Coagulation Of Natural Organic Matter In Water Characteristic Study

This paper mainly studied the coagulation characteristics of natural organic matters(NOM), analyzed the impact of inorganic particles on coagulation mechanisms and effectsof NOM. Online monitoring of the coagulation process was conducted by using PDA2000and the structure of flocs was preliminary discussed.The result shows that, the optimum coagulation pH of NOM is about 5.0 and themechanism for NOM removal varies with pH. At pH 5.0, the highest TOC removal is reachedat zero ζ potential; with the increase of Alum dose, charge reversal is observed and sweepcoagulation becomes the dominant mechanism. At pH 7.0, there is no difference between TOCand DOC removal, charge reversal is not observed and sweep coagulation is the dominantmechanism. In clay-humic acid suspension, the coagulation is subject to the organics. Thepresence of clay particles improves the settle ability of flocs.Comparing the liquid chromatography before and after coagulation, it is obvious thatcoagulation can bring about effective removal of macromolecule of organics but with almostno effect on the removal of small molecule.Online monitoring of the coagulation process by PDA2000 shows that flocculationindex is fairly consistent with the removal of TOC, the bigger the FI, the higher the TOC removal.In this paper, preliminary study on floc structure is also reported. It is found that variouscoagulation conditions lead to different floc structures.