Automatic sludge extraction and washing device for use in a water treatment settling apparatus

In a sludge bed settling apparatus of the type including a decanter containing therein a sludge bed, means for introducing fluid to be treated into said decanter and for passing said fluid upwardly through said sludge bed, whereby impurities are removed in the form of settling sludge, and a sludge concentrator for collecting a portion of said sludge;

• the improvement of means for selectively extracting sludge from said concentrator and for selectively washing said concentrator and decanter, said extracting and washing means comprising:
• at least one siphon having a first end extending into said concentrator and a second end;
• a manifold conduit extending from said fluid introducing means to a sludge removal station, said second end of said siphon being connected to said manifold conduit;
• a vacuum source;
• first valve means selectively movable from a first position connecting said siphon to said vacuum source to a second position blocking connection between said siphon and said vacuum source;
• second valve means selectively movable from a first position connecting said siphon to atmosphere and a second position blocking said siphon from atmosphere;
• third valve means selectively movable from a first position connecting said manifold conduit to said fluid introducing means and a second position blocking connection between said manifold conduit and said fluid introducing means;
• fourth valve means selectively movable from a first position connecting said manifold conduit to said sludge removal station to a second position blocking connection between said manifold conduit and said sludge removal station;
• whereby, when said first, second, third and fourth valve means are respectively in said first, second, second and first positions thereof sludge in said concentrator is sucked by said vacuum source into said first end of said siphon, out said second end of said siphon into said manifold conduit, and from said manifold conduit to said sludge removal station, thereby achieving a sludge extraction operation;
• and
• whereby, when said first, second, third and fourth valve means are respectively in said first, second, first and second positions thereof, fluid passes from said fluid introducing means into said manifold conduit, is sucked by said vacuum source into said second end of said siphon, passes through said first end of said siphon into said concentrator, thereby washing said concentrator, and overflows said concentrator, thereby falling onto and washing the bottom of said decanter, thereby achieving a washing operation.