Method and system for the efficient and sustainable electrochemical treatment of wastewater
A system for an efficient and sustainable electrochemical treatment of wastewater comprises a reactor tank, a first electrolyzer with a stack of electrolytic cells, each electrolytic cell comprising an anode of a first composition, and a second electrolyzer with a stack of electrolytic cells, each electrolytic cell comprising an anode of a second composition, and a contaminant concentration measuring device for monitoring the contaminant concentration in the reactor tank to the first or to the second electrolyzer. Wastewater to be treated is supplied from the reactor tank to the first electrolyzer until the contaminant concentration becomes substantially constant as measured by the contaminant removal rate being around 0 mg/h, which indicates the buildup of byproducts generated in the first electrolyzer, at which time the wastewater is supplied from the reactor tank to the second electrolyzer with anodes which can efficiently treat the byproducts of the reaction in the first electrolyzer.
1 . A method for the electrochemical treatment of wastewater comprising the steps of:
a. supplying a wastewater stream to be treated to a reactor tank, wherein the wastewater stream to be treated comprises a contaminant, and supplying a wastewater stream having a contaminant concentration from the reactor tank to a first electrolyzer,
b. treating the wastewater stream supplied from the reactor tank in the first electrolyzer, wherein the first electrolyzer comprises a stack of electrolytic cells, each electrolytic cell comprising an anode of a first composition, and discarding an effluent stream from the first electrolyzer into the reactor tank,
c. monitoring the contaminant concentration in the wastewater stream supplied from the reactor tank,
d. repeating the step of treating the wastewater stream supplied from the reactor tank in the first electrolyzer and discarding the effluent stream from the first electrolyzer into the reactor tank until the first electrolyzer has a contaminant removal rate of about 0 mg/h;
e. thereafter, stopping the treatment of the wastewater stream supplied from the reactor tank in the first electrolyzer and treating the wastewater stream supplied from the reactor tank in a second electrolyzer comprising a stack of electrolytic cells, each electrolytic cell comprising an anode of a second composition, which is different than the first composition of the anodes in the first electrolyzer, the second composition of the anode of the electrolytic cells in the second electrolyzer being selected from a material which treats byproducts of the reaction in the first electrolyzer,
f. treating the wastewater stream supplied from the reactor tank in the second electrolyzer and discarding an effluent stream from the second electrolyzer back to the reactor tank,
g. monitoring the contaminant concentration in the wastewater stream supplied from the reactor tank,
h. discarding the effluent stream from the second electrolyzer back to the reactor tank until the contaminant concentration in the wastewater stream supplied from the reactor tank to the second electrolyzer reaches a target value, and
i. discarding the wastewater from the reactor tank.
2 . The method of claim 1 wherein the contaminant concentration of the wastewater stream supplied from the reactor tank is monitored by measuring the chemical oxygen demand concentration in such wastewater.
3 . The method of claim 1 wherein the contaminant concentration of the wastewater stream supplied from the reactor tank is monitored by measuring the total organic carbon concentration in such wastewater.
4 . The method of claim 1 wherein the first composition of the anodes of the electrolytic cells in the first electrolyzer is selected from a material which treats contaminants in the wastewater stream supplied from the reactor tank and is not damaged by by-products generated in the first electrolyzer.
5 . The method of claim 1 wherein the second composition of the anodes of the electrolytic cells in the second electrolyzer is selected from a material which treats the contaminants in the wastewater supplied from the reactor tank.
6 . The method of claim 1 wherein stopping of the treatment of wastewater from the reactor tank in the first electrolyzer and starting the supply of wastewater from the reactor tank to a second electrolyzer is performed at a time determined experimentally to correspond to the time when the contaminant removal rate in the first electrolyzer is around 0 mg/h.
7 . The method of claim 1 wherein the wastewater stream supplied from the reactor tank contains isopropyl alcohol or isopropyl alcohol and acetone and the first composition of the anode of the first electrolyzer comprises a precious metal oxide and the second composition of the anode of the second electrolyzer comprises diamond or boron-doped diamond.