The study on removal of disinfection by-product precursors with different molecular weight in drinking water treatment process

• Main Authors: Lan, Wen-san, 籃文賢
• Other Authors: Chiang Pen-chi
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/78026052999667666253

碩士 === 國立臺灣大學 === 環境工程學研究所 === 86 === Abstract In order to prevent the formation of the disinfection by-products (DBPs) during the chlorine disinfection process in the water treatment, it is necessary to introduce the alternative oxidants such as ozone and/or to optimize the conventional treatment process and/or to install the advanced unit process. This research is focused on the removal of precursors in the water treatment process. Continuous pilot-plant including traditional﹐ pre-ozonation and post-ozonation processes﹐was employed to evaluate the removal efficiencies of the precursors. In the pilot-plant studies﹐two commercial humic acids﹐ manufactured by the Aldrich Co. and Tokyo Chemical Industry (TCI) ﹐respectively﹐were used to simulate the precursors. Ultrafiltration technique was also utilized to separate the different molecular weight cut-off as a baseline information for evaluating the capability of removing these precursors associated with each unit process. The results showed that the smaller molecular weight (approximately <5K) contained higher formation potential. In comparison with two commercial humic acids (TCI H.A. and Aldrich H.A) and the raw water from the Ban-Shin water treatment plant﹐the sequence of the DBPFP/DOC ratio is followed as: TCI H.A. > Aldrich H.A > Raw water in Ban-Shin water treatment plant. By evaluating the above water treatment units, the coagulation process has the tendency to remove the large molecular weight organic precursors, however, it is not very useful when treating small molecular weight precursors. Consequently﹐coagulation is not a suitable unit to control DBPs﹐because DBPFP is dominated by small molecular weight precursors. When the precursors was oxidated by ozone the larger molecular organic compounds would be decomposed into smaller compounds﹐which were more easily adsorbed by the GAC. As a result﹐ozonation process could reduce the reaction activity of the precursors, so as to cut down the amount of the formation of DBPs. But it was not effective to remove soluble organic compounds which could be reduced by GAC process. As a conclusion, the ozonation coupled with GAC adsorption processes could be successfully in removing the precursors and DBPs from the source water.