The sustainable handling of water is one of the core challenges of our times and is anchored in the United Nations’ Agenda 2013 as one of the sustainability goals (SDG). But how could this sustainable management look like? “We have tested water saving technologies in numerous research projects”, says Martin Zimmermann, water researcher at ISOE. “Particularly the reuse of treated wastewater offers great potential which has hardly been used so far.”
There is still not enough thought given to the matter which water quality is required for which purpose. “It remains unquestioned if drinking water should be used for gardening, washing cars, or for toilet flushing.” says Zimmermann. If treated, the same water can be used two to three times not only in households but also for industrial purposes. “Given that 70 percent of the globally available potable water is used in agriculture, the question is furthermore how the use of treated wastewater in agriculture can be organized in a reasonable manner.”
Taking off pressure on the resource: treated wastewater also for agriculture
Particularly in semi-arid regions, the reuse of treated wastewater can contribute to reduce pressure on water resources. It is important, though, to develop attractive concepts for water reuse which are optimally adapted to the specific conditions on-site. This is the aim of one of the current research projects carried out by ISOE and the Technical University of Darmstadt: In Namibia, for example, wastewater is often collected in ponds where solid substances settle down. Due to its hygienic conditions, the water cannot be used for agriculture irrigation. However, by adding simple treatment steps, for example through the separation of sludge and water, the water could be reused for irrigation. “This can serve as a blueprint for many regions in Southern Africa”, states Dr. Zimmermann.
For Germany, another innovative approach is investigated by ISOE and its partners. Here, the question is how to treat wastewater with the help of a modular technical set in such a way that it can be used as a source of water and nutrients for the operation of hydroponic systems. In hydroponic cultivation, plants are grown in soilless systems with the help of a nutrient solution. Hydroponic systems achieve a significantly higher production capacity than conventional cultivation while requiring less space and significantly less water.
This is particularly relevant with regard to the rapidly growing global population. For the provision of food security, sufficient irrigation water of adequate quality is essential. Particularly those regions which already suffer from water scarcity have to think about alternative water resources and sustainable management concepts. “The imbalance between a rising water demand and limited water resources will increase in the coming years.” states water expert Dr. Zimmermann. “With these concepts for efficient water use we can at least reduce the pressure on the resource to a certain extent.”