METHOD FOR THE TREATMENT OF COXIDIBLE CONTAMINANTS IN WASTEWATER

Abstract

Wastewater treatment systems for oxidizable contaminants may include a contaminant treatment vessel and a hydrogen peroxide delivery unit. The hydrogen peroxide delivery unit may include a hydrogen peroxide transfer line in fluid communication with the contaminant treatment vessel. A wastewater feed stream may also be in fluid communication with the contaminant treatment vessel. An effluent stream from the contaminant treatment vessel may also be in fluid communication with the contaminant treatment vessel.Methods for treating oxidizable contaminants in wastewater may include supplying wastewater to a contaminant treatment vessel, supplying hydrogen peroxide to the contaminant treatment vessel, and contacting wastewater in the contaminant treatment vessel with hydrogen peroxide. Contacting wastewater with hydrogen peroxide reduces the concentration of oxidizable contaminants based on the concentration of oxidizable contaminants in the wastewater feed stream.

Description

83805-AR-NP SYSTEMS AND METHODS FOR REDUCING OXIDIZABLE CONTAMINANTS IN A LIQUID TECHNICAL FIELD This specification generally relates to systems and processes for treating a stream and, in particular, to systems and processes for removing oxidizable contaminants from a liquid medium. BACKGROUND In a variety of industrial processes, such as hydrocarbon processes, wastewater streams may be produced. These wastewater streams may be alkaline wastewater streams containing various oxidizable contaminants, such as sulfides. Without treatment, these oxidizable contaminants may exit the facility where the industrial processes occurred. However, environmental concerns have arisen regarding the presence of oxidizable contaminants in these wastewater streams. Typically, these oxidizable contaminants are removed through complicated, multi-stage processes, such as precipitation processes. Since the presence of oxidizable contaminants is undesirable, there is a continuing need for systems and processes that can efficiently and effectively reduce the presence of oxidizable contaminants in wastewater streams. SUMMARY Embodiments of the present disclosure relate to systems and methods for reducing oxidizable contaminants that address this need. 2032427 of 19 83805-AR-NP According to one embodiment, a system for treating oxidizable contaminants in wastewater may include a contaminant treatment vessel and a hydrogen peroxide supply unit. The hydrogen peroxide supply unit may include a hydrogen peroxide transfer line in fluid communication with the contaminant treatment vessel, a wastewater feed stream in fluid communication with the contaminant treatment vessel, and an effluent stream from the contaminant treatment vessel in fluid communication with the contaminant treatment vessel. The hydrogen peroxide transfer line may include one or more hydrogen peroxide pumps, one or more ball valves, and one or more check valves.The hydrogen peroxide transfer line may be in fluid communication with the pollutant treatment vessel at a hydrogen peroxide injection point. The hydrogen peroxide injection point may be positioned above a maximum wastewater fill level of the pollutant treatment vessel such that an air gap exists between the wastewater in the pollutant treatment unit and the hydrogen peroxide injection point. The effluent stream from the pollutant treatment vessel may comprise less than 0.1 mg / L of oxidizable contaminants regardless of an initial concentration of oxidizable contaminants in the wastewater feed stream. According to another embodiment, a method for treating oxidizable contaminants in wastewater may include supplying wastewater to a contaminant treatment vessel, supplying hydrogen peroxide, 2032427 of 19 83805-AR-NP hydrogen to the pollutant treatment vessel, and contacting wastewater in the pollutant treatment vessel with hydrogen peroxide. Hydrogen peroxide may be supplied to the pollutant treatment vessel above a maximum wastewater fill line of the pollutant treatment vessel. Contacting the wastewater with hydrogen peroxide reduces the concentration of oxidizable pollutants based on the concentration of oxidizable pollutants in the wastewater feed stream. Additional features and advantages will be set forth in the following detailed description, and in part will be readily apparent to those of ordinary skill in the art from that description or will be recognized by practicing the embodiments described herein, which include the following detailed description and claims. It should be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. BRIEF DESCRIPTION OF THE FIGURES Figure 1 schematically represents a generalized flow diagram of a system for removing oxidizable contaminants from wastewater, in accordance with one or