Sewage dewatering process and equipment

• US 6,051,137 A
• Filed: 05/19/1998
• Issued: 04/18/2000
• Est. Priority Date: 04/10/1995
• Status: Expired due to Term

• Current Assignee: Franklin David Deskins
• Original Assignee: Franklin David Deskins
• Inventors: Deskins, Franklin David
• Primary Examiner(s): Wyse, Thomas G.
• Application Number:
  US09/080,943
• Time in Patent Office: 700 Days
• Field of Search: 210/150, 210/151, 210/283, 210/285, 210/289, 210/291, 210/290
• US Class Current: 210/283
• CPC Class Codes: B01D 24/22 Downward filtration, the filter material being supported by pervious surfaces
• CPC Class Codes: B01D 24/24 Downward filtration, the container having distribution or collection headers or pervious conduits
• CPC Class Codes: B01D 24/461 by scrapers
• CPC Class Codes: B01D 24/4694 containing filter material retaining means (e.g. screens, balls) placed on the surface of the filter material
• CPC Class Codes: B01D 29/23 arranged for outward flow filtration
• CPC Class Codes: B01D 29/25 open-ended the arrival of the mixture to be filtered and the discharge of the concentrated mixture are situated on both opposite sides of the filtering element
• CPC Class Codes: B01D 29/54 arranged concentrically or coaxially
• CPC Class Codes: B01D 29/68 with backwash arms, shoes or nozzles
• CPC Class Codes: B01D 37/03 using flocculating agents
• CPC Class Codes: B01F 21/00 Dissolving separating by dissolving B01D; dissolving to effect cooling F25D5/00
• CPC Class Codes: B01F 23/50 Mixing liquids with solids displacing one liquid by another in dispersions of solids in liquids B01D12/00
• CPC Class Codes: B01F 25/4316 the baffles being flat pieces of material, e.g. intermeshing, fixed to the wall or fixed on a central rod
• CPC Class Codes: B01F 25/43161 composed of consecutive sections of flat pieces of material
• CPC Class Codes: B01F 25/432 with means for dividing the material flow into separate sub-flows and for repositioning and recombining these sub-flows; Cross-mixing, e.g. conducting the outer layer of the material nearer to the axis of the tube or vice-versa
• CPC Class Codes: B01F 25/51 in which the mixture is circulated through a set of tubes, e.g. with gradual introduction of a component into the circulating flow
• CPC Class Codes: C02F 1/56 Macromolecular compounds
• CPC Class Codes: C02F 1/66 by neutralisation; pH adjustment for degassing C02F1/20; using ion-exchange C02F1/42; for flocculation or precipitation of suspended impurities C02F1/52; for removing dissolved compounds C02F1/58
• CPC Class Codes: C02F 2201/008 Mobile apparatus and plants, e.g. mounted on a vehicle for biological treatment C02F2203/008
• CPC Class Codes: C02F 2201/009 Apparatus with independent power supply, e.g. solar cells, windpower, fuel cells for electrolysis apparatus C02F2201/46165
• CPC Class Codes: Y02A 20/212 Solar-powered wastewater sewage treatment, e.g. spray evaporation

Abstract

A process of dewatering primary-treated sewage which includes mixing the sewage with a coagulant or flocculant aid, usually activated polymer. The sewage is then mixed and flocculated at conditions which involve extensive mixing turbulence of the sewage and whereby part of the sewage is recycled so as to be again subjected to such mixing and flocculating. Flocks form the solid particles in the sewage. The pH of the sewage is chemically adjusted into the basic pH range or to a higher basic pH. The sewage is applied to a sand bed whereby the flocculated solids in the sewage are separated from the liquid in the sewage, by collecting on the top of the sand bed. The flocculated solids located on the top of the sand bed are air dried. The dried flocculated solids are removed from the top of the sand bed.

Claims

1. A sand dry cell, filter or bed for dewatering sewage composed of water and particulate solids, comprising a non-porous container having at least one exit for liquid and having side walls and a bottom floor, a porous layer composed of a particulate material located in said container, a grid having open passageways which are larger than individual particles of said particulate material and being positioned horizontally in said porous layer above and so as not to contact said bottom floor of said container, and with some of said particulate material overlying said grid, and a layer of sand or "P" gravel located on top of said porous layer, individual particles of said particulate material being larger than sand or "P" gravel.

2. The sand dry cell, filter or bed as claimed in claim 1 wherein the particulate material is selected from the group consisting of pebbles, stones, crushed rock, ceramic shapes, slag pieces and plastic pieces.

3. The sand dry cell, filter or bed as claimed in claim 2 wherein each of said open passageways is of sufficient length whereby at least one individual particle of the particulate material is contained entirely within said each of said open passageways.

4. The sand dry cell, filter or bed as claimed in claim 3 wherein the top of said grid is 6 to 12 inches below the top of said sand layer.

5. The sand dry cell, filter or bed as claimed in claim 3 wherein top of said grid is 2 to 12 inches below top of said sand layer.

6. The sand dry cell, filter or bed as claimed in claim 3 wherein the open passageways are open vertical passageways.

7. The sand dry cell, filter or bed as claimed in claim 3 wherein the grid has a honeycomb shape.

8. The sand dry cell, filter or bed as claimed in claim 7 wherein the grid is composed of high density polyethylene plastic.

9. The sand dry cell, filter or bed as claimed in claim 7 wherein the individual particles of said particulate material are 1 to 6 inches in size.

10. The sand dry cell, filter or bed as claimed in claim 8 wherein the individual particles of said particulate material are 2 to 4 inches in size.

11. The sand dry cell, filter or bed as claimed in claim 8 wherein said particulate material is stone or crushed rock.

12. The sand dry cell, filter or bed as claimed in claim 3 wherein the said sand layer is at least 6 inches in thickness.

13. The sand dry cell, filter or bed as claimed in claim 7 wherein said grid is composed of plastic, resin, stainless steel, wood or concrete.

14. In a sand dry cell, filter or bed for dewatering of sewage composed of water and particulate solids, the improvement composing a grid having open passageways and positioned horizontally in a layer composed of a particulate material in the sand dry cell, filter or bed so that some of said particulate material overlies said grid and that some of the particulate material underlies said grid, the open passageways having openings which are larger than said particulate material, individual particles of said particulate material being larger than sand or "P" gravel, and a portion of said particulate material being located in said open passageways of said grid.

15. The improvement as claimed in claim 14 wherein the particulate material selected from the group consisting of pebbles, stones, crushed rock, ceramic shapes, slag pieces and plastic pieces.

16. The improvement as claimed in claim 15 wherein the grid has a honeycomb shape.

17. The improvement as claimed in claim 15 wherein the grid is composed of high density polyethylene plastic.

18. The improvement as claimed in claim 15 wherein each of said open passageways is of sufficient length whereby at least one individual particle of said particulate material is contained entirely within said passageway.

19. The improvement as claimed in claim 16 wherein the open passageways are open vertical passageways.

20. The improvement as claimed in claim 17 wherein a layer of sand overlies said layer composed of said particulate material.