Method of removing pesticides from wastewater
The present disclosure is directed to a method of removing pesticides from water. An electrolysis cell oxidizes pesticides and/or other organic components, optionally in conjunction with one or more filtration steps. Hydrogen peroxide may be added to the electrolysis process to aid oxidation.
1. A process for treating wastewater comprising:
feeding a wastewater stream (B) to a preliminary filtration stage;
feeding the permeate of the preliminary filtration stage to a primary filtration stage, wherein the preliminary filtration stage has greater porosity than the primary filtration stage, wherein the retentate of the primary filtration stage comprises a wastewater stream (A);
feeding the wastewater stream (A) to an electrolysis cell;
oxidizing the wastewater stream (A)
recirculating the effluent of the electrolysis cell through the electrolysis cell; and
passing the treated effluent of the electrolysis cell and the permeate of the filtration stage into a product stream;
wherein the wastewater stream (A) originally comprises a contaminant, the contaminant being a humic acid, a hormone, and/or a pesticide, and wherein the product stream is free of more than about 95% of the contaminant.
2. A process as defined in claim 1 , wherein the primary filtration stage is a nanofiltration stage.
3. A process as defined in claim 1 comprising the step of feeding the permeate of the primary filtration stage to a polishing filtration stage.
4. A process as defined in claim 3 , wherein the polishing filtration stage comprises producing a permeate of at least one polishing filtration stage that has a lower sodium concentration than the retentate of the at least one polishing filtration stage.
5. A process as defined in claim 1 , wherein at least one filtration stage comprises producing a permeate of the at least one filtration stage that is free of at least about 85% of the original pesticide content of the influent wastewater.
6. A process as defined in claim 1 , wherein the permeate of at least one filtration stage is free of at least 95% of the original pesticide content of the influent wastewater.
7. A process as defined in claim 1 , wherein the electrolysis cell electrodes comprise an oxide or suboxide of TiO x .
8. A process as defined in claim 7 , wherein the oxide or suboxide of TiO x is a Magneli phase material of the formula (Ti n O 2n-1 ), where n is 4, 5, 6, 7, 8, 9, or 10.
9. A process as defined in claim 8 , wherein the suboxide of TiO x is a Magneli phase material of the formula Ti 4 O 7 .
10. A process as defined in claim 1 , wherein flow of the permeate of the primary filtration stage is greater than about 0.001 m 3 /hr.
11. A process as defined in claim 1 , wherein flow of the permeate of the primary filtration stage is greater than about 1 m 3 /hr.
12. A process as defined in claim 1 , wherein the wastewater stream being fed to the electrolysis cell has a chloride ion concentration, and wherein the chloride ion concentration of the wastewater stream being fed to the electrolysis cell is greater than about 10 mg/L.
13. A process as defined in claim 10 , further comprising the step of monitoring a parameter of the flow through the electrolysis cell, the electrolysis cell being in communication with a power supply, and wherein voltage supplied to the electrolysis cell by the power supply is increased or decreased based on the monitored parameter.
14. A process as defined in claim 13 , wherein the wastewater stream being fed to the electrolysis cell has a chloride ion concentration, and wherein the process further comprises the step of monitoring the chlorine content, oxidation-reduction potential, pH, and/or pesticide content in the product stream and wherein at least one parameter within the process is changed if a monitored concentration is above a preset limit, the parameter being changed comprising the flow rate of the wastewater stream or the amount of voltage supplied to the electrolysis cell.
15. A process as defined in claim 1 , further comprising the step of adding a peroxide to the wastewater stream (A) and/or the effluent of the electrolytic cell recirculated to the electrolytic cell.
16. A system comprising:
a preliminary filter;
a primary filter; and
an electrolysis cell;
configured to execute the process of claim 1 ,
wherein a wastewater stream (B) is fed to the preliminary filter;
the permeate of the preliminary filter is fed to the primary filter, wherein the preliminary filter has greater porosity than the primary filter, wherein the retentate of the primary filter comprises a wastewater stream (A);
the wastewater stream (A) is fed to the electrolysis cell;
the wastewater stream (A) is oxidized;
the effluent of the electrolysis cell is fed through the electrolysis cell; and
the treated effluent of the electrolysis cell and the permeate of the filtration stage are passed into a product stream.