METHOD AND APPARATUS FOR TREATMENT OF WASTEWATER CONTAINING AZIDE IONS

Abstract

Disclosed is a method of treating a clinical analyser wastewater stream containing a first concentration of azide ions in solution, comprising at least the step of passing the clinical analyser wastewater stream through an anodic oxidation chamber having one or more anodic oxidation cells to provide a post-chamber treated water stream, said treated water stream having a second concentration of azide ions in solution that is less than the first concentration of azide ions in solution. A clinical analyser treatment apparatus comprising an anodic oxidation chamber having one or more anodic oxidation cells able to reduce a concentration of azide ions is also disclosed.

Claims

1. A method of treating a clinical analyser wastewater stream containing a first concentration of azide ions in solution, comprising at least the step of: passing the clinical analyser wastewater stream through an anodic oxidation chamber having one or more anodic oxidation cells to provide a post-chamber treated water stream, said treated water stream having a second concentration of azide ions in solution that is less than the first concentration of azide ions in solution.

2. The method of claim 1 wherein anodic oxidation chamber has an anodic oxidation cell having an anode, and said anode includes boron doped diamond.

3. The method of claim 1 wherein the clinical analyser wastewater stream further has a first concentration of one or more organic molecules, and wherein the treated water stream has a second concentration of the same one or more organic molecules less than the first concentration of one or more organic molecules.

4. The method of claim 3 wherein the clinical analyser wastewater stream further has a first total concentration of one or more organic molecules, and wherein the treated water stream has a second total concentration of the same one or more organic molecules less than the first total concentration of one or more organic molecules.

5. The method of claim 1 wherein all or part of the treated water stream is recirculated through the anodic oxidation chamber and re-treated.

6. The method of claim 1 wherein the second concentration of azide in the treated water stream is less than 100 ppb.

7. The method of claim 1 wherein the anodic oxidation chamber is part of a wastewater treatment apparatus.

8. The method of claim 1 further comprising the step of venting any gases generated by the anodic oxidation chamber.

9. The method of claim 8 wherein the venting of generated gases comprises at least the steps of venting and diluting said gases from the anodic oxidation chamber.

10. The method of claim 1 further comprising the step of treating the clinical analyser wastewater stream with UV irradiation.

11. The method of claim 1 further comprising the step of filtering the clinical analyser wastewater stream.

12. The method of claim 1 further comprising the step of adjusting the pH of the clinical analyser wastewater stream.

13. The method of claim 1 comprising at least the steps of: passing the clinical analyser wastewater stream through an anodic oxidation chamber having one or more cells to provide a post-chamber treated water stream, said treated water stream having a second concentration of azide ions in solution that is less than the first concentration of azide ions in solution; venting and diluting any gases generated by the anodic oxidation chamber; treating the clinical analyser wastewater stream with UV irradiation; filtering the clinical analyser wastewater stream; and adjusting the pH of the clinical analyser wastewater stream.

14. A clinical analyser treatment apparatus for treating a clinical analyser wastewater stream, comprising an anodic oxidation chamber having one or more anodic oxidation cells able to reduce the concentration of azide ions in the wastewater stream.

15. The clinical analyser treatment apparatus as claimed in claim 14, configured to reduce the concentration of azide ions in the wastewater stream to less than 100 ppb.

16. The clinical analyser treatment apparatus as claimed in claim 14 comprising an anodic oxidation chamber able to reduce the total concentration of organic molecules in the wastewater stream.

17. The clinical analyser treatment apparatus as claimed in claim 14 wherein the anodic oxidation chamber is part of an anodic oxidation subsystem,

18. The clinical analyser treatment apparatus as claimed in claim 14 comprising an anodic oxidation subsystem, a UV disinfection subsystem, a filtration subsystem and a pH adjustment subsystem.

19. The clinical analyser treatment apparatus as claimed in claim 14 further comprising a gas extraction subsystem.

Description

[0061] Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings in which:

[0062] FIG. 1 shows an anodic oxidation chamber and a method of treating according to an embodiment of the present invention;

[0063] FIG. 2 shows a method and first wastewater treatment apparatus including an anodic oxidation chamber with extraction and expulsion of the waste gases according to a second embodiment of the present invention; and

[0064] FIG. 3 shows a method and second wastewater treatment apparatus according to a third embodiment of the present invention.

[0065] FIG. 1 shows an anodic oxidation subsystem 10 that can be part of a wastewater treatment apparatus. The anodic oxidation subsystem 10 includes an anodic oxidation chamber 12 containing an anodic oxidation cell 17 having an anode 14, preferably a boron doped diamond, and a cathode 16. The anodic oxidation chamber 12 may be any size suitable for the anode oxidation cell 17.

[0066] The chamber 12 has an inlet or entry port 18 for wastewater, and an outlet or exit port 20 for treated wastewater.

[0067] The anodic oxidation cell 17 may be physically distinct, or may be defined as the area around the anode 14 and cathode 16 providing the treatment.

[0068] The anodic oxidation chamber 12 may comprise a number of anodic oxidation cells formed from a number of distinct electrodes, or formed by the sharing of a number of electrodes in a manner known in the art, and generally forming a series of inter-electrode pathways which could allow the passage of a stream therethrough in either a serpentine direction or a parallel direction, or a combination of both.

[0069] The anodic oxidation chamber 12 may be a closed chamber, or it may be open, or have one or more openings or vents towards the top, to allow the electrode gases to pass out of the wastewater being treated.

