MXPA06001189A - Methods and systems for improved dosing of a chemical treatment, such as chlorine dioxide, into a fluid stream, such as a wastewater stream - Google Patents

Abstract

The invention is directed to methods, apparatuses, and systems for treatment of a liquid flow comprising addition of a chemical treatment at at least two locations (16, 24) along a side stream of a main flow (4) of said liquid, in which the dosing by such additions is sufficient to treat the entire main flow upon return of the side stream to the main flow. Algorithms are utilized to control the additions at the locations of addition of chemical treatments. In a typical embodiment, one chemical addition is principally proportional to the flow rate of the liquid flow, and the other chemical addition is principally adjusted based on signals from a primary measuring device that measures a parameter in the flow after one or both chemical additions. The addition of chlorine dioxide as the chemical treatment, to disinfect wastewater, is discussed.

Description

METHODS AND SYSTEMS FOR IMPROVED DOSAGE OF A CHEMICAL TREATMENT, SUCH AS CHLORINE DIOXIDE, IN ONE FLUID CURRENT, LIKE A RESIDUAL WATER CURRENT TECHNICAL FIELD The field of the invention relates to methods of purification, treatment and separation of liquid, including controlling the process in response to a perceived condition.

BACKGROUND OF THE INVENTION Many fluid control systems require monitoring of the selected characteristics of the fluid stream in order to determine and control the amount of a treatment chemical to be introduced into the fluid stream. For example, in wastewater treatment facilities typically a wastewater main stream is treated with a chlorine-containing compound, often chlorine gas or sodium hypochlorite, to oxidize organic compounds in the fluid stream. When exposed to sufficient levels of oxidation chlorine species for a sufficient period, the total levels of bacteria in the wastewater stream are reduced to allowable levels to be discharged from the wastewater treatment plant into a stream, River, existing estuary, etc. It is not desirable to treat the wastewater stream incompletely because that way excessive levels of bacteria will remain in the wastewater stream. It is also undesirable to over-treat residual water with chlorine because an excessively high level of residual chlorine in the wastewater stream can damage natural flora and fauna in and beyond the mouth (ie, the end of the flow). pipeline of the treatment plant, where the effluent finds the natural body of water). Additionally, when a waste stream is over-treated and is properly detected, an additional chemical, such as sulfur dioxide, is typically added to neutralize the excess chlorine before discharging into the outlet. This is added to the cost of the excess chlorine or other treatment chemical, and also represents an unnecessary operating cost that can be minimized or avoided through the implementation of the present invention. Many advanced wastewater treatment systems include a downstream chlorine residual analyzer that monitors remaining residual chlorine levels in the wastewater stream. It is known that controllers use the results of this downstream analyzer to provide a feedback signal to the giver. In essence, if a quantity of residual chlorine is too high in the downstream analyzer, the speaker receives a signal! of reaction that slows down the introduction of chlorine. If the analyzer detects that there is not enough chlorine or there is very little chlorine, which indicates that the level of bacteria has not been sufficiently diminished, the reaction signal will cause the gilder to increase the speed with which he introduces the chlorine. Although said residual chlorine analyzers and reaction control systems are generally effective, they suffer from numerous disadvantages. For example, when the analyzer detects an amount below the chlorine residue optimum, additional treatment must still occur in the wastewater stream to properly treat the wastewater. The delay associated with the distance between the analyzer and the giver and the amount of time it takes for the chlorine analyzer to detect any change in the chlorine residue causes problems in the control. This can result in unequal, and sometimes inappropriate, treatment of wastewater. That is, such reaction systems have a tendency to enter an oscillatory state of disinfection with chlorine above or below the normal level, which only relatively also resolves slowly. This situation is especially common when the requirement, or demand, of a chemical treatment within the wastewater stream is fluctuating. In wastewater treatment systems, the demand is typically expressed as the sum of the Biological Oxygen Demand ("BOD") and the Chemical Oxygen Demand ("COD") (collectively, "CBOD"). Also, wastewater treatment facilities may incur fines for releasing wastewater that is treated incompletely or treated with chlorine-containing compounds. As indicated above, wastewater treatment facilities additionally suffer financially from the unnecessary use of excess chlorine and chlorine neutralizing chemicals, such as sulfur dioxide, when the chlorine disinfection system is not operating optimally. In previous years (and to a much lesser degree at present), the dose was based on laboratory or field results that test the affluent chemical concentration at the same time as the measurement of its flow. Subsequently, the dose calculations were made and the dosing device, a chemical feed pump for example, was manually adjusted according to the calculations. In recent years, reliable automatic analyzers for chemical concentration have been made available allowing the automation of the complete dosing procedure. In this way, the need for manual testing and manual adjustment has practically been eliminated. An additional consequence is that the automatic analyzers can also be configured to detect several important chemicals in water treatment. This makes the dosing process useful for other applications such as the addition of sodium