more embodiments shown and described in this disclosure; Figure 2 schematically represents a detailed view of the interior of a container for treating contaminants according to one or more embodiments shown and described in this description; 2032427 of 19 83805-AR-NP Figure 3A is an image of a filter paper for a wastewater sample without hydrogen peroxide treatment; and Figure 3B is an image of a filter paper for a wastewater sample after hydrogen peroxide treatment. DETAILED DESCRIPTION The present disclosure relates to methods for treating oxidizable contaminants in wastewater. In particular, the present disclosure relates to methods for treating oxidizable contaminants in wastewater comprising supplying wastewater to a contaminant treatment vessel, supplying hydrogen peroxide to the contaminant treatment vessel, and contacting wastewater in the contaminant treatment vessel with the hydrogen peroxide, wherein contacting wastewater with the hydrogen peroxide reduces the concentration of oxidizable contaminants in the wastewater. The present disclosure also relates to pollutant treatment systems for treating oxidizable contaminants in wastewater. In particular, the systems may comprise a contaminant treatment vessel and a hydrogen peroxide supply unit. The various oxidizable pollutant treatment systems and methods of the present disclosure for treating oxidizable pollutants in wastewater can provide increased efficiency in treating oxidizable pollutants compared to conventional systems and methods for treating oxidizable pollutants in wastewater. That is, the various pollutant treatment systems and methods 2032427 of 19 83805-AR-NP can efficiently and effectively reduce the presence of oxidizable contaminants in wastewater without the need for a complicated, multi-stage process. Contacting hydrogen peroxide with wastewater containing undesirable oxidizable contaminants can efficiently and effectively treat the oxidizable contaminants in the wastewater, but the combination of wastewater and hydrogen peroxide can be hazardous. Accordingly, the embodiments disclosed and described herein provide systems and processes wherein hydrogen peroxide can be combined with wastewater while minimizing any risk of undesirable combination of wastewater and hydrogen peroxide. As further described below, the combination of hydrogen peroxide with wastewater containing oxidizable contaminants can result in an exothermic reaction. Therefore, it may be important to control the combination of wastewater and hydrogen peroxide. Detailed reference will be made below to various systems and methods for reducing oxidizable contaminants in wastewater. Although the concepts of the present disclosure are described herein with primary reference to the reduction of oxidizable contaminants in wastewater streams, it is anticipated that the concepts will be applicable to other oxidizable contaminants in other liquid supplies. For example, and not as a limitation, the concepts of the present disclosure are anticipated to have applicability to open water streams containing oxidizable contaminants. Referring initially to Figures 1 and 2, a system 100 for treating oxidizable contaminants in wastewater may comprise a contaminant treatment vessel 110 and a hydrogen peroxide supply unit. The hydrogen peroxide supply unit may 2032427 of 19 83805-AR-NP comprise a hydrogen peroxide transfer line 124 in fluid communication with the pollutant treatment vessel 110. The hydrogen peroxide transfer lines 122, 124 may comprise one or more hydrogen peroxide pumps 123, one or more ball valves 121, 127, 128, and one or more check valves 125. The hydrogen peroxide transfer line 124 may be in fluid communication with the pollutant treatment vessel 110 at a hydrogen peroxide injection point 116. The hydrogen peroxide injection point 116 may be positioned above a maximum wastewater fill level 115 of the pollutant treatment vessel 110 such that an air gap exists between the wastewater in the pollutant treatment vessel 110 and the hydrogen peroxide injection point 116.The air gap may ensure that wastewater does not flow back into the hydrogen peroxide storage vessel 120. A wastewater feed stream 108 may be in fluid communication with the contaminant treatment vessel 110. An effluent stream from the contaminant treatment vessel 112 may be in fluid communication with the contaminant treatment vessel 110. Wastewater may contain various oxidizable contaminants. As used herein, it should be noted that “oxidizable contaminant” or “oxidizable contaminants” are used to represent both small compounds and minute, discrete particles suspended in a liquid medium that can be oxidized when brought into contact with hydrogen peroxide. Oxidizable contaminants may comprise, consist of, or consist essentially of sulfides, nitrites, phosphites, or combinations thereof. 