The filtration unit for removing solids from liq. effluent or the like e.g. prior to colorimetric analysis of the liq., comprises a chamber (3) with inlet (7,10) sepd. by a filter (14) from a second chamber (4) with outlet (17,8). The two chambers are only partly filled with liq. during the (continuous) filter operation, and the incoming liq. (II) is supplied such that its initial contact with the filter takes place above the liq. level (9) in the inlet chamber (3). The inlet chamber (3) may be provided with an overflow tube (6) which determines the liq. level (9) whilst the liq. is removed such that the pressure in the two chambers is approximately equal (the chambers communicate via the filter area above the level 9). Used in filtration of e.g. effluent or surface water to remove solids prior to analysis. The arrangement prevents clogging of the filter as it is constantly cleaned by the suspension running down its surface and there is no pressure differential between the chambers which would cause solids to remain lodged on that surface.
展开▼