Enhancing the ventilation of sewers by using inhaled air in the vertical stack of a building

Improving the ventilation of sewers could control the production of hydrogen sulfide (H2S) and methane (CH4), which are associated with anaerobic conditions. In this manuscript, a ventilation method using inhaled air from the drainage of the vertical stack of a building was proposed, and a model based on the dimensional method was established to calculate the airflow rate of the inhaled air. By observing the air pressure and air velocity of the ventilation cowl and the opening hole of the sewers, it was found that the inhaled air flowed down with water and that approximately 94% of the inhaled air would flow into the headspace of the sewer to enhance ventilation. According to the model and the observed service condition of toilets in the building, the daily average quantity of the air that was used to enhance the ventilation of the sewer was approximately 149.978 m/d. The concentration of H2S and CH4 in the sewers were zero, indicating that the inhaled air in the vertical stack of the building could effectively and persistently enhance the ventilation of sewers.