Wastewater treatment apparatus
An apparatus ( 20 ) for treating contaminated water has an electrocoagulation reactor ( 26 ) and a clarifier ( 30 ) to receive the effluent of the reactor. The reactor has a reaction vessel ( 48 ) having an inlet ( 58 ) and an outlet ( 62 ), a sacrificial anode ( 64 ), a rotatable cathode ( 68 ) and a non-sacrificial anode ( 66 ). A first gap ( 70 ) between the sacrificial anode and the cathode comprises a first water treatment zone. A second gap ( 74 ) between the cathode and the non-sacrificial anode comprises the second water treatment zone. The water flow path is from the inlet to the first treatment zone, then to the second treatment zone and then to the outlet. In the clarifier, the reactor effluent is separated into cleaned water and the contaminated sludge.
1. An apparatus for treating contaminated water comprising:
(a) an electrocoagulation reactor comprising:
(i) a reaction vessel having an inlet for inflow of water and an outlet for outflow of water from the reaction vessel;
(ii) a sacrificial anode;
(iii) a rotatable cathode;
(iv) a non-sacrificial anode;
(v) a first gap between the sacrificial anode and the cathode, the first gap comprising a first treatment zone downstream of the inlet, the sacrificial anode and the cathode being adapted to apply a first voltage across the first gap;
(vi) a second gap between the non-sacrificial anode and the cathode, the second gap comprising a second treatment zone downstream of the first treatment zone, the non-sacrificial anode and the cathode being adapted to apply a second voltage across the second gap, whereby a flow path of water through the reaction vessel is from the inlet to the first treatment zone, then to the second treatment zone and then to the outlet.
2. An apparatus according to claim 1 , wherein the reaction vessel is cylindrical with a circumferential side wall, a bottom wall and a top wall.
3. An apparatus according to claim 2 , wherein the inlet is through the bottom wall of the reaction vessel.
4. An apparatus according to claim 2 , wherein the non-sacrificial anode is cylindrical and adjacent to the circumferential side wall.
5. An apparatus according to claim 2 , wherein the non-sacrificial anode is a disk having an upper surface and a lower surface, the non-sacrificial anode extending between the circumferential side walls of the reaction vessel and having a bore therein for the flow of water.
6. An apparatus according to claim 2 , wherein the top wall is conical.
7. An apparatus according to claim 2 , wherein the outlet is in the top wall of the reaction vessel.
8. An apparatus according to claim 1 , wherein the sacrificial anode has a bore therethrough for the flow of water from the inlet to the first treatment zone.
9. An apparatus according to claim 1 , wherein the cathode is cylindrical with a bottom wall, a top wall and a circumferential side wall.
10. An apparatus according to claim 9 , wherein the second gap is between the circumferential side wall of the cathode and the non-sacrificial anode.
11. An apparatus according to claim 1 , wherein the first gap is between the upper surface of the sacrificial anode and the bottom surface of the cathode.
12. An apparatus according to claim 1 , wherein the second reaction zone is between the upper surface of the cathode and the lower surface of the non-sacrificial anode.
13. An apparatus according to claim 1 , wherein the cathode is rotatable on a shaft and the cathode and shaft have a bore therein for the flow of water into the first treatment zone.
14. An apparatus according to claim 1 , wherein the sacrificial anode is non-rotational.
15. An apparatus according to claim 1 , wherein the non-sacrificial anode is non-rotational.
16. An apparatus according to claim 1 , further including a separator to receive effluent from the electrocoagulation reactor outlet to separate solids from clean water.
17. An apparatus according to claim 16 , wherein the separator is a clarifier having a cylindrical side wall, an upper wall and a conical bottom wall.
18. An apparatus according to claim 17 , wherein an inlet conduit in the clarifier has an opening larger in cross-sectional area than the inner cross-sectional area of the conduit.
19. An apparatus according to claim 18 , wherein the inlet conduit opening in the clarifier is directed upwards.
20. An apparatus according to claim 17 , wherein the clarifier has an upper outlet at its top end connected to an upper outlet conduit, and a lower outlet at its bottom end connected to a lower outlet conduit.
21. An apparatus according to claim 20 , wherein the upper outlet is a solids outlet and the lower outlet is a cleaned water outlet.
22. An apparatus according to claim 20 , wherein the upper outlet is a cleaned water outlet and the lower outlet is a solids outlet.
23. An apparatus according to claim 20 , further comprising a first pump operationally connected to the upper outlet conduit and a second pump operatively connected to the lower outlet conduit.
24. An apparatus according to claim 17 , further comprising water level sensors on the upper wall of the clarifier operatively connected to the water outlet pump.
25. An apparatus according to claim 1 , wherein the rotatable cathode has an active face generally perpendicular to the axis of rotation of the cathode, the active face having a center and a periphery, the active face having surface features which define a plurality of water flow paths from the center to the periphery.
26. An apparatus according to claim 25 , wherein the surface features comprise channels.
27. An apparatus according to claim 26 , wherein the channels are curved or straight.
28. An apparatus according to claim 26 , wherein the channels flare outwardly from the center of the face to the periphery thereof.
29. An apparatus according to claim 25 , wherein the surface features comprise studs.
30. An apparatus according to claim 29 , wherein the studs are circular in a plane parallel to the face of the cathode.
31. An apparatus according to claim 1 , wherein the cathode is rotatable about a substantially vertical axis.
32. An apparatus according to claim 1 , wherein the cathode is a circular disk having a bottom surface, a top surface and a peripheral surface.
33. An apparatus according to claim 1 , wherein the cathode is movable in a direction parallel to its axis of rotation.
34. An apparatus according to claim 1 , wherein the non-sacrificial anode is movable in a direction parallel to the axis of rotation of the cathode.
35. An apparatus according to claim 1 , wherein the cathode has a shaft and the shaft is rotatably connected to the non-sacrificial anode.
36. An apparatus according to claim 35 , wherein the cathode shaft is rotatably connected to the non-sacrificial anode by a connector located within the reaction vessel.
37. An apparatus according to claim 35 , wherein the cathode shaft is rotatably connected to the non-sacrificial anode by a connector located outside the reaction vessel.
38. An apparatus according to claim 1 , further comprising power source means for applying the first voltage and the second voltage.
39. An apparatus according to claim 1 , wherein the first voltage is greater than the second voltage.
40. An apparatus according to claim 1 , wherein the first voltage is equal to the second voltage.
41. An apparatus according to claim 1 , wherein the first voltage is less than the second voltage.
42. An apparatus according to claim 1 , further comprising an electrolyte source for adding electrolyte to the water to be treated.
43. An apparatus according to claim 42 , wherein the electrolyte is sodium chloride.
44. An apparatus according to claim 1 , further comprising a hydrogen peroxide source for adding hydrogen peroxide to the water to be treated.
45. An apparatus according to claim 1 , further comprising a flocculant source for adding flocculant to the water exiting the reaction vessel.
46. An apparatus according to claim 1 , further comprising a coagulant source for adding coagulant to the water exiting the reaction vessel.
47. An apparatus according to claim 1 , wherein at least a portion of the non-sacrificial anode is coated with TiO 2 .
48. An apparatus according to claim 1 , wherein at least a portion of the cathode is coated with TiO 2 .
49. An apparatus according to claim 1 , wherein the reaction vessel is closed to the atmosphere.