Study On The Fluorescent Dissolved Organic Matter In Waste Water Treatment

The dissolved organic matter in all water samples taken from a sewage treatment plant inHefei was analyzed and the COD, the total nitrogen and ammonia nitrogen, and the UV₂₅₄inthe water sample of each treatment unit were tested. The conclusions are as follows:（1） Thewater sample contains mainly three kinds of fluorescent substances, namely protein-likesubstance, visible humic-like substance and UV humic-like substance, with their fluorescencepeak at Ex/Em=280/340, Ex/Em=260/420and Ex/Em=320/420respectively.（2） The organicmatter in wastewater can be effectively removed during A/A/O oxidation ditch process. Theremoval rate of soluble COD was67%, that of ammonia nitrogen was85%, and that of proteinwas67.7%, while the removal efficiency of UV₂₅₄was43.7%, and that of humus was32.4%.（3）A/A/O oxidation ditch process can effectively remove the protein-like substance and visiblehumic-like substance, with the removal rate at56.4%and39%respectively. However, it cannotremove the UV-visible humic-like substance.（4） In the A/A/O oxidation ditch process, theorganic matter is removed mainly in the anaerobic and anoxic zone. The fluorescence spectraanalysis shows that the removal rate of protein-like substance during the above phase is42%,that of humic-like substance is38%and UV visible humus with an increase of10%.（5） Duringthe wastewater treatment, the intensity of protein-like fluorescence and protein concentrationdetermined by Folin-phenol method were correlated, so are the intensity of humic-likefluorescence and humic acid concentration, with the correlation coefficient at0.9359and0.9603respectively. Therefore, the content of protein and humus in sewage can be represented bythe intensity of protein-like fluorescence at Ex/Em=280/340and visible humic-like fluorescenceat Ex/Em=320/420.（6） During the on-line monitoring process of sewage treatment plant, thechange of COD and the process of water treatment can be reflected by the intensity ofprotein-like fluorescence at Ex/Em=280/340and visible humic-like substance fluorescence atEx/Em=320/420together, so as to reduce the use of chemicals and promptly reflect theoperational conditions in the sewage treatment plant.