In this study the removal efficiency of humic substances by conventional drinking water treatment processes was studied in a full scale operating plant in Windsor, Ontario, Canada over a period of 16 months. A comparison of the removal efficiency of humic substances between conventional and advanced treatment processes such as ozonation (used as an oxidant before filtration) and the addition of granular activated carbon (GAC) was also carried out for the same water source (Detroit River) in a pilot scale treatment plant at the same location. The performance of different treatment processes in removing humic substances was evaluated through the quantification of humic substances and their apparent molecular size distributions (AMSD) in samples taken from the raw water and after each treatment process. The dissolved organic carbon (DOC) and the concentration of the non-humic substances for the water source (Detroit River) were also determined. Results indicate that seasonal variations in humic substances concentration occurred, showing a maximum level during the month of April when the spring turn-over of water bodies took place. These seasonal variations were associated with the corresponding changes in THM concentrations observed during the same period. The fulvic and humic acid composition of humic substances and their THM formation potential (THMFP) were quantified. Their AMSD were determined by the gel permeation chromatography (GPC) and the high performance size exclusion chromatography (HPSEC). The humic substances from the Detroit River were found to be less reactive in forming THMs (μg THM/mg C) when compared with the standard humic substances provided by the International Humic Substances Society (IHSS). Coagulation-sedimentation was the most efficient process of the conventional treatment options in the removal of humic substances. The GAC greatly improved the removal efficiency of not only the humic substances but also of a large fraction of the non-humic substances. The removal of humic substances by the use of ozone as an oxidant before filtration was similar to that obtained by the conventional treatment with prechlorination. The THMFP was determined on water samples from different processes and on their corresponding non-humic fractions. Precursor removal after each process effectively reduced the THMFP in the treated water. The non-humic fractions appeared to be potential contributors to the formation of THMs for high chlorine dosages. Source: Dissertation Abstracts International, Volume: 56-01, Section: B, page: 0389. Adviser: Nihar Biswas. Thesis (Ph.D.)--University of Windsor (Canada), 1994