carbonate in an aerated biological reactor to control nitrification or the addition of iron or aluminum salts before a clarifier to control the removal of phosphorus. However, it has been recognized that problems can occur during the automatic dosing of a chemical in the treatment system due to, among others, the inaccuracies of chemical demand measurement present in the system and the variable proportion of chemical for the liquid when the amount of liquid flow or demand is variable. An example of a water treatment system that uses automatic analyzers is found in an article presented by Nelu Puznava et al. On October 3, 1998, entitled "Reaction Control / Classic Direct Feed Applied to Methanol Dosing for Post-Denitrification" (the reference Puznava and others). Reference Puznava et al. Describes a direct feed / reaction control for methanol dosing for post-denitrification in an up-flow flotation biofilter system. The direct feed and reaction control is based on the online measurement of nitrate output and inlet concentrations, which send two signals to the control unit. Both sensors were for chemical analysis, tributary nitrate concentrations and effluent nitrate. Japanese Patent No. Sho 52-93160 and Sho 51-130055 for Tokyo Shibaura Electric Co., both refer to an apparatus for the control of the amount of feed of water purification reagents. The apparatus consists of a water quality meter of origin for the water quality measurement of the source water inlet, a reagent feeding device, a device that establishes the proportion that maintains a proportion of the amount of water supply. Reagent for the entry of water of origin, a meter to measure the quality of the water in the installation that measures the water quality of the water of the installation and outputs a signal, and a control device for the calculation that receives the signals output and sets the reagent flow rate and sets the proportion of the installation device. The apparatus measures water quality factors such as water turbidity of origin, pH, alkalinity and temperature, without concentration of the reactants. U.S. Patent No. 4,435,291 to Matsko (reference '291) describes a system for controlling the dosing of chlorine in a system for disinfecting residual water with chlorine. In reference '291, the chlorine dose is controlled by electronic controllers according to a residual chlorine derivative with respect to chlorine dose. This is mentioned to provide precise control of the chlorine to ensure the oxidation of ammonia in the wastewater. The flow transmitters perceive the flow of chlorine, base, or sulfur dioxide for their respective tanks. US Patent No. 4,544,489 to Campbell et al. (Reference '489) discloses a method and apparatus for the controlled addition of a conditioning polymer material to the sewage sludge. The reference '489 uses a computer with a connected viscometer. Based on the shear stresses measured and entered into the computer by the viscometer, the system controls the amount of pumping of the multimeter to mix with the slime. Other references describing aspects of the relevant art are U.S. Patent No. 5,011, 613 for Feray and Hubele, U.S. Patent No. 5,869,341 for Stannard et al., U.S. Patent No. 6,129,104 for Ellard et al., And U.S. Pat. USA No. 6,346,198 for Watson and Armstrong. It is also important "Problems Involved with the Automation of the Wastewater Treatment Plant" by Raymond Kudukis, Chapter 10, pgs. 74-78 of CONTROL OF INSTRUMENTATION AND AUTOMATION FOR WASTEWATER TREATMENT SYSTEMS, edited by JF Andrews and others, Permagon, New York, United States, 1974. This reference mentions, among others, that the maximum efficiency reached of a wastewater treatment plant with automated control systems remains difficult given the fact that "the periodic intensity due to the storm flow of periodic lows during dry weather seasons ... [resulting in] most of the flow time in the plant is either above or below the maximum efficiency level. " It is also important to DISINFECT RESIDUAL WATER - Manual of Practice FD-10, p. 144-155, Environmental Water Federation, Alexandria, VA, United States 1996, which teaches a number of standard feeding control strategies for the introduction of disinfectant into wastewater. None of these standard feeding control strategies is directed to the double feed in a side stream to provide the dose for the main flow, as described and claimed herein. In the specific preferred embodiments of this invention, chlorine dioxide is the chemical treatment for the disinfection of a waste water waste stream. Five references that provide relevant background information on disinfection and chlorine dioxide are "Guidelines for Drinking Water Quality", 2a. Edition, World Health Organization, Geneva, "The Chlorine Dioxide Handbook", by Donald J. Gates, June 1998, AWWA, published as part of the Water Disinfection Series, ANSI / NSF Guide 61, West, R. C, "Manual of CRC of Chemistry and Physics", 52ava. Edition, p. D-105, 1971 (no month), and basic textbook by W. J. Masschelein titled: "Chlorine Dioxide: Chemistry and Environmental Impact of Oxychlor Compounds", p. 112 to 145. 1979 (without month). Also, the description in U.S. Patent Application Serial No. 10 / 430,360, entitled "Reactor for the Production of Chlorine Dioxide, Production Methods thereof, and Related Systems and Methods of Reactor Use" is incorporated herein by reference. The above patent and non-patent references, and all patents and other references mentioned in this description, are incorporated herein by reference in this description. None of the references teach or suggest a method for automatic controlled dosing of a treatment chemical in a flow stream in a liquid treatment system that measures more correctly, in small increments or "real time", the amount of chemical required based on both the amount of variable flow and a variable demand for the treatment chemical. Accordingly, there remains a need to improve the accuracy and / or precision of the dosing of a liquid flow, such as waste water, with a desired chemical treatment.

