As the General Assembly of the UN resolved on July 28 of this year, clean drinking water and basic sanitary provision are human rights. Unfortunately, there are more than one billion people all over the world who do not have access to drinking water, while as many as 2.6 billion people live without any sanitary systems at all – that is well over one-third of the world’s population. 

Not only that, water is a pre-eminent economic factor because agriculture and industry consume more than four-fifths of this precious commodity these days. A study by the UN indicates that in future water will be more important in strategic terms than petroleum. This is the reason why 14 Fraunhofer institutes have joined forces in the Fraunhofer Alliance SysWasser to come up with sustainable water system technologies. They will be unveiling "Research for Tomorrow’s Water Utilization" in hall A4, stand 201/302 at the IFAT/Entsorga fair. 

Drinking Water from the Air

Drinking water can be extracted from the humidity in the air even in the desert or in the middle of a megacity, which is made possible by a technology developed by Fraunhofer. The principle behind it is a salt solution that runs down from a tower-shaped system and absorbs water from the air. The hygroscopic brine is then pumped into a tank that stands a couple of meters high and contains a vacuum. Then, energy from solar collectors heats up the brine and the evaporated salt-free water condenses over a distillation bridge. The brine concentrates again and flows down on the surface of the tower to absorb humidity in the air. 

This process is exclusively based on regenerative sources of energy such as simple solar collectors and photovoltaic cells, meaning that this method is completely energy self-sufficient. That means that it functions in areas where there is no electrical infrastructure. This process is particularly well suited for extracting drinking water in arid and semi-arid areas where more water evaporates than precipitation falls. 

Managing Drinking Water Systems

How can we best operate drinking water supply systems? Are there leaks in the line system? The researchers at Fraunhofer developed the HydroDyn management solution along with drinking water suppliers to provide answers to these questions. First of all, the drinking water system is recorded and modeled in the computer because that is the best way to figure out the optimum operating regime for these systems, or to plan how to expand supply systems. Beyond this, the system can automatically localize leaks. This is the reason why this software solution is already being used in Mongolia, Libya and Saudi Arabia as well as at the department of works in some German cities. 

Tracking Down Leaks

There is a certain portion of our precious water that does not even get to consumers because of leaky pipes and rust and instead it seeps unused into the soil. "Intelligent" probes that check lines from the inside are one means of tracking down damage. Cracks or damage from corrosion in the pipes can also be localized with long-range ultrasound waves and these systems are suited for fresh water and sewage pipes as well as for pipelines. 

Diamonds Clean Sewage Water

Diamond-coated electrodes make it possible to clean water without chemistry. The idea is that hydroxyl radicals are formed in the water on electrodes coated with conductive diamonds. This highly effective oxidant destroys all substances containing carbon, meaning the organic pollution load of solvents right down to bacteria and pesticides. The only things that remain are harmless salts and carbon dioxide that escape as gases. This is how we can produce germ-free water without any problems. Researchers will demonstrate how this technique functions at their fair stand using the example of the textile dye indigo carmine, because the discolored water can be easily stripped of its color in an electrochemical cell with diamond electrodes. 

Money-Saving Disposal

Heavy metals, cyanide salts, solvents and complex chemical compounds - heavily polluted waste water from the metallurgical or printing industries constantly has to be disposed of as hazardous waste in a costly process. The problem is the fact that the pollution is highly diluted, with the proportion of water sometimes being as much as 90% and even more. That makes it very expensive to dispose of. This is the reason why researchers at Fraunhofer have devised a low-cost modular vacuum evaporation process where the waste water is thickened in a vacuum at temperatures from approx. 40°-50 °C. The waste water can be easily heated up with waste or solar heat and the desalinized water can even be used in production again. 

More Biogas from Sewage Sludge

More than 10,000 sewage treatment plants clean the polluted water from households, factories and restaurants in Germany. The clean water is then discharged into rivers and lakes again and the only thing that remains is the sewage sludge. Researchers at Fraunhofer have come up with a process to reduce the volume and mass of sewage sludge where a portion of the sludge is treated with ultrasound and then mechanically disintegrated. The residues processed in this fashion supply more biogas which means that they can be more easily drained. This new process has already been successfully applied to sewage treatment plants. 

Researchers at Fraunhofer will be showcasing these and other solutions for sustainable water supply at their joint stand. In addition to this, the Fraunhofer Water Systems Alliance will be presenting "Research for Tomorrow’s Water Utilization" in a seminar starting at 4 p.m. on September 16 in the forum of hall B1.