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<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>

6.4 Reuse (Topic d)

The direct reuse of treated effluent in agriculture is not a common practice in Western Europe though in the Mediterranean countries, some of the wastewater is reused to augment rainfall. In most of the Mediterranean countries, there is a water imbalance, especially during the summer months, e.g. Greece, Southern France and Italy and Spain. Intensive agriculture must be irrigated. Water demand for irrigation is rapidly increasing. Among the environmental priorities, water management in irrigated and drained areas and the proper use of non-conventional water resources stand out. Regarding the latter, the focus at this time is on the careful reuse of treated wastewater and use of other low-quality water. There is concern that projects for the reuse of wastewater will not impair acceptability of agricultural products and that no projects are implemented before the environmental and sanitary risk associated with the reuse are researched and tested in pilot operations.

EUREAU is in the process of establishing a database which will become available early in the year 2000; a preliminary report emphasizes the need for a EU guideline (or a Directive) to harmonize existing standards for the reuse of effluent (Angelikas et al. 1997), especially as regards the standard for faecal coliforms and intestinal nematodes. Standards are in effect in most of the countries but there are variations regarding faecal coliforms and other criteria, and the degree of prior treatment is still not satisfactory in many cases.

A case study on the reuse of treated effluent in Spain is contained in Section 6.11.3.

Two of the factors which deter the reuse of effluent in the Mediterranean EU countries have been, on the one hand, the yet considerable lack of adequate sewage treatment in some of the countries concerned and, on the other hand, the high cost associated with meeting the existing standards for the protection of public health. However, this will change in two ways during the next few years when the EU Directive 91/271/EEC will be implemented (see Section 6.6.1):

  • A substantially increased amount of treated effluent will be available once the target set by the EU Directive for sewerage and treatment has been reached. Table 6.8 indicates that in some of the countries, secondary and tertiary treatment of considerable amounts of wastewater is yet to meet the Directive's provisions.
  • Article 12 of the Directive stipulates that "Treated waste water shall be reused whenever appropriate". This implies that water pollution abatement considerations will supplement the agronomic demand for more reuse of treated effluent in the Southern part of Western Europe.

Concerning the reuse of sewage sludge, reference is made to Section 6.3.2. It has been discussed there that an increasing amount of sewage sludge is used in agriculture in EU countries. Information on permissible loads on land and limits for metals in soil have also been presented in that Section.

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