In May 1999, a project using a dissolved air flotation (DAF)/ozone/filtration pilot plant was started to study the effects of pre-ozonation on the flocculation of particles and removal of organic matter in an advanced treatment process. Results indicate that small doses of ozone pre-ozonation slightly improve the flocculation of particles and their subsequent removal in the DAF unit when used in conjunction with alum or PACl. However, it was found that high ozone doses impeded flocculation. More significant is ozone's benefit for the removal of UV-absorbing organic matter. The study also found that DAF is very effective at removing turbidity causing particles and colour from the water, thereby improving filter performance.
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