This paper presents results of laboratory and pilot scale experiments of direct filtration and explains the influences of particle concentration and the quantity and quality of natural organic material (NOM) on filtration performance. These results demonstrate that there is a lower limit to the concentration of particles in direct filtration such that below this limit filter ripening may be extremely slow causing the effluent quality to be unacceptable for long periods of time at the start of a filter run. The organic quality and quantity of an influent water determine both the coagulant dose and filtration performance to a far greater extent than turbidity. In fact low turbidity waters with moderate levels of organic material require relatively high coagulant doses making direct filtration difficult. Furthermore, changes in organic quality can exacerbate the difficulties in treating waters with even low levels of NOM (1-3 mg/l TOC).
|Original language||English (US)|
|Issue number||3-4 supp|
|State||Published - Dec 1 1991|
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