System and method for water treatment including granular activated carbon regeneration
A water treatment system includes an adsorption column including granular activated carbon (GAC) that adsorbs contaminants from untreated water onto the GAC, thereby producing treated water, a first electrode disposed at a proximal side of the adsorption column, with a gap between the first electrode and the GAC, a second electrode disposed at a distal side of the adsorption column, a drain outlet in fluid communication with the adsorption column for draining water out of the adsorption column, a gas inlet in fluid communication with the adsorption column for injecting a displacement gas into the adsorption column, a high voltage power supply electrically connected to one of the first electrode and the second electrode for generating a plasma discharge within the GAC, thereby regenerating the GAC within the adsorption column, and a gas outlet in fluid communication with the adsorption column for venting waste gas produced by the plasma discharge.
1. A water treatment system comprising:
an adsorption column including granular activated carbon (GAC) that adsorbs contaminants from untreated water onto the GAC, thereby producing treated water;
a first electrode disposed at a proximal side of the adsorption column, with a gap between the first electrode and the GAC;
a second electrode disposed at a distal side of the adsorption column;
a drain outlet in fluid communication with the adsorption column for draining water out of the adsorption column;
a gas inlet in fluid communication with the adsorption column for injecting a displacement gas into the adsorption column;
a high voltage power supply electrically connected to one of the first electrode and the second electrode for generating a plasma discharge within the GAC, thereby regenerating the GAC within the adsorption column; and
a gas outlet in fluid communication with the adsorption column for venting waste gas produced by the plasma discharge.
2. The water treatment system of claim 1 , wherein the first electrode is a high voltage electrode, the second electrode is a ground electrode, and the high voltage power supply is electrically connected to the first electrode.
3. The water treatment system of claim 1 , wherein the first electrode is a ground electrode, the second electrode is a high voltage electrode, and the high voltage power supply is electrically connected to the second electrode.
4. The water treatment system of claim 1 , wherein the plasma discharge is an arc plasma discharge.
5. The water treatment system of claim 1 , wherein the second electrode is embedded in the GAC at the distal side of the adsorption column.
6. The water treatment system of claim 1 , wherein the proximal side is a top side and the distal side is a bottom side of the adsorption column.
7. The water treatment system of claim 1 , further including a temperature sensor that measures temperature of the GAC.
8. The water treatment system of claim 1 , wherein contaminants include perfluorooctane sulfonate, perfluorooctanoic acid, or any combination thereof.
9. The water treatment system of claim 1 , wherein the displacement gas is a hydrocarbon gas heavier than air.
10. The water treatment system of claim 9 , wherein the displacement gas is propane, butane, or a mixture thereof.
11. The water treatment system of claim 1 , wherein the gap is in a range of between 0.5 cm and 1 cm.
12. The water treatment system of claim 1 , further including an untreated water inlet into the adsorption column and a treated water outlet out of the adsorption column.
13. The water treatment system of claim 12 , further including a pump in fluid communication with the untreated water inlet.
14. The water treatment system of claim 13 , wherein the pump includes a variable frequency motor.
15. A method of regenerating granular activated carbon (GAC) in a water treatment system, the method comprising:
draining water out of an adsorption column containing GAC of a water treatment system;
injecting a displacement gas into the adsorption column;
generating an electrical voltage between a first electrode disposed at a proximal side of the adsorption column and a second electrode disposed at a distal side of the adsorption column to form a plasma discharge within the GAC, thereby regenerating the GAC within the adsorption column; and
venting waste gas produced by the plasma discharge.
16. The method of claim 15 , wherein the first electrode is a high voltage electrode, the second electrode is a ground electrode, and a high voltage power supply is electrically connected to the first electrode.
17. The method of claim 16 , further including adjusting output power of the high voltage power supply based on a thermostatic feedback signal from a temperature sensor that measures temperature of the GAC.
18. The method of claim 15 , wherein the first electrode is a ground electrode, the second electrode is a high voltage electrode, and a high voltage power supply is electrically connected to the second electrode.
19. The method of claim 18 , further including adjusting output power of the high voltage power supply based on a thermostatic feedback signal from a temperature sensor that measures temperature of the GAC.
20. The method of claim 15 , wherein the electrical voltage is generated for a regeneration time that is less than 30 min.
21. The method of claim 20 , wherein the regeneration time is less than 10 min.
22. The method of claim 21 , wherein the regeneration time is less than 1 min.
23. A method of treating water, the method comprising:
flowing untreated water into an adsorption column including granular activated carbon (GAC) that adsorbs contaminants from the water onto the GAC, thereby producing treated water;
flowing the treated water out of the adsorption column;
draining water out of the adsorption column;
injecting a displacement gas into the adsorption column;
generating an electrical voltage between a first electrode disposed at a proximal side of the adsorption column and a second electrode disposed at a distal side of the adsorption column to form a plasma discharge within the GAC, thereby regenerating the GAC within the adsorption column; and
venting waste gas produced by the plasma discharge.
24. The method of claim 23 , wherein the first electrode is a high voltage electrode, the second electrode is a ground electrode, and a high voltage power supply is electrically connected to the first electrode.
25. The method of claim 24 , further including adjusting output power of the high voltage power supply based on a thermostatic feedback signal from a temperature sensor that measures temperature of the GAC.
26. The method of claim 23 , wherein the first electrode is a ground electrode, the second electrode is a high voltage electrode, and a high voltage power supply is electrically connected to the second electrode.
27. The method of claim 26 , further including adjusting output power of the high voltage power supply based on a thermostatic feedback signal from a temperature sensor that measures temperature of the GAC.
28. The method of claim 23 , wherein the electrical voltage is generated for a regeneration time that is less than 30 min.
29. The method of claim 28 , wherein the regeneration time is less than 10 min.
30. The method of claim 29 , wherein the regeneration time is less than 1 min.