【摘要】：人工回灌過(guò)程中的堵塞問(wèn)題一直是影響其推廣的瓶頸,目前回灌過(guò)程中大顆粒懸浮物導(dǎo)致的堵塞機(jī)理研究較多,對(duì)膠體類(lèi)顆粒物的堵塞機(jī)理研究相對(duì)少。采用室內(nèi)砂柱實(shí)驗(yàn),研究不同離子強(qiáng)度和不同水流流速條件下膠體在飽和多孔介質(zhì)中的遷移-滯留特征。選擇大腸桿菌為實(shí)驗(yàn)?zāi)z體,設(shè)計(jì)在不同離子強(qiáng)度、不同水流條件下的砂柱回灌實(shí)驗(yàn);運(yùn)用Hydrus-1D軟件模擬,擬合穿透曲線(xiàn)后得到表征膠體沉積的相關(guān)參數(shù)。實(shí)驗(yàn)結(jié)果表明,在相同的離子強(qiáng)度下,流速增大會(huì)促進(jìn)膠體的遷移,穿透曲線(xiàn)峰值增高,膠體的吸附率減小。在中等離子強(qiáng)度條件下(IS=30、50 mmol·L-1)流速對(duì)膠體的這種影響比在更低的離子強(qiáng)度(≤10 mmol·L-1)或更高的離子強(qiáng)度(≥300 mmol·L-1)條件下更為顯著;相反地,同一流速條件下,離子強(qiáng)度從10 mmol·L-1升高到300 mmol·L-1時(shí),膠體的吸附隨著離子強(qiáng)度的增加而迅速增加。從膠體和介質(zhì)相互作用勢(shì)能來(lái)看,隨著離子強(qiáng)度的增加,膠體和砂表面的相互作用增強(qiáng),有利于膠體吸附在介質(zhì)表面,增加介質(zhì)堵塞的概率。但是,在一定的離子強(qiáng)度下,流速的增加產(chǎn)生的水動(dòng)力剪切力有利于促進(jìn)膠體的遷移,不利于膠體的吸附或阻塞,減少了微小顆粒堵塞的概率。模擬結(jié)果顯示吸附速率系數(shù)k、最大固相沉積量Smax隨著離子強(qiáng)度的增大而增大,隨著流速的增大而減小。從整體上來(lái)看,回灌過(guò)程中膠體微粒的遷移滯留行為主要受控于離子強(qiáng)度,但水流因素會(huì)干擾離子強(qiáng)度的控制作用。在實(shí)際的人工回灌過(guò)程中,有效的預(yù)防堵塞需要將化學(xué)(降低離子強(qiáng)度)和水動(dòng)力(增加回灌水流速)手段有效地結(jié)合起來(lái)。
[Abstract]:The blockage problem in the artificial recharge process has been the bottleneck to its popularization. At present, there are more studies on the blockage mechanism caused by the suspension of large particles in the recharge process, but less on the blocking mechanism of the colloidal particles. The migration and retention characteristics of colloids in saturated porous media with different ionic strength and flow velocity were studied by laboratory sand column experiments. Escherichia coli was selected as the experimental colloid to design the sand column recharge experiment under different ionic strength and different flow conditions, and the relevant parameters of colloid deposition were obtained by using Hydrus-1D software to simulate and fit the penetration curve. The experimental results show that under the same ionic strength, the increase of flow velocity will promote the migration of colloids, the peak value of the penetration curve will increase, and the adsorption rate of the colloid will decrease. The effect of flow rate on colloid at medium plasma intensity (IS=30,50 mmol L-1) is more significant than that at lower ion intensity (鈮，

本文編號(hào)：2269791