BRIEF DESCRIPTION OF THE INVENTION The invention relates to fluid control systems that are configured to control the introduction of at least one treatment chemical, each typically in a liquid solution, into a fluid stream to cause a selected characteristic of the fluid stream match a desired level. More particularly, this invention relates to the addition of at least one treatment chemical, of at least two distinctly controlled chemical input sources with a treatment current deviating from a main fluid stream. For example, a fluid solution containing a treatment chemical is added to the treatment stream from two distinctly controlled sources. The addition of the treatment chemical from the first source is proportional to the amount of flow of the main fluid stream. This proportionality is applied over a wide range of flow, and is subject to certain "infallible" restrictions. The addition of the treatment chemical of the second source is adjusted based on the results of a measuring probe which measures the level of the treatment chemical at a point downstream from the introduction point (s) of the first and second sources. The modalities also include related control systems that add said at least one treatment chemical to the treatment stream through the sources. Thus, in certain modalities, the regulation and modulation are carried out through a first addition point mainly established proportionally to the amount of main current flow, and a second addition point, mainly adjusted based on the degree of a reaction of chemical treatment with compounds of liquid in the lateral stream. Among such embodiments, this degree of reaction is determined through a measurement made at a main measurement site downstream of the first and second addition points (ie, sources, or site of entry). Even more particularly, the present invention relates to the treatment of waste water through a disinfectant, chlorine dioxide, which is introduced into two points of addition of a lateral stream, the addition at each point depends on the different algorithms, after from which additions the side stream returns to the main stream, carrying enough disinfectant to properly treat the compounds (i.e., CBOD) in the main wastewater stream. The measurement of the chemical treatment and the adjustment of the second influx can be repeated many times per minute, resulting in adjustments "in real time" semi-continuous or essentially continuous for the load or other relevant parameter (s) in the liquid stream. Through such a procedure, the lateral stream contains an appropriate amount of chemical treatment for suitably, and exactly and / or more precisely (depending on the attributes of the wastewater and the disinfectant), to treat the full flow of the main liquid stream. In practice, a sidestream deviates from the flow of the main fluid at a desired point before a contact area and the reaction of the main fluid flow, or main fluid stream, with the chemical treatment being added. This sidestream has a first sidestream addition point (typically comprising a dispenser and an injector) that injects a variable amount of the chemical treatment, preferably in liquid form, into the side stream. The main determinant of the amount of chemical treatment added at this first point, during normal flow-rate conditions, is the amount of flow of the main stream. Then, at a desired distance from this first point of addition, a second sidestream addition point (which typically comprises a dispenser and an injector) injects a variable amount of the chemical treatment, preferably in liquid form, within the lateral stream. The main determinant of the amount of chemical treatment added at this second point, during normal flow-rate conditions, is the change in a parameter as measured by a primary measurement device (or analyzer) of a probe or a sample taken in a Main or first measurement point. For example, where chlorine dioxide is being added to disinfect a mainstream wastewater treatment plant (ie, blackwater) after secondary treatment, the primary measurement device measures the concentration of chlorine dioxide, which reflects the decrease in chlorine dioxide while reacting with oxidizable compounds in wastewater (ie, as reflected in CBOD levels). The measurement point is after the first addition, or after the first and second additions. Through repeated adjustments of the addition levels of the first and second addition points, the dose for the mainstream is maintained at or near the dose actually required based on the amount of mainstream flow and the CBOD load. that requires such treatment. More generally, the primary measuring device measures the level of the selected characteristic present in the lateral fluid stream. This typically measures the level of one or more chemicals in the chemical treatment, but alternatively can measure a reaction product or an intermediate in a reaction that is known to take place between at least one component of the chemical treatment and at least one component of the chemical treatment. fluid in the lateral (and main) stream. The result of this analysis is reported to a controller that controls the level of chemical treatment addition at the second point of lateral stream addition. The point of this first analysis may be in a number of positions relative to the first and second influxes of chemical treatment, as explained below. Additionally, other secondary measuring points can be added to the system for additional information on the condition of the lateral or main currents. This additional information can be provided to the controllers for the first and / or second addition points to refine and better adjust the addition levels. Also, the algorithms used in the control aspect of the invention are designed to compensate for changes in the characteristics of the main fluid stream. That is, certain restrictions in the basic algorithm are applied to deal with unusual or non-normal flow conditions. For example, heavy rains in the service area of a wastewater treatment plant typically result in the total flow increased for the plant. This flow typically has less biological load per 3,785 liters, but may have a higher level of Total Suspended Solids ("TSS"). The algorithm that determines how much chemical treatment is added to the first chemical input point that is mainly proportional to the flow is adjusted to compensate for this deviation in the volume and quality of the main waste stream. Generally, this change will be to decrease the amount of disinfectant added per 3,785 liters of flow. Also, as another example of a restriction imposition modification of a basic algorithm, when the flow falls below a specified amount that corresponds to a set fixed point, the addition in the second chemical entry is modified from its algorithm of " normal range. " In such a circumstance any addition in the second chemical entry is made through such restriction imposition modification of the general algorithm Alternatively, or in combination with this modification, when a dramatic decrease in the amount of flow is detected, this may also activate and result in a modified proportion of treatment at the first addition point. The implementation of these and other "infallible" modifications to the algorithms that operate during normal flow conditions depend on the system, flow characteristics, legal standards for effluent in effect, and other factors. Based on the foregoing, a primary object of the present invention is to provide a system for adjusting a degree of introduction of chemical treatment fluid into a main fluid stream that causes a selected characteristic of the main fluid stream to match a set point for the selected characteristic, or remain within a specified range for a selected characteristic. More particularly, an object of the present invention is to provide methods, systems, and apparatuses for adding chemical treatment through two independently regulated input sources of a chemical treatment in a side stream, in order to provide treatment of the main liquid stream complete that is more attuned to the level of treatment really necessary. The use of the same fluid stream (ie, waste water) that is to be treated in the main stream as the fluid medium that is used in the side stream is advantageous, since it allows the assessment of 1) the effect of the residual water components in the concentration (or other attribute) of the chemical treatment at a time and place after its addition to the lateral stream, and / or 2) the effect of the chemical treatment on water quality parameters of the same water residual (such as during its passage in the lateral stream after the introduction of the chemical treatment). This provides different advantages, and is in contrast to, the methods of addition currently practiced in wastewater treatment plants ("WWTPs") that use potable water or other water from non-waste stream sources as the medium in which a chemical treatment (such as a chlorine-containing compound) is added before being mixed with the main waste stream. Among the advantages are: reduce the consumption of drinking water or other water; and provide a means to assess the interaction of chemical treatment with the actual fluid to be treated in the main flow, so that appropriate adjustments can be made, effectively in "real time", in accordance with the variable quality of the actual fluid to be treaty. Thus, in the preferred embodiments, the invention more precisely controls the amount of treatment fluid to be introduced into a main fluid flow to cause a selected characteristic of the main fluid flow to consistently achieve a desired result for the selected feature in the main fluid flow. For example, where the main wastewater fluid flows in a sewage treatment plant are being chemically treated, such as with chlorine dioxide, the use of the system of the present invention results in the most consistent disinfection with time. even with a variable range of flow quantities and biological and chemical loads. Advantageously, this is achieved with less overdose and consequently less desorption at the end of the system than is common in less bulky control systems. Also, this is achieved with less incomplete dose that may result in the discharge of wastewater effluent treated incompletely. Thus, another object of the present invention is to provide a chemical treatment system for treating a fluid flow that minimizes an amount of chemical treatment. Accordingly, another object of the present invention is to provide a system for treating wastewater that treats reliably in wastewater with chlorine dioxide without over-treating or incompletely treating the waste water. A related object is to reduce or eliminate the need to remove excess chlorine dioxide from such wastewater at the end of the treatment system. Another object of the present invention is to provide a chemical treatment system for treating a fluid flow that can operate with minimal operator monitoring and intervention. Another object of the present invention is to provide a chemical treatment system for treating a fluid flow that can display and record data associated with the analysis of selected characteristics of the fluid stream for review by an operator. Another object of the present invention is to provide a wastewater treatment system that uses a primary chlorine dioxide assay to control an amount of chlorine dioxide introduced into a wastewater stream. The foregoing has delineated some of the most pertinent objects of the present invention. These objectives should be constructed to be only illustrative of some of the most prominent features and applications of the invention. The following detailed description and the modalities are illustrative and explanatory only and should not be seen as restrictive of the present invention, as claimed. These and other objects, features and advantages of the present invention will become apparent upon review of the full detailed description, the described embodiments and the appended claims. As will be appreciated by one skilled in the art, many other beneficial results and applications can be obtained by applying the modifications known in the art to the invention as described. Such modifications are within the scope of the appended claims to this.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic diagram illustrating the main components of the basic system of this invention as they would exist when the system of this invention is incorporated into a wastewater treatment system.

