污水处理过程中曝气方式对挥发性有机物排放量影响研究

针对污水处理厂逸散挥发性有机物(VOCs)加重城市雾霾的环境问题,实验研究了污水生化处理中不同曝气强度、曝气方式对VOCs排放量的影响.研究表明:在SBR处理工艺中,曝气阶段产生VOCs占全过程排放总量的88.34%,曝气强度、曝气方式是影响VOCs排放量的主要因素;在均匀曝气条件下,不同时刻VOCs逸散浓度先急剧上升,在4~6 min达到峰值,然后呈下降趋势,约50~60 min后趋于稳定;不同曝气强度条件下,VOCs产生量与曝气强度正相关,当曝气强度在175 m L·min~(-1)时,既满足出水污染物去除效果,又能使VOCs的排放量最少;在渐减曝气方式中,采用曝气强度分别为200、175、150、125 m L·min~(-1),持续1 h递减的四阶段运行方式和同一曝气强度(175 m L·min~(-1))均匀曝气相比,前者的VOCs总排放量减少了19.51%,曝气量减少了7.14%,说明现有污水处理厂通过优化曝气方式可明显减少VOCs排放.

Study on the effect of aeration mode on the emission of volatile organic compounds in sewage treatment

The emission of volatile organic compounds (VOCs) from sewage treatment plant might pose an air-pollution hazard. The experiment studied VOCs production characteristics of different aeration intensity and different aeration mode in biochemical sewage treatment. The results show that:in the SBR process, the aeration stage plays a very important role in the emission of VOCs. It may account for 80% of the total emissions of each stage. Aeration intensity and aeration mode are the main factors influencing VOCs emission. Under the same aeration condi4tion, VOCs emission concentration increased sharply, and it reached the highest value at 4~6 min, and then it starts to fall quickly at times. It declined gently after about 50~60 min. There is a positive correlation between aeration intensity and the amount of VOCs. With the aeration intensity of 175 mL·min^-1, it not only meets the removal effect of pollutants, but also make the emission of VOCs least. To ensure the effluent water quality, the aeration intensity are 200, 175, 150, 125 mL·min^-1 in the tapered aeration stage, respectively. Compared with the uniform aeration stage, the total of VOCs decreased by 19.51% under tapered aeration stage. The current study provided a critical evidence for VOCs emission reduction in wastewater treatment plants.