Patent ID: 7479224

Claim:
A plant for the biological purification of waste water, said plant including in sequence a unit for decomposing organic matter, a first sludge sealing unit, a nitrification unit and a sludge settling unit, characterised in said plant includes an aerated primary settling unit prior to said units, wherein said plant further includes an aerated primary settling tank ( 1 ), a primary chamber ( 2 ) having an immersed bio filter ( 3 ), said bio filter being aerated by a diffuser ( 4 ) positioned beneath the filter unit, said plant further including a settling tank ( 5 ) collecting the sludge from the biological process as said sludge is fed back into the primary settling tank ( 1 ) by means of a pump system ( 6 ), and said plant further including a vertical settling tank ( 7 ), a secondary chamber ( 8 ), which in the same way as the primary chamber ( 2 ) is equipped with an immersed bio filter ( 3 ′) aerated by a diffuser ( 4 ′) positioned beneath the filter unit, said plant also including a secondary settling tank ( 9 ) from which purified water is discharged through an outlet.