Method for monitoring the water quality of treated water after treatment for COD and / or phosphorus and / or nitrogen and / or cyanide, and apparatus for preparing analytical samples.

Abstract

This invention provides a water quality monitoring method for treated water that confirms that the treated water, after coagulation and sedimentation treatment of COD / phosphorus / nitrogen / cyanide in collected dust (raw water), meets water quality standards, predicts deterioration in treatment efficiency during coagulation and sedimentation treatment, enables early detection of abnormal water, and facilitates rapid response to abnormal water. [Solution] A water quality monitoring method for treated water, comprising: a measurement step for automatically measuring the amount of COD / phosphorus / nitrogen / cyanide in treated water; a coagulation-sedimentation step for obtaining treated water by circulating raw water containing coagulated material including copper, iron, etc., and performing mixing, coagulation, and sedimentation treatment in that order; a sampling and analysis step for collecting an analytical sample, in which a portion of the raw water in a mixing tank is intermittently separated while it is circulating, a portion of the separated raw water is injected under pressure into the cylinder of a cylindrical ceramic filter which is a porous material, a portion of the filtered water obtained is taken out, and the filtered water is automatically introduced into an analytical device as an analytical sample for measuring the amount of nitrogen, etc. in the raw water, and the amount of nitrogen, etc. in the sample is automatically measured; and a control step for controlling the operating conditions of the coagulation-sedimentation step using the measured values ​​obtained in the analysis step.

Description

Technical Field

[0001] The present invention relates to a method for monitoring the water quality of treated water after treatment of COD and / or phosphorus and / or nitrogen and / or cyanide, and an apparatus for preparing an analytical sample that can be suitably used in the method.

Background Art

[0002] For example, dust-collecting wastewater, which is dust-collected water obtained by wet dust collection of exhaust gas, may contain COD and / or phosphorus and / or nitrogen components, cyanide components, etc. These wastewaters are treated in treatment facilities for COD and / or phosphorus and / or nitrogen and / or cyanide to remove COD components, phosphorus components, nitrogen components, and cyanide components, and then discharged or the like. When discharging or the like, for the treated water after the removal treatment of COD and / or phosphorus and / or nitrogen and / or cyanide, the content of COD and / or phosphorus and / or nitrogen and / or cyanide is continuously measured, and after confirming that the treated water meets the water quality standards, it is discharged or the like.

[0003] Dust-collecting wastewater generally contains various suspended substances such as soot, dust, coal powder in thermal power generation, and iron powder and coke powder in the steel industry. It is difficult to separate the suspended substances suspended in the dust-collecting wastewater without adding chemicals. Therefore, usually, a flocculant is added to perform flocculation sedimentation treatment to remove the suspended substances. And various proposals have been made as technologies for improving the removal performance of suspended substances. For example, a proposal for a method of improving the removal performance of suspended substances by adding an inorganic flocculant to coarsen the suspended substances and then adding a polymer flocculant to perform flocculation treatment (see Patent Document 1), and a method of adding an anionic polymer flocculant having a colloid equivalent value in a specific range to raw water at a specific concentration to perform flocculation treatment have been proposed (see Patent Document 2). <​​​​​​​​​​​Japanese Patent Publication No. 2006-231115 [Patent Document 2] Japanese Patent Publication No. 2007-216146 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In treatment facilities that process COD and / or phosphorus and / or nitrogen and / or cyanide in collected water (raw water) obtained by wet dust collection of exhaust gas, in all cases, suspended solids precipitated during the treatment of COD and / or phosphorus and / or nitrogen and / or cyanide in the water to be treated (raw water), as well as water-insoluble salts generated in the wastewater, are removed by coagulation and sedimentation. Specifically, the reaction liquid is introduced from the reaction tank where the water to be treated (raw water) has been treated into a solid-liquid separator (sedimentation tank) to remove the precipitate and obtain treated water. The content of COD and / or phosphorus and / or total nitrogen and cyanide in the treated water obtained after treatment is continuously and automatically measured to confirm the water quality of the treated water. If the content of COD and / or phosphorus and / or total nitrogen and cyanide in the treated water does not meet the water quality standards, reprocessing is performed to obtain treated water that meets the standards. As can be understood from this, the automatic measurement of COD and / or phosphorus and / or nitrogen and / or cyanide content in treated water after coagulation and sedimentation also plays a role in controlling the treatment conditions to a favorable state by monitoring the treatment efficiency of the coagulation and sedimentation treatment through the measured values ​​of the treated water and determining whether it is good or bad. Hereinafter, "COD and / or phosphorus and / or nitrogen and / or cyanide," which are pollutants in the raw water and treated water targeted by the water quality monitoring method of the present invention, will also be written as "COD / phosphorus / nitrogen / cyanide."

[0006] Here, in the treatment facility that processes COD / phosphorus / nitrogen / cyanide in the dust collected water (raw water) obtained by the wet dust collection treatment of exhaust gas described above, the automatic measurement of COD / phosphorus / nitrogen / cyanide content is performed on the treated water in the treatment tank after coagulation and sedimentation treatment. The inventors have found the following problems with this. Specifically, while the current method of monitoring the water quality of treated water poses no problem in terms of releasing treated water that meets water quality standards, the monitoring and determination of the treatment efficiency of coagulation and sedimentation treatment, and the control of treatment conditions to improve treatment efficiency when water quality deteriorates, is reactive, and this is a cause of impaired treatment efficiency. In particular, the current monitoring of the treatment efficiency of coagulation and sedimentation treatment is based on the COD / phosphorus / nitrogen / cyanide content in the treated water after coagulation and sedimentation treatment, which is measured automatically. Therefore, abnormal values ​​in the water quality of the treated water become apparent as a result of coagulation and sedimentation treatment being performed under conditions of poor treatment efficiency, and only after this determination are the coagulation and sedimentation treatment conditions adjusted to achieve good treatment efficiency.

