# **Box  2.8  Tunisia—direct use of treated wastewater**

Wastewater irrigation has had Government support since 1975, and since a severe drought in 1989, treated wastewater use in irrigation has been a part of the Government’s overall water resources management and environmental pollution control strategies. Water quality standards for wastewater use are based on the 1989 WHO Guidelines. Over 78 percent of the urban population is connected to sewerage, and 83 percent of the collected sewage is treated to adequate standards – about 4.7 m<sup>3</sup> /s. However, only about 1.1 m<sup>3</sup> /s is currently used for irrigation of 7,000 hectares of fruit trees and fodder. It is estimate that by 2020 about 20,000-30,000 ha, or about 7-10 percent of total irrigated area will be using treated wastewater. Despite strong government support, farmers currently prefer not to use reclaimed wastewater. Among the problems identified are: social acceptance; regulations restricting irrigation of high-value vegetable crops; water quality problems leading to clogging of drip irrigation systems; concerns about long-term impacts of saline wastewater; and inability to match the timing of supply and demand for water due to inadequate storage capacity for treated effluent.

In addition to technical and social concerns, there are institutional and economic issues to be resolved. It is recognized that there is a multiplicity of agencies involved in treated wastewater use, sometimes with conflicting objectives and overlapping responsibilities – efforts are underway to increase coordination and stakeholder involvement. On the economic side, efforts to develop a market-based strategy of treated wastewater should focus on the preferences of intended wastewater users.

_Source:_ Shetty, 2004; Bahri, 2008b; Kfouri _et al_ ., 2009; Louati and Bucknall, 2009.

_Wastewater irrigation in high-income countries._ Wastewater reclamation and use in irrigation is a well-developed practice in the high-income countries, or parts of the countries, that are facing water scarcity, rapid urban growth, and water quality problems. Many OECD countries have achieved technological advances in physical, chemical, and biological processing of wastewater, together with the development of a rational regulatory framework controlling wastewater reclamation and use practices. Examples include the United States (especially the States of California and Florida), Australia, and European countries such as Spain and the southern provinces of France and Italy.

In non-OECD countries, there has also been an effort toward wastewater reclamation and use in irrigation in the water-short countries of the Mediterranean Basin and the Middle East, such as Bahrain, Cyprus, Israel, Kuwait, Malta, Oman, Qatar, Saudi Arabia, and the United Arab Emirates (Jimenez and Asano, 2008b). In addition to water scarcity, wastewater use in these countries is driven by the marginal cost of alternative sources of water of sufficient volume and quality. For example, in Bahrain, cost of tertiary treated effluent is about $0.32/m<sup>3</sup> while the cost of desalinated water is about $0.79/ m<sup>3</sup> (Bahri, 2008a). These countries also have established regulatory frameworks for controlling wastewater reclamation and use practices, and invested in advanced wastewater treatment technologies.

The volume of reclaimed wastewater used for irrigation and the intensity of wastewater use (in volume per million capita) for key OECD and non-OECD countries is shown in Table 2.5. The data confirms that in response to water scarcity and drought, countries with resources are willing to make the considerable investments required in order to assure water supply augmentation and environmental protection through wastewater reclamation and use.

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