2032427 of 19 83805-AR-NP modalities, oxidizable contaminants may be capable of undergoing a chemical reaction with oxygen. Sulfide, nitrite, phosphite, or a combination of these compounds may be present in the wastewater in an amount greater than 0.1 mg / L based on the volume of wastewater, such as an amount greater than 0.5 mg / L, greater than 1.0 mg / L, greater than 2.0 mg / L, or greater than 5.0 mg / L. The wastewater may be any water that has been contaminated by human use. The wastewater may be a byproduct of industrial activities. The wastewater may comprise a pH greater than 7. The wastewater may comprise a pH greater than 14. Alternatively, the wastewater may comprise a pH less than 14. The wastewater may be an alkaline wastewater. That is, the wastewater may comprise a pH greater than 7. Alternatively, the wastewater may be a highly alkaline wastewater. As used throughout the present disclosure, a “highly alkaline wastewater” may refer to an alkaline wastewater comprising a pH greater than 10. In embodiments, the wastewater may comprise a pH of about 10.5. The wastewater may be referred to as caustic. That is, the wastewater may be corrosive. The contaminant treatment vessel 110 may be downstream of the hydrogen peroxide supply unit 105. The contaminant treatment vessel 110 may be any vessel or other similar apparatus suitable for mixing two or more streams. The contaminant treatment vessel 110 may include a mixer, such as an agitator. The contaminant treatment vessel 110 may include one or a plurality of vessels. If the contaminant treatment vessel 110 includes a plurality of vessels, the vessels may be in series or in parallel. The contaminant treatment vessel 110 may be operated to put into operation 2032427 of 19 83805-AR-NP contacts the wastewater feed stream 108 with hydrogen peroxide in the hydrogen peroxide transfer line 124 to form an effluent stream from the pollutant treatment vessel 112. The contaminant treatment vessel 110 may be operated to contact the wastewater feed stream 108 with hydrogen peroxide from the hydrogen peroxide transfer line 124. By contacting the wastewater feed stream 108 with hydrogen peroxide discharged from the hydrogen peroxide transfer line 124, oxidizable contaminants in the wastewater feed stream 108 may be treated. In the contaminant treatment vessel 110, hydrogen peroxide discharged from the hydrogen peroxide transfer line 124 may interact with oxidizable contaminants in the wastewater feed stream 108. The hydrogen peroxide discharged from the hydrogen peroxide transfer line 124 may oxidize the oxidizable contaminants in the wastewater feed stream 108.When the oxidizable contaminants include sulfides, nitrites, phosphites, or combinations thereof, hydrogen peroxide discharged from hydrogen peroxide transfer line 124 can oxidize the oxidizable contaminants to sulfates, nitrates, phosphates, or combinations thereof, respectively. The oxidized forms of the above contaminants are not hazardous and are considered safe to be in the effluent from pollutant treatment vessel 112. If the above contaminants are not oxidized prior to discharge, they can reduce dissolved oxygen levels in the water over time and may endanger aquatic life forms. 2032427 of 19 83805-AR-NP The pollutant treatment vessel 110 may operate at a temperature less than 70 degrees Celsius (°C). For example, the pollutant treatment vessel 110 may operate at a temperature less than 60°C or less than 50°C. In embodiments, the pollutant treatment vessel 110 may operate at a temperature from greater than 20°C to less than 50°C, such as from 30°C to less than 50°C or from 40°C to less than 50°C. Contacting hydrogen peroxide with wastewater at temperatures above 70°C may result in the hydrogen peroxide degrading more rapidly than desired and not effectively and efficiently treating oxidizable pollutants in the wastewater. Still referring to Figure 1, the system 100 may include the hydrogen peroxide supply unit 105. The hydrogen peroxide supply unit 105 may be disposed downstream of the pollutant treatment vessel 110. The hydrogen peroxide supply unit 105 may include a hydrogen peroxide transfer line 122, 124 in fluid communication with the pollutant treatment vessel 110. The hydrogen peroxide supply unit 105 may further include a hydrogen peroxide storage vessel 120. The hydrogen peroxide storage vessel 120 may be disposed downstream of the hydrogen peroxide transfer line 122, 124. The hydrogen peroxide storage vessel 120 may be any unit operable to store a quantity of hydrogen peroxide to ultimately be supplied to the pollutant treatment vessel 110 as needed. While it is envisioned that the hydrogen peroxide storage vessel 120 may store pure hydrogen peroxide, hydrogen peroxide may be disposed downstream of the hydrogen peroxide transfer line 122, 124. 