浑水质量分数对石英砂滤料过滤性能的影响

为了正确评价泥沙颗粒对微灌系统堵塞的影响,试验配置了4种质量分数分别为0.3‰,0.5‰,0.8‰和1‰的浑水,通过微灌用砂过滤器模型,研究了滤后水的浊度、粒径变化以及泥沙颗粒质量浓度随时间的变化规律.结果表明:浑水质量分数影响滤后水浊度和颗粒质量浓度,浑水质量分数大,则滤后水浊度和颗粒质量浓度高;不同质量分数浑水过滤10 min后,滤后水浊度均逐渐下降,而当浑水质量分数增大到0.8‰时,过滤10 min时滤后水浊度极不稳定,滤层截留较多的粒径大于0.1 mm颗粒,也有2%~3%的大粒径颗粒穿过了滤层.当浑水质量分数小于0.5‰时,滤后水中粒径小于0.1 mm颗粒的质量分数增大较少,粒径大于0.1 mm颗粒的质量分数不到1%.随着浑水质量分数的增大,平均浊度滤除率和颗粒质量浓度减少率均呈负二次曲线变化,当浑水质量分数为0.8‰时,分别达到56.69%和57.61%.大质量分数的浑水具有较大的浊度滤除率和颗粒质量浓度减少率,但易于造成砂滤层的堵塞,降低其过滤效果、缩短过滤时间.

Influence of muddy water mass fraction on performance of packed quartz sand bed

A series of experiments were conducted on performance of a filter model with packed quartz sand bed applied in micro-irrigation by using muddy water respectively with four kinds of mass fractions: 0. 3‰,0. 5‰,0. 8‰ and 1‰ to properly evaluate effect of sediments in the muddy water on clogging in that irrigation system. In those experiments,the variation of turbidity of filtrated water,change of sand grain size as well as the relationship between sand concentration and time were measured. The results showed that the mass fraction of muddy water affected the turbidity and particle concentration in filtered water;particularly,the more mass fraction,the poorer the turbidity and the higher sand concentration in filtered water. The turbidity of filtered water declined gradually after a filtration was lasted for 10 minutes for the muddy water with less than 0. 8‰ mass fraction;however,when the mass fraction was increased to 0. 8‰,the turbidity of filtered water showed a significant fluctuation even the water had been filtered for 10 minutes. Moreover,most the particles with a size larger than0. 1 mm had stayed in the filtering bed,fortunately there still were 2%-3% large size particles that had gone through the bed. For the muddy water with a mass fraction less than 0. 5‰,the mass fraction of particles with a size smaller than 0. 1 mm in the filtered water increased slowly,and the fraction of particles with a size larger than 0. 1 mm was less 1%. The average filtration ratio of turbidity and decrease rate of sandy particle concentration showed a quadratic relation with a negative quadratic coefficient as the mass fraction of muddy water was increased; especially they had reached 56. 69% and57. 61% respectively when the mass fraction was at 0. 8‰. The muddy water with a higher mass fraction had a better filtration ratio and a larger decrease rate of sand concentration,but the filter bed could be jammed easily,reducing filtering effect and shortening filtration time.