Method and apparatus for treating wastewater using membrane filters

• US 6,517,723 B1
• Filed: 07/27/2000
• Issued: 02/11/2003
• Est. Priority Date: 07/27/2000
• Status: Expired due to Term

• Current Assignee: CH2M Hill Incorporated (CH2M Hill Companies Limited)
• Original Assignee: CH2M Hill Incorporated (CH2M Hill Companies Limited)
• Inventors: Daigger, Glen T., Wollmann, Albert M., Fleischer, Edwin J., Broderick, Thomas A., Murthy, Sudhir N.
• Primary Examiner(s): Barry, Chester T.
• Application Number:
  US09/626,879
• Time in Patent Office: 929 Days
• Field of Search: 210/798, 210/605, 210/196
• US Class Current: 210/605
• CPC Class Codes: C02F 1/283 using coal, charred products, or inorganic mixtures containing them
• CPC Class Codes: C02F 2209/22 O2
• CPC Class Codes: C02F 3/006 Regulation methods for biological treatment
• CPC Class Codes: C02F 3/12 Activated sludge processes
• CPC Class Codes: C02F 3/121 Multistep treatment
• CPC Class Codes: C02F 3/1226 comprising an absorbent material suspended in the mixed liquor
• CPC Class Codes: C02F 3/1273 Submerged membrane bioreactors
• CPC Class Codes: C02F 3/30 Aerobic and anaerobic processes
• CPC Class Codes: C02F 3/308 Biological phosphorus removal
• CPC Class Codes: Y02W 10/10 Biological treatment of water, waste water, or sewage

Abstract

An apparatus using activated sludge for the removal of biological nutrients from a wastewater includes a bioreactor for containing a mixture of wastewater under treatment and activated sludge. The bioreactor is divided into a plurality of serially connected treatment zones and includes a wastewater inlet, a downstream aerobic zone and an upstream aerobic zone between the wastewater inlet and the downstream aerobic zone. A membrane filter is provided in the downstream aerobic zone so that it functions as an immersed membrane filter with a bioreactor containing an operative volume of wastewater and activated sludge. The immersed membrane filter filters treated water flowing from the bioreactor through a first outlet. An aerator is operative associated with the membrane filter for purging solids from the membrane filter. A second outlet in the downstream aerobic zone is connected to an inlet in the upstream aerobic zone for recycling activated sludge charged with oxygen from the downstream aerobic zone to the upstream aerobic zone.

A method for removal of nutrients from a wastewater includes providing a wastewater to an inlet of a serial, multi-zone, activated sludge bioreactor containing an activated sludge. The bioreactor has a downstream aerobic zone from which water is removed and an upstream aerobic zone between the wastewater inlet and the downstream aerobic zone. Treated water is filtered from the activated sludge in the downstream aerobic zone through an immersed membrane filter. Solids are purged from the immersed membrane filter with an oxygen containing gas and return activated sludge charged with oxygen is recycled from the downstream to the upstream aerobic zone or to an upstream deaeriation zone.

Claims

1. A method for removal of biological nutrients from a wastewater, comprising:

providing a serial multistage bioreactor containing activated sludge having in hydraulic series an anaerobic zone, an upstream anoxic zone, an upstream aerobic zone, a downstream anoxic zone and a downstream aerobic zone, each zone having an upstream inlet and a downstream outlet;

providing wastewater to the anaerobic zone inlet;

filtering treated water from the activated sludge in the downstream aerobic zone through an immersed membrane filter;

purging solids from the immersed membrane filter with an oxygen containing purge gas;

recycling return activated sludge charged with oxygen associated with the oxygen containing purge gas from the downstream aerobic zone to near the inlet of the upstream aerobic zone;

recycling a nitrogen rich recycle from near the upstream aerobic zone outlet to near the upstream anoxic zone inlet; and

recycling a de-nitrified mixed liquor from near the upstream anoxic zone outlet to near the anaerobic zone inlet.

2. An apparatus utilizing activated sludge for the removal of biological nutrients from a wastewater, comprising:

a bioreactor for containing a mixture of wastewater under treatment and activated sludge, the bioreactor being divided into a plurality of hydraulically serially connected treatment zones including an anaerobic zone, an upstream anoxic zone, an upstream aerobic zone, a downstream anoxic zone and a downstream aerobic zone, the bioreactor being configured to flow wastewater from a downstream outlet of an upstream zone to an upstream inlet of a downstream zone;

a membrane filter in the downstream aerobic zone, the membrane filter being situated in the downstream aerobic zone so that it functions as an immersed membrane filter with the bioreactor containing an operative volume of wastewater and activated sludge, the immersed membrane filter filtering treated water flowing from the bioreactor through a first outlet;

an aerator operatively associated with the membrane filter for purging solids from the membrane filter with an oxygen containing purge gas;

a first recycle conduit in liquid communication between the downstream aerobic zone and near the inlet to the upstream aerobic zone for recycling return actuated sludge charged with oxygen associated with the oxygen containing purge gas from the downstream aerobic zone to the upstream aerobic zone;

a second recycle conduit in liquid communication between near the upstream aerobic zone outlet and near the upstream anoxic zone inlet for recycling a nitrogen rich recycle to the upstream anoxic zone; and

a third recycle conduit in fluid communication between near the upstream anoxic zone outlet and near the anaerobic zone inlet for recycling a de-nitrified mixed liquor to the anaerobic zone.