HYBRID SOLAR STILL AND ANAEROBIC MEMBRANE BIOREACTOR FOR WASTEWATER TREATMENT

Abstract

The hybrid solar still and anaerobic membrane bioreactor for wastewater treatment (10) produces both purified water (PW) and biogas by combining a solar still (11) with an anaerobic membrane bioreactor. The solar still (11) receives feed wastewater (WW) and produces condensed water (CW) and concentrated wastewater (CWW) therefrom through solar distillation. An anaerobic process tank (12) receives the concentrated wastewater (CWW) from the solar still (11) and produces digested waste sludge and a process liquid (PL) therefrom through anaerobic digestion. A membrane tank (20) receives the process liquid (PL) from the anaerobic process tank (12), and also receives the condensed water (CW) from the solar still (11). Through membrane filtration, the membrane tank (20) produces purified water (PW) and retained wastewater (RWW). The retained wastewater (RWW) is recirculated back to the anaerobic process tank (12).

Claims

1. A hybrid solar still and anaerobic membrane bioreactor for wastewater treatment, comprising: a solar still for receiving feed wastewater and producing condensed water and concentrated wastewater therefrom; an anaerobic process tank in fluid communication with the solar still for receiving the concentrated wastewater therefrom and producing digested waste sludge and a process liquid therefrom; and a membrane tank in fluid communication with the anaerobic process tank for receiving the process liquid therefrom, the membrane tank being in further fluid communication with the solar still for receiving the condensed water therefrom, the membrane tank producing purified water and retained wastewater, the retained wastewater being recirculated back to the anaerobic process tank.

2. The hybrid solar still and anaerobic membrane bioreactor for wastewater treatment as recited in claim 1, wherein the anaerobic process tank has a drain for selectively releasing the digested waste sludge.

3. The hybrid solar still and anaerobic membrane bioreactor for wastewater treatment as recited in claim 1, wherein the membrane tank further receives sparged biogas from the anaerobic process tank.

4. The hybrid solar still and anaerobic membrane bioreactor for wastewater treatment as recited in claim 3, wherein released biogas is recirculated from the membrane tank back to the anaerobic process tank.

5. The hybrid solar still and anaerobic membrane bioreactor for wastewater treatment as recited in claim 4, wherein the anaerobic process tank has a vent for selectively releasing excess biogas.

6. A method of treating wastewater, comprising the steps of: feeding wastewater to a solar still and producing condensed water and concentrated wastewater therefrom through solar distillation; feeding the concentrated wastewater from the solar still to an anaerobic process tank and producing digested waste sludge and a process liquid therefrom through anerobic digestion; feeding the process liquid from the anaerobic process tank to a membrane tank; feeding the condensed water from the solar still to the membrane tank to dilute the process liquid; filtering the diluted process liquid in the membrane tank through a membrane filter to produce purified water and retained wastewater; and recirculating the retained wastewater back to the anaerobic process tank.

7. The method of treating wastewater as recited in claim 6, further comprising the step of selectively draining the digested waste sludge from the anaerobic process tank.

8. The method of treating wastewater as recited in claim 6, further comprising the step of feeding sparged biogas from the anaerobic process tank to the membrane tank.

9. The method of treating wastewater as recited in claim 8, further comprising the step of recirculating released biogas from the membrane tank back to the anaerobic process tank.

10. The method of treating wastewater as recited in claim 9, further comprising the step of selectively venting excess biogas from the anaerobic process tank.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 is a schematic diagram of a hybrid solar still and anaerobic membrane bioreactor for wastewater treatment.

[0013] FIG. 2 is a schematic diagram of a conventional anaerobic membrane bioreactor of the prior art.

[0014] Similar reference characters denote corresponding features consistently throughout the attached drawings.

BEST MODES

[0015] The hybrid solar still and anaerobic membrane bioreactor for wastewater treatment 10 is similar to the anaerobic membrane bioreactor (AnMBR) 100 of FIG. 2, but with the addition of a solar still 11. As is well-known in the art, solar stills distill water with substances dissolved therein, such as wastewater, by using the heat from solar radiation to evaporate water so that it may be cooled and collected, thus purifying the water and leaving a concentrated waste byproduct. In the hybrid solar still and anaerobic membrane bioreactor for wastewater treatment 10, the initial wastewater (WW) stream is fed into the solar still 11 such that the water contained therein may be evaporated and condensed, leaving behind a concentrated wastewater (CWW) byproduct. The concentrated wastewater is fed into the anaerobic process tank 12 through a feed line 18, and the operation of anaerobic process tank 12 is similar to that of anaerobic process tank 112 described above with regard to FIG. 2. Digested waste sludge leaves the anaerobic process tank 12 through a drain 40. It should be understood that solar still 11 may be any suitable type of solar still having any suitable configuration for producing condensed water and concentrated wastewater from the feed wastewater through solar distillation. It should be further understood that any necessary valves, ports, conduits, pumps, or the like, which are required to transport the concentrated wastewater from solar still 11 to the anaerobic process tank 12, may be used. Additionally, it should also be understood that the digested waste sludge may be selectively drained from anaerobic process tank 12 using any suitable type of valve, drainage port, or the like.

