Sewage treatment plants

Claim 1

BIO-FILTRATION APPARATUS COMPRISING AN ANNULAR PRIMARY SETTLING CHAMBER, MEANS FOR INTRODUCING LIQUID SEWAGE INFLUENT INTO SAID PRIMARY SETTLING CHAMBER, AN ANNULAR FINAL SETTLING CHAMBER CONCENTRIC TO SAID PRIMARY SETTLING CHAMBER, A DIGESTER CHAMBER BELOW AND IN COMMUNICATION WITH SAID SETTLING CHAMBERS FOR RECEIVING SLUDGE SETTLING FROM THE LIQUID SEWAGE IN SAID SETTLING CHAMBERS, AN ANNULAR PRIMARY FILTER BED ABOVE SAID PRIMARY SETTLING CHAMBER, AN ANNULAR SECONDARY FILTER BED CONCENTRIC TO SAID PRIMARY FILTER BED, ROTATABLE MEANS FOR CONDUCTING LIQUID SEWAGE FROM SAID PRIMARY SETTLING CHAMBER AND FOR UNIFORMLY DISTRIBUTING THE SAME ONTO THE UPPER SURFACE OF SAID PRIMARY FILTER BED, MEANS FOR DIVIDING THE FILTRATE FROM SAID PRIMARY FILTER BED INTO TWO COMPONENTS AND FOR RETURNING ONE SUCH COMPONENT TO SAID PRIMARY SETTLING CHAMBER, MEANS FOR COMBINING THE ENTIRE QUANTITY OF THE OTHER SUCH COMPONENT WITH LIQUID DRAWN FROM SAID FINAL SETTLING CHAMBER, ROTATABLE MEANS FOR CONDUCTING THE THUS COMBINED LIQUIDS AND FOR UNIFORMLY DISTRIBUTING THE SAME ONTO THE UPPER SURFACE OF SAID SECONDARY FILTER BED, MEANS FOR CONVEYING THE FILTRATE FROM SAID SECONDARY FILTER BED TO SAID FINAL SETTLING CHAMBER, AN EFFLUENT DISCHARGE FROM THE UPPER SURFACE OF THE LIQUID IN SAID FINAL SETTLING CHAMBER, AND MEANS FOR REMOVING DIGESTED SLUDGE FROM SAID DIGESTER CHAMBER.