Design and operation of land treatment systems for minimum contamination of ground water
1974
Bouwer, Herman
Low-rate or irrigation-type systems for land application of sewage effluent or similar wastewater are often used in humid areas because they have a small impact on the underlying ground water. In arid areas, low-rate systems cannot be used to produce renovated water for ground-water recharge, because the renovated water will have a much higher salt content than the effluent. Renovated water of relatively low salt content can only be produced with high-rate systems. Such systems, which require permeable soil, can also be used in humid areas to reduce the land requirements. To minimize the impact of high-rate systems on ground-water quality, the system should be managed to remove as much of the pollutants (particularly nitrogen and phosphorus) as possible from the wastewater as it seeps through the soil, and to restrict the spread of renovated wastewater in the ground-water basin. Nitrogen removal can be maximized by stimulating denitrification in the soil. Certain soils can store large quantities of phosphate. The spread of renovated water in the ground water can be controlled by intercepting the flow of renovated water with wells or drains for reuse or discharge into surface water. Techniques for predicting the underground flow system are presented.
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