Anaerobic Membrane Bioreactor for Treating a Waste Stream
AssigneeVeolia Water Solutions & Technologies Support
InventorJohn Ewing
Life of this patent
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Abstract
A waste stream having anaerobically biodegradable components is fed to an anaerobic reactor where the components react with microorganisms to biodegrade the components and produce biomass and biogas. Mixing occurs in select portions of the anaerobic reactor, particularly the bottom and top portions of the reactor. Relatively heavy solids settle to the bottom and are mixed with the mixed liquor while relatively light or fine solids float to the top portion of the anaerobic reactor where they are mixed with the mixed liquor. Mixed liquor is pumped from an intermediate portion of the anaerobic reactor to a membrane separation unit where the mixed liquor is separated into a permeate stream and a retentate stream that is concentrated with solids.
Claims6
A method of treating a waste stream having anaerobically biodegradable components, comprising:
- a. feeding a waste stream having the anaerobically biodegradable components into an anaerobic reactor;
- b. reacting the biodegradable components with anaerobic biomass in the anaerobic reactor to reduce the amount of biodegradable components and in the process produce biomass and biogas;
- c. stratifying the mixed liquor in the anaerobic reactor into three mixed liquor zones by forming a first lower mixed liquor zone where the mixed liquor in the first lower mixed liquor zone includes relatively heavy solids, forming a second mixed liquor zone above the first lower mixed liquor zone where the mixed liquor in the second mixed liquor zone includes a solids concentration substantially less than the concentration of solids in the first lower mixed liquor zone, and forming a third mixed liquor zone over the second mixed liquor zone where the third mixed liquor zone includes relatively light solids;
- d. directing mixed liquor from the second mixed liquor zone in the anaerobic reactor to a membrane separation unit and separating the mixed liquor into a permeate stream and a retentate stream;
- and
- e. recycling at least a portion of the retentate stream to the anaerobic reactor and mixing the retentate stream with the mixed liquor in the reactor.
A method of treating a stream containing soluble and insoluble COD in an anaerobic membrane bioreactor, the method comprising:
- a. feeding the stream having soluble and insoluble COD into an anaerobic reactor;
- b. reacting the soluble and insoluble COD with anaerobic biomass in the anaerobic reactor to reduce the amount of soluble and insoluble COD and in the process produce a mixed liquor and biogas in the anaerobic reactor;
- c. providing a mixing action in a lower portion of the anaerobic reactor to mix the relatively heavy solids in the mixed liquor;
- d. providing a mixing action in an upper portion of the anaerobic reactor to mix the relatively light solids in the mixed liquor:
- e. wherein in an intermediate portion of the anaerobic reactor a relatively lower concentration of solids in mixed liquor is present;
- f. pumping the mixed liquor from the intermediate portion of the anaerobic reactor to a membrane separation unit and separating the mixed liquor into a permeate stream and a retentate stream which substantially contains the concentrated biomass;
- g. recycling at least a portion of the retentate stream to the anaerobic reactor and;
- h. pumping mixed liquor with the relatively heavy solids from the bottom portion of the anaerobic reactor to a solids separator, and separating the heavier solids from the lighter solids containing biomass;
- and
- i. recycling at least a portion of the lighter solids containing the biomass to the anaerobic reactor.
Dependencies are inferred from the claim text.