System and method for treatment of wastewater via enhanced electroflotation

Patent metadata

Field	Value
Publication number	US-11180388-B2
Application number	US-201716346779-A
Country	US
Kind code	B2
Filing date	Oct 31, 2017
Priority date	Nov 3, 2016
Publication date	Nov 23, 2021
Grant date	Nov 23, 2021

Abstract

A method for treating wastewater involves electrolyzing a stream of seawater and wastewater mix within one or more electrolytic cells mounted outside a batch tank. The electrolyzed stream is piped to a quelling chamber which is mounted above the batch tank. A diluted polymer solution is injected at upstream of an in-line mixer piping into the quelling chamber substantially concurrently with the electrolyzed stream. The polymer solution and the electrolyzed stream are dispersed as a fine shower over residual seawater and wastewater in the batch tank. The polymer solution facilitates flocculation of the suspended solid particles and creates a distinct buoyant layer of flocculated solid particles attached with micro bubbles. A substantially clarified effluent is separated from the flocculated layer and neutralized prior to discharge. The flocculated layer is pumped from the batch tank to a dewatering system where entrained solids are compacted to a desired level. A centrate generated during the solids/sludge dewatering step is recirculated to the batch tank prior to addition of seawater during a subsequent treatment cycle as a supplement to the seawater.

First claim

The invention claimed is:

1. A method for treating wastewater comprising:
filling a batch tank with seawater until it reaches a first predetermined level;
transferring the wastewater to the batch tank until a seawater and wastewater mix in the batch tank reaches a second predetermined level, wherein the wastewater comprises suspended solid particles;
subjecting a stream of the seawater and wastewater mix to electrolysis within an electrolytic cell, wherein the electrolytic cell is mounted outside the batch tank;
piping the electrolyzed stream to a quelling chamber, wherein the quelling chamber is mounted above the batch tank, and wherein the electrolyzed stream comprises entrained micro/fine gas bubbles generated during the electrolysis;
injecting a diluted defoamer solution via a chemical injection pump from a defoamer storage chamber at the exit of the electrolytic cell;
injecting a diluted polymer solution at upstream of an in-line mixer piping, wherein the polymer solution is piped into the quelling chamber substantially concurrently with the electrolyzed stream;
enabling dispersion of the polymer solution and the electrolyzed stream as a fine shower over residual seawater and wastewater in the batch tank, wherein the polymer solution facilitates flocculation of the suspended solid particles;
creating a distinct buoyant layer of the flocculated solid particles attached with the micro bubbles; and
separating a substantially clarified effluent from the flocculated layer.

2. The method according to claim 1 , further comprising macerating the suspended solid particles prior to the electrolysis step.

3. The method according to claim 1 , wherein the defoamer solution manages excess foam buildup in the electrolyzed stream before it is piped to the quelling chamber.

4. The method according to claim 1 , further comprising blending, in an in-situ polymer mixing system, a neat cationic polymer with a predetermined volume of service water to produce the diluted polymer solution, wherein the polymer mixing system comprises a polymer mixing chamber/column.

5. The method according to claim 4 , wherein concurrently with the transferring of the seawater to the batch tank, pumping the neat cationic polymer into the polymer mixing chamber/column for the blending step.

6. The method according to claim 4 , further comprising providing the polymer mixing chamber/column with a first/upper switch and a second/lower switch to detect polymer solution levels in the polymer mixing chamber/column and thereby ensure an optimal amount of the polymer solution is added to the batch tank.

7. The method according to claim 1 , further comprising facilitating a settling time cycle to enable the separation of the substantially clarified effluent from the flocculated layer.

8. The method according to claim 1 , further comprising discharging the clarified effluent from the batch tank.

9. The method according to claim 8 , wherein the discharging of the clarified effluent is terminated when a third predetermined level is reached.

10. The method according to claim 9 , further comprising spraying the batch tank with a mixed slurry to remove residual solid particles residing along an inside wall of the batch tank.

