Treatment of Potato Processing Waste Water on Agricultural Land

The chemical oxygen demand (COD) and the total N and NO?-N concentrations in potato (Solanum tuberosum L.) processing plant waste water and in the soil solution at several depths in a treatment field where the waste water was applied were studied for a 2-year period. The COD decreased 95 to 99% from 850 to 2,000 ppm in waste water to 4 to 40 ppm after passing through 150 cm of soil. A similar decrease in the total N concentration was found. The NO?-N concentration in the waste water ranged from 0.1 to 9.0 ppm and the concentration in the soil solution at the 150-cm depth was generally < 1.0 ppm. During the second year 1,076 kg N/ha were applied in the waste water. The grass crop removed about 320 kg N/ha (about 30% of that applied). Results indicated that only about 10 kg N/ha passed into the water table each year. Land disposal is a practical method for disposing of potato processing waste waters with a low pollution potential