The disclosed method and apparatus separates solid impurities from a fluid containing solid impurities. The method and apparatus allow the introduction of influent comprising a fluid containing solid impurities into a plurality of channels and allowing at least a portion of the solid impurities initially present in the influent to settle on upward-facing surfaces of a plurality of plates forming the channels or slide down the upward-facing surfaces, while permitting fluid, which has been depleted of at least a portion of solid impurities, to flow upward toward the top edges of the plurality of plates. The influent is introduced into the plurality of channels in a manner that inhibits a disrupting or disturbing of the solid impurities, which have separated from the influent.