MEMBRANE SUPPORTED BIOFILM APPARATUS AND PROCESS

• US 20100126929A1
• Filed: 04/14/2008
• Published: 05/27/2010
• Est. Priority Date: 04/20/2007
• Status: Active Grant

• Current Assignee: BL Technologies Inc. (Ashland Global Holdings, Inc.)
• Original Assignee: Fengshen Fan, Heather Lossing, Hidayat Husain, Minggang Liu, Reid Bayly, Richard Wong, Rocco Mazzaferro, Youngseck Hong
• Inventors: Wong, Richard, Fan, Fengshen, Lossing, Heather, Mazzaferro, Rocco, Hong, Youngseck, Bayly, Reid, Liu, Minggang, Husain, Hidayat
• Granted Patent: US 8,528,745 B2
• Time in Patent Office: Days
• US Class Current: 210/610
• CPC Class Codes: B01D 2313/143 on the feed side
• CPC Class Codes: B01D 2313/21 Specific headers, end caps
• CPC Class Codes: B01D 2313/23 Specific membrane protectors, e.g. sleeves or screens
• CPC Class Codes: B01D 2315/06 Submerged-type; Immersion type
• CPC Class Codes: B01D 63/043 with separate tube sheets
• CPC Class Codes: B01D 67/0097 Storing or preservation
• CPC Class Codes: C02F 2203/006 details of construction, e.g. specially adapted seals, modules, connections
• CPC Class Codes: C02F 3/102 Permeable membranes
• CPC Class Codes: C02F 3/208 Membrane aeration C02F3/201 takes precedence
• CPC Class Codes: C02F 3/2806 Anaerobic processes using solid supports for microorganisms
• CPC Class Codes: C02F 3/302 Nitrification and denitrification treatment C02F3/308 takes precedence
• CPC Class Codes: Y02W 10/10 Biological treatment of water, waste water, or sewage

Abstract

A membrane supported biofilm apparatus has a plurality of hollow fiber gas permeable membranes in a tank containing water to be treated. The membranes have an outside diameter of about 200 microns or less and occupy between 0.5% and 4% of the tank volume. A biofilm supported on the membranes occupies between about 40% and 80% of the volume of water to be treated in a reactor. The membranes may be oriented generally vertically and a spreader may be located near the bottom of the apparatus to disperse the membranes. Wastewater treatment processes are described. A process to dentrify water or treat oxidized contaminants comprises introducing hydrogen into an inner volume of the membranes to grow autotrophic organisms in the biofilm near the membrane and heterotrophic organism near the water. Another process is operated at a biomass concentration of at least 10 g/L and up to about 40 g/L to maintain a biofilm having a surface area of over 1000 square metres per cubic metre of tank volume. A hybrid process has suspended biomass and a membrane supported biofilm.

Claims

1. A membrane supported biofilm apparatus comprising a module having a plurality of gas permeable hollow fiber membranes collected at a lower end in a header and having upper ends adapted to be held or floated near a water surface when the module is immersed in a tank of water with the header on or near the bottom of the tank.

2. The apparatus of claim 1 wherein the membranes impermeable to bulk or advective water flow and have an outside diameter of about 200 microns or less and a length within the range of about 3-10 metres.

3. The apparatus of claim 1 comprising a tank, wherein the membranes are placed in the tank at a dry fiber packing density in the range of about 0.5% to 4%.

4. The apparatus of claim 1 comprising a tank, wherein the membranes are located in the tank and support a biofilm occupying about 40% or more of the volume of the tank.

5. The apparatus of claim 1 comprising a spreader near the header to horizontally space some of the plurality of membranes from others of the plurality of membranes.

6. The apparatus of claim 1 wherein the header is attached to an air supply manifold on or near the bottom of a tank containing the membranes.

7. The apparatus of claim 1 wherein a first module located in a first tank has a lower dry fiber packing density than a second module located in a second tank downstream of the first tank.

8. The apparatus of claim 1 wherein the module is located in a tank and further comprising a mixer and a solids removal port on or near the bottom of the tank.

9. The apparatus of claim 1 comprising a tank, wherein the membranes are located in the tank and support a biofilm occupying about 80% or less of the volume of the tank.

10. The apparatus of claim 1 wherein the membranes are located in a tank comprising channels at a feed end of the tank for feed dispersal.

25. The process of claim 12 comprising a step of providing an apparatus according to claim 1.

30. The bioreactor of claim 26 comprising the apparatus of claim 1.

11. A method of handing a module of hollow fiber membranes comprising the step of wrapping the membranes in a water soluble film or wrap, installing the wrapped membranes into a tank of water, and allowing the film or wrap dissolve into the water.

12. A process for treating water comprising the steps of introducing hydrogen into the inner volume of a gas permeable membrane immersed in water and introducing a carbon source to the water to grow a biofilm on the membrane having autotrophic organisms near the membrane and heterotrophic organism near the water.

13. The process of claim 12 further comprising introducing carbon dioxide into the inner volume.

14. The process of claim 12 further comprising recirculating the water.

15. The process of claim 12 wherein the carbon source is added at a COD/N ratio in the range of about 2:

1 to 4;

1.

16. The process of claim 12 wherein the ORP of the water is maintained in the range of about 0 to −

100 mV.

17. The process of claim 12 comprising maintaining a biomass concentration of about 20 g/L or more and a biofilm surface area of about 1000 square meters per cubic meter of reactor volume or more.

18. The process of claim 12 further comprising removing accumulated solids from the tank.

19. A process for treating water comprising the steps of providing hollow fiber gas permeable membranes in a tank of water to be treated, growing a biomass on the membranes and removing accumulated solids from the tank.

20. The process of claim 19 wherein the biofilm has a concentration of at least 20 g/L and a surface area of about 1000 square meters per cubic meter of water in the reactor or more on the surface of the membranes.

21. The process of claim 19 wherein the feed water contains over 2000 mg/L of CODt and the biofilm supported on the membranes is grown to occupy between about 50% and 80% of the volume of a tank containing the membranes.

22. The process of claim 19 further comprising operating at a F/M ratio of between about 0.1 and 0.2 g CODt/g Total Biofilm Solids/d.

23. The process of claim 19 further comprising recirculating the water.

24. The process of claim 23 wherein the water is recirculated to provide an inlet concentration in the range of about 500-5000 mg/L of CODt.

26. A bioreactor having a tank for holding water to be treated containing both a suspended biomass and a membrane supported biofilm.

27. The bioreactor of claim 26 having a downstream solids separation device and a recycle of separated solids to the tank.

28. The bioreactor of claim 27 wherein the recycle passes through an anoxic stage before returning to the tank.

29. The bioreactor of claim 26 having a mixer to kept the suspended biomass in suspension.