(472d) Principals of Reusing Municipal and Industrial Wastewater Discharges for Irrigated Agriculture

Many regions around the world are currently facing water shortages which inhibit development and economic growth. Although some of the allocation problems faced by these regions can be partially alleviated by improving agricultural irrigation efficiencies, another means for substantial water savings involves the reuse of municipal and industrial discharges to offset freshwater demands. In many cases, the pollutants associated with these wastewater discharges are actually valuable crop nutrients (i.e., nitrogen, potassium, phosphorus, magnesium, etc.) that can actually improve crop production. By utilizing industrial and municipal discharges to augment agricultural production, regions around the world can realize multiple economic gains through improved agricultural productivity, reduced wastewater treatment requirements, and the more efficient use and allocation of water resources.

A land-based wastewater management system, often referred to as land application, is a cost-effective, natural way to reuse wastewater and its associated pollutants in a soil/crop system by applying the water in a controlled manner. The area to which the water is applied is managed so that constituent loadings are at or slightly below the agronomic and hydraulic uptake rates of the designated soil/crop system. There are many economic and environmental benefits of land applying wastewater. The benefits of using land application versus other treatment and discharge methods can include lower capital investment, lower maintenance, lower energy, reduced system upsets, potential opportunities for local revenue improvements, and net water savings. This paper reviews the principal challenges and solutions for incorporating land application as part of a wastewater management strategy and provides several examples of where this approach was successfully used for managing discharges from municipalities, food-processing plants, the oil and gas industry, and power-generating facilities.