Transformations of Carbon and Sulfur Wastewater Components Under Aerobic–Anaerobic Transient Conditions in Sewer Systems

Abstract

Wastewater quality changes in the carbon and sulfur cycles in pressure sewers and in a gravity sewer that followed a pressure sewer were studied. The primary focus was on changes in chemical oxygen demand (COD) components during transport, which were investigated using oxygen uptake rate measurements and volatile fatty acid analyses. Sulfide formation in the pressure sewers and sulfide oxidation in the gravity sewer were also studied. Anaerobic hydrolysis, which resulted in a net production of readily biodegradable substrate in the pressure sewers, was quantified. A process model description, which included the main aerobic and anaerobic processes in the water phase and in the biofilm, was presented; model parameters were determined based on calibration. This simulation procedure made it possible to consider integrated aspects of hydrogen sulfide and variations in COD components in sewers such as odor and sewer corrosion by hydrogen sulfide and the inadequacy of advanced wastewater treatment because of the input of low‐quality wastewater. It is possible to include wastewater quality changes and, thereby, process aspects for sewer design and operation.