Water Reuse in Agriculture - Pros and Cons Dr. Konrad Buchauer Moldova WATER REUSE

Table of Contents 1.Reuse Applications 2.International Development of Water Reuse 3.Pros of Water Reuse 4.Cons of Water Reuse 5.Summary

1. Reuse Applications Agricultural Reuse Urban Reuse: green areas, parks, golf courses, etc. Recreational Reuse: lakes for swimming, boating, fishing, snow-making, etc. Environmental Enhancement: creation / enhancement of wetlands, stream flow Groundwater Recharge: potable water, salt water intrusion & subsidence control Industrial Reuse: process water, cooling water, etc. Residential Reuse: toilet, laundry, air-conditioning, etc. Potable Reuse: direct or after blending with other sources Paddy field irrigationOsaka Castle (Japan)Groundwater recharge (Los Angeles, USA) Agricultural Reuse is just one out of many options

2. International Development of Water Reuse (1) California, USA (2) Israel Water reuse as compared to overall wastewater treatment Two examples out of many: Water reuse is on the rise

3. Pros of Water Reuse Advantages Reliable source of supply: little dependence on weather conditions. Reduced stress on ‘traditional’ water supply: reduced demand for investments into expansion of existing water supply schemes, since part of ‘traditional’ water sources is replaced by reused sources. Availability near to agricultural application, i.e. mostly outside cities. High content of nutrients (N, P) permits to reduce application of synthetic fertilizers, thereby reducing cost. Benefits for rural population. Long experience exists in many countries at different levels of development. Attractiveness of investment (private & public) in the wastewater sector increases as a whole, if there is a market for water reuse. ‘WHO Guidelines for the safe use of wastewater, excreta and greywater. Vol.2: Wastewater use in agriculture’ (2006) permit for a flexible approach towards treatment standards.

4. Cons of Water Reuse Necessary considerations Social acceptance? Co-operation of different sectors is sometimes difficult. Requirement for treatment and agricultural expertise, to analyse specific requirements and adjust to flexible treatment standards. Risk to human health? - Pathogens: bacteria, viruses, Helminths Risk to environment? - Heavy metals - Organics (endocrine disrupters, antibiotics, halogenated compounds) - Salinity

5. Summary 1.Agricultural reuse is just one out of many water reuse applications. 2.There is a strong tendency worldwide to water reuse applications. 3.Water reuse in agriculture offers attractive benefits, since it is a reliable source of supply combined with a potential for cost savings (both for water utility and farmers). 4.Concerns (health, environment, social, organisational) have to be addressed.

Literature 1.World Bank, The Water for Food Team: Investing in the reuse of treated wastewater. Agricultural and Rural Development Notes, Issue 17, June UNEP, GEC: Water and wastewater reuse California Department of Water Resources, Recycled Water Task Force: Water Recycling May H. Cikurel, A.Aharoni, N.Tal: Water reuse in Israel