Abstract: A device for measuring the total organic carbon content (TOC) of a sample fluid comprises a measuring cell (2) defining a volume (3) for containing a sample fluid and an excimer lamp (20) arranged to cause an oxidation reaction of the sample fluid by emitting radiation onto the sample fluid in the volume (3). A pair of electrodes is arranged to measure the conductivity of the sample fluid during the oxidation reaction and at least one temperature senor (31) is arranged on the measuring cell (2) to measure a temperature that is related to the sample fluid. The total organic carbon content (TOC) of the sample fluid is determined on the basis of the measured conductivity compensated by the temperature related to the sample fluid.

Abstract: Disclosed is an organic carbon detector that can be used with a liquid chromatography equipment such as a size exclusion chromatography. The organic carbon detector contains a carbon oxidization subsystem and a stripping and CO2 detection subsystem arranged and detachably connected with each other in said order. The carbon oxidization subsystem contains a microfluidic agent injection module (1), an inorganic carbon removal module (2), a microfluidic ultraviolet oxidation module (3) and a vacuum pumping system (4), configured to remove inorganic carbons and oxidize organic carbons. The stripping and CO2 detection subsystem contains a stripping module (7) and a CO2 detector (12), using a carrier gas to transfer the organic carbon converted gas to the CO2 detector (12). Also disclosed is a method of using the organic carbon detector in water quality monitoring.

Abstract: An embodiment provides a method for oxidizing organic carbon, including: introducing, in a reaction chamber of a total organic carbon analyzer, a fluid sample comprising organic carbon, wherein the reaction chamber includes an electrochemical cell and wherein the electrochemical cell comprises an SP3 substituted solid carbon electrode doped with a conductivity elevating composition; applying, using a generator, a positive potential to the SP3 substituted carbon electrode, the positive potential being sufficient to oxidize organics in the fluid sample to produce carbonate and partially oxidized organics; introducing, in the reaction chamber, at least one acid reagent comprising a metallic catalyst, prior to or substantially simultaneously during the application of the positive potential to the SP3 substituted carbon electrode, that converts the carbonate and the partially oxidized species to carbon dioxide; and detecting, using at least one detector, the carbon dioxide produced by the oxidation.

Abstract: An electrochemical sensor system and membrane and method thereof for increased accuracy and effective life of electrochemical and enzyme sensors.

Abstract: The invention relates to a method and to a device for sulfur characterization and quantification in a sample of sedimentary rocks or of petroleum products wherein the following stages are carried out: heating said sample in a pyrolysis oven (1) in a non-oxidizing atmosphere, oxidizing part of the pyrolysis effluents and continuously measuring the amount of SO2 generated by said part after oxidation, then transferring the pyrolysis residue of said sample into an oxidation oven (1?) and continuously measuring the amount of SO2 contained in the effluents resulting from said oxidation heating.

Abstract: The present invention provides a solid diamond electrode, a reactor, in particular a reactor comprising an anode, a cathode and at least one bipolar electrode having first and second major working surfaces positioned therebetween wherein the at least one bipolar electrode consists essentially of diamond, and methods in which the reactors are used.

Abstract: A control system includes an estimator configured to determine a present state of a device and compare the present state of the device with an expected state of the device. The control system further includes a predictor operatively coupled to the estimator, and configured to predict an event for execution by the device to reach the expected state of the device. The control system also includes a supervisory control unit operatively coupled to the predictor and the device, and configured to facilitate execution of the predicted event by the device.

Abstract: A measurement module for glucose testing includes a glucose testing measurement module housing, a test strip receptacle formed in the housing, and a connector portion formed in the housing and shaped to permit mechanical removable attachment of the housing to a hand-held computer. Electronics determine the amount of glucose present in a sample of body fluid, when the test strip is positioned in the receptacle and the body fluid is placed on a test strip, and communicate the glucose amount to the hand-held computer via the connector portion.

Abstract: The present invention relates to a rapid method for estimation of Chemical Oxygen Demand (COD) of water, COD is an important parameter for determining the extent of pollution in water bodies, the basic principle of COD estimation is not much different from prior art but the time taken is reduced considerably and the results are equally sensitive and reproducible as other methods and the method used to generate data on the performance of effluent treatment plants in remote areas or rural areas, it also provide regular and sequential information on the quality of effluent generated by food processing industries.

