Sewer ventilation and odor transport model for sanitary sewers

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Our existing sanitary sewer systems have been designed to efficiently carry sewage flow without the consideration for air movement in sewer headspace. As a result, many municipalities are facing the nuisance of odor (foul air) releases from sewers. The odor, mainly hydrogen sulfide (H2S), is generated from sulfur or sulfate in sewage by bacteria in anaerobic condition. The H2S will release from sewage to sewer headspace air, and then be transported by the air flow inside the sewer systems. When the air in sewers is pressurized, H2S will leak into the atmosphere via openings such as manhole pickholes or catch basins in combined sewer systems. The odor of H2S is a nuisance to the public and substantially impacts the living quality of the communities close to release points. At a high concentration, it can also be toxic and responsible for sewer pipe corrosions. Municipalities have been working hard on sewer odor control but with limited successes due to the complexity of the issue. Four researchers from the University of Alberta will work closely with the City of Edmonton to develop sewer ventilation (air movement) and odor transport model. Laboratory experiments, numerical modeling and field monitoring will be carried out to study odor (H2S) generation and release in sewer systems, and hydraulic study on air entrainment in drop structures and by sewage flow with the consideration of air curtains and air jumpers. Computer model will be developed on sewer ventilation and odor transport, either as a stand-alone software or embedded as module in a commercial software such as Mike Urban. It will train a total of eight graduate students (2 PhD, 2 M.Sc. and 4 MEng students), as well as two post-doctoral fellows, to work on the important topic related to our infrastructural renewal. The proposed study will provide a useful tool for municipalities on designing sewer ventilation and odor control strategies, as well as retrofitting existing sewer systems and their future design.