Sang Lang-Tao, Shi Xuan, Zhang Tong, Fu Bo-Wen, Jin Peng-Kang
School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
Huan Jing Ke Xue. 2017 May 8;38(5):1965-1971. doi: 10.13227/j.hjkx.201610033.
In order to investigate the scouring and deposition law of pollutants in urban sewer systems, the investigation of sewer systems was carried out in Xi'an. The results showed that the thickness of sediment in the branch pipe and the main pipe varied obviously. At the peak of the drainage, the velocity increased gradually, and the thickness of the pipeline sediment decreased. At the bottom of the drainage trough, the changes of the velocity and the thickness of the pipeline sediment were opposite, with variations of 0-24 mm and 0-12 mm, respectively. And the probability of granular contaminants sedimentation and scouring in sewer systems was high, while the thickness of sediment in sewage main pipe was less than the above mentioned pipes, the variation of which was 0-7 mm. In addition, the sedimentation and scouring in the main pipeline kept relatively balanced and the thickness of sediment remained stable. In order to clarify the relationship between the concentration of pollutants and the flow velocity, a pilot sewer system was established. The effects of different flow rates, which were 0.1, 0.3, 0.6, 0.9, 1.2 m·s, respectively, on the contents of carbon (organic), nitrogen and phosphorus in the pipeline were studied. The results showed that with the increase of the flow velocity, the scour intensity increased and the concentration of pollutants in the pipeline also increased sharply. As shown by the monitoring results of the static light scattering particle size analyzer, the carbon organic pollutants in the pipeline were easily adsorbed on the larger particles, while nitrogen and phosphorus pollutants were easily adsorbed on the particles with smaller size. Analysis on the change of the urban sewage pipeline showed, when the flow rate was less than 0.6 m·s, the sedimentation of granular pollutants in the sewage was greater than the scouring effect. When the flow velocity was higher than 0.6 m·s, the water scouring intensity increased and the scouring action was greater than the sedimentation, meanwhile, the sediments were carried by the water and the thickness of the sediments was reduced. The increase of the organic pollutants in the sewage was bigger than the nitrogen and phosphorus pollutants, so that the existing sewage carbon source was improved.
为了研究城市排水系统中污染物的冲刷和沉积规律，在西安开展了排水系统调查。结果表明，支管和主管中沉积物厚度变化明显。在排水高峰期，流速逐渐增加，管道沉积物厚度减小。在排水低谷期，流速和管道沉积物厚度的变化相反，分别变化0 - 24毫米和0 - 12毫米。并且下水道系统中颗粒污染物沉积和冲刷的概率较高，而污水主管中沉积物厚度小于上述管道，其变化为0 - 7毫米。此外，主管道中的沉积和冲刷保持相对平衡，沉积物厚度保持稳定。为了阐明污染物浓度与流速之间的关系，建立了一个试验性排水系统。研究了分别为0.1、0.3、0.6、0.9、1.2米·秒的不同流速对管道中碳（有机）、氮和磷含量的影响。结果表明，随着流速的增加，冲刷强度增大，管道中污染物浓度也急剧增加。如静态光散射粒度分析仪的监测结果所示，管道中的碳有机污染物容易吸附在较大颗粒上，而氮和磷污染物容易吸附在较小颗粒上。对城市污水管道变化的分析表明，当流速小于0.6米·秒时，污水中颗粒污染物的沉积大于冲刷作用。当流速高于0.6米·秒时，水流冲刷强度增加，冲刷作用大于沉积作用，同时沉积物被水流带走，沉积物厚度减小。污水中有机污染物的增加幅度大于氮和磷污染物，从而改善了现有污水碳源。
