Phosphorus concentrations and flow in maize wet-milling streams

Marketing of coproducts such as corn gluten meal (CGM) and corn gluten feed (CGF) is important to the maize wet-milling industry. High phosphorus concentrations could lead to limited markets for CGF due to its potential to increase phosphorus in animal wastes. The objective was to measure the concentration and flow of phosphorus in the wet-milling process and identify streams that could be altered. Samples were taken from 21 process streams of three facilities and the phosphorus content of each was determined. Flow of phosphorus was simulated using a computer model for a 2,700 tonne/day (105,000 bu/day) wet-milling plant. Phosphorus concentrations of streams varied from <10 mg/kg to >14,000 mg/kg. Phosphorus content of many streams differed significantly among facilities. Flow of phosphorus (kg/day) varied dramatically among streams. However light steepwater, light gluten, and process water streams (5,960, 3,080, and 970 kg/day, respectively) accounted for much of the phosphorus flow. Modification of these streams could reduce phosphorus content of coproducts. The high phosphorus content of either CGF or CGM could be reduced markedly if phosphorus was reduced in the appropriate streams.