food industries.

In addition to the classical method of chlorination, treatment with ozone and disinfection by means of UV light have been established as reliable and environmentally friendly processes. Mainly tubular low-pressure mercury vapor lamps that emit radiation of the wavelength 254 nm are currently in use.

Biofilms and hygiene

Biofilme — © Fraunhofer IGB
Identification of microorganisms.

At Fraunhofer IGB, we have been working for several years on issues involving the interactions between microbial cells and surfaces. We also have the technical expertise to characterize biofilms and surfaces and to develop individual approaches to prevent bacterial deposits.

Our interdisciplinary team of experts will also be happy to advise you on hygiene concepts.

Membrane filtration processes

In industry, membrane technology has also proven itself as a separation technology for the treatment of raw water to process water or for the purification of process wastewater. They operate without phase change, and the equipment required is kept within limits. Further advantages are simple upscaling (modularity) and low chemical consumption.

At Fraunhofer IGB, membrane materials, membranes and membrane processes are researched and developed for microfiltration (MF, suspended particles, bacteria), ultrafiltration (UF, macromolecules, viruses and colloids), nanofiltration (NF, organic compounds and divalent ions) and reverse osmosis (monovalent ions).

Membranes for water purification

Enrichment and elimination using membrane adsorbers

A further focal point are membrane adsorbers, which combine the advantages of membranes with those of adsorber materials. For this purpose we equip membranes with special functional groups in order specifically to remove contaminants such as heavy metal ions (Pb, Cd, Cu) or organic molecules (penicillin G, bisphenol A) from process wastewater by means of adsorption. The membrane adsorbers can be operated at low pressures, they retain suspended particles and achieve water flux values in the range of MF membranes.

Membrane adsorbers are also used for concentrating solutions with a low pollutant concentration in order to treat the enriched solution energy-efficiently with AOP technologies, e.g. electrolytic, photolytic or plasma-technological oxidation processes, and to destroy the pollutant.

Separation of micropollutants and metals with membrane adsorbers

Removal of trace organics from water

Batch-Reaktor zur UV-C/H2O2-Behandlung von Wasser. — Batch-Reaktor zur UV-C/H₂O₂-Behandlung von Wasser.

The IGB offers independent scientific consulting on pollutants and trace pollutants removal to public and industrial customers. Our technicians regularly test degradation of biologically inert organic pollutants called hard COD by ozone and UV-C-H₂O₂. Because accumulation of hard COD prevents closed water cycles in many production lines. Our engineers and scientists compare these treatment options to our customer’s respective alternatives, e.g. filtration and adsorption units.