Abstract: An apparatus and method for monitoring microbiological activity in a process stream by measuring dissolved oxygen is disclosed. Bulk microbiological activity and surface associated biological activity are measured using this apparatus and method.

Abstract: Disclosed is a total organic carbon (TOC) measurement apparatus capable of facilitating reduction in size of the apparatus and achieving enhanced measurement accuracy. The TOC measurement apparatus includes an organics oxidation unit, a carbon-dioxide separation unit and a conductivity measurement unit, which are integrally formed by laminating a plurality of plates to define therebetween and incorporate therein an oxidizing flow passage, an aqueous-sample flow passage, a gas permeable membrane, a measurement-water flow passage and a conductivity measuring electrode. The TOC measurement apparatus is designed such that carbon oxide in an aqueous sample is transferred from the aqueous-sample flow passage to the measurement-water flow passage through the gas permeable membrane, and a conductivity of measurement water which contains the carbon oxide and flows through a flow passage facing the conductivity measuring electrode is determined and converted to a TOC content.

Abstract: The present invention is directed to devices and methods for carrying out and/or monitoring biological reactions in response to electrical stimuli. A programmable multiplexed active biologic array includes an array of electrodes coupled to sample-and-hold circuits. The programmable multiplexed active biologic array includes a digital interface that allows external control of the array using an external processor. The circuit may monitor, digitally control, and deliver electrical stimuli to the electrodes individually or in selected groups.

Abstract: The present invention deals with a device for quick estimation of biochemical oxygen demand of beverage waste water. This device consists of an immobilized microbial membrane attached to an electrode, multimeter and a laptop workstation installed with a developed software. BOD measurement of beverage waste water using this device is rapid, reproducible and effective as compared to conventional titration based methods. This device also excludes COD estimation as required for BOD estimation of waste water. This bio-electrochemical device may find wide commercial application in beverage industries emanating waste waters.

Abstract: An electroconductive carboxylic acid functionalized monomer corresponding to Formula (I), wherein A represents a hydrogen or a carboxyl group. Polymerized monomers of Formula (I) conjugated with a biomolecule result in conjugated PEDOT polymers of Formula (III) wherein A is a hydrogen or a carboxylic acid group and B is a biomolecule selected from the group consisting of a peptide, a protein, a lipid, a carbohydrate and a polynucleotide. The biomolecule conjugated polymers can be disposed onto an electrically conductive substrate wherein the substrate has a first layer of PEDOT polymerized on a surface of the substrate and a second layer of biomolecule conjugated PEDOT polymer of Formula (III) polymerized on the first layer of PEDOT. The first and second layers form a charge transport material in electrical communication with the conductive substrate. The electrically conductive substrate further comprises a dopant.

Abstract: A Biological Indicator Evaluator Resistometer (BIER vessel) provides enhancements in controlling the start and end points of exposure to a sterilant gas. The end point control employs a large volume relative to the test chamber volume upon which is drawn a deep vacuum and then exposed to the test chamber to quickly exhaust the sterilant gas from the test chamber.

Abstract: An apparatus and method for measuring nitric oxide production and oxygen consumption in cultures of adherent cells continuously and without destroying the cells. The method involves flowing growth media through a tube having adherent cells are adhered to the inner surface thereof and then contacting the growth media with an NO or O2 sensor to detect the concentration of NO or O2 in the growth media.

Abstract: Apparatus and methods for supplying a portion of a fluid stream and, alternately, a fluid of known composition and concentration to an analyzer are provided. The fluid stream is directed through a series of connected chambers formed in an integral housing. A sampling needle has an inlet in one of the chambers and an outlet in fluid communication with the analyzer. When desired, a tube or vial containing a known fluid may be inserted into a chamber containing the sampling needle, so that the known fluid will be supplied to the analyzer. A second needle provides ventilation to the vial to prevent the formation of a vacuum as the known fluid is drained from the vial.

Abstract: Embodiments of the invention provide an analytical method and analytical reagent solutions for determining the concentration of electrolyte components, such as copper, acid and chloride constituents in an acid or basic metal plating bath using a chemical analyzer. Common methods for measuring the concentration of copper general require two reagent solutions/two steps. This invention provides a novel analytical reagent solution that simplifies the chelating, buffering, and cleaning functions of separate regent solutions required for measuring electrolyte concentration. This has the benefits of reducing chemical inventory and associated dispensing equipment, and thus reducing chemical consumption.

