Abstract: Apparatus for effecting clarification of liquid having particulate material entrained therewithin includes a filter screen and a filter-cleaning device disposed adjacent thereto operable for removing particulate material from the filter screen which has been deposited or accumulated thereon from a particulate-laden liquid discharged onto the filter screen. The filter-cleaning device includes a dispenser which is selectively positioned, in an automatic manner, relative to the filter screen to direct a fluid flow against the filter screen at variable locations thereon to impart movement to the retained particulate material relative to the filter screen. Additionally, the filter-cleaning device of the present invention includes a plurality of nozzles, which form the dispensing device, mounted on a carriage which is operable for carrying the dispensing device so that the nozzles will be presented over the filter screen in a selective, reciprocally shifting manner.