横流式复合生物滤池对高氮景观水体净化效能的研究

发布时间：2018-08-19 06:33

【摘要】：随着景观水体越来越受到大众生活的青睐,然而中国水资源一直处于短缺状态,尤其是北方城市由于降水资源以及河湖较少,故其景观水体的补水资源自然一直困扰着城市建设。城市污水厂尾水作为景观水体重要的补充水源之一,但是污水厂尾水存在氮、磷等营养盐浓度超标,易造成水体富营养化;浊度过大,影响景观水体的美学价值;尾水中存在致病细菌病毒,对于具有一定暴露量的景观水体,危害到人体的健康;因此需要寻找符合我国现阶段发展并且与景观环境协调一致的新型处理工艺,使得污水厂尾水达到景观水体的补水要求。本研究中根据研究区内高氮尾水补充湿地公园的条件,采用横流式复合生物滤池。通过对横流式复合生物滤池进行为期一年的监测,该滤池对进水各个主要污染物均有着较为良好的净化效果;TN、TP、SS和COD的去除率分别为33.14%、19.07%、58.58%和28.82%;与此同时研究不同温度、不同有机物负荷条件下处理效果的变化;分析沿程中污染物去除的规律;由于进水为高氮水体,故分析氮素在横流式复合生物滤池中的迁移转化规律以及C/N比对除氮的影响;对出水回用于景观水体从人体健康风险、感官指标和富营养化三个方面进行回用评价,研究结果表明:(1)不同温度条件下,TN在一年四季内的平均去除率分别为29.9%、43.3%、20.1%、9.37%;NO_3-N在一年四季内的平均去除率分别为28.1%、45.1%、12.5%、3.0%;COD在一年四季内的平均去除率分别为26.5%、33.4%、23.9%、15.2%;SS在一年四季内的平均去除率分别为54.3%、63.9%、30.9%、26.7%;表明温度是影响污染物去除效果的重要因素。(2)沿程处理过程中,TN在前后两段火山岩填料区去除率分别为22.95%和22.74%;前段火山岩填料区NO_3-N的去除率为25.57%,占到NO_3-N的去除率(57.80%)的一半;COD的去除主要在滤池前端火山岩填料区到滤池中段的砾石区的中间,到1中COD的去除率为32.12%,其中火山岩填料区COD的去除率为16.33%;SS在滤池两端的火山岩填料段去除显著,其中滤池前端的火山岩填料区SS去除率为41.56%,后端的火山岩填料区为24.17%。(3)有机负荷增加时,TN去除率先升高后降低,有机负荷为27.43kg/d时,TN去除率最高达到75.53%;NO_3-N去除率大体上为增长的趋势;有机负荷在30.42kg/d时NO_3-N去除率为最高达到97.49%;COD去除率缓慢下降(由52.4%下降到12%)。当有机负荷为33kg/d时,出水中悬浮物含量增加,出水变得混浊。(4)不同形态的氮去除率贡献率分别为硝氮为58.33%,其他形态的氮(主要是有机氮)为30.17%,氨氮为11.51%;前段火山岩填料区内硝氮浓度下降的幅度最大;而氨氮浓度呈上升趋势,有机氮浓度大以及高浓度硝氮加速反硝化反应的进行,导致硝化作用相对抑制;滤池各个阶段的过程中,水中氮形态分布均以硝氮为主;有机氮的浓度只在前后两段火山岩填料区有一定程度的降解;亚硝氮浓度很小,且变化的幅度不大;当TN浓度为15mg/L左右时,当C/N比提升到约为5时,TN去除率达到74.5%;进水浓度为10mg/L左右时,C/N比提升到约5.5,TN去除率达到72.7%和65.4%,TN最好去除效果发生在C/N比为5左右。(5)生物滤池出水,年风险值小于可接受年风险10-4的概率在90%以上;出水表观色度均值为29.2度;表观色度的平均去除率为47.3%;出水浊度较为稳定,均值为1.7 NTU;浊度平均去除率达到87.6%;夏季生物滤池出水总氮(6.39 mg/L)、氨氮(1.24 mg/L)和总磷(0.81 mg/L)均满足再生水回用景观环境的水质标准;整个夏季的监测过程中,生物滤池出水水体富营养状态均处于轻度富营养状态。
[Abstract]:As the landscape water body is more and more popular in the public life, however, China's water resources have been in a state of shortage. Especially in northern cities, the supplementary water resources of landscape water body have been puzzling the urban construction because of the lack of precipitation resources and rivers and lakes. The excessive concentration of nutrients such as nitrogen and phosphorus in the tail water of sewage treatment plant is easy to cause eutrophication; the excessive turbidity affects the aesthetic value of landscape water; the existence of pathogenic bacteria and viruses in the tail water is harmful to human health for the landscape water with a certain amount of exposure; therefore, it is necessary to find a suitable development at this stage in China and to cooperate with the landscape environment. According to the conditions of Wetland Park supplemented by high nitrogen tail water in the study area, a cross-flow composite biofilter was adopted. Through one-year monitoring of the transverse-flow composite biofilter, the main pollutants in the influent were detected. The removal rates of TN, TP, SS and COD were 33.14%, 19.07%, 58.58% and 28.82%, respectively. Meanwhile, the change of treatment effect under different temperature and different organic loading was studied; the regularity