Study On The DOM Degradation In The Constructed Wetland And Its Interaction With Dye By Three-Dimensional Fluorescence Technology

Dissolved Organic Matter (DOM) is a kind of organic compounds which widely exist in the environment. It is full of some active group, such as hydroxyl, carboxyl, amino-group, aromatic ring, enoyl-group, and thiol-group. It can react with many contaminants due to the presence of many active groups, leading to change in the movement and existence form of environmental contaminants. Therefore, much attention has been paid on the research of DOM removal. The constructed wetland is a kind of highly effective and practical sewage treatment system and has gradually been come mature. In this thesis, the three-dimensional fluorescence technology was used to study:(1) the performance of the constructed wetland for DOM removal; (2) the distribution of DOM within the wetland area; (3) interaction between Extracellular Polymer Substances (EPS) and dye.The following results can be obtained through our study:(1) The wetland can efficiently remove DOM. For example, the studied constructed wetland system can remove 51.20%-77.85% DOM in the sewage. Although the DOM concentration significantly decreases, the composition of effluent becomes complicated. Compared with plants, the influence of filler on DOM removal is more obvious. The cinder is better than gravel in removing DOM. The plants can improve the performance of wetlands for DOM removal when filled with cinder, but it has no obvious influence on that filled with gravel.(2) It is found that there are high organic loading in the part of wetlands near influent, which makes it easy to cause clog in this part. As compared with upper layer water sample, higher DOM concentration was found in the bottom layer water sample. The ability of wetlands to remove humic substances is better than that to protein substances. The effect of the plant and microorganism in wetlands on DOM was complicated, leading to complex fluorescent compositions. The decomposition of root, stem and leaves of plants can increase the content of the DOM.(3) EPS extracted from active sewage presents fluorescence peak T1 and T2, both of which are protein fluorescence peaks. As compared with T1 protein fluorescence peak, peak T2 is easier to combine with RHB than peak T1 to cause quenching of RHB fluorescence. When peak T2 and peak T1 react with RHB, temperature has great influence on the former. RHB is easier to react with the florescence constituent of EPS than metals.