As it becomes ever more important to conserve water resources, the re-use of wastewater is playing an increasingly significant role. In agricultural irrigation, treated wastewater is an excellent alternative, and one that saves valuable resources.
"In view of the large quantities of water needed for agricultural production of food, great potential is seen in the reuse of wastewater for irrigation purposes," says Prof. Dr.-Ing. Peter Cornel from the wastewater technology department at the Technical University of Darmstadt. In arid and semi-arid regions, it is common practice. The International Waste Water Management Institute (IWMI, Sri Lanka) found three years ago that of the 53 cities in Latin America, the Middle East, Africa and Asia it investigated, around 80 percent were using part- or non-treated water in agriculture.
IFAT will look at the subject of irrigation, taking into account several examples of successful irrigation all over the world. In Jordan, a project funded by German bank KfW Entwicklungsbank uses treated municipal effluent from three treatment plants in the Irbid region for irrigation purposes, allowing each inhabitant of Jordan´s capital city Amman to have an additional 20 litres of drinking water available to them each day. The substantial difference in altitude between the location of the treatment plants near Irbid and the Jordan valley is to be exploited by constructing a power station to use the transport of the treated effluent to generate electricity for up to 15,000 households.
In Peru in 2009 SEDAPAL, the water resources agency for Lima, launched a treatment plant near the Peruvian capital to process effluent into water specifically for irrigating over 400 hectares of arable land. The concept and the components for the system were delivered by ITT.
In China, German research company ttz Bremerhaven is developing a new irrigation technique for energy wood plantations, in cooperation with Alensys AG based in Erkner, Germany, and Hydro-Air GmbH from Niedergörsdorf, Germany. In this BIOWARE project, sponsored by the German Ministry of Economics, municipal wastewater and ground water are mixed to produce a suitable nutrient solution. When this water is delivered via a controlled system of drip irrigation, savings can be made in terms of both cost and conventional fertilisers.
In addition to these centralised, large-scale treatment concepts, there is also the possibility of processing wastewater for irrigation decentrally, in much smaller units. In Indonesia for example, high water prices and the need to irrigate several parks prompted the operators of one hotel on the island of Sumatra to install a membrane bioreactor system in 2008. The technology for this, from Hans Huber AG of Berching (Germany), is housed in one of the lower floors of the hotel. Each day this plant delivers around 250 m3 of water for use in irrigating the landscaped gardens.