Figure 2 is a schematic diagram illustrating the system shown in Figure 1 with additional downstream components of a typical wastewater treatment system, including additional optional measurement sites and signal paths. Figure 3 is a schematic diagram similar to Figure 2, showing alternative sites of the primary measurement point. Figure 4 is a schematic diagram of a specific embodiment of the invention that uses nozzles to add chemical treatment, in which each injector is controlled by a separate control device.

DESCRIPTION OF THE PREFERRED MODALITIES As used throughout this specification, including the claims, the term "mainly proportional" is intended to indicate that the parameter thus described (e.g., amount of main stream flow, for the first addition, and change in a measured parameter, for the second addition) is the first in importance between the parameters that are used to determine the amount of addition of a chemical treatment at the respective addition point, under flow quantity and normal operating conditions. Similarly, as used herein, the term "mainly adjusted" and "principal variable" are meant to indicate that the parameter thus described (e.g., amount of main stream flow for the first addition, and change in a parameter measured for the second addition) is the first in importance among the parameters (or variables) that are used to adjust (or determine) the amount of addition of a chemical treatment at the respective point of addition, under amount of flow and normal operating conditions. The "primary fluid stream" and "main stream" as used herein are intended to indicate the main fluid flow, from which a "treatment", "pilot", or "lateral" stream is diverted. While not limiting, the primary fluid stream may be: wastewater, as in a municipal wastewater treatment plant or facility; processing water, as in a chemical or industrial production facility (which may be a particular recycling or re-use procedure, cooling, heating or another different stream, or a collected waste stream that carries particular or variable levels of chemical demand and or biological oxygen); potable water (such as from a deep well, a shallow well near a river, lake or other body of water, or another source); storm water (such as before being released to a body of natural water or before injection into a designated water layer); a liquid process flow that needs a treatment reagent or chemical in relation to a component in the flow; or another water designed to be used in or to refill a body of water or aquifer. As used throughout this specification, including the claims, the term "computational control device" is intended to include, without being limited, a dedicated programmed circuit (including, but not limited to, an integrated circuit or a microprocessor) that is capable of to send control signals based on the algorithm that receives data input from one or more sources; a programmable general-purpose computing device, such as a computer, that is capable of sending control signals based on an algorithm that receives data inputs from one or more sources, and a programmable special-purpose computational device, such as a computer, which is capable of sending control signals based on an algorithm that receives input from one or more sources. Also, through this description and the claims, the use of "first" does not need to be interpreted to necessarily be fluid upstream of the "second" point of addition; such a nomenclature does not consider the relative location. In fact, both sources of addition can introduce the chemical essentially in the same point along the lateral current, although the sources that provide the chemical treatment modify their entrances based on different criteria. Referring to the drawings, in which like reference numbers represent similar parts through the various drawing figures, reference number 10 is generally directed to a system for the treatment of a main flow and a fluid flow, 2, such as wastewater. In addition, in the modalities described in Figures 1-4, and discussion of them, the chemical treatment is chlorine dioxide, and this is being added to disinfect a main flow of wastewater in a municipal wastewater treatment plant ( one type of WWTP) following the secondary treatment. None of the figures is drawn to scale. Figure 1 is a diagram illustrating the present invention by adding chlorine dioxide to a side stream of a main stream for disinfection purposes. A main flow of a fluid stream, 2, passes in the direction shown by the arrows through a main fluid conduit, 4 (either a lock, pipe, or other type of structure), after the secondary treatment. A fluid side stream, 6, is pumped from a point of deflection, 8, through a smaller pipe, 12. A centrifugal pump, 14, energizes the flow of the fluid sidestream, 6. The pump, 14 , pumping the sidestream fluid, 6, passes a first point of addition, 16, which receives a chlorine dioxide solution from a first chlorine dioxide dispenser, 18. This chlorine dioxide is supplied from a chlorine dioxide generator. chlorine or deposit, shown in Figure 1 as 22. The chlorine dioxide thus added at the first addition point, 16, is mixed with the wastewater from the side stream, 6, in a stream downstream of the first addition point, 16. The chlorine dioxide is also added to a second point of addition, 24, which receives the chlorine dioxide solution from a second chlorine dioxide dispenser, 26, which is also supplied from the chlorine dioxide generator or tank, 22. After that, an analyzer d The primary chlorine dioxide, 28, with the probe connected, 29, detects the level of chlorine dioxide in the sidestream fluid, 6, downstream of the second point of addition, 24, and provides the signals that provide this data to the controller, 100. Lateral side wastewater flows back into the main stream at a return point, 30. Appropriate diffusers can be used here to better and faster diffuse and distribute chemically treated sidestream wastewater with the main flow , 2, which has remained in the main pipe, 4, between points 8 and 30. In certain preferred embodiments, each chlorine dioxide input source is an in-line chlorine dioxide reactor, as described in the US Patent Serial No. 10 / 430,360, entitled "Reactor for the Production of Chlorine Dioxide, Methods for the Production of Same and Related Systems and Methods for the Use of the Reactor". In such modalities, the amounts of the entry of precursor chemicals into the reactor through the supply pipes are those that are being modified by a control system. Accordingly, the concentration of the result of each reactor, i.e., chlorine dioxide, is based on an algorithm used by the control system of the present invention for that reactor, and is a result of modifications of the amounts of the chemical input precursor through the control system of the present invention. In typical embodiments, the levels of chlorine dioxide addition at the first point of addition, 16, and the second point of addition, 24, are determined and distributed over time as follows. A flow meter, 32, placed in the main pipe, 4, detects the flow amount of the main flow, 2, and transmits signals that provide this information to the controller, 100. The determination of the flow quantity can be made periodically, semi-continuously or continuously. The controller, 100, enters the amount of flow information thus provided in an algorithm for the first point of addition, 16. The addition of chlorine dioxide in this first point is mainly proportional to the amount of flow determined by the flow meter , 32. The addition of chlorine dioxide at the second point of addition, 24, is mainly adjusted based on how much the level of added chlorine dioxide has decreased from the point (s) of addition at the location of the probe. , 29, of the primary chlorine dioxide analyzer, 28. Chlorine dioxide analyzers are widely known and available. Three commercial sources for such analyzers (which can alternatively be termed detectors or meters), and the specific probes for detecting chlorine dioxide, are: ATI; Prominent Analyzers; and Control Technology Aldos (Germany). Chlorine dioxide analyzers and probes from these commercial sources are useful in the present invention. Where the oxidizable chemical and biological demand in the wastewater is relatively high, the standard addition at the first addition point, 16, will have decreased below the lower end of an established range. This will result in the signals of the primary chlorine dioxide analyzer, 28, being captured in algorithm for the second addition point, 24, and the algorithm that is directed to a certain level of chlorine dioxide addition at the second point of addition, 24. Through the repeated reaction signals of the primary chlorine dioxide analyzer, 28, to the controller, 100, the second chlorine dioxide dispenser will be adjusted to a level that adds enough chlorine dioxide to supplement the chlorine dioxide of the chlorine