[0007] As described above, the current monitoring of the deterioration in the treatment efficiency of coagulation and sedimentation treatment is not configured to predict deterioration in treatment efficiency in advance. Instead, when the coagulation and sedimentation treatment deteriorates and good treatment is not performed, abnormal values ​​appear in the automatically measured data for COD / phosphorus / nitrogen / cyanide content of the treated water. Only at this point is the deterioration in treatment efficiency recognized, and the treatment conditions of the coagulation and sedimentation treatment are normalized based on the abnormal values ​​in the treated water. The inventors of this invention recognized that, as such, the current monitoring of the treatment efficiency and adjustment of treatment conditions for coagulation and sedimentation treatment are performed retrospectively, and therefore do not effectively prevent coagulation and sedimentation treatment from being performed under conditions of poor treatment efficiency, and that this point needs to be improved. With the conventional technology described above, there is a high possibility that a large amount of treated water will be generated under conditions of poor treatment efficiency, and on the other hand, treated water showing abnormal values ​​that do not meet water quality standards requires retreatment, which also presents a practical problem of greatly impaired treatment efficiency.

[0008] Therefore, the object of the present invention is to develop a simple and effective water quality monitoring method for treated water after COD / phosphorus / nitrogen / cyanide treatment, which is used in a treatment facility that treats COD / phosphorus / nitrogen / cyanide in dust collected by wet dust collection treatment of exhaust gas, the raw water, and in a water quality monitoring method that controls treatment conditions in response to deterioration in the treatmentability of the coagulation and sedimentation treatment, which is recognized when abnormal values ​​occur in the treated water. This method allows for prediction and response to deterioration in the treatmentability of the coagulation and sedimentation treatment at an earlier stage, rather than relying solely on retrospective responses based on analytical values ​​of the treated water as in the past, thereby enabling early detection of abnormal water and rapid initial response to the occurrence of abnormal water. [Means for solving the problem]

[0009] The above objective is achieved by the present invention described below. That is, the present invention provides a method for monitoring the water quality of treated water after treatment with COD / phosphorus / nitrogen / cyanide. [1] A water quality monitoring method used in a treatment facility for which wastewater obtained by wet dust collection treatment of exhaust gas requiring treatment of dissolved components is used as raw water, and treated to obtain treated water by treating COD and / or phosphorus and / or nitrogen and / or cyanide in the raw water, wherein in addition to a configuration for checking the water quality of treated water obtained after coagulation and sedimentation treatment of COD and / or phosphorus and / or nitrogen and / or cyanide in the raw water, a configuration is provided to enable early response to abnormalities occurring in the water quality of the treated water, A configuration for confirming the water quality of the treated water includes a measurement step for automatically measuring the COD and / or phosphorus and / or nitrogen and / or cyanide content in the treated water, The raw water, which contains suspended solids precipitated in the treatment process and / or aggregates containing at least one of copper, iron, and calcium resulting from the treatment of COD and / or phosphorus and / or nitrogen and / or cyanide components, is circulated in the aforementioned treatment facility, and the facility has a mixing tank, a coagulation tank, and a sedimentation tank arranged in this order, and the main treatment for obtaining the treated water is performed by carrying out mixing, coagulation, and sedimentation in this order, comprising a coagulation-sedimentation treatment step, In addition, as a configuration to enable the aforementioned early response, the raw water in the mixing tank is continuously circulated while a portion is intermittently separated, and a filtration device having a cylindrical ceramic filter made of a porous ceramic body is used to pressurize the separated raw water into the cylinder of the ceramic filter, allowing the moisture in the raw water to permeate into the cylinder to obtain filtered water and perform pretreatment of the raw water, a portion of the filtered water from the pretreated cylinder is taken out, and the extracted filtered water is automatically introduced into an analytical measuring device as an analytical sample for measuring the COD and / or phosphorus and / or nitrogen and / or cyanide content in the raw water, and the analytical measuring device is... A method for monitoring the water quality of treated water after treatment for COD and / or phosphorus and / or nitrogen and / or cyanide, characterized by comprising: a sampling and analysis step of an analytical sample in which the content of COD and / or phosphorus and / or nitrogen and / or cyanide in the analytical sample is automatically measured using a constant device; and a control step of predicting the occurrence of an abnormality in at least one of the measured values ​​of the content of COD and / or phosphorus and / or nitrogen and / or cyanide in the treated water obtained in the measurement step by using the measured values ​​obtained in the sampling and analysis step, and controlling the operating conditions of the coagulation and sedimentation treatment step based on the prediction.