[0070] The subsystem 10 has a subsystem feed conduit 22 to bring a clinical analyser wastewater stream 22 to be treated to the entry port 18 of the anodic oxidation chamber 12, and a subsystem outlet conduit 24 to take a post-chamber treated water stream 24 from the chamber 12 through the exit port 20. The wastewater may leave the anodic oxidation chamber 12 under pressure, either residual pressure from the feed conduit 22 if the anodic oxidation chamber 12 is closed, or if the top of the chamber 12 is open, then via an overflow in the wall of the anodic oxidation chamber 12, or a pump sited either within the anodic oxidation chamber 12 or in the outlet conduit 24.

[0071] An optional recirculation conduit 26 is shown. This allows repeated treatment of the wastewater to increase the amount of treatment it receives and further reduce the concentrations of azide ions and/or organic molecules in the wastewater. The recirculation may be for all, part or none of the flow in the outlet conduit 24 at any instant, and may be controlled based on readings from sensors (not shown) in either the outlet conduit or elsewhere in the wastewater treatment apparatus.

[0072] When a voltage is applied to the electrodes 14, 16 a current is passed through the wastewater. Azide ions are attracted to the anode 14, and at the anode 14 form nitrogen, or react with hydrogen ions generated at the anode 14 to form ammonia. Oxidising species, such as peroxide radicals, are generated at the interface between the anode 14 and the wastewater, and these react with the organic molecules in the wastewater to form smaller organic molecules, or eventually carbon dioxide and water. If the organic molecules contain nitrogen atoms, then gaseous nitrogen and/or ammonia may be produced. Other electrode reactions may produce oxygen at the anode 14 and hydrogen at the cathode 16. The gases produced in the anodic oxidation cell 17 either pass out of the chamber 12 as a gas stream 28 or are carried downstream where they may later pass out of the wastewater.

[0073] FIG. 2 shows a first wastewater treatment apparatus 100, including an anodic oxidation subsystem 110 within a chassis 130. The anodic oxidation subsystem may be the subsystem 10 shown and described in FIG. 1. The chassis includes a wastewater inlet port 132, from which subsystem feed conduit 122 carries the wastewater to the anodic oxidation chamber, and a treated wastewater outlet port 134 connected to the anodic oxidation subsystem by a subsystem outlet conduit 124. Gasses 128 generated in the anodic oxidation subsystem 110 pass into the chassis 130 and will accumulate in the headspace 136 of the chassis 130.

[0074] The first wastewater treatment apparatus 100 further includes a gas extraction subsystem 140. A fan or pump 142 extracts air from the laboratory where the wastewater treatment apparatus 100 is located, and passes it down an air conduit 144 to an air exit point 146 also located within the laboratory. In the air conduit 144 is an ejector 148. Ejectors are known in the art and the passage of a fluid through the ejector causes a low pressure area which is able to draw another fluid into the ejector, the combined fluids then passing out of the ejector. Ejector 148 causes a suction on a gas extraction conduit 150 connected to a port 152 in the chassis 130. Operation of the fan or pump 142 causes the gas in the headspace 136 of the chassis 130 to be drawn into the flow of air in the ejector 148 and for it to be diluted and passed out of the apparatus 100 into the laboratory at concentrations that are safe to the operators.

[0075] FIG. 3 shows a second wastewater treatment apparatus 200 including an anodic oxidation subsystem 210 within a chassis 230. The second wastewater treatment apparatus 200 shares many of the components with the first wastewater treatment apparatus 100 so uses numbering of +100 to represent like components and features.

[0076] The second wastewater treatment apparatus 200 further includes a UV disinfection subsystem 260 fed by with the partially treated wastewater from the anodic oxidation subsystem 210 via conduit 224; a filtration subsystem 262 fed by with the partially treated wastewater from the UV disinfection subsystem 260 via conduit 266; and a pH adjustment subsystem 264 fed by with the partially treated wastewater from the filtration subsystem 266 via conduit 268, the outlet of which is passed to the treated wastewater outlet port 234 via conduit 270.

[0077] Recirculation of partially treated wastewater from within or after any subsystem to or before any upstream subsystem may be enacted in any means known in the art via conduits not shown.

EXAMPLE

[0078] Apparatus as described in the FIG. 3 using the subsystem 10 and chamber 12 of FIG. 1 was operated with a synthetic wastewater of pH 9.0. Azide was added to the wastewater and passed through the anodic oxidation subsystem containing an anodic oxidation cell having a double sided boron doped diamond anode bordered by a stainless steel cathode on either side of the anode, with a 2 mm gap between the anode and cathodes through which the wastewater was passed.

[0079] With no power there was no change in the concentration of azide ion through the anodic oxidation subsystem. When power was applied to the anodic oxidation cell a concentration of azide ions of 161 ppm before the anodic oxidation cell was reduced to 120 ppm after the processing by the anodic oxidation cell.

[0080] A second wastewater stream having an azide ion concentration of 1.7 ppm was run through the same apparatus, and the concentration of azide ion was reduced to 1.2 ppm on passage through the powered anodic oxidation cell.

[0081] A third wastewater stream having an azide ion concentration of 200 ppm was passed into the same apparatus with complete recirculation of the treated water back to prior to the anodic oxidation cell as shown in FIG. 1. The concentration of azide ion decreased with time, and after 120 minutes no azide ion was detectable in the wastewater at a limit of detection of 100 ppb.