US 5,853,588 AGranted

Wastewater treatment process

AssigneePolytechnic University

InventorsAlan H. Molof, Zuwhan Yun, Sungtai Kim

Life of this patent

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Abstract

A wastewater treatment process having improved solids separation characteristics and reduced biochemical oxygen demand (BOD) in the purified wastewater comprising the steps of: passing wastewater containing suspended solids and biodegradable organic substances through a main aerobic biological oxidation zone; passing the effluent from said aerobic biological oxidation zone to an aerobic/mixing zone and therein mixing said effluent with effluent from the anoxic/anaerobic zone; passing the effluent from said aerobic/mixing zone to a settling zone and therein separating purified wastewater and sludge containing suspended solids; passing a portion of the sludge formed in the settling zone and volatile acids to an anoxic/anaerobic zone; and recycling an effective amount of the effluent from said anoxic/anaerobic zone to said aerobic/mixing zone. In an alternative embodiment, a volatile acid is added to a zone to which no additional oxygen has been added that is in the flow path from the main aerobic biological oxidation zone or, alternatively, it may be added to the anoxic/anaerobic zone and the thus-treated effluent is passed to the aerobic/mixing zone wherein phosphate is removed from the effluent.

Claims24

Dependent claims

A wastewater treatment process providing increased nitrogen, phosphate and biochemical oxygen demand removal comprising the steps of:

(a) passing wastewater containing ammonia nitrogen, phosphate and biochemical oxygen demand through a main aerobic biological oxidation zone and therein oxidizing at least a portion of the ammonia nitrogen to nitrate nitrogen and at least a portion of the biochemical oxygen demand and converting at least a portion of the biochemical oxygen demand into suspended solids;
(b) passing (i) effluent from the main aerobic biological oxidation zone, (ii) at least one volatile acid, and (iii) final sludge recycled from settling step (d) to a zone to which no additional oxygen is added and therein reducing at least a portion of the ammonia and nitrate nitrogen to molecular nitrogen and thereby releasing phosphate;
(c) passing effluent from the zone of step (b) to an aerobic/mixing zone wherein the effluent is mixed under aerobic conditions and molecular nitrogen and phosphate are removed;
(d) passing effluent from the aerobic/mixing zone to a final settling zone and therein separating
(i) a purified wastewater having decreased biochemical oxygen demand and a decreased phosphate and nitrogen content and
(ii) a final sludge containing suspended solids and phosphate;
and
(e) recycling at least a portion of the final sludge to the zone of step (b).

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/794,660Filed 3 Feb 1997 · division
Priority: 2 Aug 1989
Granted: 29 Dec 1998
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

C02F 3/1221
Particular type of activated sludge processes: comprising treatment of the recirculated sludge
C02F 3/04
Aerobic processes: using trickle filters
C02F 3/308
Aerobic and anaerobic processes: biological phosphorus removal
Y02W 10/10
Technologies for wastewater treatment: biological treatment of water, waste water, or sewage

Family

Serial388,955Parent of this continuation-in-part · filed 2 Aug 1989
Serial909,027Parent of this continuation · filed 6 Jul 1992
Serial335,203Parent of this division · filed 7 Nov 1994
Serial577,821Parent of this division · filed 22 Dec 1995
US 5,651,891 AParent of this division
US 5,733,455 AParent of this division
US 5,128,040 AParent of this continuation-in-part
US 5,853,588 AThis patent

From the US filing history. Foreign family members aren’t listed.