[0010] The following are examples of preferred methods for monitoring the water quality of treated water after the above-mentioned COD / phosphorus / nitrogen / cyanide treatment. [2] A method for monitoring the water quality of treated water after COD / phosphorus / nitrogen / cyanide treatment as described in [1] above, wherein in the step of collecting and analyzing the sample for analysis, the extracted filtered water is cooled to room temperature and then used as the sample for analysis. [3] The method for monitoring the water quality of treated water after COD / phosphorus / nitrogen / cyanide treatment according to [1] or [2] above, wherein the pore size of the cylindrical ceramic filter made of the porous material is 0.1 μm or more and 5.0 μm or less. [4] A method for monitoring the water quality of treated water after COD / phosphorus / nitrogen / cyanide treatment, wherein the cylindrical ceramic filter made of the porous body is made of a porous material mainly composed of alumina or diatomaceous earth, according to any one of [1] to [3] above. [5] A method for monitoring the water quality of treated water after COD / phosphorus / nitrogen / cyanide treatment according to any one of [1] to [3] above, wherein in the step of collecting and analyzing the sample for analysis, the cylindrical ceramic filter made of the porous body is made of a porous material mainly composed of diatomaceous earth, a stainless steel brush is provided so as to be able to contact the cylindrical surface of the cylindrical ceramic filter, and the stainless steel brush is used to scrape off and remove any solid matter in the raw water remaining on the cylindrical surface of the cylindrical ceramic filter when obtaining the filtered water.

[0011] As another embodiment of the present invention, the following apparatus for preparing analytical samples is provided. [6] An analytical sample preparation apparatus used in a treatment facility that uses dust collected water obtained by wet dust collection treatment of exhaust gas as raw water and treats COD and / or phosphorus and / or nitrogen and / or cyanide in said raw water, the apparatus contains suspended solids precipitated in the treatment process and / or aggregates containing at least one of copper, iron and calcium resulting from the treatment of COD and / or phosphorus and / or nitrogen and / or cyanide components, and is used when measuring the COD and / or phosphorus and / or nitrogen and / or cyanide content in said raw water, A pre-processing apparatus for obtaining the aforementioned analytical sample, An analytical sample preparation apparatus comprising a filtration means for filtering the raw water, wherein the filtration means comprises a pressure-resistant casing having at least two openings, and containing one or more cylindrical ceramic filters made of porous ceramic material, the ceramic filters having the function of allowing water in the raw water to permeate into the cylinder and become filtered water when the raw water is injected into the casing under pressure, and allowing solid components in the raw water to remain on the surface of the cylinder.

[0012] The following are examples of preferred configurations for the apparatus used to prepare the analytical samples described above. [7] The apparatus for preparing analytical samples according to [6] above, wherein the cylindrical ceramic filter is made of a porous material having a pore size of 0.1 μm to 5.0 μm. [8] The apparatus for preparing analytical samples according to [6] or [7], wherein the cylindrical ceramic filter is made of a porous material mainly composed of diatomaceous earth, and a stainless steel brush for scraping off solid matter in the raw water remaining on the surface of the cylinder is provided in a manner that allows it to contact the cylindrical surface of the cylindrical ceramic filter. [9] The apparatus for preparing analytical samples according to [6] or [7] above, wherein a filtration unit is arranged inside the pressure-resistant casing, comprising a cylindrical ceramic filter and a stainless steel brush for scraping off solid matter in the raw water remaining on the surface of the cylinder. [Effects of the Invention]

[0013] According to the present invention, the following excellent effects can be obtained in a water quality monitoring method used in a treatment facility that processes COD / phosphorus / nitrogen / cyanide in dust collected water (hereinafter also referred to as raw water) obtained by wet dust collection treatment of exhaust gas, which is the raw water, for the purpose of confirming that the treated water obtained after coagulation and sedimentation treatment of COD / phosphorus / nitrogen / cyanide in the raw water meets water quality standards, and controlling treatment conditions in response to deterioration in the treatmentability of the coagulation and sedimentation treatment that is recognized when abnormal values ​​occur in the treated water. Specifically, according to the present invention, by separating the raw water to be subjected to coagulation and sedimentation treatment and applying an effective and simple pretreatment to the raw water, a simple analytical system is added that makes it possible to measure the COD / phosphorus / nitrogen / cyanide content in the raw water. This provides a simple and effective water quality monitoring method for treated water after COD / phosphorus / nitrogen / cyanide treatment that enables early detection of abnormal water and rapid initial response to the occurrence of abnormal water, rather than relying solely on post-treatment based on analytical values ​​of the treated water as in the conventional technology. [Brief explanation of the drawing]

[0014] [Figure 1] This schematic diagram illustrates the treatment flow for a treatment facility that processes COD / phosphorus / nitrogen / cyanide in dust collected water obtained by wet dust collection treatment of exhaust gas, which is the raw water, as an example of applying the water quality monitoring method of the present invention. [Figure 2] This is a schematic diagram illustrating the flow of the water quality monitoring method of the present invention, which involves preparing an analytical sample by intermittently separating raw water from a mixing tank and filtering it using a cylindrical ceramic filter (ceramic membrane) (labeled as an analytical pretreatment device in Figure 1), and then transferring the well-filtered raw water to an analyzer. [Figure 3] This figure shows the difference in appearance between simulated raw water and the filtrate obtained after filtering the simulated raw water with a cylindrical ceramic filter that constitutes the present invention. [Figure 4-1]This is a diagram schematically showing an example of a filtration device (a pretreatment device for raw water used in analysis) constituting the present invention for explaining the flow of raw water when performing filtration treatment by supplying raw water intermittently collected from a mixing tank using one cylindrical ceramic filter (ceramic membrane), and the flow of filtrate toward an analyzer after the filtration treatment. [Figure 4-2] In another example of a filtration device provided with a brush for scraping off clogging generated on the surface of a ceramic filter, the arrangement state of a plurality of cylindrical ceramic filters (ceramic membranes) and the brush, and the flow of raw water when raw water intermittently collected from a mixing tank is supplied to each ceramic filter for filtration treatment using the device, and a schematic for explaining the flow of filtrate flowing out of the ceramic filter and toward an analyzer are schematically shown. [Figure 4-3] This is a diagram showing a cross-sectional view taken along the line A-A of the filtration device in FIG. 4-2.