Abstract: A system for the rapid characterization of multi-analyte fluids, in one embodiment, includes a light source, a sensor array, and a detector. The sensor array is formed from a supporting member into which a plurality of cavities may be formed. A series of chemically sensitive particles are, in one embodiment positioned within the cavities. The particles may be configured to produce a signal when a receptor coupled to the particle interacts with the analyte. Using pattern recognition techniques, the analytes within a multi-analyte fluid may be characterized.

Abstract: The invention relates to an assay for testing oxidative stress of a subject by measurement of oxidants in biological fluids such as urine, plasma, bioreactor medium and respiratory aspirants. There is provided a method of determining oxidative stress in a mammalian subject. The method comprises: obtaining a sample of a biological fluid from the subject; mixing the biological fluid with a ferrous reaction reagent; incubating the biological fluid and the reaction reagent; and detecting a colored reaction product. There is further provided a ferrous reaction reagent suitable for use in assaying oxidative stress, said reaction reagent comprising 2-deoxyglucose, TBA, EDTA, and ferrous sulfate, and being substantially free of ascorbic acid.

Abstract: A Biological Indicator Evaluator Resistometer (BIER vessel) provides enhancements in controlling the start and end points of exposure to a sterilant gas. The end point control employs a large volume relative to the test chamber volume upon which is drawn a deep vacuum and then exposed to the test chamber to quickly exhaust the sterilant gas from the test chamber.

Abstract: An analysis device, preferably in the form of a floating buoy, is disclosed for the analysis of fluids, such as waste water. The device has a main body portion and a removable cartridge containing consumable ingredients for use in analysis.

Abstract: A method includes triggering an oxygen scavenger; and storing the scavenger in a container configured such that the oxygen scavenger exhibits no substantial oxygen scavenging activity while inside the container. The triggered oxygen scavenger can later be removed from the container, and used in packaging oxygen sensitive products. A stored oxygen scavenger, triggered, is also disclosed. A method of distributing an oxygen scavenger film includes providing a tubular film at a first location, the film having oxygen barrier and oxygen scavenger layers; triggering the oxygen scavenger; collapsing the film; rolling up the film; transporting the film to a second location; and triggering the oxygen scavenger. Another method of distributing an oxygen scavenger film includes providing an oxygen scavenger film at a first location; transporting the film to a second location; triggering the oxygen scavenger; storing the oxygen scavenger film in a container; and transporting the film to a third location.

Abstract: Elemental analysis of a sample is carried out in an oxygen atmosphere in a combustion reactor and the volume of oxygen required for analysis is determined by means of the algorithm Qo=&Dgr;(Qc)  [1] where Qo is the volume of oxygen required and Qc is the weight of the sample to be analyzed and &Dgr;=Qo1/Qc1 where Qo1 is the volume of oxygen necessary for the combustion of a predetermined quantity Qc1 of the sample to be analyzed, the volume of oxygen Qo is then fed in pulsed mode to the combustion reactor, by means of a flow detector.

Abstract: An analyzer compensates for gas flow perturbations by providing a makeup flow of carrier gas to maintain the pressure and/or flow rate of analyte and inert gas through a detector constant such that a accurate determination of a low concentration of an analyte in the presence of a high concentration of a second analyte can be accurately determined. In one embodiment, a carrier gas is introduced through a valve responsive to the detected pressure in the gas flow stream between a scrubber and a subsequent detector for maintaining the pressure constant during an analysis. In another embodiment of the invention, a flow transducer is positioned in the gas flow path between the scrubber and detector and coupled to a flow control valve coupled to introduce carrier gas as a function of detected gas flow such that the flow rate of gas into the detector is maintained constant.

Abstract: The presently disclosed disinfection process for use in the processing of foodstuffs is designed as an intervention step in poultry processing to allow for continuous on-line processing of poultry carcasses that may have accidentally become contaminated during the evisceration process. Such on-line processing is designed to replace the need for off-line manual washing and cleaning of the contaminated carcasses. By eliminating such off-line manual washing, food safety will be enhanced due to the elimination of the physical handling of carcasses and the cross-contamination that may result from such physical handling. An additional benefit is that the production process will also be able to run with a reduced number of interruptions, which will result in a more efficient production process.