dioxide. first addition point based mainly on amount of flow, 16. This represents the! method and set system of double standard measurement reaction when the amount of flow of the main flow, 2, is within the normal parameters. Figure 2 provides a schematic diagram of the aspects of the invention in Figure 1, in combination with additional components of a wastewater treatment system typically downstream of a secondary treatment. After the point in the conduit, 4, in which the lateral current returns to the main stream, 30, the main flow, 2, flows into a contact chamber, 40. After a given residence time there (depending on the amount of flow), the main flow, 2, continues to a 50th vent basin. At the end of the stream downstream of the vent, 50, the flow passes through an outlet duct (a pipe, lock, channel , etc.), 52, towards the outlet of effluent, 70, and due to that, typically, in a natural body of water (a stream, river, lake, estuary, ocean, etc.). Along this outlet conduit, 52, there is a final residual chlorine dioxide meter, 54, placed upstream of a sulfur dioxide addition point, 56. Based on the reading of this meter, 54, and Current requirements for chlorine or maximum chlorine dioxide in the discharge water, sulfur dioxide can be added to the waste stream at the point of addition of sulfur dioxide, 56. Optionally, the readings of this meter, 54, they can also be provided to the controller, 100 (the line passing the signals is not shown in Figure 3). This can help refine the dose, as discussed for secondary analyzers, later. It should be noted that the provision of a sulfur dioxide or similar end-of-line system to remove chlorine or chlorine dioxide from a system utilizing the present invention is considered a backing, or "infallible" characteristic. By using the present invention, which adjusts the dosage of the chemical treatment to real-time requirements of the main flow fluid characteristics, the requirement of the end-of-line system to remove the chlorine or chlorine dioxide is greatly reduced or eliminated. excess. In general, secondary detection analyzers (ie, an additional chlorine dioxide meter when using chlorine dioxide, or other types of analyzers, where chlorine dioxide is not used), with probes or sampling ports, can optionally be provided in addition to the downstream in the lateral stream, 6, and / or in the main stream, 2, after the return point, 30. Figure 3 provides a schematic diagram similar to Figure 2, showing the points preferred for the primary analyzer and for secondary analyzers. A preferred, simple method to monitor is to have an individual, primary analyzer in position A in Figure 3; that is, after the first and second points of chemical treatment addition along the lateral stream. Another preferred method is to have a primary analyzer in the A position, and to have a second (but also primary) analyzer in the B position, between the first and second chemical treatment addition points. Another simple method to monitor is to have an individual, primary analyzer in position B in Figure 3; that is, between the first and second points of chemical treatment addition along the lateral stream. Any of these configurations of side stream analyzers can be combined with one or more secondary downstream analyzers, such as at points C, D or E. One or more secondary analyzers can provide data signals that help to assess, example, the amount of daily dissolving time of a photo-reactive oxidant, such as chlorine dioxide, due to the ultraviolet light of sunlight. These data can help refine the dose to compensate for this. More generally, data from such secondary data sources can be used to supplement the primary measurements taken at the primary measurement point, to better refine the dose. Generally, the primary analyzer is spaced in the sidestream line after sufficient residence, or contact time, has elapsed between the chlorine dioxide (or other chemical treatment) and the wastewater. When chlorine dioxide has been used in pilot-scale wastewater treatment systems, it has been observed that a distance of only 1.21m along the lateral stream is sufficient space between the second point of addition of the chemical treatment and the primary analyzer. This is when the flow is approximately 227.12 liters per minute. When using chlorine dioxide analysis techniques, then the wastewater is monitored to measure the amount of chlorine dioxide still in the wastewater. This is done either with a probe in the sidestream, or by using a diverter tube line for sampling directed towards the analyzer. For some analyzers, a pH-regulating solution is added to the diverting tube line for sampling and then a sampling cell measures the sample of wastewater appropriately regulated at its pH. Secondary analyzers can take a form similar to that of the primary analyzer. Optionally, samples from one or more secondary analyzers can be appropriately addressed to, and integrated with, the primary analyzers so that that individual sample analyzer can be used. In such a configuration, an individual analyzer receives all the samples, which arrive from the side stream and / or the main stream. Such data can be used in the algorithms that control the first and second chemical addition points to better refine the accuracy and / or accuracy of the additions, such as due to climatic conditions that affect the reaction, etc. This method, although it is more demanding up to the point of the sample transport for the individual analyzer, virtually eliminates the error due to the variation of readings due to the differences (in calibration, probes, etc.) in several analyzers. In general, the use of additional secondary analyzers can contribute to the ongoing realization of optimal performance under a variety of environmental conditions. In another embodiment, shown in Figure 4, there is a separate control device for each chemical treatment source instead of the individual controller as shown and described in Figures 1-3. As for the previously described figures, in Figure 4 a main flow of a residual fluid stream, 2, is treated in a controlled manner according to the system, 10, of this invention. A lateral stream, 6, deviates from the main flow of the residual fluid stream, 2, at the point of deviation, 8. At the first addition point, 16, in which the Injector 1 is placed, an amount is added. precisely measure chlorine dioxide in the side stream, 6. This is added from a chlorine dioxide generator or tank, 22, and the addition is regulated by a first chlorine dioxide dispenser, 18, which distributes chlorine dioxide inside from side stream 6 through Injector 1 (placed at 16). The addition in the Injector 1, as controlled by the first chlorine dioxide dispenser, 18, is based on a first algorithm that is primarily proportional to the flow amount of the main flow 2, such as a measured near point 8 through the flow meter 32. Flow meter data signals, 32, travel to a first dedicated addition point control device, 40. This can be any controller as defined, above, or a dedicated integrated control circuit, or any equivalent known to those experts in the art. A second chlorine dioxide dispenser, 26, distributes chlorine dioxide in the side stream 6 through the Injector 2, which is placed in a second point of addition, 24. The addition in the Injector 2, controlled by the second dispenser of Chlorine dioxide, 26, is based on an algorithm that is mainly adjusted based on the measured decrease in the level of chlorine dioxide, as measured by a chlorine dioxide meter, 28 (for example, the primary analyzer). The chlorine dioxide meter, 28, has a probe, 29, placed in the side stream, 6, after the first point of addition, 16, and after the second point of addition, 26. The data signals of the dioxide meter of chlorine, 28, travel to a second dedicated addition point control device, 42. This may be any controller as defined above, or a dedicated integrated control circuit, or any equivalent known to those skilled in the art. In a basic mode, the signals indicating the levels of chlorine dioxide through the primary analyzer, the chlorine dioxide meter at 28, are transmitted, for example through electrical signals along a conductive cable, to the second chlorine dioxide dispenser, 26. These signals, which transmit the chlorine dioxide levels measured at the 26th place, are used to adjust the level of addition in the Injector 2, which is controlled by the second chlorine dioxide dispenser , 26. The measurements are taken semi-continuously in desired periods, or are measured continuously. The adjustments are made in accordance with a second algorithm which, in the preferred embodiments, is adapted for the particular installation and the purposes of the treatment. Thus, for the embodiment illustrated in Figure 4, there is no single controller that receives data signal inputs and controls the first and second additions of chemical treatment. Instead, a dedicated individual control