Mode for Carrying Out the Invention

[0015] The present invention will be described in detail below by giving preferred embodiments. As described above, the present inventors do not retrospectively determine that the treatability is impaired based on the abnormality of the quality of the treated water obtained after coagulation sedimentation treatment, but recognize the usefulness of predicting the deterioration of the treatability of coagulation sedimentation treatment at an earlier stage, and as a result of earnestly studying a simple and highly practical method that can improve this point, a simple and effective method for monitoring the quality of treated water after treating COD / phosphorus / nitrogen / cyanide has been found, leading to the present invention. That is, as described below, according to the method for monitoring the quality of treated water of the present invention, by a simple method of adding an analysis system that enables automatic measurement of the content of COD / phosphorus / nitrogen / cyanide in raw water to the conventional treatment flow, early detection of the occurrence of abnormal water and rapidization of the initial response to the occurrence of abnormal water can be realized, and the state where coagulation sedimentation treatment is continuously performed in a state where the treatability has deteriorated can be suppressed. As a result, it becomes possible to realize a coagulation sedimentation treatment method that can more efficiently and stably obtain treated water that meets water quality standards.

[0016] The raw water targeted by this invention is dust collected by wet dust collection treatment of exhaust gas. The treatment equipment that processes COD / phosphorus / nitrogen / cyanide in this raw water is a facility that processes large volumes of wastewater, so it takes time to detect abnormal values ​​in the automatically measured COD / phosphorus / nitrogen / cyanide levels of the treated water. The primary purpose of monitoring the water quality of the treated water is to confirm that the treated water meets the water quality standards. Therefore, it is necessary to analyze the treated water (water in the treated water tank) that has passed through the sedimentation tank, which is the final stage of the treatment flow shown in Figure 1. In particular, it takes time to obtain analytical values ​​in facilities with large volumes of water. For this reason, it is difficult to quickly identify the occurrence of abnormal values ​​in the treated water when the treatment efficiency of coagulation and sedimentation deteriorates and water with a different concentration than normal flows into the treated water tank. In addition, since the treatment equipment targeted by this invention is a facility that treats large volumes of wastewater, the conventional reactive approach taken in response to abnormal values ​​detected in the treated water has the problem that a large amount of abnormally treated water (i.e., the amount in the sedimentation tank) is generated when there is an abnormality in the coagulation and sedimentation treatment where the treatment efficiency deteriorates. Furthermore, the abnormally treated water generated during this process requires retreatment, which creates a significant practical problem: a substantial loss of treatment efficiency.

[0017] In contrast to the conventional technology described above, the inventors of this invention conducted diligent research, considering that if the COD / phosphorus / nitrogen / cyanide content in the collected water (raw water) obtained by wet dust collection treatment of exhaust gas before treatment, which is the target of coagulation and sedimentation treatment, could be measured accurately, precisely, and simply, it might be possible to predict in advance the deterioration of treatment efficiency in coagulation and sedimentation treatment. As a result, they discovered a new water quality monitoring method of the present invention, which does not involve the retrospective monitoring that has been used in the past. First, in treatment equipment that processes COD / phosphorus / nitrogen / cyanide in raw water, as shown in Figure 1, the equipment is usually arranged in the order of mixing tank, coagulation tank, and sedimentation tank, and a coagulation and sedimentation treatment process is provided in which mixing treatment, coagulation treatment, and sedimentation treatment are performed in this order. Specifically, raw water is introduced into a mixing tank (sometimes called a pH adjustment tank), a coagulant is added and mixed, and then a polymer coagulant is added in the next coagulation tank to coagulate the raw water, which is then introduced into a sedimentation tank to perform solid-liquid separation and obtain treated water. The obtained treated water is transferred to a treated water tank and then discharged, etc. Conventional water quality monitoring methods used to address abnormalities in treated water quality, as mentioned earlier, monitor for abnormalities in the treatment process by automatically measuring the COD / phosphorus / nitrogen / cyanide content of treated water in the treatment tank after coagulation and sedimentation treatment. However, the timing of obtaining monitoring information is reactive, after an abnormality has occurred.

[0018] In contrast to the conventional technologies described above, the inventors of this invention discovered that if they could establish a new analytical method that allows for the measurement of COD / phosphorus / nitrogen / cyanide content in raw water (mixed water) containing a large amount of suspended solids (hereinafter also referred to as SS), which are the target of coagulation and sedimentation treatment, with a simple configuration, in addition to the automatic measurements that are constantly performed to confirm that the treated water meets water quality standards, without significantly changing the conventional treatment system, it would be possible to obtain highly accurate analytical values ​​for the raw water, thereby enabling prior monitoring of the treatment status in coagulation and sedimentation treatment. This led to the present invention. The present invention is characterized by the addition of a new analytical system that enables the measurement of COD / phosphorus / nitrogen / cyanide content in raw water with a simple configuration. According to the present invention, it is possible to quickly identify the possibility of deterioration in the treatment efficiency of coagulation and sedimentation treatment and the occurrence of abnormal values ​​in the treated water resulting from such deterioration, and to respond to such abnormal values ​​at an early stage.

