The effect of anaerobic pre-treatment on the inert soluble COD of fermentation industry effluents

The objective of this study is to determine the inert soluble COD of wastewaters from the fermentation industry. In this context, a series of experiments were performed for various effluents from baker's yeast industry including raw process wastewater, anaerobic pre-treatment plant effluents, domestic and washing waters mixture. The inert COD ratio (S₁/S₀) for the raw effluents from baker's yeast industry was determined as 0.1. This ratio was in the range of 0.20 to 0.30 for the anaerobically pre-treated effluents. The S₁/S₀ ratios for the wastewater simulating the effluent of the existing full-scale aerobic treatment plant have varied from 0.18 to 0.4S. Such a large variation has been originated from the operating conditions of the existing full-scale anaerobic treatment plants. The higher volumetric loading rates and shorter sludge retention times correspond the lower S₁/S₀ ratios for the full-scale anaerobic treatment systems in general.