circuit, such as can be integral with an automated chemical dispenser, or any type of controller (i.e., using a computer control device) as described above, controls each point of control. different addition. As for a dedicated individual control circuit, the characteristics of such control circuits are known to those skilled in the art, and the discussion in this description of the characteristics of an individual controller can also be applied to a dedicated control circuit for a point of addition of different chemical treatment. A number of algorithms can be used in the present invention to achieve the maintenance of a desired level of addition of a chemical treatment under varying conditions of primary fluid stream composition. A two-equation algorithm that is for use in the present invention is provided below to provide dose quantities for two pumps. A first pump (or chemical treatment source), P1, is proportional to the flow and is set to a proportion of the total desired nominal additional level of a chemical treatment, such as chlorine dioxide. The percentage of the total addition that is provided by the first pump, preferably takes into account site-specific and facility-specific factors. For example, where the flow of a WWTP is being treated chemically after secondary treatment, when the flow is consistent, mostly for houses, and is not subject to large fluctuations in the sum of BOD and COD, then the percentage of the total addition provided by the first pump proportional to the flow is relatively large, typically 70 to 90 %. The basic equation for this first pump is: P1 DR = (a) ODR, where: P1DR = number of doses of pump 1; a is the nominal (ie, initial, or calculated) fraction of the total treatment dose given by pumps 1 and 2 in pump 1; Y ODR is the optimum dose amount, as determined by the initial test of the characteristics of a particular main fluid stream (such as a wastewater stream). The algorithm for a second pump (or chemical treatment source) being adjusted based on the measurement results of a downstream monitoring device, is as follows: P2DR = (b) ODR + (P1 DR - X) (F), wherein: as above, P1DR = pump dose amount 1 and ODR is the optimum dose amount, as determined by the initial test of the characteristics of a particular main fluid stream (such as a wastewater stream); b is the nominal (ie, initial, or calculated) fraction of the total dose of the treatment given by pumps 1 and 2 in pump 2, where a + b - 1.0 (that is, the total Quantity of Dose) Optimum, ODR); X = result averaged by time of the monitoring device downstream (here, particularly, for CI02); P2DR = number of pump doses 2; and F = a factor to adjust the desired sensitivity of the system for changes based on time in the flow, for the demand in the liquid being treated that does not count for the short retention time before the site of the point of sample from the downstream monitoring device provide data signals to obtain the value, X, and other factors that can be determined to be of importance (eg, but not limited to, the desired "overdose" that may be acceptable in a situation of given treatment). First, without considering the percentage of the total flow of the main stream flowing in the lateral stream, it was observed that the above equations operate to alter the P2DR based on the X reading of the chemical parameter at a downstream monitoring point. For example, when chlorine dioxide treats a stream of wastewater, and at a particular point in time this wastewater stream has high combined BOD and COD, an upward change of the nominal or initial dose may result as follows: before the influx of wastewater with high combined BOD and COD are: P1DR = (a) ODR, P1DR = (0.8) (2.0 ppm) = 1.6 ppm distributed in pump 1. P2DR = (D) ODR + (P1 DR) - X) (F), P2DR = (0.2) (2.0 ppm) = initial amount of 0.4 ppm; then, for the period before the influx noted, assume that P1 DR = X, so this amount of 0.4 ppm does not change. The quantities immediately after the inflow of wastewater with high combined BOD and COD are: P1 DR = (a) ODR, P1 DR = (0.8) (2.0 ppm) = 1.6 ppm distributed in pump 1. This quantity does not change in the present. P2DR = (b) ODR + (P1DR - X) (F), P2DR = (0.2) (2.0 ppm) + (0.8 - 0.6) (F) = 0.4 + (0.2) (F), where F = 1.5 for count the demand adjusted by time (given the location of the monitoring device in relation to the additional demand downstream), then P2DR will adjust up: 0.4 + (0.2) (1.5) = addition amount of 0.7 ppm in P2. That is, due to the loading of CBOD in the liquid being treated, which resulted in a sufficient decrease detected at the downstream monitoring point, the algorithm provides an additional amount of chemical through the second entry. With the readings taken multiple times per minute and adjustments made multiple times per minute, the increase in wide increase provided in this example probably will not take place. Rather, in practice, with a computer that controls changes in small increments of time, much smaller incremental changes are made in short periods. In this way, this example aims to show the total effect of changes in the quality of the liquid in the flow stream, and how this algorithm compensates for such changes. Looking to the other side of this hypothetical "connector" of residual water of high combined BOD and COD, at a certain point the flow will return to a more normal CBOD profile. While this is happening, one of the iterations to calculate and alter P2DR is exemplified as follows, based on a time-averaged X value of 0.75 ppm at the downstream monitoring site: P2DR = (D) ODR + (P1 DR - X) (F) , P2DR = (0.2) (2.0 ppm) + (0.8 - 0.75) (F) = 0.4 + (0.05) (F), and where F = 1.5, P2DR = 0.4 + (0.075) = addition amount of 0.475 ppm . In this way, iteratively, when the wastewater returns to a normal level of BOD and COD, the P2DR will return to its nominal level. In addition, in certain modalities, such as a standard convention of the basic algorithm, if the second part of the P2DR equation, mainly "(P1 DR - X) (F)" is calculated by one or a designated number of time intervals to be below zero, then the same P1 DR is decreased. For example, if an X value averaged per time at the downstream monitoring site is 0.87 (when, for example, P2DR is providing 0.2 (ODR)), and P1 DR = 0.8, then (P1 DR - X) (F) is less than zero. Accordingly, with one or more such sequential results, P1 DR is decreased incrementally until (P1 DR-X) (F) is greater than zero. Also, when the above algorithm is implemented for typical systems, a dilution factor, DF, is incorporated into the programming of the process control system. The DF is derived from the proportion of the flow in the main stream (at the point before or after the deviation of a portion of this stream for the treatment stream, or lateral) for the flow of the treatment or sidestream: DF = flow in main stream / flow in treatment stream (lateral), where the flow units are the same are canceled to provide a simple numerical proportion. An example is illustrative of the coordinated use of the above equations, as would occur in a software program developed to automate the addition control of a treatment chemical in a liquid stream to be treated. It is assumed that the amount of desired or required dose (designated as Final Target Concentration, or TFC) to be achieved in the mainstream is 1.2 ppm of CI02 measured at a point downstream Z (where Z is more downstream than the meter of measurement that X provides). It is also assumed that the DF is 400. In this way, the ODR to be delivered by pump 1 and 2 is: ODR = (TCF) (DF) = (1.2 mg CI02 / L total flow) (400 liters of total flow / sidestream flow of liter) = 480 mg CI02 / liter sidestream flow. In this way, a total of 480 mg of CI02 will be added by both pumps for every 400 liters that pass through the main flow, which, in the DF of 400, is added to one liter of the lateral current flow. This is added either in a time-based addition program or a flow quantity basis for the lateral current flow. Then, based on a review of the historical flow and chemical parameters of the facility (or similar facilities), a decision is made as to how to initially provide the total addition of treatment chemical between pumps 1 and 2. For example, when the current The liquid to be treated is absolutely uniform over time in its concentration of the compounds to be treated (ie, the sum of the biological and chemical oxygen demands), a larger proportion of the addition of total treatment by the "first", pump proportional to the flow. That is, this pump would be established by the first upper equation to be proportional to the flow. In this example, it is assumed that the liquid to be treated is moderately consistent in its compounds to be treated and there are no periodic entries of interfering compounds. Therefore, the proportional pump per flow is operated at a relatively high percentage of the ODR, 0.8: P1 DR = (a) ODR = (0.8) (480 ppm) = 384 ppm.

