PVA/CaO_(2)底泥原位修复材料的制备及其应用

Preparation of PVA/CaO_(2) and Its Application to in-situ Bottom Mud Remediation

该文以过氧化钙(CaO_(2))为释氧材料,活性炭、铁碳微电解填料为吸附和催化材料,以聚乙烯醇PVA为包埋剂,制备系列PVA/CaO_(2)复合材料。研究结果表明,PVA包埋的缓释氧材料(OSRC)释氧速率为0.134 mg/(L·h),相对于未包埋的CaO_(2)粉末(0.955 mg/(L·h))减缓了7/8,呈现显著的缓释效果;活性炭和铁碳微电解填料的加入可进一步降低OSRC的释氧速率(0.057 mg/(L·h)),颗粒活性炭掺杂OSRC具有更好的释氧效果,释氧时间可达400 h以上,同时实现了对于水体中TN、TP等富集和降解。将改性PVA/CaO_(2)复合材料应用于底泥修复中,结果表明改性PVA/CaO_(2)复合材料显著增加了上覆水溶解氧浓度(30.7%)。经过40余天的底泥修复试验表明,投加改性PVA/CaO_(2)复合材料可以显著降低上覆水和底泥间隙水中TP、NH_(4)-N等浓度,上覆水中TN、TP和NH_(4)-N去除率分别为29.8%、42.0%和51.3%,底泥间隙水中TN、TP和NH_(4)-N去除率分别为34.0%、52.5%和86.3%。改性PVA/CaO_(2)复合材料可以同时实现提高水体溶解氧浓度、为微生物提供附着基质、吸附与富集水体中污染物以及催化氧化还原水体污染物等多种作用,有效改善水-泥界面微环境、阻隔内源营养物质释放等,从而实现水质提升和水生态系统恢复的目的。

This study described the application of new materials(PVA/CaO_(2)composite) for remediation of bottom-mud of water bodies. Preparation of the materials involved calcium peroxide(CaO_(2)) which was used as the active material, and activated carbon plus iron-carbon micro-electrolysis packing used as adsorption and catalytic materials, and polyvinyl alcohol(PVA) used as the embedding agent. Experiment with the composite materials as OSRC(O_(2)slow-releasing compounds)showed that the O_(2)release rate of the PVA-embedded slow-release oxygen material equaled to 0.134 mg/(L · h), which was 7/8 slower than that without PVA-embedded CaO_(2)powder(0.955 mg/(L·h)), showing significant slow-release effects.Furthermore, addition of activated carbon and iron-carbon micro-electrolysis packing could enhance reducing the oxygen release rate of OSRC;OSRC doped with granular activated carbon could be releasing O2extending for more than 400 h, and at same time had better re-oxygenation effects, thus realizing the functions of adsorption, enrichment and degradation of TN, TP and other contaminants in water bodies. When the modified PVA/CaO_(2)composite materials were applied to the water-bodies ’bottom mud remediation, the concentration of dissolved oxygen(DO) in the overlying water could be remarkably increased, up 30.7%. With more than 40 days elapsed, result of the bottom-mud remediation experiment shown that adding OSRC oxygen release agent to the sediment could significantly reduce the concentration of TP, NH_(4)-N and other pollutants in the overlying water and the interstitial water of the sediment, i.e. the removal rates of TN, TP, and NH_(4)-N contained in the overlying water attained 29.8%, 42.0%, and 51.3%, respectively, and removal rates of TN, TP, and NH4;N in the interstitial water of the bottom mud were 34.0%, 52.5%, and 86.3%, respectively. In summary, PVA/CaO_(2)composite materials could simultaneously achieve multiple functions such as increasing concentration of DO in the water body, providing an attachment matrix for microorganisms, adsorbing and enriching pollutants in the water body, and catalyzing the oxidation and reduction of contaminants in water body, thereby improving the micro-environment of water-mud interface and obstructing inner-source’s nutrients release. Thus, It is expected that upgrading water quality and recovery of ecological system of water body can be realized.