| 摘要 |
<p>Filtration apparatus comprises a column (1) having a lower liquid inlet (7), an upper liquid outlet (2), and an intermediate internal screen (4) adapted to confine a bed (5) of buoyant particles therebelow; means (8) adapted to cause liquid to flow up the column; and means (9, 10) adapted to expand the bed. Such apparatus can be used to remove biodegradable impurities from a liquid, by causing the liquid to flow up the column, the column including, below the or each screen, buoyant particles on which biomass will collect; and intermittently operating the expansion means. For example, an aeration pump may be operated such that, in normal flow conditions, the bed is substantially undisturbed, and intermittently such that the particles are less buoyant and biomass on the particles is removed by attrition as the particles circulate.</p> |
