Abstract:In the sewage treatment plants,lakes,reservoirs,estuaries and aquaculture ponds where the dissolved oxygen level needs to be elevated by artificial aeration,it is very important to maintain the dynamic equilibrium of dissolved oxygen through the aerator.There are always surfactants in the domestic sewage and urban wastewater.When these waste waters flow into the above aerated water body,they would affect the oxygenation performance and mass transfer effect of aeration system.In order to investigate the effect of surfactants on the oxygenation performance of microporous aeration system,a series of microporous aeration tests were carried out in a glass tank of 2.0 m long,0.8 m wide and 0.8 m high,in five different air flow rates and anionic surfactant concentration,according to the Standard Test Method for Oxygen from American Society of Civil Engineers (ASCE).The microporous aeration plate fixed in the center of the tank bottom was taken as aerator and the anionic surfactant,i.e.,sodium dodecyl benzene sulfonate (SDBS),was used introduced.Based on the theory of air bubble mass transfer,the oxygen mass transfer coefficient,Sauter mean diameter and form factor were calculated and analyzed.The results showed that,at 1.0 mg/L SDBS concentration,the oxygen volumetric mass transfer coefficient was increased and the oxygen mass transfer effect was improved in different air flow rates.But at 1.0～5.0 mg/L SDBS concentration,with the increase of the concentration,the oxygen volumetric mass transfer coefficient decreased.The Sauter mean diameter of the bubbles in water containing surfactant was decreased by 22.76 % compared to pure water.The variation of the form factor was small,and thus the air bubbles were kept in the almost spherical shape.While,in the tests without surfactants,the form factor of the bubbles had a larger variation and the shape of the air bubbles tended to be flat.