Redefining MBR Nutrient Removal For Drinking Water Equivalent Reuse in a Large Potato Industry

This paper is focused on the real-life operational and performance factors during start-up and commissioning of a Process Water Treatment and Return Plant (PWTRP) for a new very large potato processing facility in Caldwell, ID. The PWTRP is on-line for recovery of process water equivalent to drinking water quality. The treatment system is reviewed from a lessons-learned perspective for those that may be considering water reuse. The PWTRP design peak flow is 3.2 million gallons/day (mgd) with up to 1.4 mgd of flow treated to equivalent to drinking water quality for processing reuse in contact with potatoes and food products. The project broke new ground in a number of ways including (a) it is the first biological treatment plant on high carbohydrate food waste to successfully achieve enhanced biological phosphorus removal (b) it proved that membrane bioreactors can be successfully operated at very low solids retention time (SRT) and (c) it proved that a biological nutrient removal bioreactor configuration with the anoxic zone preceding the anaerobic zone is the most cost effective configuration for membrane bioreactors treating wastes with high concentrations of readily biodegradable COD.