11. The method according to claim 8 , further comprising neutralizing residual chlorine in the clarified effluent with one or more chemicals prior to the discharge step.

12. The method according to claim 11 , further comprising measuring turbidity of the clarified effluent prior to and/or after the neutralization step.

13. The method according to claim 8 , further comprising substantially trapping the flocculated layer in the batch tank using a device such that it is prevented from being discharged with the clarified effluent.

14. The method according to claim 13 , further comprising pumping the flocculated layer from the batch tank into a sludge tank until a shutoff level is detected in the batch tank, wherein the shutoff level corresponds to a substantially empty batch tank.

15. The method according to claim 14 , further comprising resuming filling of the batch tank with seawater to commence a subsequent cycle for treating the wastewater.

16. The method according to claim 13 , further comprising pumping the flocculated layer to a dewatering system, wherein the dewatering system comprises a centrifuge unit for dewatering the wet solids/sludge whereby entrained solids are compacted to a desired level.

17. The method according to claim 16 , further comprising recirculating a centrate generated during the solids/sludge dewatering step to the batch tank for use during a subsequent treatment cycle.

18. The method according to claim 17 , wherein the centrate is added back to the batch tank prior to the addition of seawater during the subsequent treatment cycle, and wherein the centrate supplements the seawater.

19. A system for treating wastewater comprising:
a batch tank for receiving wastewater and seawater, wherein the wastewater comprises suspended solid particles;
an electrolytic cell in operable communication with the batch water tank, wherein the electrolytic cell is mounted outside the batch tank, and wherein a stream of the seawater and wastewater mix is subjected to electrolysis within an electrolytic cell, wherein the electrolyzed stream comprises entrained micro/fine gas bubbles generated during the electrolysis;
a quelling chamber, wherein the quelling chamber is mounted above the batch tank and is in fluidic communication with the batch tank; and
an in-situ polymer mixing system for blending a neat polymer with a stream of service water to produce a polymer solution, wherein the polymer solution facilitates flocculation of the suspended solid particles
wherein the batch tank comprises one or more sensors, wherein the one or more sensors are configured for detecting:
a first predetermined level, wherein the first predetermined level corresponds to a predetermined seawater fill level in the batch tank;
a second predetermined level, wherein the second predetermined level corresponds to a predetermined wastewater fill level in the batch tank;

wherein the quelling chamber comprises a coalescing pack having integral flow diffuser plates for dispersing the polymer solution and the electrolyzed stream as a fine shower over residual seawater and wastewater in the batch tank to create a distinct buoyant layer of the flocculated solid particles attached with the micro bubbles with substantially clarified effluent beneath the flocculated layer.

20. The system according to claim 19 , wherein the system is skid-mounted.

21. The system according to claim 19 , further comprising a defoamer injector, wherein the defoamer injector is located outside the batch tank and in proximity to the electrolytic cell.

22. The system according to claim 19 , further comprising a dechlorination injector for neutralizing the clarified effluent, wherein the dechlorination injector is located in proximity to a port for discharging the clarified effluent.

23. The system according to claim 19 , further comprising a dewatering system, wherein the dewatering system comprises a centrifuge for receiving the flocculated solid particles in a wet slurry form.

24. The system according to claim 23 , wherein the dewatering system further comprises piping for circulating a centrate generated from centrifugation/dewatering of the flocculated solid particles/wet slurry to the batch tank.

Assignees

• Industrie De Nora Spa

Inventors

• Casbeer Dana
• Bariya Rubin
• Patel Sehul
• Matousek Rudolf
• Reeves Thomas

Classifications

• C02F9/20

  Portable or detachable small-scale multistage treatment devices, e.g. point of use or laboratory water purification systems · CPC title

• C02F2303/185

  The treatment agent being halogen or a halogenated compound · CPC title

• C02F2301/046

  Recirculation with an external loop · CPC title

• C02F11/127

  by centrifugation · CPC title

• C02F1/4674

  with halogen or compound of halogens, e.g. chlorine, bromine · CPC title