地下水修复系统中释氧材料的改进及pH调控

在采用释氧材料的地下水污染修复系统中,释氧材料提供溶解氧的同时,往往造成体系pH的升高。针对这一问题,将过氧化钙(CaO2)、水泥、河沙、膨润土和KH2PO4按一定比例混合在一起制作了3种释氧材料,并在柱实验中观测了不同释氧材料对水体溶解氧(DO)及pH值的影响。实验数据表明,水泥对释氧材料的缓释作用明显,有助于保证释氧速率平稳,避免由于释氧材料反应过快所带来的高pH问题;在释氧材料中添加一定量KH2PO4(质量分数小于10%),可以起到缓冲体系pH值的作用,并且不会造成修复系统磷污染;电气石具有降低溶液高pH值的作用,以粒径为1～2 mm的电气石作缓冲介质可以将体系pH值由11.3降至10.2。

Optimization of oxygen-releasing materials and pH regulation in groundwater remediation system

Using oxygen-releasing materials to supply oxygen for groundwater remediation system can result in pH increase of groundwater. To solve this problem, three kinds of oxygen-releasing materials were made by blending cement, calcium peroxide (CaO₂), sand, bentonite, KH₂PO₄ and water together with certain proportion. Column experiments were conducted to evaluate the influence of oxygen-releasing materials on dissolved oxygen (DO) and pH of groundwater. The experimental results showed that cement has a good effect on controlling oxygen-releasing rate. High proportion of cement in oxygen-releasing materials can delay the oxygen-releasing rate and avoid high pH of water caused by the fast reaction of oxygen-releasing materials. Adding KH₂PO₄(mass fraction less than 10%)in oxygen-releasing materials can decrease pH of system and total phosphorus concentration in water can meet the drinking water standard. Using granular tourmaline (1~2 mm in diameter) as the buffering zone can decrease high pH from 11.3 to 10.2