Washoff behavior of in-sewer deposit in combined sewer system through artificial flushing experiment

摘要

In-sewer deposits in combined sewer systems (CSSs) are closely related with the behaviornof first foul flush and combined sewer overflows. However, the research paying attention tonthe role of in-sewer deposits is quite rare, furthermore, their contributions for the washoffnpatterns of each pollutant including pathogenic microorganisms are almost never discussed sonfar. The artificial flushing experiment separating the washoff of in-sewer deposits from theninflow of surface pollutants was carried out to simulate the first foul flush in a CSS. The washoffnbehaviors of each pollutant including bacterial indicators and enteric viruses were investigated.nSeveral morphological analyses for the concentration and load curves of each parameter werenconducted and all patterns were classified according to their washoff characteristics and firstnfoul flush patterns. The washoff behaviors of each pollutant and microorganism are differentnfrom each other and categorized into several groups according to their (i) time-seriesnconcentration and load curves and (ii) concentration vs. flow rate curves, respectively.nThe first foul flush patterns of each parameter were to be categorized into typical 3 groups;nstrong-, partial-, and no first foul flush group. The order of these groups signifies the strengthnof the first foul flush phenomena and the runoff priority as well.