Treatment of waste water from a multi product food-processing company, in upflow anaerobic sludge blanket (UASB) reactors: The effect of seasonal variation

Abstract

We have investigated the treatment of waste waters from a multi product food-processing company using a UASB reactor concept. The company Frigodan processes over the season: peas, carrots, celery roots and leeks, resulting in four different types of waste waters. Four lab-scale UASB reactors were started with the individual waste waters. The biomass was characterized after the reactors were adapted to the individual waste water streams and steady state had been reached. Significant differences in both the activities of the different metabolic groups and the numbers of bacteria in the different metabolic groups were found, indicating that problems could occur when changing from one waste water to another. To investigate this further, the waste waters were changed between the different UASB reactors to allow as many different combinations of changes to be tested as possible. Significant decreases in the overall efficiency were observed in the following cases: (1) When changing from celery waste water to any other waste waters due to a significant increase in the organic loading rate of the reactor. (2) When leek waste water with high content of lipids and protein was fed to the reactor. Criteria for treating of waste waters with seasonal variations were developed.