Plant Nutrients in Potato Processing Waste Water Used for Irrigation

Food processing industries discharge large volumes of waste water that are generally characterized by high organic matter content, large amounts of suspended solids, and various inorganic constituents including nitrogen, phosphorus, and potassium (3, 4, 5, 6). Until recently, food processing waste water was discharged into streams or rivers, but governmental regulations now prohibit this. Food processors must either treat their waste water to meet established water quality standards before discharging it, or find an alternative waste water disposal method. Secondary treatment, although expensive, has been satisfactory in some cases, but tertiary treatment with removal of nitrogen and phosphorus may be required in the future. Energy requirements for secondary treatment are high, and plant nutrients usually contained in the waste water are a valuable resource. Irrigating cropped agricultural land requires little energy and some of the nutrients can be used by growing plants. Therefore, irrigating with food processing waste water may be a long-term solution to the waste water disposal problem. This report gives the nitrogen, phosphorus, and potassium concentrations in potato processing waste water and the amounts of water and included nutrients applied to fields at five potato processing plants in Idaho