[0019] In COD / phosphorus / nitrogen / cyanide treatment facilities, the raw water undergoes treatment processes that may result in the precipitation of suspended solids (SS), and the formation of aggregates during the treatment of COD / phosphorus / nitrogen / cyanide components, requiring post-treatment coagulation. Therefore, in order to obtain accurate and precise values ​​for the COD / phosphorus / nitrogen / cyanide content in the raw water that can be used to judge the efficiency of coagulation-sedimentation treatment, it is necessary to sufficiently remove SS from the analytical sample supplied to the analyzer. On the other hand, according to the inventors' studies, removing SS using only cartridge filters, which is a common practice, frequently results in SS blockage in the filters, necessitating frequent manual filter replacement. Thus, with SS removal using only cartridge filters, which is a common practice, frequent maintenance of the analyzer is required, making automatic operation difficult, and it is not possible to stably obtain analytical values ​​that can be used to predict deterioration in treatment efficiency after coagulation-sedimentation treatment.

[0020] In response to the above situation, the inventors recognized the importance of developing a sample preparation device (analytical system) that is useful as a sample preparation device for an analyzer, capable of automatic operation and with low maintenance load, capable of sufficiently removing suspended solids (SS) from the analytical sample to be supplied to the analyzer when measuring the COD / phosphorus / nitrogen / cyanide content in raw water. In other words, if such a sample preparation device can be developed, accurate and precise measurements of the COD / phosphorus / nitrogen / cyanide content in raw water before it is introduced into the sedimentation tank of the coagulation-sedimentation process can be obtained automatically at appropriate times as needed. As a result, by utilizing the obtained measurements (analytical values), deterioration in the processability of the coagulation-sedimentation process can be determined early, and early action can be taken based on this determination. This provides a superior effect that could not be obtained with conventional water quality monitoring of treated water, which is performed retrospectively only by automatic measurement of the treated water obtained after coagulation-sedimentation. For example, in conventional reactive measures against abnormal values ​​occurring in treated water, a significant practical benefit can be obtained by effectively suppressing situations where a large amount of abnormally treated water (equivalent to the sedimentation tank) is already generated when an abnormality occurs in the treated water, and retreatment is required for this large amount of abnormally treated water.

[0021] The effects of the present invention described above are achieved by a method for preparing analytical samples that is useful as a pretreatment device for analyzers, capable of automatic operation and low maintenance load, and capable of sufficiently removing suspended solids (SS) from analytical samples to be supplied to the analyzer. First, the treatment equipment targeted by the present invention has a coagulation-sedimentation treatment process in which raw water containing suspended solids precipitated in the treatment process and / or coagulated matter resulting from the treatment of COD / phosphorus / nitrogen / cyanide components is circulated in the treatment equipment, and mixing treatment, coagulation treatment and sedimentation treatment are performed in this order in equipment in which a mixing tank, a coagulation tank and a sedimentation tank are arranged in this order (see Figure 1). The object of the present invention is to enable the early detection of abnormal situations in the above coagulation-sedimentation treatment process using an unprecedented method, thereby enabling more stable treatment in treatment equipment that treats COD / phosphorus / nitrogen / cyanide in "dust collected water obtained by wet dust collection treatment of exhaust gas," which is the raw water.

[0022] The above objective is achieved by continuously circulating the raw water in the mixing tank of the treatment facility, intermittently separating a portion of it, and filtering the separated raw water using a filtration device having one or more cylindrical ceramic filters made of porous ceramic material. Specifically, by filtering the raw water separated from the mixing tank using a cylindrical ceramic filter, it is possible to prepare an analytical sample in a good condition with reduced suspended solids (SS), thereby achieving the objective of the present invention. That is, the present invention is characterized by adding a "sample collection and analysis step" to the conventional method for monitoring the water quality of treated water after COD / phosphorus / nitrogen / cyanide treatment, which has a coagulation-sedimentation step in which mixing, coagulation, and sedimentation are performed in that order, and automatically introducing a portion of the filtered water, which has been pressurized into the cylinder of a porous ceramic filter, into an analytical measuring device as an analytical sample for measuring the COD / phosphorus / nitrogen / cyanide content, and measuring the COD / phosphorus / nitrogen / cyanide content in the analytical sample.

[0023] The filtration device (pretreatment device) that characterizes the present invention, as shown in Figure 4-1, uses at least one cylindrical ceramic filter made of a porous ceramic material. Raw water separated from the mixing tank is injected under pressure into the cylinder of the ceramic filter, allowing the water in the raw water to permeate into the cylinder and obtain filtered water. A portion of the filtered water in the cylinder is taken out and automatically introduced into an analytical measuring device as an analytical sample for measuring the COD / phosphorus / nitrogen / cyanide content in the raw water. The COD / phosphorus / nitrogen / cyanide content in the analytical sample obtained above is then measured. The filtered water obtained by filtering the raw water as described above has a high removal rate of SS of 95% or more, and even 98% or more, and exhibits extremely high transparency (see Figure 3). Therefore, it does not affect the measurement of the COD / phosphorus / nitrogen / cyanide content in the analytical sample. As described above, the raw water for filtration (pretreatment) with the ceramic filter can be separated from the mixing tank while it is in a constantly circulating state. Furthermore, the raw water used for filtration (pretreatment) with a ceramic filter of a specific configuration, which is necessary when obtaining analytical samples in this invention, can be any raw water taken from within the mixing tank. It is not limited to raw water taken directly from within the mixing tank, but may also be raw water taken from a tank with a smaller capacity than the mixing tank, which is provided separately from the mixing tank as needed, and into which a portion of the raw water is branched off from the mixing tank and normally circulated back to the mixing tank.

