The Effect of Sewer Network Conditions on the Quality of Plant Influent Waste Water and the Performance of the BNR Process

A full-scale study focused on the characteristics of the influent waste water in a middle-sized WWTP receiving only domestic sewage. The objective was to understand sewer transformations and their influence on the influent water quality in order to better control prefermentation and BNR process. A correlation between sewer system conditions and the presence of readily biodegradable organic matter in the feed waste water was found. It was shown, that during warm water period biological oxidation of biodegradable material and nitrification of ammonia in the aerobic part of the sewer network were responsible for decreasing the nutrient load to the treatment plant. A positive effect of the increased VFAs on the nitrogen and phosphorus removal could also be statistically confirmed. The study offered valuable information about the seasonal behavior of the sewer network and allowed to build a strategy for maximizing the fermentation potential of the sewer system.