The two designated fields are wastewater treatment to obtain a effluent which can be reused in agriculture and irrigation techniques which are compatible with sustainable agricultural practices.

A. Wastewater treatment to produce treated water for irrigation

The first aim is the development of new technology in the treatment of wastewater from small settlements, villages and towns to produce treated water for irrigation. Traditional wastewater treatments have not succeeded due to the high costs of both construction and maintenance as well as to the highly specialized personnel needed for their supervision. The proposed project will investigate natural vegetation from the Mediterranean region (Free Water Surface system and Epuvalisation) as well as Long Term Storage in maturation ponds. Such a technology should be considered: (a) Low cost, (b) appropriate for the existing conditions, (c) adaptable to the Mediterranean environment and (d) appropriate for producing advanced treated effluent.

B. Irrigation technics compatible with sustainable agricultural practices

The use of wastewater may potentially have adverse impacts on both the environment and the public health, largely depending on wastewater characteristics, the degree of purification, the method and location of use and the crops irrigated. Soil, groundwater and surface water pollution are among the most important potential disadvantages of the wastewater use. However, scientifically sound planning and effective management of the irrigation or fertilization regime according to water and nutrient requirement of selected crops, can minimize these disadvantages to the level of environmental insignificance. Selection of crops is one of the most powerful means to protect public health. Flowers and particularly those which are dried, industrial crops, crops consumed after transformation, give new dimensions on wastewaters use since they can be used on a profitable and sustainable bases.

The goals are to produce in sustainable way, irrigated crops with wastewater treated by low cost technology adapted to the Mediterranean environment.

The treatment of wastewater by Free Water System (FWS) experimented recycle and non-recycle units. The recycle unit with olive oil wastewater (OOW) shows a significant effect on removal for Biological Oxygen Demand (BOD₅) and Total Suspended Solid (TSS).

The Long Term Storage (LTS) demonstrates that the removal of bacteria in an open basin is more important with higher initial contamination, thanks to higher competition between micro-organism, and with the size of the opened surface. No sanitary quality differences was observed between agricultural products irrigated with the wastewater coming from the basin and groundwater.

The epuvalisation, low cost tertiary treatment technique, met in one case intrusion of seawater in the system, by the sewage network and have delayed the experimental protocol and is in construction for the second case.

The irrigation techniques studied for the impact of wastewater on irrigation systems demonstrate that the system with integrated drippers gave better yields and better irrigation uniformity.

The soil/plant complex under irrigation shows systematically higher yields on potatoes crops in Tunisia when irrigated with wastewater than groundwater, however the irrigation system used and identical fertigation.

In Morocco, wastewater purified by epuvalisation have a fertilisation rate so high that a depressive effect is observed on the number of eggplant fruits produced. The hydrical consummation of the culture is also lower. The same water and wastewater purified by infiltration-percolation system are classified according to the World Health Organisation (WHO) criteria in the first class (A). It means that they may be used non-restrictively for irrigation of uncooked edible crops.

In Israel, under non irrigated maize crops, the nitrate rate in the soil increases and the sodium rate rises under irrigation. Phosphorus rate in the soil is more important for plants growing in non-irrigated conditions. Potassium rate observed is constant, Israeli’s soils are naturally rich in this element. But it is a limiting factor to the plant’s growth as a deficiency leads to non-response to the nitrate fertilisation.

Research in Palestine found a variety of chickpea adapted to the irrigation with wastewater. Biomass parameters, grain yields and quality of grain formation are even improved under irrigation with wastewater. Similar results are observed under drip irrigation, surface irrigation and sub-surface irrigation systems. Sub-irrigation systems give the best microbiological contamination reduction. Further research test other chickpea variety.

The complementation irrigation for cereal crops in Morocco gave statistically better yields on durum wheat under irrigation with wastewater treated by infiltration-percolation system than under irrigation with groundwater. The yields of the soft wheat crops depends more on quantity of fertiliser agents than on hydrical nutrition.

Optimisation of the nitrogen fertilisation under irrigation with wastewater shows in Belgium that under irrigation with wastewater, additional nitrogen gives a small yields increase but let an environmental unbearable nitrogen rate in the soil. The recommended nitrogen optimum quantity leads to a better use of nitrogen by the culture and the rests in the soil generate no pollution.

In Morocco, irrigation with wastewater or with groundwater complemented with fertilisers leach nitrate down in quantity variable with the stage of the culture, but in any case superior to the limit recommended by the WHO.