Tidal vertical flow wastewater treatment system and method

• US 6,863,816 B2
• Filed: 06/17/2003
• Issued: 03/08/2005
• Est. Priority Date: 06/17/2002
• Status: Expired due to Fees

• Current Assignee: Dharma IP LLC
• Original Assignee: Dharma Living Systems, Inc.
• Inventors: Lohan, Eric, Austin, David C.
• Primary Examiner(s): Prince, Fred G.
• Application Number:
  US10/463,199
• Publication Number:
  US 20040000517A1
• Time in Patent Office: 630 Days
• Field of Search: 210/602, 210/622, 210/150, 210/151, 210/170, 210/259, 210615-617, 210/620, 210/621, 210/252, 210/603, 210/903
• US Class Current: 210/602
• CPC Class Codes: C02F 3/302 Nitrification and denitrification treatment C02F3/308 takes precedence
• CPC Class Codes: C02F 3/327 characterised by animals and plants
• CPC Class Codes: Y02W 10/10 Biological treatment of water, waste water, or sewage
• CPC Class Codes: Y10S 210/903 Nitrogenous

Abstract

A wastewater treatment system includes a tidal, sequential vertical flow marsh cell system having at least three marsh cells in serial forward fluid communication. Incoming wastewater to be treated is channeled to at least the first and a second marsh cell, and a portion of water exiting a final marsh cell, to the first marsh cell surface. Each marsh cell is alternately flooded and drained for enhancing aeration of incoming water and marsh cell contents, which include media and plant roots having biofilms growing thereon, the biofilms including a population of nitrifying and denitrifying bacteria, for achieving substantially simultaneous nitrification and denitrification of the wastewater.

Claims

1. A wastewater treatment system comprising:

a first, a second, and a third vertical flow marsh cell, each having an outlet adjacent a bottom thereof, particulate media, and plants having roots extendible into the media, the roots and the media positioned to contact water flowing into each marsh cell;

means for transporting water to be treated to a surface of the first and the second marsh cell, from the first marsh cell outlet to the second marsh cell surface, from the second marsh cell outlet to a surface of the third marsh cell, from the third marsh cell outlet to the first marsh cell surface for process recycling, and from the third marsh cell outlet to a discharge outlet, the water transporting means further comprising means for substantially emptying each marsh cell on a predetermined cycle for a predetermined time, for permitting aeration of contents of each marsh cell.

2. The system recited in claim 1, wherein the first, the second, and the third marsh cell each comprise:

a basin having a hole adjacent a bottom thereof, the hole comprising the marsh cell outlet;

a drain collection trough positioned beneath the hole for collecting water exiting therefrom; and

wherein the means for transporting water from the respective first, second, and third marsh cell outlet comprise respective first, second, and third sumps and first, second, and third pumps positioned within the respective first, second, and third sumps.

3. The system recited in claim 2, wherein each of the first, the second, and the third marsh cells further comprise a mat positionable above the particulate media, the mat adapted for permitting the plants to root therein.

4. The system recited in claim 3, wherein the mat is positionable atop the particulate media in spaced relation from a top of each basin.

5. The system recited in claim 3, wherein the mat is adapted for permitting the plants to substantially cover a surface of each marsh cell.

6. The system recited in claim 2, wherein the water transporting means further comprises piping for distributing water at a unitary point of the respective first, second, and third marsh cell surface.

7. The system recited in claim 2, wherein the particulate medium comprises an aggregate having a diameter no smaller than approximately 2 mm.

8. The system recited in claim 7, wherein the aggregate comprises at least one of a high-porosity plastic medium and expanded shale.

9. The system recited in claim 7, wherein the aggregate has a bulk density substantially the same as a bulk density of water, the aggregate substantially nonbuoyant.

10. The system recited in claim 2, wherein the first and the second marsh cell is each adapted to maintain at least one of a population of aquatic invertebrates and a population of detritivores.

11. The system recited in claim 1, further comprising a programmable controller for controlling the water transporting means.

