<prompt> True about slow sand filter isOccupies less spaceMore expensiveRequires longer durationSand size 0.4 - 0.7 mm  <response>: Slow sand filter occupies large area more space.Slow and filter requires less skilled operation.Slow sand filter removes more bacteria and has better bacterial control 99.9-99.99Slow sand filter requires longer duration for purification.Size of sand is smaller 0.2-0.3 mm.Slow sand filter requires more time duration. 