Wastewater treatment and use in agriculture

Reuse of wastewater for agricultural purposes is becoming more necessary as good quality water becomes more scarce. In arid and semi-arid lands, a high percentage of the agricultural production comes from fields under irrigation. Urban population growth with the resulting increase in water supply and sewerage yields a large amount of wastewater; most of which contains domestic sewage and some industrial effluents. The proper use of this wastewater for irrigation has a two-fold advantage; it conserves a valuable resource and takes advantage of nutrients present in sewage for crop requirements. This report outlines the presently available methods of wastewater and sludge treatment which can eliminate pathogens and reduce some pollutants to render the product safe for use in irrigation. A detailed list of crop tolerances to elements such as sodium, chloride, boron and some other trace elements is included. Irrigation practices such as leaching, crop rotations, seed placement, irrigation scheduling and water mixing are discussed in detail. Case studies from the US, Jordan, West Bengal, Tunesia and other countries are presented.