Water recycling for agricultural irrigation

water reuse for agricultural irrigation

Water shortages, deterioration of water quality, and environmental constraints, have led to an increased interest of treated wastewater in many parts of the world. The major problem in wastewater recycling is the water quality requirements, which become more and more stringent, and the cost associated with achieving this quality.

Normally municipal wastewater (instead of industrial wastewater) effluent is used for agricultural water reuse. Water recycling for agricultural applications is mostly used in arid regions.

Agricultural reuse is advantageous because wastewater treatment requirements are often moderate, wastewater contains plant nutrients and soil amendments, agricultural areas may be adjacent to treatment plants, and income is gained by growing cash crops.

The major contamination problems are percolation of nitrate to groundwater, and retention of heavy metals in the soils, and pathogenic hazards to farm workers. [1]

To remove organic compounds from the effluent, biological treatment can be used, followed by deep-bed sand filtration, for the removal of heavy metals. [2]

Further disinfection is needed for the elimination of pathogens. This can be done by means of;

Ozone treatment: Ozone treatment can be used to disinfect the drain water. Ozone is the second most powerful sterility in the world and its function is to destroy bacteria, viruses and odors. An ozone supply of 10 g/h/m3 water with an exposure time of 1 h is sufficient to kill all pathogens.

UV disinfection: Another way to disinfect the drain water is the use of UV-radiation. Ultra-violet radiation (or UV) is a proven process for disinfecting water, air or solid surfaces that are microbiologically contaminated. For eliminating bacteria and fungi an energy dose is recommended of 100mJ/cm2. For viruses a dose of 250 mJ/cm2 is recommended.

Information sources for irrigation water quality find below:

- Irrigation water quality

- Irrigation water lab analysis

- Salinity hazard of irrigation

- SAR hazard of irrigation

- toxic ions hazard of irrigation water

- Trace elements hazard of irrigation water

- Bicarbonate hazard of irrigation

[1] Hammer, M.J. Hammer, M.J. Jr. Water and wastewater technology, New Jersey, USA, 1996.

[2] Brenner, A. Shandalov, S. Oron, G. Rebhun, M. Deep-bed filtration of SBR effluent for agricultural reuse - pilot plant screening of advanced secondary and tertiary treatment for domestic wastewater. Haifa, Israel 1994

Should you know of any other interesting or more recent book, report, article or publication, concerning water reuse please let us know, so that we can include reported case-studies in the above overview.

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