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Use of wastewater for irrigation - A global approach blending water treatment, irrigation with various systems on various crops and institutional / organisational aspects

Objectif

- Water tertiary treatment and heavy metals removal
Water treatment: to elaborate techniques to reduce the level of contamination in micro-organisms and heavy metals in the water to reach an acceptable level for agriculture. The project will work on tertiary treatment of the water for activated sludge plants, lagooning and sand filtration will be tested in situ and comparative analysis carried out.
Heavy metals' elimination from the water will be tested by algae and macrophytes. A methodology for the use of algae to reduce the heavy metals' levels in wastewaters will be designed and tested in situ. The absorption by macrophytes will be tested and the possibility to use them for heavy metals' removal assessed.

- Irrigation practices ant their impact
Irrigation practices that match the field requirements, the water treatment capacities and the quality of the water, sanitary aspects both on micro organisms and heavy metals' studies will be concluded by guide lines on field practices following the soil type, crop type and wastewater quality.
Different types of crops ranging from vegetables (open air and greenhouses), annual industrial crops, tree crops and forest will be used to study the sanitary problems together with irrigation techniques, their timing and ways of water distribution.
The impact of such practice will be studied by analysing the crops, soils and ground water for the contamination levels in micro-organisms and heavy metals as well as the effect on animals fed with fodder cultivated on water irrigated lands.
The effect of irrigation on the different crops will be described and the guide-lines for each type of crop described in the final report.

- Organisational and institutional recommendations, institutional implications of each techniques and its social acceptance
Most countries have a legal and institutional problem: waste water reuse is presently not allowed for irrigation although it is unofficially done due to the scarcity of water. It is not clear which institution will be responsible for the treatment of water, the quality control, the management of the tertiary treatments, the water pricing and financial flow.
The project will propose institutional structures adapted to each case. The relations between implied parties will be determined as present and an institutional plan will be worked out.


Results so far

- Belgium
- With respect to the objectives of the study, it is clear that irrigation in general and on cultivated soil has no influence on the movement of nitrates and on the leaching of residues. Irrigation using wastewater does not contribute to soil nitrogen enrichment, as any inputs are compensated for by greater uptake by the irrigated plants. Yields are much more constant and irrigation represents a guarantee of revenue to the farmer and a secure supply for industry.

- Tunisia
- In the case of irrigation by burried pots, when water from the water table is used, less faecal contamination of the soil is detected than when wastewater is used; this is the case whatever the distance from the pot and whatever the depth.
- In the case of furrow irrigation, the surface soil is contaminated more than when irrigated with the same water by burried pots.

- Morocco
- With reference to the three elements analysed (Zn, Pb, Cu), the content of heavy metals in Ouarzazate wastewater confirms the absence of large industrial sites. The presence of zinc in notable quantities is probably due to mining activities associated with the drilling of the drinking water supply.
- However, the results show that the experiments planned for fixation of heavy metals might need the effluents to be enriched before being introduced into the algal system.
- Following a test in Agadir, it appears that micro-irrigation with purified wastewater does not seem to present any problems on the condition that a good filtration system is placed upstream of the water distribution network. Use of wastewater treated by rapid infiltration has allowed the same yield for melon culture and an increased yield for tomato in comparison with plants irrigated by fertilizer enriched wellwater. This has allowed us to economise on the amount of fertiliser for these two crops and to obtain a product similar in bacteriological and parasitological quality to the control.

- Portugal
- The results obtained in these pot experiments showed that A. Pintodasilvae was tolerant towards several heavy metals. Only cadmium application to the soil had a negative effect on dry matter accumulation. However, the mineral composition of A. Pintodasilvae was influenced by the presence of heavy metals. Increased uptake and translocation of heavy metals was observed in artificially contaminated soils, but the capacity to hyperaccumulate was retricted to Ni.
- Continued growth and harvest of A. Pintodasilvae was possible, suggesting that the plant might be used in the future to extract Ni from polluted soils, especially when Cd contamination is not very severe.

- Cyprus
- The yield results indicate the superiority of the treated wastewater and the possibility of producing high yields without additional fertilizers. Soil analyses in progress are aiming at identifying effects on soil and eventual pollution of soil and groundwater particulary by N03-N.
- Belgium
The Belgian team will work on following issues, besides the co-ordination work :
- Research on irrigation with wastewater;
- Control of the nitrogen fertilisation;
- Impact of the wasterwater irrigation on the fungi's infections;
- Heavy metals' removal with algae;
- Institutional and organisational considerations.

- Tunisia
- The conception and management of a retreatment lagoon are studied in view of the quality of the water needed. The introduction of algae will be evaluated in collaboration with other partners (Morocco Ouarzazat and Belgium);
- The conception of wastewater storage will be assessed and its impact on water quality;
- The retreatment of wastewater down stream a water treatment plant (activated sludge). The method will use sand filtering columns observed in laboratory, the water being measured before and after filtering for the major biologic and health parameters.

- Morocco
- The algae's cycle will be experimented in a high yielding channel for algae cultivating, in connection with the Belgian partner;
- The Agadir centre is working on the reuse of wastewater for the irrigation in plastic greenhouses. The present project will work on high value added crops in greenhouses: melons and carnation (Dianthus). The water is treated with two systems (Epuvalisation and infiltration percolation) in comparison with well water. During the growth and at harvest time the bacteriology and parasitology of all products will be carefully checked (EC, pH, DCO, DBO and salt content), the products being meant for export.

- Greece :
- The Greek partner is studying the reuse of water for forest irrigation. The city of Athens is surrounded by forests that are regularly devastated by fires. The use of wastewater to irrigate non fire susceptible trees (two types of trees: Eucalyptus and Pseudoaccacia) is studied on trial plots (tree treatments and four blocks). Physical and chemical changes of soil properties are monitored, plant production and the chemical and microbiological content of water will be analysed.

- Portugal :
- The effect of heavy metals (trace elements, mainly Pb, Cd, Cr) using lysimeters (1 m3 capacity) and pots (10 kg soil) with contaminated water is in the focus of this partner. They want to assess the fate of the elements in the soil, plant and runoff water. Two types of soils, three crops and four levels of metal ions in the water will be tested.

- Cyprus :
- The effects of irrigation on the soils and the sanitary problems on crops and animals are analysed;
- The crops are open air vegetables (eggplant and tomatoes), industrial crops (sudax and cotton) and fodder (alfalfa). Routine analyses are performed on the water and on the vegetal products. Faecal and blood samples taken from all animals are analysed for haematoparasites and blood smears for haemoparasitis. Blood samples will be analysed for brucellosis, ricketsiosis, leptospirosis and toxoplasmosis. The treatment will include animals that will be given daily sewage water to drink.

Programme(s)

Thème(s)

Data not available

Appel à propositions

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Régime de financement

CSC - Cost-sharing contracts

Coordinateur

Faculté Universitaire des Sciences Agronomiques de Gembloux
Contribution de l’UE
Aucune donnée
Adresse
2,Passage des Déportés
5030 Gembloux
Belgique

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Coût total
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Dernière mise à jour: 25 Août 1998

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Permalink: https://cordis.europa.eu/project/id/AVI*940002/fr

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