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1. WO1992020628 - PROCESSUS DE DIGESTION ANAEROBIE

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a method of treating waste products containing concentrations of suspended solids by an anaerobic digestion process within an anaerobic reactor, the improvement comprising the step of separating solids containing active biomass from liquids using anoxic gas in a gas flotation process and then recirculating the separated solids containing active biomass to the anaerobic reactor to increase the biomass bacterial population within the anaerobic reactor, such that the efficiency of the reactor is increased and the size of the reactor may be reduced.

2. The method of Claim 1 wherein the separation of solids from liquids is carried out by the dissolved gas lotation process using anoxic gas.

3. The method of Claim 1 wherein the separation of solids from liquids is carried out by the dispersed gas lotation process using anoxic gas.

4. The method of Claim 1 wherein the separation of solids from liquids is carried out by the vacuum gas flotation process using anoxic gas.

5. The method of Claim 1 wherein the separation of solids from liquids is carried out by the roth lotation process using anoxic gas.

6. The method of Claim 1 wherein the separation of solids from liquids is carried out by the foam lotation process using anoxic gas.

7. The method of Claim 1 wherein the separation of solids from liquids is carried out by a combination of known gas flotation processes employing anoxic gas.

8. A method of treating waste products having concentrations of suspended solids therein by an anaerobic digestion process including the steps of:
(a) digesting the waste products in an anaerobic reactor;
(b) separating solids containing active biomass from the reactor effluent by means of a gas lotation process employing anoxic gas; and -li¬

te) recirculating the solids containing active biomass to said reactor to maintain a high concentration of active biomass therein such that the efficiency of the reactor is increased.

9. The method of Claim 8 including the step of withdrawing anoxic gas from the anaerobic reactor and employing at least a portion of said gas in said gas flotation process to separate solids from the reactor effluent.

10. In an anaerobic activated sludge process for treating waste having concentrations of suspended solids therein, the improved steps of:
(a) digesting the waste in an anaerobic reactor;
(b) treating the effluent of said reactor by separating solids containing active anaerobic microorganisms from liquids by means of an anoxic gas flotation process; and
(c) recirculating the solids to the anaerobic reactor to increase the concentration of anaerobic microorganisms therein, thereby increasing the efficiency of the reactor such that its size may be reduced.

11. An improved anaerobic digestion process for waste having suspended solids therein comprising the steps of:
(a) transporting the waste to be treated to an anaerobic reactor containing anaerobic microorganisms;
(b) heating and mixing the waste within the reactor to cause digestion thereof;
(c) withdrawing biogas from the reactor and transporting the anoxic biogas to a gas lotation liquid solid separator device or separating solids from liquids;
(d) transporting treated effluent comprising solids containing active anaerobic microorganisms and liquids from the reactor to the gas flotation liquid solid separator device;
(e) separating said solids containing active anaerobic microorganisms from liquids in the gas flotation liquid solid separator device using said biogas;
(f) recirculating separated solids containing active anaerobic microorganisms to the anaerobic reactor to maintain high concentrations of anaerobic microorganisms within the reactor to increase the efficiency of the reactor;
(g) discharging liquids containing few solids from the liquid solid separator device for further treatment or disposal; and
(h) periodically discharging separated solids from the system.

12. The method of Claim 13 including the steps of collecting separated active biomass within the anaerobic reactor and mixing the active biomass with the waste products to be treated.

13. In a method of treating waste products containing suspended solids by an anaerobic digestion process within an anaerobic reactor and withdrawing an anoxic gas and treated effluent from said reactor, the improvement consisting essentially of:
(i) conducting a separate gas lotation step on effluent from said reactor in a manner such that active biomass is substantially separated from the digester effluent, wherein said gas flotation employs an anoxic gas and a chemical aid to promote separation of said active biomass, withdrawing an ef luent rom said gas flotation step; and then
(j) recirculating said separated active biomass to said anaerobic reactor to substantially increase the biomass within said anaerobic reactor, whereby the efficiency of the reactor is increased and the size of the reactor may be reduced.

14. The method of Claim 13 wherein at least a portion of said gas withdrawn from said reactor is employed in said gas flotation process to separate solids from the reactor ef luent.

15. The method of Claim 13 wherein the separation of solids from liquids is carried out by the froth flotation process using anoxic gas.

16. The method of Claim 13 wherein the separation of solids from liquids is carried out by the foam flotation process using anoxic gas.

17. The method of Claim 13 wherein the separation of solids from liquids is carried out by a combination of known gas flotation processes employing anoxic gas.

18. A method of maintaining a high biomass concentration in a process of treating waste products containing suspended solids therein using an anaerobic digestion process and withdrawing an anoxic gas and treated effluent from said reactor, consisting essentially of:
(k) digesting the waste products in an anaerobic reactor and withdrawing an anoxic gas and effluent from said reactor;
(1) separating active biomass from the reactor effluent in a liquid/solid separator by means of a gas flotation process employing anoxic gas and further employing a chemical aid to promote separation of said active biomass, whereby said active biomass floats to the top of said separator, withdrawing an effluent from said gas flotation step; and then
(m) recirculating the active biomass directly to the reactor, thereby maintaining a high concentration of active biomass in said reactor, such that the e ficiency of the reactor is increased.

AMHJDED CLAIMS
[received by the International Bureau on 21 October 1991 (21.10.91) ; original claims 1-18 cancelled; new claims 19-25 added (2 pages) ]

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

19. In a method of treating waste products containing suspended solids by an anaerobic digestion process within an anaerobic reactor and withdrawing an anoxic gas and treated effluent from said reactor, the improvement consisting essentially of:
conducting a separate gas flotation step on effluent from said reactor in a manner such that active biomass is substantially separated from the digester effluent, wherein such gas flotation employs an anoxic gas and a chemical aid to promote separation of active biomass, withdrawing an effluent from said gas flotation step, and then
recirculating said separated active biomass to said anaerobic reactor to substantially increase the biomass within said anaerobic reactor, whereby the efficiency of the reactor is increased and the size of the reactor may be reduced.

20. The method Claim 19, wherein the separation of solids from liquids is carried out by the dissolved gas flotation process using anoxic gas.

21. The method of Claim 19, wherein the separation of solids from liquids is carried out by the froth flotation process using anoxic gas.

22. The method of Claim 19, wherein the separation of solids from liquids is carried out by the foam flotation process using anoxic gas.

23. The method of Claim 19, wherein the separation of solids from liquids is carried out by a combination of known gas flotation processes employing anoxic gas.

24. The method of Claim 19, wherein at least a portion of the gas withdrawn from said reactor is employed in said gas flotation process to separate solids from the reactor effluent.

25. A method of maintaining a high biomass concentration in a process of treating waste products containing suspended solids therein using an anaerobic digestion process, consisting essentially of: digesting the waste products in an anaerobic reactor and withdrawing an anoxic gas and treated effluent from said reactor;
separating active biomass from the reactor effluent in a liquid/sold separator by means of a gas flotation process employing anoxic gas and further employing a chemical aid to promote separation of said active biomass, whereby said active biomass floats to the top of said separator, withdrawing an effluent from said gas flotation step; and then
recirculating the active biomass directly to the reactor, thereby maintaining a high concentration of active biomass in said reactor, such that the efficiency of the reactor is increased.