[0016] Similar to the AnMBR 100 of FIG. 2, the hybrid solar still and anaerobic membrane bioreactor for wastewater treatment 10 also includes a distinct membrane tank 20 containing an immersed membrane filter. The membrane tank 20 is similar in construction and operation to the membrane tank 120 of FIG. 2. Wastewater being treated recirculates between the process tank 12 and the membrane tank 20. The process liquid (PL) flows from the anaerobic process tank 12 to the membrane tank 20 through a process liquid line 24. It should be understood that any necessary valves, ports, conduits, pumps or the like, which are required to transport the process liquid from anaerobic process tank 12 to membrane tank 20, may be used.

[0017] In addition to the process liquid, the condensed water (CW) produced by the solar still 11 also enters the membrane tank 20 through line 14, thus diluting the process liquid within the membrane tank 20. A portion of the wastewater process liquid entering the membrane tank 20 permeates through the membrane filter and leaves the membrane tank 20 through a permeate line 28 as purified water (PW). It should be understood that any necessary valves, ports, conduits, pumps or the like, which are required to transport the condensed water from solar still 11 to the membrane tank 20, may be used. It should be further understood that the purified water may be extracted through permeate line 28 using any suitable type of valve, drain, pump or the like, and that the purified water may be collected and stored or be fed into a conduit or the like for transport thereof to any desired location or additional process or plant.

[0018] Retained wastewater (RWW) flows from the membrane tank 20 to the anaerobic process tank 12 through a process liquid recirculation line 26. It should be understood that any necessary valves, ports, conduits, pumps or the like, which are required to transport the retained wastewater from the membrane tank 20 back to anaerobic process tank 12, may be used. Biogas is created by microorganisms digesting the wastewater, and travels into the headspace of the anaerobic process tank 12. Some biogas is taken from the headspace, and this sparged biogas (SB) passes through a gas sparging line 30 into the membrane tank 20. It should be understood that any necessary valves, ports, conduits, pumps, blowers or the like, which are required to transport the sparged biogas from the anaerobic process tank 12 to the membrane tank 20, may be used.

[0019] As discussed above with regard to the AnMBR 100, the sparged biogas enters the membrane tank 20 through a gas sparger near or below the bottom of the membrane filter. The sparged biogas is released as bubbles, which rise through or in contact with the membrane filter to inhibit fouling of the membranes and generate liquid flow through the membrane filter. The bubbles burst at the surface of wastewater in the membrane tank 20 and release biogas into a pocket at the top of the membrane tank 20. The released biogas (RB) then returns to the anaerobic process tank 12 through a gas recirculation line 32. It should be understood that any necessary valves, ports, conduits, pumps, blowers or the like, which are required to transport the released biogas from the membrane tank 20 back to the anaerobic process tank 12, may be used.

[0020] Biogas may be selectively released as exhaust through a vent line 16, which may be connected, for example, to the headspace of the anaerobic process tank 12. The vent line 16 may be selectively opened by a suitable valve or the like when gas pressure exceeds a predetermined maximum and closes when gas pressure falls below a predetermined minimum. The predetermined minimum biogas pressure may be chosen to provide at least a material enhancement to transmembrane pressure differential and flux through the membrane filter of the membrane tank 20. This exhaust biogas may be collected or directly used as a power source. The biogas may be, or may contain, methane, which is a combustible gas that may be used to at least partially power the hybrid solar still and anaerobic membrane bioreactor for wastewater treatment 10.

[0021] It is to be understood that the hybrid solar still and anaerobic membrane bioreactor for wastewater treatment is not limited to the specific embodiments described above, but encompasses any and all embodiments within the scope of the generic language of the following claims enabled by the embodiments described herein, or otherwise shown in the drawings or described above in terms sufficient to enable one of ordinary skill in the art to make and use the claimed subject matter.