[0024] As the cylindrical ceramic filter (ceramic membrane) made of a porous ceramic material that characterizes the present invention, for example, commercially available diatomaceous earth filter tubes with a pore size of 0.45 μm to 3.0 μm, or alumina membrane treatment with a pore size of 0.1 μm to 2.0 μm can be used. Both ceramic membranes have excellent heat resistance and can withstand raw water at high temperatures of 60°C, making them effective as ceramic filters used in the preparation of analytical samples by removing suspended solids (SS) from collected water (raw water) obtained by wet dust collection treatment of exhaust gas, which constitutes the present invention. Furthermore, the range of pore size is suitable for removing the above SS, and is not particularly limited as long as it can effectively and sufficiently remove SS from the raw water when a portion is intermittently separated while the raw water in the mixing tank is constantly circulated, and the separated raw water is filtered with the ceramic filter. According to the inventors' studies, the filtration treatment (pretreatment) performed to remove suspended solids (SS) from the raw water as described above should be carried out approximately 30 minutes before measuring the COD / phosphorus / nitrogen / cyanide content in the raw water.

[0025] As shown in Figure 2, when analyzing raw water, as described above, the raw water separated from the mixing tank is filtered through a ceramic filter, and a valve for shutting off water in the flow path leading to the analyzer is opened to adjust the amount of filtrate needed for measurement to be introduced into the analyzer. On the other hand, under normal conditions other than when analyzing raw water, as shown in Figures 1 and 2, the raw water separated from the mixing tank and introduced into the filtration device flows through the filtration device where the ceramic filter is installed, and is returned to the mixing tank by opening a valve for shutting off water in the flow path leading to the mixing tank as circulating water.

[0026] Among the commercially available products mentioned above, diatomaceous earth ceramic membranes, for example, have excellent surface strength and durability, and as explained below, the filtration surface can be easily restored. When clogging occurs on the surface (filtration surface) of a cylindrical ceramic filter due to suspended solids (SS) in the raw water during filtration, the pore size can be restored to a good state by, for example, applying a stainless steel brush to the filtration surface as shown in Figures 4-2 and 4-3, and automatically scraping the surface of the ceramic membrane with the brush. The resulting shavings containing the ceramic membrane are processed without any problems as sludge in the coagulation and sedimentation process performed on the raw water. By performing the above-described automated pore size restoration operation, the replacement frequency of the ceramic membrane can be extended to, for example, 50 to 150 days, depending on the SS concentration in the raw water and the frequency of preparing analytical samples after removing SS and analyzing the COD / phosphorus / nitrogen / cyanide content in those samples. Therefore, by using the above-mentioned unique cylindrical ceramic filter for filtration, the workload can be significantly reduced, and SS removal can be performed in a way that is excellent in terms of workability and cost-effectiveness. In contrast, according to the inventors' studies, when SS is removed from raw water using a conventional cartridge filter to obtain a sample for analysis, the filter must be replaced manually every 1 to 2 days, which places an extremely heavy burden on the replacement work, making practical application difficult based on this point alone.

[0027] Referring to Figure 2, an outline of a method for analyzing COD / phosphorus / nitrogen / cyanide using an analytical pretreatment device (filtration device) is described. In this invention, a new path is provided in which the raw water in the mixing tank is constantly circulating by operating a sampling pump at all times. A branch is provided in this path to intermittently separate a portion of the circulating raw water at a desired time (timing), and to prepare an analytical sample by removing suspended solids (SS) in the separated raw water using the filtration process described above. With this configuration, when no analytical sample is being collected, the raw water in the above path is returned to the mixing tank as circulating water. On the other hand, when preparing an analytical sample, the shut-off valve on the branch side is opened, allowing the raw water to be branched off from the constantly circulating path and filtered using the cylindrical ceramic filter described above to sufficiently remove SS from the raw water, thus preparing an analytical sample in good condition.

[0028] The preparation of analytical samples can be easily performed using the preparation apparatus of the present invention described below. The preparation apparatus for analytical samples of the present invention has a filtration means for filtering raw water, and as shown in Figure 4-1, the filtration means comprises one or more cylindrical ceramic filters (filtration membranes) made of a porous ceramic material housed in a pressure-resistant casing having at least two openings. The ceramic filter is characterized in that, when the raw water is injected under pressure into the casing, the water in the raw water permeates into the cylinder to become filtered water, and the solid components in the raw water remain on the surface of the cylinder. The cylindrical ceramic filter is preferably made of a porous material with a pore size of 0.1 μm to 5.0 μm. According to the inventors' studies, it is more preferable that the pore size of the porous material is 0.1 μm to 3.0 μm. The ceramic filter that characterizes the present invention is a cylindrical porous material with thick walls and is used housed in a pressure-resistant casing having openings for introducing raw water. Specifically, raw water is introduced into the casing through an opening and pressurized, allowing moisture from the raw water to permeate the cylinder through the pores on the surface of the cylindrical porous ceramic filter. This easily yields filtered water, and a portion of the filtered water obtained from the cylinder is taken out through an opening in the casing to prepare an analytical sample. For the ceramic filter that characterizes this invention, it is preferable to use one with a wall thickness of, for example, 10 mm to 20 mm.

