Study on zero-emission treatment methods for dioxins and other hazardous organics in river water and sediment

研究了日本大阪木津河和住吉河受污染表层沉积物中粒径对二恶英含量的影响。粒径越小，样品中二恶英含量越高，粒径小于20μm的样品二恶英含量最高。粒径越小，二恶英浓度越高，其有机碳含量越高。研究了粒径对间接热解吸法修复沉积物中多环芳烃（PAHs）、二恶英和多氯联苯（pcb）等有害有机物污染的影响。由于有机碳含量较高，大粒径组分中的有机物比小粒径组分中的有机物更易蒸发，从而增加了有机质与小粒径组分中的有机碳之间的结合力。较小体积的有机物在继续加热的过程中降解并蒸发。上述结果说明了沉积物中有害有机物的粒度分布对沉积物中有害有机物含量的影响，以及间接热解吸法对污染沉积物的修复作用。从结果中可以明显看出，基于粒度分离的适当方法应该比传统方法更能有效地修复污染沉积物。研究了微滤法对污染沉积物水中二恶英的去除效果。通过混凝和微滤相结合的方法，几乎完全去除了沉积物水中的二恶英。此外，光催化、臭氧化和光催化臭氧化等高级氧化工艺对水和废水中顽固有机物的降解和矿化非常有效。

Effect of grain-size on dioxin contents in contaminated surface sediment samples obtained from Kizu and Sumiyoshi Rivers in Osaka, Japan, was investigated. Dioxin contents in the samples increased with smaller grain-size fractions, and less than 20μm fraction had the highest dioxin concentrations. The higher dioxin concentrations in smaller grain-size fractions were due to bigger organic carbon contents. Influence of grain-size on remediation of sediments contaminated with hazardous organics like polycyclic aromatic hydrocarbons (PAHs), dioxins and polychlorinated biphenyls (PCBs) by indirect thermal desorption method was also investigated. The organics in bigger grain-size fractions evaporated easily than those in smaller-size fractions due to bigger organic carbon contents resulting in increased binding force between the organics and organic carbon in the latter. The organics in smaller-size fractions degraded, and consequently evaporated on continued heating. These results did indicate the significance of grain-size distribution on the contents of hazardous organics in sediments, and remediation of contaminated sediments by indirect thermal desorption method. It was evident from the results that appropriate methods based on grain-size separation should be more relevant than the conventional approach for effective remediation of contaminated sediments. Removal of dioxins from contaminated sediment-water by microfiltration was also examined. Almost a complete removal of dioxins from the sediment-water was achieved by combined coagulation and microfiltration. In addition, advanced oxidation processes like photocatalysis, ozonation and photocatalytic ozonation were very effective for degradation and mineralization of recalcitrant organics present in water and wastewater.