In this way, the first pump is operated to deliver 384 milligrams of chlorine dioxide to one liter of sidestream water. In the DF of 400, this corresponds to 80% of the ODR for 400 liters of main flow water. This dose of 384 milligrams is distributed in the same unit of time in which the 400 liters of the main flow water flow passes a given point. As noted above, this is added either in a time-based addition program or on the basis of flow quantity for the lateral current flow. With respect to the last point, it is noted that in certain embodiments the sidestream pump system is established to be proportional to the flow with the main flow. This requires a variable flow pump and a controller. In such embodiments the addition amount for the sidestream may be "based on flow amount". That is, each net source addition for the lateral current is made proportional to the amount of lateral current flow, which by itself is proportional to the amount of main current flow. Alternatively, in other embodiments a single speed pump can pump water through the sidestream system. In such embodiments, the pump may be of positive displacement type, centrifuge, or other common types. For example, a centrifugal pump having a flow amount of 227.12 liters per minute (nominal) has been used to pump a side stream in various systems using the present invention. When a pump is not positive displacement, depending on the design of the system, the head pressure of the main flow can affect the actual flow through the side stream. In the systems in which the present invention has been used, this variation in the actual flow amount has not been determined to adversely affect the efficacy of the total dose of the present invention. In certain systems with relatively large head differences in the mainstream, and relatively large vertical heights for pumping the sidestream water, such variable head head differences can more significantly affect the efficacy of the dose. In such cases, several corrections can be made, or a positive displacement pump can be used. Alternatively, where a non-positive displacement pump is used and head difference errors are considered for not justifying the corrections, the amount of chemical input in the sidestream can be "time based". For example, in the modalities where the flow is not proportional, and it is not constant (as it would be with a positive displacement pump), the dosage of the chemical treatment in the lateral stream is done to correspond to the unit of time in the which a given quantity of main flow liquid passes a given point in the main flow system. In this way, the addition is not based on the amount of flow in the side stream, but on the amount of flow in the main stream, so the addition is based on the time it takes for the X liters to pass to a point in the mainstream. This is programmed into a computational control device that receives data inputs that indicate the amount of mainstream flow. This method reduces the errors that can result from adding to the side stream based on a liquid per unit in the side stream. In an example, not to be limiting, the controller, 100, in the Figure 1 is preferably in the form of at least one application specification integrated circuit that is configured using known techniques to receive several different inputs identified above and to make adjustments to the system 10 to achieve desired results by an operator. The controller 100 preferably additionally includes a screen (not shown) and also an output system (not shown) for printing on hard copy or other media a hard copy to record the data indicating the total performance of several different portions of the system. It is noted for these and other modalities, that the signals of the detectors or other sensors may be communicated by any means known to those skilled in the art. That is, the signals can be communicated through conventional means, such as sending electrical impulses along a conduction cable, through more sophisticated means, such as by converting the signals into radio waves and transmitting these waves to that a receiver receives the signals and thereafter sends them to the integrated circuit, microprocessor, special-purpose computer, or general-purpose computer (of which all are represented in Figure 1 as the controller 100), or through any other form now known or developed later. Similarly, each individual control circuit, such as for a single chemical treatment feed pump, may be of the types set forth herein. The controller 100 receives an entry of the chlorine dioxide detected by the analyzer 28 which takes measurements at a first measuring point 27 through the probe 29. The controller 100 also receives data input from the flow meter, 32, in the current (and of the pump or flow meter, not shown, which indicates the amount in the side stream, where it is implemented) and receives and controls the amount of chlorine dioxide addition by the first chlorine dioxide dispenser 18 and the second chlorine dioxide dispenser 26. Where such a component is part of the system being controlled, the injection amount of S02 of the injection subsystem of S02 (not shown) is also controlled by the controller 100. The controller 100 additionally includes a established point, typically entered by the operator, which indicates the desired level of chlorine dioxide at one or more points downstream. Each set point can be a single point or it can be configured as an acceptable range or a tolerance level above and below the individual set point. In addition, the controller 100 may be programmed by the operator to control what information is displayed on a standard data output screen (not shown, but, for example, a video screen) and what information is recorded and presented through the data logger / printer outputs (not shown) provided by the controller 100. Other configurations and initial settings for the first chlorine dioxide dispenser 18 and the second chlorine dioxide dispenser 26, and the S02 injection subsystem (when exists and is being controlled by the controller 100) can be provided by the operator. Finally, the controller 100 may receive an optional verification signal from a verification analyzer (not shown) that periodically provides a review of the accuracy and precision of the analyzer, 28. The controller 100 has appropriate logic provided by the specific integrated circuit of the application, or other logical devices, such as software operating within a personal computer or other programmable computing device, which acts on the inputs provided by the operator and the signals received from the various different inputs, as indicated in Figure 1 , to generate several different output signals. First, the controller 100 provides a first chlorine dioxide signal 40 which is coupled to the chlorine dioxide pump 18 to cause the chlorine dioxide pump 18 to provide an addition according to the desired algorithm in use. Second, the controller 100 provides a second chlorine dioxide signal 42 which is coupled to the chlorine dioxide pump 26 to cause the chlorine dioxide pump 26 to provide an addition according to the desired algorithm in use. These control signals, as described herein, fluctuate based on inputs from, for example, the main flow flow meter, 32, and the chlorine dioxide detected by the meter 28. Optionally, where this is a part of the system which is being controlled, the controller 100 produces an output side control signal of S02, which adjusts an amount at which a S02 pump delivers S02 at the end of the chlorine dioxide contact region to remove chlorine dioxide levels remaining unwanted. As indicated above, the latter is an "infallible" system that expects to be minimally required, or not at all, when used in the present invention in the ways described above. Thus, in the simple control systems of the present invention, a dedicated control circuit can be preprogrammed and set with a specific algorithm. However, in preferred embodiments, the control system may provide an omission to allow manual control, the ability to change from one algorithm to another, as may be desired by an operator, and the ability to modify set point ranges within a given algorithm or program. The above discussion, which has specific described embodiments of the present invention, indicates the modalities of the methods of the present invention. More particularly, and with reference to Figure 1, a basic method of the present invention for controlling the level of addition of a chemical treatment for a main stream of a fluid waste stream, comprising: a. diverting a side stream, 6, of said main flow, 2, at a point of deviation,; b. determining the flow amount of said main flow (such as, but not limited to, having a flow meter, 32, in the main flow, 2, near the deviation point 8); c. add said chemical treatment at a first point of addition, 16, of said lateral stream, 6, at an addition level based primarily on the proportionality for said main stream flow amount of residual current; d. measuring, at a first measuring point, 27, downstream of said first addition point, 16, the concentration of said chemical treatment in said lateral current; and. adding said chemical treatment at a second point of addition, 24, of said sidestream, 6, at an addition level based primarily on the difference between the addition level at the first addition point, 16, and the concentration measured at the step 'd'; and f. returning said lateral stream, 6, to said main flow, 2, of said residual current downstream of said deflection point, 8; with it the chemical treatments added in that way are sufficient to treat the complete flow of the residual stream with a desired level of chemical treatment additions to achieve the particular purpose for the chemical addition. This control method works well with the addition of chlorine dioxide to disinfect the wastewater treatment effluent. In the treatment of other liquid streams, where even the closest tolerances are necessary for the addition of the chemical treatment for the composition of the liquid stream, one or more of the following strategies and / or modifications are useful to implement the precision even a little larger than the delivery of a chemical to treat a liquid flow in accordance with the present invention. In alternate modes, instead of measuring the concentration of the chemical treatment added to said sidestream, a parameter of the fluid stream if a reagent, intermediate, by-product or final product of a reaction is measured with a component of the chemical treatment. Also, ozone or other disinfecting agents, such as chlorine gas or sodium hypochlorite, can be used as the chemical treatment instead of the chlorine dioxide described above. Alternatively, the chemical addition in the side stream may be in a gaseous state, a liquid state or a solid (i.e., pulverized) state. In a broader perspective, although the methods and systems of the present invention have been described in detail for embodiments in the context of a wastewater treatment system, the present invention is also applicable to other fluid flow treatment systems . In all those embodiments, a chemical treatment is added to a portion of the main fluid stream that has been diverted to a side stream, where said chemical treatment is added at at least two points of addition (an addition primarily based on quantity of flow, a second principally proportional addition for a measured change in the amount of the chemical treatment after a given period of time in contact with the lateral stream after the first and / or second addition (s)), at least one point measurement is downstream of at least one addition point, the measurement at this measurement point is used to mainly determine the second addition noted above, and the lateral current treated in that way, when it is returned to the main current of the current of fluid, provides the desired treatment. Thus, it is within the scope of the present invention that there are more than two addition points, with additional addition points placed either in the side stream or in the main stream, while the two sidestream addition points operate as described here. Similarly, it is within the scope of the present invention that the sequence of the placement of the two side stream addition points does not need to be sequenced as above, for example, the addition point provided of main stream amount upstream of the primary addition to analyzer base. As well, it is recognized that algorithms are often adapted for the particular site. Also, the data of environmental conditions, such as temperature, wind speed and direction, and irradiation of sunlight, and time of day can be captured in the controller and can be factors in the algorithms that direct the chemical addition. More generally, the algorithms can be modified based on the season. In addition, in other modalities the chemical treatment, the composition of the main flow, the measured parameters, and the exact addition and measurement sites vary according to the system requirements and relevant parameters. For example, the present invention can be used to treat water for potable use or other uses, or for various liquid flows in an industrial process treatment. Hence, this detailed description, including the examples that follow, are not to be construed as limiting this invention to wastewater treatment systems.

