A method of operating an electrochemical cell including introducing an aqueous solution into the electrochemical cell, applying a current across an anode and a cathode to produce a product, monitoring the voltage, dissolved hydrogen, or a condition of the aqueous solution, and reversing polarity of the anode and the cathode responsive to one of the measured parameters is disclosed. An electrochemical system including an electrochemical cell including an anode and a cathode, a source of an aqueous solution having an outlet fluidly connectable to the electrochemical cell, a sensor for measuring a parameter, and a controller configured to cause the anode and the cathode to reverse polarity responsive to the parameter measurement is disclosed. Methods of suppressing accumulation of hydrogen gas within the electrochemical cell are also disclosed. Methods of facilitating operation of an electrochemical cell are also disclosed.

Provided is a wastewater treatment method including measuring a chemical oxygen demand (COD) of wastewater containing organic matter in real time, calculating the amount of ozone associated with a concentration of the organic matter using the measured COD value, and controlling a production of ozone of an ozone generator based on the calculated amount of ozone. The present invention provides a wastewater treatment method and system for adjusting the production of ozone used as an oxidizing agent for decomposing organic matter in wastewater in association with a load of organic matter in wastewater to be oxidized.

Disclosed herein is a method for remediating sewage that contains persistent contaminants. The method comprises ozofractionating the sewage under conditions whereby a foam fractionate comprising persistent contaminants is produced and separated from an ozofractionated wastewater, quiescing the ozofractionated wastewater, whereby a residual ozone content of the ozofractionated wastewater is reduced, and contacting the quiesced ozofractionated wastewater with a microorganism population under conditions effective to biologically remediate the ozofractionated wastewater.

A wastewater treatment device has: an ozone generator which supplies ozone; a mixer which mixes ozone supplied from the ozone generator with wastewater and supplies ozone mixed wastewater; an ozone oxidation unit which progresses ozone oxidation in the ozone mixed wastewater while passing the ozone mixed wastewater therethrough and discharges wastewater in which the ozone has been consumed; a biological treatment unit which performs biological treatment on the wastewater discharged from the ozone oxidation unit using microorganisms; and an adjusting device which adjusts the amount of ozone to be mixed with the wastewater by the mixer so that ozone in an amount that inhibits the microorganisms of the biological treatment unit does not remain in the wastewater discharged from the ozone oxidation unit.

A water treatment system comprises a flow path through a first activated carbon filter, a second activated carbon filter downstream of the first activated carbon filter, a particulate filter downstream of the second activated carbon filter, for example a ceramic membrane, and a UV sterilizer downstream of the particulate filter. Ozone is introduced into the process water ahead of a water storage vessel for storing treated water produced by the system. A recycle subsystem is periodically operated to withdraw treated water from the water storage vessel to form recycled water, introduce the recycled water to the water lines upstream of the UV sterilizer, and return the recycled water to the water storage vessel. A main programmable logic controller (PLC) controls a flow of the process water through the water treatment system and controls the recycle subsystem.

An illustrative expendable or reconstructable ozone generator cartridge for an aqueous ozone delivery device, for example, for antimicrobial sanitizing and/or medical treatment, includes a housing for a water treatment manifold providing parallel and operably fixed water pathways through ozone generating cells coupled to the manifold, and optionally a data logging and authentication feature.

An ozonated water supply method includes: feeding dissolving water contained in a circulation tank to an ozonation device at a given feed rate while feeding ultrapure water to the circulation tank, and returning ozonated water that has not been used at a use point to the circulation tank, dissolving ozone in the dissolving water using the ozonation device to obtain ozonated water, and feeding the ozonated water to the use point; feeding oxygen gas having a nitrogen gas content of 0.01 vol % or less to a discharge-type ozone gas-producer, and feeding the resulting ozone-containing gas to the ozonation device; adjusting the feed rate of the ultrapure water to the circulation tank; and adjusting the dissolved ozone concentration in the ozonated water. The method can reduce or suppress the accumulation of nitric acid in the recirculation system when a discharge-type ozone gas-producer is used as the ozone gas-producer.

A method of treating water containing arsenic and manganese. Ozone is injected into the water at a concentration in the range of 0.2 to 1.0 mg/L, oxidizing As(III) to As(V) and Mn(II) to Mn(IV). Ferric chloride coagulant is added to the ozonated water, coagulating the As(V) and the Mn(IV). The water is then filtered with a first filter medium selected for removal of the Mn(IV) followed by a second filter medium selected for removal of As(V). This removes the coagulate to produce treated water. The method removes arsenic and manganese to low levels acceptable for drinking water, using low concentrations of ozone as an oxidant. An advantage is that the ozone system can have a relatively small footprint, and use less energy, an important factor for climate change. Further, a quenching agent for removal of residual ozone is not required.

An accelerated oxidation treatment method of performing oxidation treatment upon treatment water by supplying ozone and hydrogen peroxide to the treatment water, including an accelerated oxidation treatment process of bringing hydrogen peroxide and ozone into contact with the treatment water, and a bromate ion concentration measurement process of measuring the bromate ion concentration in the treatment water after the accelerated oxidation treatment process, with the amount of hydrogen peroxide supplied in the accelerated oxidation treatment process being adjusted on the basis of the measured value of bromate ion concentration.

In accordance with the present invention there is provided a method for treating a wastewater stream, comprising the steps of:—introducing O.sub.3 in the wastewater stream, thereby dissolving at least part of the O.sub.3 in the wastewater stream;—optionally irradiating the wastewater stream with ionizing radiation; and—optionally contacting the wastewater stream with a heterogeneous catalyst. In case the ozone treatment is combined with a heterogeneous catalyst, the wastewater treatment can be more effective than with ozone treatment alone, depending on the type of impurities in the wastewater stream. The type of heterogeneous catalyst can be chosen depending on the source of the wastewater and the specific pollutants associated with such wastewater sources. Advantageously, the ozone required for this process can be generated by electrolysis of water. In the current energy market, hydrogen (H.sub.2), which is also produced during electrolysis of water, is becoming increasingly important as a fuel, and therefore, increasing amounts of hydrogen are being produced, preferably using electricity generated using renewable resources. Therefore, oxygen (O.sub.2) and ozone (O.sub.3), which are produced alongside hydrogen during water electrolysis, and which are currently often discarded as an invaluable byproduct, can instead be used for wastewater treatment. Therefore, according to another aspect of the invention, there is also provided the use of O.sub.2 and/or O.sub.3 obtained by electrolysis of water for wastewater treatment.