[0029] In the present invention, as shown in Figure 2, it is also preferable to configure the system so that the filtered water obtained as described above is cooled to room temperature before being introduced into the analytical measuring device as an analytical sample. Furthermore, since the analytical samples necessary to effectively contribute to the control of operating conditions in the coagulation and sedimentation process, which is the ultimate goal of the present invention, can be prepared intermittently, as shown in Figures 1 and 2, the raw water in the filtration device separated from the mixed water is returned to the mixing tank and circulated when no analytical samples are being prepared. [Examples]

[0030] Next, a confirmation test was conducted to determine whether a good analytical sample could be prepared using simulated raw water with the analytical sample preparation apparatus of the present invention.

[0031] [Simulated raw water used in the verification test] For the verification test, simulated wastewater containing the following components was used as the raw water. Specifically, ion-exchanged water was used to achieve a pH of 7.8, and the concentrations of each component were as follows: thiocyanate ion (SCN) - ) 40 mg / L, total cyanide (T-CN) 19.5 mg / L, COD 44 mg / L, total nitrogen (TN) 160 mg / L, ammonia nitrogen (NH4) + A simulated wastewater (raw water) was prepared with -N at 140 mg / L, Ca at 150 mg / L, and Cu2O at 60 mg / L. The left side of Figure 3 shows the appearance of the simulated raw water prepared as described above in a beaker. The simulated raw water in the beaker on the left of Figure 3 was prepared by adding desired amounts of COD treatment agent, nitrogen treatment agent, cyanide treatment agent, and pH adjuster to the simulated wastewater with the above component composition, as shown in Figure 1, in order to make it the same condition as the raw water in the mixing tank of a treatment facility that treats COD / phosphorus / nitrogen / cyanide in dust collected by the wet dust collection treatment of exhaust gas shown in Figure 1. As shown in the beaker on the left side of Figure 3, discoloration due to the above-mentioned components of the simulated wastewater was observed, and it was very turbid. The SS of the simulated raw water in the beaker was measured according to JIS K0102 and was 320 mg / L.

[0032] In the simulated test to confirm the effectiveness using the simulated raw water prepared as described above, all steps were automated: the process of separating the raw water, the process of preparing the analytical sample by filtering the separated raw water using the filtration device described earlier with a cylindrical ceramic filter, and the subsequent process of transferring the prepared analytical sample to each analytical instrument. In addition, 30 minutes before analysis with the analytical instrument, the process of injecting the separated raw water under pressure into a cylindrical ceramic filter for filtration and flowing the resulting filtrate in the cylinder into the channel leading to the analyzer was initiated. Figures 4-2 and 4-3 show a schematic of the filtration device used in the above confirmation test. As shown in these figures, the confirmation test used a filtration device consisting of six cylindrical ceramic filters of the same size and shape.

[0033] The filtration apparatus used in the process of preparing analytical samples by filtering them with the six cylindrical ceramic filters used in the above-mentioned confirmation test will now be described. The filtration apparatus used in the confirmation test, as shown in Figures 4-2 and 4-3, is an automatic cleaning type, consisting of a filtration unit housed in a pressure-resistant, barrel-shaped stainless steel casing, with six thick-walled cylindrical ceramic filters and a stainless steel cleaning brush positioned so that the tip of the brush contacts the filtration surface of the ceramic filters. Each ceramic filter used was made of diatomaceous earth, Cerapore (product name), with a pore size of 3 μm. Each cylindrical ceramic filter was 430 mm long, 82 mm in outer diameter, and 20 mm thick.

[0034] In the confirmation test, simulated wastewater (simulated raw water) prepared as described above, with the desired amounts of COD treatment agent, nitrogen treatment agent, cyanide treatment agent, and pH adjuster added to match the raw water in the mixing tank, was filtered using a filtration device to obtain filtrate for use as an analytical sample. The right side of Figure 3 shows the filtrate in the beaker obtained after filtration. As shown in Figure 3, the filtrate was clear and extremely transparent, completely different from the colored and turbid simulated raw water shown on the left side of Figure 3. The SS removal rate of the obtained filtrate was calculated to be 98.8%, showing an extremely high removal rate, confirming that almost no SS remained. As a result, it was confirmed that the properties of the analytical sample prepared by introducing simulated raw water into the filtration device with the above configuration were in good condition, with SS in the raw water removed at the high removal rate described above, and not affecting the subsequent measurement of COD / nitrogen / cyanide content using each analytical instrument.

[0035] The filtration device used in the verification test, as shown in Figures 4-2 and 4-3, has an automatic cleaning filtration unit equipped with six cylindrical ceramic filters (filtration membranes) and one stainless steel cleaning brush. When the verification test was continued, clogging of the pore size occurred on the surface (filtration surface) of each ceramic filter. When the cleaning brush was used to restore the surface (filtration surface) of each ceramic filter, it was confirmed that the filtration surface could be effectively restored to a normal, unclogging state within the filtration device. This indicates that if a filtration device consisting of the ceramic filters and stainless steel cleaning brush described above is used, the ceramic filters can be used for a longer period without replacement. According to the inventors' studies, for example, if the surface of each ceramic filter is brushed for about 100 to 200 seconds once a day while intermittently filtering raw water, it may be possible to use the filters for a period of about 100 to 200 days. Furthermore, this indicates that while conventional methods for removing suspended solids require frequent manual cartridge replacement, the use of the unique filtration device defined in this invention drastically reduces the workload.