2032427 of 19 83805-AR-NP of hydrogen in the hydrogen peroxide storage vessel 120 may be a dilute hydrogen peroxide solution. In embodiments, the hydrogen peroxide may be 20% hydrogen peroxide, 25% hydrogen peroxide, 30% hydrogen peroxide, 35% hydrogen peroxide, 40% hydrogen peroxide, 45% hydrogen peroxide, or 50% hydrogen peroxide. The hydrogen peroxide may be diluted in water. As one of skill in the art will appreciate, in 20% hydrogen peroxide, for example, 20% of the solution may be hydrogen peroxide and 80% of the solution may be water. The hydrogen peroxide transfer line 122, 124, the hydrogen peroxide storage vessel 120, and the pollutant treatment vessel 110. The hydrogen peroxide transfer line 122, 124 may include various valves and pumps operable to regulate the amount of hydrogen peroxide supplied to the pollutant treatment vessel 110. Still referring to Figure 1, the system 100 may comprise a plurality of valves. The valves may be operated to control the flow of wastewater and hydrogen peroxide into the treatment vessel 110 as well as effluent from the treatment vessel 112 passing out of the treatment vessel 110. The system 100 may comprise one or more ball valves, one or more check valves, one or more pressure relief valves, or combinations thereof. Those skilled in the art will appreciate that the presence and position of these various valves may not necessarily be the same as depicted in Figure 1. 2032427 of 19 83805-AR-NP The various different types of valves will be described in greater detail below. A ball valve may refer to a valve that has a hollow, perforated, pivoting ball to control flow through it. It is open when the hole in the ball is in line with the flow and closed when pivoted 90 degrees by the valve handle. In embodiments, a ball valve may be a vented ball valve. A check valve is a valve that allows fluid to flow in only one direction. A check valve can be a two-port valve, with one port allowing fluid to enter and the other allowing fluid to exit. A check valve may also be called a hinged valve, non-return valve, reflux valve, check valve, or one-way valve. A pressure relief valve is a safety valve used to control or limit pressure in a system. A pressure relief valve is designed or configured to open at a predetermined pressure to protect pressure vessels and other equipment from being subjected to pressures that exceed their design limits. In addition to the various valves, the system 100 may comprise a plurality of pumps. The pumps, together with the valves, may be operated to control the flow of wastewater and hydrogen peroxide into the treatment vessel 110 as well as effluent from the treatment vessel 112 passing out of the treatment vessel 110. The pumps of the system 100 may comprise air diaphragm pumps. An air diaphragm pump may refer to a positive displacement pump that uses a 2032427 of 19 83805-AR-NP combination of the reciprocating action of a rubber, thermoplastic or Teflon diaphragm and suitable valves on either side of the diaphragm for pumping a fluid. The hydrogen peroxide supply unit 105 and its various valves and pumps provided in the embodiment described herein will be described in greater detail below. As described above, hydrogen peroxide may be stored in a hydrogen peroxide storage vessel 120. When hydrogen peroxide is supplied to the pollutant treatment vessel 110, it may be passed through hydrogen peroxide transfer lines 122, 124. The hydrogen peroxide may first be passed through a valve, such as a vented ball valve. The vent from the ball valve 121 may vent into the hydrogen peroxide storage vessel 120. After passing out of the ball valve 121, the hydrogen peroxide may continue to be passed through the hydrogen peroxide transfer line 122 to the hydrogen peroxide pump 123. In embodiments, the hydrogen peroxide pump 123 may be an air diaphragm pump. After passing out of the hydrogen peroxide pump 123, the hydrogen peroxide may continue to be passed through the hydrogen peroxide transfer line 122. At least a portion of the hydrogen peroxide may then be passed through the hydrogen peroxide transfer line 124 to the pollutant treatment vessel 110. Before entering the pollutant treatment vessel 110, the hydrogen peroxide may pass through a check valve 125 and another ball valve 127. Again, in embodiments, this ball valve 127 may be a vented ball valve.The 127 ball valve vent can vent to the check valve. 