微灌用均质砂滤料过滤粉煤灰水时对颗粒质量分数与浊度的影响

Effects of filter with uniform sandy filtration medium used in micro-irrigation on mass fraction of particles and turbidity of water with fly ash

为了搞清楚微灌用均质砂滤料的过滤效果,作者开展了均质砂滤料过滤对粉煤灰水质的固体颗粒质量分数和水质浊度影响的模型试验。对颗粒质量分数影响试验显示:虽然颗粒质量分数的平均滤除率均在59%以上,但试验数据变化幅度很大,说明过滤对颗粒质量分数的影响较为复杂;滤除率与过滤速度成负相关,与原水颗粒质量分数成正相关;试验数据验证了敏茨过滤方程表述的"过滤是吸附和脱落交互发生的过程"对微灌过滤条件的合理性,证明了微灌过滤水流流态均为非层流,多数情况处在层流与紊流的过渡区内。对浊度影响试验发现:滤层厚度对浊度滤除比起决定性的作用,浊度粒子吸附与脱落时间均大约在5～6min,滤速对浊度去除率的影响是有限的。比较2个试验可看出:滤后水的颗粒质量分数和浊度值是2个不相关的参数,其过滤过程是截然不同的,进而得出以浊度指标来判断微灌过滤和反冲洗效果是不科学的。该试验为今后微灌过滤技术的发展提供了参考。

The aim of the research is to make clear the filtration effect of the uniform sandy filtration medium in micro-irrigation. An experimental research on the effects of filter with uniform in micro-irrigation on mass fraction of particles and turbidity of water with fly ash was carried out. The results of mass fraction of particles test showed that,the average removal rate of the mass fraction of particles was above 59%. However,the variation range of test data was large which indicated a complicated filtration process. Removal rate of the mass fraction of particles in filtered water was negatively correlated with filtration speed,and positively correlated with the mass fraction of particles of influent water. The conclusion described by the Mintz filter equation was showed its correctness in micro-irrigation through this study,namely,the filtration was a course that adsorption and abscission ocoured alternatively. The filtration flow regime was proven to be non-laminar flow,in most cases,might be in the transition region between the level flow and turbulence. The results of the turbidity test showed that the filtration layer thickness played decisive role in the removal rates of turbidity. Both the adsorption time and the abscission time were all about 5–6 min. The effect of the filtration rate on the removal rates of turbidity was limited. It could be summarized by comparing the two tests that the mass fraction of particles of filtered water and turbidity were two parameters that were not related with each other. The two filtration processes were different,so it was not correct that judge the effects of filtering and backwashing by turbidity index. The experiment can provide some references for the development of the future micro-irrigation.