Abstract: Apparatus for eliminating halide ions such as chloride ions from aqueous solutions having a hollow cylindrical sample holding chamber (2), the front end of which has an orifice (3) and in the vicinity of which is disposed a filter plate (4) that extends over the cross section of the sample holding chamber (2) and is liquid-permeable and essentially impermeable for solids and is inserted in a fixed manner into the hollow cylinder; a plunger (6) which can move to and fro in the sample holding chamber (2) and has a plunger stem (7) attached thereto engages in the open rear end (5) of the sample holding chamber, and, in the sample holding chamber (2) between the filter plate (4) and the plunger (6) is disposed a freely movable bed (7) of an adsorbent reacting with halide ions and forming a sparingly soluble compound, which bed fills a part of the sample holding chamber (2). The adsorbent is preferably charged with silver nitrate as compound reactive with halide ions.

Abstract: The present invention relates to a rapid method for estimation of Chemical Oxygen Demand (COD) of water, COD is an important parameter for determining the extent of pollution in water bodies, the basic principle of COD estimation is not much different from prior art but the time taken is reduced considerably and the results are equally sensitive and reproducible as other methods and the method used to generate data on the performance of effluent treatment plants in remote areas or rural areas, it also provide regular and sequential information on the quality of effluent generated by food processing industries.

Abstract: A device for monitoring a processing liquid comprising at least one sensor for generating at least one monitoring signal, and a device for processing the monitoring signal and for generating a control signal for directly or indirectly influencing the composition or condition of the processing liquid. A device is also provided for detecting, storing, and maintaining the reliability of performance of the sensor. In addition, actuators are provided for converting given criteria or specified values.

Abstract: The present invention provides a specific methanogenic activity measuring apparatus, in which a carbon dioxide gas absorbing container 6 is removably accommodated in a pressure vessel 4 with a cover 3 removably set thereon, the pressure vessel 4 is removably accommodated in a thermostatic water bath 7 with a pressure transducer 8 based on the pressure-electricity converting system connected to a recorder 5 attached to the cover 3, and further a supporting member for supporting a carbon dioxide gas absorbing container and a generated gas piping 16 are attached to an external bottom surface and an internal bottom surface of the carbon dioxide gas absorbing container 6 respectively, and gas piping 12 with valves for gas phase replacement to the cover 3 of the pressure vessel 4.

Abstract: A sample substrate in a microbially catalysed biochemical reaction is measured by incubating the substrate with an excess of a microorganism and an excess of a co-substrate until the substrate is oxidized to a predetermined end point, and measuring the quantity of reduction of the co-substrate.

Abstract: A method of assessing the condition of a fruit, vegetable, plant, or flower is provided. The method includes maintaining the fruit etc. in a substantially gas tight enclosure to trap gases produced by the fruit etc. A sample of the trapped gases is removed and the concentration of at least one volatile gas in the sample is measured by contacting the sample with a colorimetric reagent that changes colour on contact with the volatile gas. The condition of the fruit etc. is assessed on the basis of the colour change of the colorimetric reagent.

Abstract: An analyzing system for analyzing fluid samples includes a measuring buoy immersible in a body of fluid to be tested. The buoy forms a sample chamber in which samples of the fluid are to be tested. The sample chamber communicates with a settling chamber through a chamber opening, and the settling chamber communicates with the body of fluid through a floor opening formed in the buoy below the chamber opening. A gas exchange apparatus communicates with the sample chamber and with a source of air or gas for introducing the air or gas into the sample chamber to drain sample fluid therefrom, and for discharging the air or gas from the sample chamber to admit sample fluid into the sample chamber from the settling chamber. A testing device is disposed in the sample chamber for testing the sample fluid, and is connected to a control and analysis device.

Abstract: An improved apparatus and method is disclosed utilizing hydrogen absorption in combination with photolysis and/or electrolysis for in situ generation, i.e., without the need for adding chemical oxidizing agents, or enhancement of oxidizing conditions used to promote oxidation of organic compounds to form carbon dioxide, and the use of the same in connection with high-accuracy determination of even extremely low levels of organic and/or inorganic carbon compounds both in flowing aqueous streams and in bulk solutions.

Abstract: A method for the determination of total organic carbon in an aqueous sample by trapping the organic matter on a sorbent which is carbon free and analyzing the sorbent by combustion and determination of total CO2 by IR.