2032427 of 19 83805-AR-NP 125. After passing the ball valve 127, the hydrogen peroxide may continue to be passed through the hydrogen peroxide transfer line 124 to the contaminant treatment vessel 110. The hydrogen peroxide supply unit 105 may further include a hydrogen peroxide emergency pressure release line 126. It may be undesirable to have too much pressure in the hydrogen peroxide supply unit 105. Therefore, the hydrogen peroxide emergency release line 126 may direct excess hydrogen peroxide from the hydrogen peroxide transfer line 124 out of the system 100. In the hydrogen peroxide emergency pressure release line 126, a portion of the hydrogen peroxide may be removed or purged from the system 100. A portion of the hydrogen peroxide in the hydrogen peroxide transfer line 122 may be passed through the hydrogen peroxide emergency pressure release line 126.The emergency hydrogen peroxide release line 126 may include a valve, such as a ball valve 128, which may be always open during operation. The vent of the ball valve 128 may vent to the hydrogen peroxide pump 123. After passing the ball valve 128, the hydrogen peroxide in the emergency hydrogen peroxide pressure relief line 126 may be passed to a pressure relief valve 129. The pressure relief valve 129 may be used to allow hydrogen peroxide to be removed or purged in the event that excess pressure is generated by the hydrogen peroxide from the hydrogen peroxide storage vessel 120 to the hydrogen peroxide transfer line 122, such that the excess pressure and hydrogen peroxide. 2032427 of 19 83805-AR-NP hydrogen cannot be fed to the pollutant treatment vessel 110 through the hydrogen peroxide transfer line 124. It may be undesirable for excess hydrogen peroxide to be fed to the pollutant treatment vessel 110. If excess hydrogen peroxide is allowed to be fed to the pollutant treatment vessel 110, no additional benefit may be recognized and hydrogen peroxide may be wasted. The one or more hydrogen peroxide pumps 123, in conjunction with the various valves described above, may be operated to precisely provide the proper amount of hydrogen peroxide to the pollutant treatment vessel 110 such that excess hydrogen peroxide is not fed to the pollutant treatment vessel 110. Likewise, it may be undesirable for wastewater in the contaminant treatment vessel 110 to flow back to the hydrogen peroxide supply unit 105. If the wastewater is allowed to flow back to the hydrogen peroxide supply unit 105, a runaway reaction may occur. Since the reaction between the wastewater and hydrogen peroxide can be highly exothermic, the reflux of wastewater to the hydrogen peroxide supply unit 105 may result in a highly exothermic reaction with large pressure increases in the hydrogen peroxide supply unit 105.The various valves (ball valves, check valves, pressure relief valves, or combinations thereof) provided in the hydrogen supply unit 105 can reduce or eliminate the possibility of backflow of residual water into the hydrogen peroxide supply unit 105, and more specifically into the hydrogen peroxide storage vessel 120. In the event of a. 2032427 of 19 83805-AR-NP additional pressure increase in the hydrogen peroxide supply unit 105, the additional pressure can be released through the pressure relief valve 129. Still referring to Figure 1, the wastewater feed stream 108 may be pumped by a wastewater feed pump 109. After passing the wastewater feed pump 109, the wastewater feed stream 108 may be supplied to the contaminant treatment vessel 110. Referring now to Figure 2, the hydrogen peroxide in the hydrogen peroxide supply unit 105 may be supplied to the pollutant treatment vessel 110 via the hydrogen peroxide transfer line 124 at a hydrogen peroxide injection point 116. The pollutant treatment vessel 110 may comprise a maximum wastewater fill level 115. The maximum wastewater fill level 115 may refer to the maximum height of the wastewater in the pollutant treatment vessel 110. As described herein, it may be important that there be a sufficient air gap between the maximum wastewater fill level 115 of the pollutant treatment vessel 110 and the hydrogen peroxide injection point 116. The air gap may be at least half a meter, one meter, such as at least two meters, at least three meters, at least four meters, or at least five meters. Referring again to Figure 1, the system 100 may comprise an effluent stream from the contaminant treatment vessel 112 in fluid communication with the contaminant treatment vessel 110. The effluent stream from the contaminant treatment vessel 112 may comprise less oxidizable contaminants than the feed water stream. 