12. The system recited in claim 11, wherein the controller is operable to achieve the drainage of the first, the second, and the third marsh cell at least once per day.

13. The system recited in claim 12, wherein the controller is operable to achieve the drainage of the first, the second, and the third marsh cell in a range of approximately 1-20 times per day.

14. The system recited in claim 1, wherein the means for transporting incoming water comprises means for transporting water substantially equally between the first and the second marsh cell.

15. The system recited in claim 1, wherein water exiting the discharge outlet is treated to at least advanced secondary standards.

16. The system recited in claim 15, wherein water exiting the discharge outlet is treated to at least advanced tertiary standards.

17. The system recited in claim 1, further comprising illumination means positioned to promote plant growth in the first, the second, and the third marsh cells.

18. The system recited in claim 17, further comprising means for controlling an on-off cycle of the illumination means.

19. The system recited in claim 18, wherein the on-off cycle comprises substantially equal 12-hour cycles per day.

20. The system recited in claim 1, wherein water exiting from the discharge outlet has a yield of substantially zero.

21. A wastewater treatment system comprising:

a first, a second, a third, a fourth, and a fifth vertical flow marsh cell, each having an outlet adjacent a bottom thereof, particulate media, and plants having roots extendible into the media, the roots and the media positioned to contact water flowing into each marsh cell;

means for transporting incoming water to be treated to a surface of the first, the second, and the third marsh cell, from the first marsh cell outlet to the second marsh cell surface, from the second marsh cell outlet to the third marsh cell surface, from the third marsh cell outlet to the fourth marsh cell surface, from the fourth marsh cell outlet to the fifth marsh cell surface, from the fifth marsh cell outlet to the first marsh cell surface for process recycle, and from the fifth marsh cell outlet to a discharge outlet, the water transporting means further comprising means for substantially emptying each marsh cell on a predetermined cycle for a predetermined time, for permitting aeration of contents of each marsh cell.

22. The system recited in claim 21, wherein the means for transporting incoming water comprises means for transporting water substantially equally among the first, the second, and the third marsh cell.

23. The system recited in claim 21, wherein the water transporting means is configured so that water exiting the discharge outlet has experienced an average hydraulic retention time of approximately 12-36 hours.

24. The system recited in claim 23, wherein the average hydraulic retention time is configurable dependent upon the composition and strength of the incoming water to be treated.

25. The system recited in claim 21, further comprising:

a sixth vertical flow marsh cell having a surface, an outlet adjacent a bottom thereof, particulate media, and plants having roots extendible into the media, the roots and the media positioned to contact water flowing into the sixth marsh cell, the sixth marsh cell positioned downstream of the fourth marsh cell and upstream of the fifth marsh cell; and

wherein the transporting means comprises means for transporting water from the fourth marsh cell outlet to the sixth cell surface and from the sixth cell outlet to the fifth cell surface.

26. A wastewater treatment system comprising:

a tidal, sequential vertical flow marsh cell system, the marsh cell system comprising at least three marsh cells in serial forward fluid communication;

means for distributing incoming wastewater to be treated to surfaces of the marsh cells, including at least the first and a second marsh cell, the second marsh cell immediately following the first marsh cell;

means for alternately flooding and draining each marsh cell for enhancing aeration of incoming water, the draining means further for enhancing aeration of contents of the marsh cells, the marsh cell contents including means for achieving substantially simultaneous nitrification and denitrification of the wastewater; and

means for recycling a portion of water exiting a final marsh cell to the first marsh cell surface.

27. A method of treating wastewater comprising the steps of:

providing at least three vertical flow marsh cells, in forward serial fluid communication with each other;

step feeding incoming wastewater to be treated onto surfaces of a first and a second marsh cell;

recycling a portion of water exiting a final marsh cell to the first marsh cell surface; and

alternately and periodically flooding and draining each marsh cell for enhancing aeration of incoming water, the draining step for enhancing aeration of contents of the marsh cells, the flooding and draining steps permitting the marsh cell contents to substantially simultaneously nitrify and denitrify the wastewater.