Abstract: A method and apparatus for determining nitrification effectiveness of activated sludge in an aqueous solution, includes supplying equivalent quantities of an activated sludge, an aqueous solution, and a gas containing oxygen to each of first and second reaction vessels; simultaneously delivering a nitrification inhibitor to only the second reaction vessel; performing a bacterial respiration reaction in the vessels for either a preselected period of time or continuously in which case the materials are supplied per unit of time so that the bacterial respiration reaction in the first reaction vessel, where oxygen consumption as a result of total bacterial respiration occurs and includes oxygen consumption as a result of endogenous respiration, oxygen consumption as a result of nitrification, and oxygen consumption as a result of degradation of carbon compounds, may be compared with the respiration reaction in the second reaction vessel where oxygen consumption includes oxygen consumption as a result of endogenou

Abstract: In order to determine the biological oxygen demand of sewage, a sample of sewage is taken into a reaction vessel in which there is a biological bath which is kept moving turbulently by an agitator. An oxygen probe measure the oxygen consumption per unit time. After each measuring cycle the reaction vessel is rinsed with diluting water and is then ready for another measuring cycle. The reaction vessel penetrates into the sewage to be tested. The sewage sample enters the reaction vessel via an aperture.

Abstract: Apparatus and processes for water impurity analysis and for impurity analysis of various other liquids as well. More particularly, the present invention concerns apparatus and processes for chemical oxidant and catalyst enhanced total organic carbon analysis of liquid samples for determination of the level of organic contamination of the samples. In particular the present invention concerns a novel reactor for TOC anlysis in which carbon, particularly organic carbon is oxidized to CO.sup.2 gas for further measurement by a CO.sub.2 gas detector, preferably a non-dispersive infrared analyzer. The invention also concerns a process for TOC analysis wherein by measuring the CO.sub.2 gas created by combining carbon with oxygen (either in the water, with a carrier gas of oxygen (O.sup.2), or a chemical oxidant, such as sodium persulfate, the carbon in the water sample is determined. A process and apparatus are employed for TOC analysis in which UV light having a wave length in the range of from about 3.8 to about 4.

Abstract: An on-line respirometer for measuring oxygen uptake by wastewater samples, plants, or animals due to respiration. A closed reaction vessel is adapted to receive and expel wastewater samples or the like. The vessel contains oxygen-sensing probes that constantly evaluate the concentration of oxygen either in the headspace of the vessel or in the samples contained in the slurry within the vessel. The oxygen that is consumed during the respiration of the test samples is immediately replaced by concurrent oxygen injection to maintain a constant oxygen concentration in the reaction vessel. This rapid oxygen replacement is accomplished through an oxygen feedback supply circuit that restores oxygen concentration to its original level in a matter of seconds. The respirometer uses a constant air flow system that allows for the precise oxygen level control. Direct measurement of the oxygen injected for equilibrium control is equated to the uptake.

Abstract: A microwave system is provided which is capable of performing both open and closed vessel microwave chemistry in an efficient and productive manner. For open vessel chemistries, such as digestions, the system offers a microwave oven with: liquid cooled refluxing of samples; reagent dispensing, and temperature control. The open vessel module can quickly and easily be interchanged with a high pressure module capable of operating at pressures in excess of 600 psi.

Abstract: A method for measuring NO.sub.x in biochemical processes which includes a) isolating a liquid sample; b) adjusting the pH or ionic strength of the sample; c) recording mV values present in the sample after predetermined time periods; d) determining NO.sub.x concentrations in the sample at each of the predetermined time periods from the mV values; e) determining the difference in NO.sub.x in the sample from the NO.sub.x concentrations at each of the predetermined time periods; and f) determining the NO.sub.x concentration of the liquid sample from the difference in NO.sub.x and the predetermined time periods.

Abstract: A method of pretreating aqueous chemical oxygen demand (COD) samples to remove the risk of potential chloride ion interference. The method comprises acidifying an aqueous COD test sample, and thereafter passing the acidified sample through a source of pentavalent bismuth (Bi.sup.5+) such as sodium bismuthate.

Abstract: A dye couple compound is provided for use in a test device containing a reagent system for detecting the presence or quantity of an analyte in a sample. The reagent system comprises one or more enzymes which, in the presence of the analyte, produce an oxidizing agent in quantities indicative of the quantity of analyte in the sample. The compound of choice is meta?3-methyl 2-benzothiazolinone hydrozone!N-sulfonyl benzenesulfonate monosodium.