2032427 of 19 83805-AR-NP wastewater 108. The effluent stream from the pollutant treatment vessel 112 may comprise less than 0.1 mg / L of oxidizable contaminants regardless of the initial weight percent of oxidizable contaminants in the wastewater feed stream 108. For example, the effluent stream from the pollutant treatment vessel 112 may comprise less than 0.09 mg / L of oxidizable contaminants, such as less than 0.08 mg / L of oxidizable contaminants, less than 0.07 mg / L of oxidizable contaminants, less than 0.06 mg / L of oxidizable contaminants, less than 0.05 mg / L of oxidizable contaminants, less than 0.04 mg / L of oxidizable contaminants, or less than 0.03 mg / L of oxidizable contaminants regardless of the initial weight percent of oxidizable contaminants in the wastewater feed stream 108. Referring now to Figures 1 and 2, equipment that may be in contact with hydrogen peroxide (e.g., the hydrogen peroxide supply unit 105, the contaminant treatment vessel 110, or both) may be constructed of materials resistant to the corrosiveness of hydrogen peroxide. In embodiments, the equipment that may be in contact with hydrogen peroxide may be pickled, passivated, or both. Referring again to Figures 1 and 2, methods for treating oxidizable contaminants in wastewater may include supplying wastewater to the contaminant treatment vessel 110, supplying hydrogen peroxide to the contaminant treatment vessel 110, and contacting wastewater in the contaminant treatment vessel 110 with hydrogen peroxide. The hydrogen peroxide may be supplied to the contaminant treatment vessel 110 above the maximum wastewater fill line 115 of the contaminant treatment vessel 110. Contacting the hydrogen peroxide may also include contacting the hydrogen peroxide in the contaminant treatment vessel 110 with the hydrogen peroxide. The hydrogen peroxide may be supplied to the contaminant treatment vessel 110 above the maximum wastewater fill line 115 of the contaminant treatment vessel 110. 2032427 of 19 83805-AR-NP in contact with hydrogen peroxide, wastewater can reduce the concentration of oxidizable contaminants based on the concentration of oxidizable contaminants in the wastewater feed stream 108. The contaminant treatment vessel 110 can have any of the features or operating conditions described above in the present disclosure for the contaminant treatment vessel 110. Examples The embodiments of the present disclosure will be further clarified by the following examples. Example 1: Treatment of alkaline wastewater with hydrogen peroxide In Example 1, alkaline wastewater was treated with hydrogen peroxide to reduce oxidizable contaminants, such as sulfide, from the alkaline wastewater. In this example, 500 milliliters (mL) of the synthetic alkaline wastewater were prepared and purged with nitrogen to remove all dissolved oxygen. Na2SOH2O was added so that the alkaline wastewater initially contained sulfide in an amount of 12.2 milligrams per liter (mg / L) of alkaline wastewater. H2O2 solution was injected onto the surface of the previous sample at a dose of 50 mg / L. An additional sample was prepared without injecting the H2O2 solution. Each of these two samples was then added to two other empty sample bottles containing ZnAc powders to precipitate the remaining S2-. The resulting sample was filtered, and the filter paper was examined under a microscope for the presence of S2(ZnS). The results are shown in Figure 3A and Figure 3B.Figure 3A shows the filter paper for the sample without H2O2 treatment and Figure 3B shows the. 2032427 of 19 83805-AR-NP results after treatment with H2O2. It can be seen that treatment with H2O2 reduced the amount of S2- in the prepared alkaline wastewater sample. As can be seen from Figure 3A and Figure 3B, treating alkaline wastewater with hydrogen peroxide can reduce oxidizable contaminants, such as sulfides, from the alkaline wastewater. The hydrogen peroxide dosage can vary depending on the alkaline wastewater and the desired amount of oxidizable contaminant reduction. It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Therefore, it is intended that the specification cover modifications and variations of the various embodiments described herein, provided that such modifications and variations are within the scope of the appended claims and their equivalents. 2032427 of 19 Alejandra Aoun - 27184140328 Digitally signed by PORTALTRAMITES - INPI Date: 2022.11.11 13:15:44 -03:00 Reason: Digitally signed by the INPI Location: Buenos Aires, Argentina 2032427

Claims

1. A method for treating oxidizable contaminants in wastewater, said method characterized in that it comprises: supplying wastewater to a contaminant treatment vessel; supplying hydrogen peroxide to the contaminant treatment vessel, wherein: the hydrogen peroxide is supplied to the contaminant treatment vessel above a maximum wastewater fill line of the contaminant treatment vessel; and contacting wastewater in the contaminant treatment vessel with hydrogen peroxide, wherein contacting wastewater with hydrogen peroxide reduces the concentration of oxidizable contaminants relative to the concentration of oxidizable contaminants in the wastewater feed stream;wherein hydrogen peroxide is supplied to the contaminant treatment vessel at least half a meter above the maximum wastewater fill line of the contaminant treatment vessel. Seven claims follow;