28. The method recited in claim 27, wherein:

the flooding step of the first marsh cell uses incoming water and water recycled from the final marsh cell;

the flooding step of the second marsh cell uses incoming water and water emerging from the first marsh cell; and

the flooding step of a third through the final marsh cell uses water channeled from an upstream marsh cell.

29. The method recited in claim 28, wherein:

the draining step channels water from the first through a penultimate marsh cell to a downstream marsh cell; and

the draining step further channels water from the final marsh cell to the first marsh cell surface and to a discharge outlet.

30. The method recited in claim 27, wherein the flooding and draining steps facilitate a series of biochemical reactions occurring within the water and marsh cell contents, the marsh cell contents including microbes resident within biofilms growing thereon.

31. The method recited in claim 30, wherein incoming ammonia ions during the flooding steps adsorb to biofilms and nitrify during the draining steps when exposed to atmospheric oxygen.

32. The method recited in claim 31, wherein nitrate ions formed from the ammonia ion nitrification desorb into water during the flooding stages and, in the presence of organic carbon, mediated by the microbes, are denitrified to form at least nitrogen gas.

33. The method recited in claim 31, wherein nitrogen gas is formed from the ammonia ions by microbes mediating heterotrophic nitrification.

34. The method recited in claim 31, wherein a periodicity of the flooding and draining steps is substantially less than an enzyme mobilization time required for facultative denitrifiers in the biofilms to convert substantially wholly to using one of oxygen and nitrate as a terminal electron acceptor for heterotrophic respiration.

35. The method recited in claim 31, wherein a periodicity of the flooding and draining steps is sufficiently rapid to create conditions in the biofilms favorable to a growth of a substantial population of constitutive denitrifiers, the denitrifiers adapted to substantially simultaneously produce enzymes for using both oxygen and nitrate as terminal electron acceptors for heterotrophic respiration.

36. The method recited in claim 30, wherein incoming nitrite ions during the flooding steps are converted to nitrogen gas in the presence of inorganic carbon by the microbes mediating anaerobic autotrophic denitrification.

37. The method recited in claim 27, wherein the step feeding, the recycling, and the flooding and draining steps are all under the control of an electronic controller.

38. The method recited in claim 27, wherein the periodically flooding and draining is caused to occur in cycles ranging from 1 to 20 times per day.

39. A method of constructing a wastewater treatment system comprising the steps of:

establishing at least three vertical flow marsh cells in serial fluid communication, each marsh cell having an outlet adjacent a bottom thereof, particulate media, and plants having roots extending into the media, the roots and the media positioned to contact water flowing into each marsh cell;

providing means for step feeding wastewater to be treated onto surfaces of at least a first and a second marsh cell;

providing means for recycling water from a final marsh cell outlet to the first marsh cell surface;

providing means for transporting water sequentially from each upstream cell outlet to each downstream cell surface;

providing means for transporting water exiting from the final marsh cell outlet to a discharge outlet;

providing means for alternately flooding and draining each marsh cell for facilitating aeration of water being transported and of marsh cell contents, and for facilitating the nitrification and denitrification of water by the marsh cell contents; and

predosing the first and the second marsh cells with a nitrifying activated sludge for providing an initial bacterial community thereto.

40. The method recited in claim 39, further comprising the step of providing an electronic controller in signal communication with and in controlling relation to the step feeding, the recycling, the water transporting, and the flooding and draining means.

41. The method recited in claim 40, wherein the step feeding, the recycling, the water transporting, and the flooding and draining means comprise pumps.

42. The method recited in claim 39, further comprising the step, if natural lighting conditions are insufficient to sufficiently support plant growth, of illuminating the plants periodically.

43. The method recited in claim 42, wherein the illuminating step is caused to occur on approximately 12-hour cycles.

44. The method recited in claim 39, wherein the predosing step comprises inoculating the first and the second marsh cells with muck and water from a pond and biosolids.