天然胶体对含水介质中氨氮迁移的影响

Effect of Natural Colloid on Ammonia Nitrogen Transport in Water-bearing Media

为了研究天然胶体对氨氮在滨海含水介质中迁移的影响,文章采用室内土柱实验,分析了0、70、160、265和630mg/L五种不同浓度胶体影响下氨氮的迁移-转化规律。研究结果表明:氨氮在胶体影响下的穿透曲线表现为"未穿透"、"开始穿透"和"完全穿透"三个阶段,但是不同胶体浓度下三个阶段出现的孔隙体积数不同。胶体对氨氮迁移的影响与胶体浓度有关,当胶体浓度为70mg/L和160mg/L时,氨氮完全穿透时的孔隙体积数小于无胶体情况,胶体对氨氮的迁移具有促进作用;当胶体浓度为265mg/L和630mg/L时,氨氮完全穿透时的孔隙体积数大于无胶体情况,胶体对氨氮的迁移具有阻滞作用。这说明在160mg/L和265mg/L之间存在一个临界浓度;当胶体浓度达到临界浓度之前,胶体对氨氮的迁移起促进作用;当浓度超过临界浓度后,胶体对氨氮的迁移起阻滞作用。

Effects of natural colloids on transport of ammonia nitrogen were studied in sand packed laboratory columns under five different concentrations of colloid. Solutions of deionized water （DI）, 70,160,265 and 630mg/L were used in saturated columns. Results showed that breakthrough curves of ammonia nitrogen presented as three stages including not-yet- breakthrough, breakthrough in process and complete breakthrough. The pore volumes of three stages were different under various colloid concentration conditions. When colloid concentrations were 70mg/L and 160mg/L, the presence of colloids facilitated the transport of ammonia nitrogen through sand columns, which the pore volumes of ammonia nitrogen complete breakthrough were obtained smaller than in the absence of colloids, while colloid concentration at 265mg/L and 630mg/L were opposite, which showed that there was a critical colloid concentration between 160mg/L and 265mg/L, with colloid facilitating ammonia nitrogen migration when its concentration up to the critical concentration and retarding when beyond the critical concentration.