of pollutant removal in the process was analyzed; because the influent was high nitrogen, nitrogen was analyzed in the cross-flow biofilter. The results showed that: (1) Under different temperatures, the average removal rates of TN were 29.9%, 43.3%, 20.1% and 9.37% in four seasons of a year, respectively; and the removal rates of NO_3-N were 29.9%, 43.3%, 20.1% and 9.37% in four seasons of a year. The average removal rates of COD were 26.5%, 33.4%, 23.9% and 15.2% respectively in four seasons of a year, and SS was 54.3%, 63.9%, 30.9% and 26.7% respectively in four seasons of a year, indicating that temperature was an important factor affecting the removal efficiency of pollutants. The removal rate of NO_3-N was 25.57%, accounting for half of the removal rate of NO_3-N (57.80%). The removal rate of COD was mainly between the volcanic rock filling area in the front of the filter and the gravel area in the middle of the filter. The removal rate of COD was 32.12% in the volcanic rock filling area. The removal rate of SS was 41.56% at the front of the filter and 24.17% at the back of the filter. The removal rate of NO_3-N reached 97.49% at the organic loading of 30.42 kg/d, and COD decreased slowly (from 52.4% to 12%). The concentration of nitrate and nitrogen in the filling area of volcanic rocks in the early stage decreased the most, while the concentration of ammonia and nitrogen increased, and the denitrification reaction was accelerated by the concentration of organic nitrogen and high concentration of nitrate nitrogen, which resulted in the relative inhibition of nitrification. The concentration of organic nitrogen was only degraded to a certain extent in the filling area of the volcanic rocks in the first and second stages; the concentration of nitrous nitrogen was very small, and the range of change was not large; when the TN concentration was about 15 mg/L, when the C/N ratio was about 5, the removal rate of TN reached 74.5%; when the influent concentration was about 10 mg/L, the C/N ratio was about 5.5, the removal rate of TN reached 72.7% and 65.4%, and the TN was the highest. The best removal effect occurred at C/N ratio of about 5. (5) Biofilter effluent, the annual risk value is less than the acceptable annual risk of 10-4 probability of more than 90%; effluent apparent chroma mean value is 29.2 degrees; the average removal rate of apparent chroma is 47.3%; effluent turbidity is relatively stable, the average removal rate of turbidity is 1.7 NTU; the average removal rate of turbidity is 87.6%; biological filter effluent in summer. Total nitrogen (6.39 mg/L), ammonia nitrogen (1.24 mg/L) and total phosphorus (0.81 mg/L) all met the water quality standards of the reclaimed water reuse landscape environment, and the eutrophication status of the effluent of the biofilter was slightly eutrophic throughout the monitoring process in summer.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X52

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