INFILTRATION/INFLOW CONTROL FOR MEMBRANE BIOREACTOR

• US 20100326906A1
• Filed: 04/01/2008
• Published: 12/30/2010
• Est. Priority Date: 04/02/2007
• Status: Active Grant

• Current Assignee: Evoqua Water Technologies LLC
• Original Assignee: Siemens Industry Incorporated (Siemens AG)
• Inventors: Barnes, Dennis J.
• Granted Patent: US 8,318,028 B2
• Time in Patent Office: Days
• US Class Current: 210/614
• CPC Class Codes: C02F 1/008 Control or steering systems not provided for elsewhere in subclass C02F
• CPC Class Codes: C02F 1/44 by dialysis, osmosis or reverse osmosis general membrane separation processes B01D61/00, membrane modules B01D63/00, electrodialysis C02F1/4693, combination of membrane modules and bioreactors C02F3/1268
• CPC Class Codes: C02F 1/52 by flocculation or precipitation of suspended impurities C02F1/463 takes precedence
• CPC Class Codes: C02F 2103/001 Runoff or storm water
• CPC Class Codes: C02F 2209/10 Solids, e.g. total solids [TS], total suspended solids [TSS] or volatile solids [VS]
• CPC Class Codes: C02F 2209/40 Liquid flow rate
• CPC Class Codes: C02F 2209/42 Liquid level
• CPC Class Codes: C02F 2301/043 Treatment of partial or bypass streams
• CPC Class Codes: C02F 3/006 Regulation methods for biological treatment
• CPC Class Codes: C02F 3/1268 Membrane bioreactor systems
• CPC Class Codes: C02F 9/00 Multistage treatment of water, waste water or sewage
• CPC Class Codes: Y02W 10/10 Biological treatment of water, waste water, or sewage

Abstract

A method and system for wastewater treatment comprising a first treatment zone (11) fluidly connected to one or more further treatment zones (12, 13, 14), a membrane module (16) comprising a filter membrane positioned in or fluidly connected to the further treatment zone (14), a gravity settling device (15) fluidly connected to the first treatment zone (11) to receive overflow therefrom; and a flow control device (23) between the first treatment zone (11) and the gravity settling device (15) to control the flow of liquid therebetween.

Claims

1. A method of treating wastewater comprising:

flowing a wastewater through one or more treatment zones to produce a fluid product which is passed through a filter membrane to produce a concentrated mixed liquor and a filtrate;

returning at least a portion of the concentrated mixed liquor to at least one of said treatment zones;

when the flow of wastewater exceeds a predetermined level, flowing a portion of said returned mixed liquor to a gravity settling device;

clarifying the mixed liquor within the gravity settling device; and

controlling the size of the portion of returned mixed liquor in dependence on the flow of wastewater.

2. A method according to claim 1 further comprising controlling the flow of liquid between treatment zones and the filter membrane by one or more pumps operating in response to the liquid level in the first treatment zone or a furthest upstream treatment zone.

3. A method according to claim 1 further comprising controlling the flow of liquid between treatment zones and the filter membrane is by a weir in the first or the furthest upstream treatment zone, such that where the influent flow rate is higher than a predetermined level, the liquid level in the first treatment zone or the furthest upstream treatment zone rises and liquid flows over the weir to the gravity-settling device.

4. A method according to claim 3 wherein the weir is a fixed weir.

5. A method according to claim 3 wherein the height of the weir is adjustable.

6. A method according to claim 5 wherein the weir height is automatically adjustable based on an influent flow meter signal or other process measurement.

7. A method according to claim 1 further comprising controlling the ratio between the amount of mixed liquor from the membrane filter which is returned to the upstream treatment zones and the amount of returned mixed liquor which is fed to the downstream treatment zones and to a feed side of the membrane filter.

8. A method according to claim 7 further comprising controlling the liquid flow ratio between the upstream and downstream treatment zones by calculating the proportion of the total flow being treated by the gravity-settling device based on measurements of the total influent flow rate to the system and the feed flow being treated by the membrane filter.

9. A method according to claim 8 wherein the proportion of returned mixed liquor to be sent via the upstream treatment zones to the gravity-settling device is calculated by a programmable control device using a mass balance equation to determine the flow ratio required to maintain the required Mixed Liquor Suspended Solids (MLSS) concentration in the liquid flow being transferred to the gravity-settling device.

10. A method according to claim 9 wherein the mass balance equation is a function includes one or more of the following variables:

1) the average Total Suspended Solids (TSS) concentration in the mixed liquor.

2) the desired MLSS concentration in the upstream treatment zones.

3) the total influent flow to the treatment process, and

4) the percentage of that flow being treated by the gravity settling device.

11. A method according to claim 1 further comprising returning sludge separated from the mixed liquor in the gravity settling device to a treatment zone downstream of the treatment zone feeding the gravity settling device.

12. A wastewater treatment system comprising:

a first treatment zone fluidly connected to one or more further treatment zones;

a membrane module comprising a filter membrane positioned in or fluidly connected to the further treatment zone;

a gravity settling device fluidly connected to the first treatment zone to receive overflow therefrom; and

a flow control device between the first treatment zone and the gravity settling device to control the flow of liquid therebetween.

13. A wastewater treatment system according to claim 12 further comprising one or more pumps operable in response to the liquid level in the first treatment zone or a furthest upstream treatment zone to control the flow of liquid between treatment zones and the filter membrane.

14. A wastewater treatment system according to claim 12 further comprising a weir in the first or the furthest upstream treatment zone, wherein the flow of liquid between treatment zones and the filter membrane is controlled by a weir such that where the influent flow rate is higher than a predetermined level, the liquid level in the first treatment zone or the furthest upstream treatment zone rises and liquid flows over the weir to the gravity-settling device.

15. A wastewater treatment system according to claim 14 wherein the weir is a fixed weir.

16. A wastewater treatment system according to claim 14 wherein the height of the weir is adjustable.

17. A wastewater treatment system according to claim 16 wherein the weir height is automatically adjustable based on an influent flow meter signal or other process measurement.

22. A wastewater treatment system according to claim 12 further comprising means for returning sludge separated from the mixed liquor in the gravity settling device to a treatment zone downstream of the treatment zone feeding the gravity settling device.

18. A wastewater treatment system according to claim comprising control means for controlling the ratio between the amount of mixed liquor from the membrane filter which is returned to the upstream treatment zones and the amount of returned mixed liquor which is fed to the downstream treatment zones and to a feed side of the membrane filter.

19. A wastewater treatment system according to claim 18 wherein the control means controls the liquid flow ratio between the upstream and downstream treatment zones by calculating the proportion of the total flow being treated by the gravity-settling device based on measurements of the total influent flow rate to the system and the feed flow being treated by the membrane filter.

20. A wastewater treatment system according to claim 19 wherein the proportion of returned mixed liquor to be sent via the upstream treatment zones to the gravity-settling device is calculated by a programmable control device using a mass balance equation to determine the flow ratio required to maintain the required Mixed Liquor Suspended Solids (MLSS) concentration in the liquid flow being transferred to the gravity-settling device.

21. A wastewater treatment system according to claim 20 wherein the mass balance equation is a function includes one or more of the following variables:

—

3) the average Total Suspended Solids (TSS) concentration in the mixed liquor.

4) the desired MLSS concentration in the upstream treatment zones.

3) the total influent flow to the treatment process, and

4) the percentage of that flow being treated by the gravity settling device.