In the context of wastewater treatment, what is irrigation?

In the context of wastewater treatment, irrigation refers to the application of secondary treated effluent to land or crops. This process involves using treated wastewater that has undergone a comprehensive treatment process, which typically includes biological treatment methods to remove organic matter and pathogens, ensuring that the water is sufficiently clean for agricultural use.

Using secondary treated effluent for irrigation is beneficial because it provides an alternative water source for crops, particularly in areas where freshwater is scarce. This practice also helps in nutrient recycling, as treated effluent can return valuable nutrients like nitrogen and phosphorus back to the soil, improving soil fertility and crop yield.

The distinction between secondary treated effluent and other forms of wastewater (raw or primary treated) is critical. Raw wastewater has not been treated and can pose significant health risks, while primary treated effluent, though somewhat cleaner, may still contain harmful pathogens and contaminants that make it unsuitable for direct application to crops. Hence, secondary treatment ensures a higher safety standard for irrigation purposes.