污水土地处理系统承托层及集水层对流态的影响

Effect of Bearing Layer and Water Collection Layer in Wastewater Land Treatment System on Flow Pattern

在污水土地处理系统的反应器模型中进行流态试验,使用停留时间分布(RTD)分析理论,考察不同管网布设形式下承托层及集水层对流态的影响。结果表明,管网布设为全网时,集水层及承托层对流态的影响不大:集水层使无效体积中滞留区所占的比例略有增加,轴向扩散系数依然接近低等扩散程度;承托层的增设对流态改变很小。管网布设为半网时,由于集水层的集水作用及承托层的布水作用,集水层和承托层的使用可以显著改善水流流态:集水层改变了水流流动的方式,消除了短流及大部分的滞留区;承托层增加了体积效率,无因次平均停留时间由0.816升高为1.093,即减小了死区所占比例,但对流经填料的水流流态影响不大。

Flow pattern experiment was conducted in a wastewater land treatment reactor. The residence time distribution （RTD） function was used to investigate the effect of bearing layer and water collection layer on flow pattern in different pipeline distributions. The result showed that if the pipeline was fully distributed, beating layer and water collection layer had no great effect on flow pattern. The proportion of stagnant volume in ineffective volume increased, and the degree of axial dispersion was lower due to the water collection layer. The flow pattern did not greatly change after bearing layer was added. But if the pipeline was half distributed, the water collection layer and the bearing layer could improve the flow pattern effectively. The water collection layer changed the water flow pattern and eliminated bypassing and a large portion of stagnant volume. The beating layer increased the volumetric efficiency, and the dimensionless mean residence time increased from 0. 816 to 1. 093. The proportion of dead volume was decreased, but the plug flow of water was not affected.