EXAMPLE 1 The following table of data exemplifies how the present invention, using the algorithms described above, operates to refine dosages of chlorine dioxide in a wastewater treatment plant. The lateral current flow is a percentage of the main current, and the ODR has been determined to be 1.4 ppm in the main stream (ie 140 ppm in the side stream). The division between the first (proportional to the flow) and the second (variable) dose points is 0.75 and 0.25. The factor F is set at 1.35.

Thus, as exemplified above, using the algorithms explained above serves to maintain a desired level of combined chemical addition of the first and second addition points for the lateral stream. This dosing system operates under a range of wastewater conditions and the wastewater treatment plant. It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in view of the foregoing will be suggested to persons skilled in the art and will be included within the spirit and limit of this application and the scope of the appended claims.

Claims (16)

NOVELTY OF THE INVENTION CLAIMS

1. - A method for controlling the level of addition of a chemical treatment for a main flow of a residual fluid stream being treated therewith, for a particular purpose, comprising: a. forming a sidestream of said main flow at a point of deflection; b. determine the amount of flow of said main flow; c. adding said chemical treatment at a first point of addition of said side stream, at an addition level based primarily on the proportionality for said principal flow amount of the residual stream; d. measuring, at a first measurement point downstream of said first addition point, the concentration of said chemical treatment in said lateral stream; and. adding said chemical treatment at a second point of addition of said side stream, at an addition level based primarily on the difference between the level of addition at said first point of addition and the concentration measured in step d; and f. returning said lateral current to said main flow of said residual current downstream of said deflection point; therefore said waste stream is thus provided with a desired level of chemical treatment additions to achieve said particular purpose.

2. The method according to claim 1, further characterized in that said chemical treatment comprises chlorine dioxide.

3. The method according to claim 1, further characterized in that said measurement is conducted between said first point of addition and said second point of addition.

4. The method according to claim 1, further characterized in that said measurement is conducted downstream of said first addition point and said second addition point.

5. The method according to claim 1, further characterized in that said addition in said first point is determined by an algorithm that has, as its main variable, a parameter change indicative of the flow amount of said main current.

6. The method according to claim 1, further characterized in that said addition in said second point is determined by an algorithm that has, as its main variable, a parameter change indicative of the reaction of said chemical treatment with one or more components in said lateral stream.

7. The method according to claim 1, further characterized in that it additionally comprises sending data signals from said measurement, step d, to a computational control device, and sending control signals of said computational control device to a second device. of addition point control which controls the amount of said addition of said chemical treatment at said second addition point.

8. The method according to claim 7, further characterized in that it further comprises sending data signals of said determination, step d, to said computational control device, and sending control signals of said computational control device to a first device of addition point control which controls the amount of said addition of said chemical treatment at said first addition point.

9. The method according to claim 1, further characterized in that it further comprises sending data signals of said determination, step d, to a computational control device, and sending control signals of said computational control device to a first device of addition point control which controls the amount of said addition of said chemical treatment at said first addition point.

10. The method according to claim 9, further characterized in that it additionally comprises sending data signals of said measurement, step d, to the computational control device, and sending control signals of said computational control device to said second computing device. addition point control which controls the amount of said addition of said chemical treatment at said second addition point. 11.- A system for dosing the main flow of a liquid that needs the treatment of chlorine dioxide with chlorine dioxide, which includes: a. a lateral stream that deviates from said main flow of said liquid, comprising:. a deflection point that provides an inlet for the liquid within said lateral stream from said main flow; 2. a first point of addition in which a first addition of chlorine dioxide is added to said side stream, said first addition mainly proportional to the amount of flow of said main stream; 3. a second point at which a second addition of chlorine dioxide is added to said lateral stream, said second addition mainly adjusted based on data signals from a primary measuring device, wherein said device measures a parameter in said indicative liquid of a reaction between said chlorine dioxide and the component (s) in said liquid; and 4. a return point placed downstream of said deflection point, through which the liquid in said lateral current returns to said main current; b. said primary measurement analyzer, placed downstream of said first addition point, and providing data of said measurement of said change, said data being used to establish said second addition; and c. at least one computational control device, which receives signals indicating said amount of flow of the main current and which uses said signals to control the first addition according to a first algorithm, and receive data from said primary measurement analyzer, and use said data for adjusting the second addition according to a second algorithm, wherein said sidestream controller provides a sufficient addition of chlorine dioxide to achieve a desired purpose in the fluid in the mainstream. 12. The system according to claim 11, further characterized in that the sample point of said primary measurement analyzer is placed along the lateral stream after the first and second addition points. 13. The system according to claim 12, further characterized by additionally comprising a secondary point of measurement, wherein the sample point of said secondary point of measurement is placed in the mainstream after the point of return. 14. The system according to claim 11, further characterized in that said primary measurement analyzer measures the level of chlorine dioxide. 15. The system according to claim 11, further characterized in that said first algorithm is P1 DR = (a) ODR, wherein: P1 DR is a quantity of dose at said first addition point; a is the nominal fraction of the total chlorine dioxide addition that is provided at said first addition point, and ODR is a predetermined objective dose amount, and wherein P1DR of dose amount at said first addition point is added with based on the dissolution in the main flow as determined by the periodic, semi-continuous, or continuous measurement of said main flow. 16. The system according to claim 11, further characterized in that said second algorithm is P2DR = (b) ODR + (P1 DR-X) (F), wherein P1 DR is a quantity of dose in said first point of addition, ODR is a predetermined objective dose amount, b is the nominal fraction of the total addition of chlorine dioxide at said first and second addition points, where a + b = 1.0, X is the result of data from the analyzer of primary measurement, P2DR is the amount of dose in said first addition point; and F is a selected adjustment factor, and wherein P2DR of dose amount at said second addition point is based on the dissolution within the main flow, as determined by the periodic, semi-continuous, or continuous measurement of said flow. principal.