Claims

1. A water quality monitoring method is provided for use in a treatment facility that uses wastewater obtained from wet dust collection treatment of exhaust gas requiring treatment of dissolved components as raw water, and for obtaining treated water by treating the COD and / or phosphorus and / or nitrogen and / or cyanide in the raw water. This method includes a configuration for checking the water quality of the treated water obtained after coagulation and sedimentation treatment of the COD and / or phosphorus and / or nitrogen and / or cyanide in the raw water, as well as a configuration for enabling early response to abnormalities occurring in the water quality of the treated water. A configuration for confirming the water quality of the treated water includes a measurement step for automatically measuring the COD and / or phosphorus and / or nitrogen and / or cyanide content in the treated water, The raw water, which contains suspended solids precipitated in the treatment process and / or aggregates containing at least one of copper, iron, and calcium resulting from the treatment of COD and / or phosphorus and / or nitrogen and / or cyanide components, is circulated in the aforementioned treatment facility, and the facility has a mixing tank, a coagulation tank, and a sedimentation tank arranged in this order, and the main treatment for obtaining the treated water is performed by carrying out mixing, coagulation, and sedimentation in this order, comprising a coagulation-sedimentation treatment step, In addition, as a configuration to enable the aforementioned early response, the raw water in the mixing tank is continuously circulated while a portion is intermittently separated, and a filtration device having a cylindrical ceramic filter made of a porous ceramic body is used to pressurize the separated raw water into the cylinder of the ceramic filter, allowing the moisture in the raw water to permeate into the cylinder to obtain filtered water and perform pretreatment of the raw water, a portion of the filtered water from the pretreated cylinder is taken out, and the extracted filtered water is automatically introduced into an analytical measuring device as an analytical sample for measuring the COD and / or phosphorus and / or nitrogen and / or cyanide content in the raw water, and the analytical measuring device is used. A method for monitoring the water quality of treated water after treatment for COD and / or phosphorus and / or nitrogen and / or cyanide, characterized by comprising: a sampling and analysis step of an analytical sample in which the content of COD and / or phosphorus and / or nitrogen and / or cyanide in the analytical sample is automatically measured using a constant device; and a control step of predicting the occurrence of an abnormality in at least one of the measured values ​​of the content of COD and / or phosphorus and / or nitrogen and / or cyanide in the treated water obtained in the measurement step by using the measured values ​​obtained in the sampling and analysis step, and controlling the operating conditions of the coagulation and sedimentation treatment step based on the prediction.

2. The method for monitoring the water quality of treated water after COD and / or phosphorus and / or nitrogen and / or cyanide treatment, according to claim 1, wherein in the step of collecting and analyzing the sample for analysis, the extracted filtered water is cooled to room temperature before being used as the sample for analysis.

3. The method for monitoring the water quality of treated water after treatment with COD and / or phosphorus and / or nitrogen and / or cyanide, according to claim 1 or 2, wherein the pore size of the cylindrical ceramic filter made of the porous body is 0.1 μm or more and 5.0 μm or less.

4. The method for monitoring the water quality of treated water after treatment of COD and / or phosphorus and / or nitrogen and / or cyanide, according to claim 1 or 2, wherein the cylindrical ceramic filter made of the porous body is made of a porous material mainly composed of alumina or diatomaceous earth.

5. A method for monitoring the water quality of treated water after treatment of COD and / or phosphorus and / or nitrogen and / or cyanide, according to claim 1 or 2, wherein in the step of collecting and analyzing the sample for analysis, the cylindrical ceramic filter made of a porous body is made of a porous material mainly composed of diatomaceous earth, a stainless steel brush is provided so as to be able to contact the cylindrical surface of the cylindrical ceramic filter, and the stainless steel brush is used to scrape off and remove solid matter in the raw water remaining on the cylindrical surface of the cylindrical ceramic filter when obtaining the filtered water.

6. An analytical sample preparation device used in a treatment facility that uses dust collected water obtained by wet dust collection treatment of exhaust gas as raw water and treats COD and / or phosphorus and / or nitrogen and / or cyanide in said raw water, the device contains suspended solids precipitated in the treatment process and / or aggregates containing at least one of copper, iron and calcium resulting from the treatment of COD and / or phosphorus and / or nitrogen and / or cyanide components, and is used when measuring the COD and / or phosphorus and / or nitrogen and / or cyanide content in said raw water, A pre-processing apparatus for obtaining the aforementioned analytical sample, An analytical sample preparation apparatus comprising a filtration means for filtering the raw water, wherein the filtration means comprises one or more cylindrical ceramic filters made of a porous ceramic material housed in a pressure-resistant casing having at least two openings, and the ceramic filters have the function of allowing water in the raw water to permeate into the cylinder and become filtered water when the raw water is injected under pressure into the casing, and allowing solid components in the raw water to remain on the surface of the cylinder.

7. The apparatus for preparing analytical samples according to claim 6, wherein the cylindrical ceramic filter is made of a porous material having a pore size of 0.1 μm to 5.0 μm.

8. Furthermore, the apparatus for preparing analytical samples according to claim 6 or 7, wherein the cylindrical ceramic filter is made of a porous material mainly composed of diatomaceous earth, and a stainless steel brush for scraping off solid matter in the raw water remaining on the surface of the cylinder is provided in a manner that allows it to contact the cylindrical surface of the cylindrical ceramic filter.

9. The apparatus for preparing analytical samples according to claim 6 or 7, wherein a filtration unit is arranged within the pressure-resistant casing, comprising a cylindrical ceramic filter and a stainless steel brush for scraping off solid matter remaining on the surface of the cylinder in the raw water.

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