Innovative Solutions for Water Reuse in Agriculture

The availability of water is becoming an increasing challenge worldwide. Even water-rich countries such as Germany are experiencing longer periods of drought, leading to local and regional water shortages. The reuse of treated wastewater can make a decisive contribution to securing the water supply. The potential is particularly high in agriculture, which consumes about 70 percent of the world's drinking water. To further develop the use of treated water in agriculture, four new research projects have been launched in the current funding round of the German-Israeli Water Technology Cooperation. They will investigate how to make water reuse safer, more efficient and more sustainable. The results will not only be used in these two countries, but are also of key importance for other countries in the Middle East, which are among the most affected by water shortages worldwide.

In Israel, treated wastewater has been successfully reused for irrigation for decades. The recycling rate is almost 85%. The cooperation projects therefore benefit from the extensive experience of the Israeli partners in this field. Interest in alternative water resources is also growing in Germany. So far, only a very small amount of the water extracted in Germany is used for agricultural irrigation. However, due to increasing drought in recent years, there is growing regional interest to recycle wastewater in order to conserve groundwater reserves.

Consistent Water Quality, Smart Nutrition Management, Environmentally Friendly Pollutant Removal and Optimized Water Infiltration

Depending on its origin and treatment, reclaimed wastewater might still contain contaminants. To ensure that reuse is safe for people and the environment, it must meet high and application-specific quality requirements. In agriculture, for example, irrigation water must be hygienically safe. To ensure this, the StaySafe cooperation project is investigating how to maintain consistently high microbiological water quality during the transport and storage of treated wastewater. Fluctuating operating conditions are a particular challenge: During dry periods, a lot of water is needed, while during rainy periods it often remains in the distribution system for a long time. This can encourage the growth of pathogens and antibiotic-resistant genes in storage tanks. StaySafe is investigating how to efficiently manage such dynamic systems, for example by using digital twins to predict water quality through simulation, or by adapting disinfection strategies to current water demand.

In addition to pathogens, excessive nutrient levels in treated water can be problematic. Although nitrogen and phosphorus are essential for plants, excessive loads can cause environmental problems. In the INNUWA project, participants are developing an intelligent system for monitoring and controlling nutrients in treated wastewater. The goal is to increase the efficiency of water and nutrient use while reducing the environmental impact of excess nutrients. Advanced sensors and artificial intelligence are used to accurately analyze the nutrient content of irrigation water. This data is fed into an online decision support system. It helps farmers to optimize the use of water and fertilizer. The system is being tested under real-life conditions in Germany and Israel, in both hydroponics and open field cultivation.

Organic micropollutants in wastewater are particularly challenging because their removal is difficult and costly. These substances include pharmaceutical residues, pesticides, industrial chemicals and endocrine disruptors. Even low concentrations can have long-term effects on humans and the environment. Activated carbon is often used to combat such contaminants. But most of them are made from environmentally harmful fossils such as lignite or expensive imported coconut shells. It is also energy intensive to produce, has a limited capacity to absorb pollutants, and is expensive to reuse. The PaWAC project is developing a sustainable and cost-effective alternative: activated carbon made from renewable organic waste materials. For example, agricultural waste, wood residues and residues from food production are utilized. This resource-conserving alternative is expected to filter and bind pollutants from wastewater as well or even better than conventional activated carbon.

To make more treated wastewater available for agricultural irrigation, it can be infiltrated and stored in aquifers. During this natural filtration process, any microorganisms and pollutants still present in the wastewater are further reduced. The German-Israeli team in the DataSAT project is working to optimize infiltration in the Shafdan-SAT water recovery system in the greater Tel Aviv area. For example, machine learning and digital models are being used to predict infiltration capacity and automatically control the system. The project participants intend to publish the models and simulations developed as open source software so that they can be used for similar water reclamation systems worldwide