Abstract: Apparatus and methods for the measurement of total organic carbon, total inorganic carbon and total carbon of water are described. The ample is acidified and split into an inorganic carbon stream and a total carbon stream. The inorganic carbon in the inorganic stream is oxidized and both the organic and inorganic carbon in the total carbon stream is oxidized. The resulting carbon dioxide is measured in each stream using carbon dioxide sensors employing a gas permeable membrane dividing deionized water from the oxidized sample water and a pair of micro-conductivity and temperature sensors.

Abstract: Apparatus and methods for the measurement of total organic carbon, total inorganic carbon and total carbon of water are described. The sample is acidified and split into an inorganic carbon stream and a total carbon stream. The inorganic carbon in the inorganic stream is oxidized and both the organic and inorganic carbon in the total carbon stream is oxidized. The resulting carbon dioxide is measured in each stream using carbon dioxide sensors employing a gas permeable membrane dividing deionized water from the oxidized sample water and a pair of micro-conductivity and temperature sensors.

Abstract: The invention relates to apparatus (1) for monitoring condition of a biomass, particularly that naturally occurring in activated sewage sludge, comprising a vessel (2) for holding a liquid in the form of the activated sewage sludge containing a biomass (3), a device in the form of an aeration ring (4) for continuously aerating the sludge (3) in use, a hopper (5) and valve V2 arrangement to dose the biomass (3) in the vessel (2) with an additive in the form of an additional dose or charge of a feed solution, and a dissolved oxygen probe (6) to measure the dissolved oxygen content of the sewage in the vessel (2) whereby to monitor the condition of the biomass. Poisoning of the biomass is detected using the probe and associated electronic equipment (FIG. 3), such poisoning being shown by a sudden reduction in the measurement of the current of oxygen used per dose of sewage feed solution.

Abstract: An analytical device for determining the gas consumption of matter, specifically the oxygen demand of organic matter includes a container for holding the sample which is to be analyzed and a cop to seal the container gas-tight. Electrical and/or electronic measurement components are integrated in the cap. These components include an electrical pressure sensor which communicates with the interior of the container through a pressure connection, electronic measuring circuitry to which the pressure sensor output signal is sent in order to calculate a value which is proportional to gas consumption, keys for operating the electronic measuring circuitry, and a display for displaying measured, calculated, or stored values. The cap also contains a power source for the electrical/electronic components.

Abstract: An oxidation reactor having particular utility in a system for measuring carbon in an aqueous sample. A first chamber and second chamber are separated by a hydrogen-permeable electrode, each chamber having a separate electrolysis cell. The hydrogen-permeable electrode acts as the anode of one cell and the cathode of the other cell. The sample stream flows into one chamber and the electrolysis cell produces oxygen from the water at one optically transparent electrode and in combination with short wave ultraviolet light oxidizes organic carbon to CO.sub.2 and produces hydrogen at the other electrode which passes through the hydrogen-permeable electrode into the second chamber. The electrolysis cell in the second chamber produces oxygen at hydrogen-permeable electrode to react with the hydrogen that passes through the hydrogen-permeable electrode to form water, thereby maintaining the maximum concentration gradient of hydrogen across the hydrogen-permeable electrode to improve hydrogen transferring efficiency.

Abstract: The invention provides a method and apparatus for providing periodical measurements of the real-time readily biodegradable chemical oxygen demand (RBCOD) of a wastewater stream. The apparatus includes a bio-reactor having an inlet for accepting a feed from the stream and an overflow outlet, whereby a sample volume can be maintained within the reactor. A feed rate is chosen to ensure an hydraulic retention time (HRT) in the reactor sufficient for substantially complete oxidation of the readily biodegradable compounds in the feed. Air is periodically passed through the sample volume for set periods and the oxygen up-take (OUR) is determined by measuring the dissolved oxygen content via a probe during the air-off periods. An RBCOD value is then calculated for each OUR value. The invention may be used to monitor the performance of wastewater treatment plants.

Abstract: A system is provided for producing an oxidizing zone within a saturated zone of an aquifer for in-situ decontamination of groundwater carrying contaminants in a plume wholly located below a water table in said saturated zone of said aquifer. The system comprises a source of gas for providing a gas capable of producing an oxidizing environment in the groundwater which can oxidize the contaminant to purify the groundwater and the aquifer. Gas injectors are connected to the source of gas, for injecting the gas into the groundwater below the plume at a gas injection rate, thereby producing the oxidizing environment in the groundwater. Auxiliary apparatus is provided for testing decomposition of the contaminants in the oxidizing environment and for determining the gas injection rate.