Nitrogen-containing malodorous gas pollutants emission characteristics and health risk assessment from an A/O wastewater treatment plant

Unpleasant odorous emitted from wastewater treatment plants (WWTPs) have been of great concern for many years, especially among local communities with high population density. Knowledge about characteristics of odorous gas release from WWTP can assist in developing gas pollution reduction technologies. This study investigated the emission and variation of NH3 and organic amines (CH3NH2, C2H6NH, and C3H9N) at the water-air interface and concentrations of ambient air exposure from different treatment units in a wastewater treatment plant in North China, which uses the anaerobic/oxic (A/O) treatment process. Results demonstrated that NH3 and C2H6NH emission fluxes had followed a descending order of aeration treatment units > non aeration treatment units. NH3 and C2H6NH achieved the highest release concentration throughout the whole wastewater treatment process, where 0.0023 g of NH3 and 0.0018 g of C2H6NH were emitted during the treatment of 1 m3 wastewater, while CH3NH2 and C3H9N had never been detected. The emission of NH3 and C2H6NH from biological aeration tanks account for 98 % and 95 % of the total discharge of wastewater treatment plant, respectively. The odor pollution of NH3 and C2H6NH in the ambient air of different treatment units of WWTP was the most serious in summer. At the sensory level, NH3 dominated the malodorous effect and its exposure concentration posed a certain non carcinogenic risk to workers in wastewater treatment plant.