JP5214424B2 - Wastewater treatment equipment - Google Patents

Description

  The present invention relates to a wastewater treatment apparatus that reduces the amount of additives used and efficiently collects suspended substances in wastewater.

  In general industries such as the electronic component manufacturing industry, the machine processing industry, and the food processing industry, wastewater is generated in factories. The wastewater generated in the factory is usually sent to a wastewater treatment facility in the factory and discharged as sewage after chemical or physical treatment or reused in the factory.

  As an example of the wastewater treatment, there is a filtration treatment for collecting and removing suspended substances contained in the wastewater using a filtration filter. On the other hand, the suspended solids contained in the wastewater include easily filterable suspended solids that are easy to filter, and difficult-to-filter suspended solids that are difficult to filter. When such a difficult-to-filter suspended substance is filtered, for example, the filtration flow rate of the filtration filter is reduced (constant pressure filtration) or the filtration differential pressure is rapidly increased (quantitative filtration) in a short time. Therefore, there is a problem that the filter needs to be replaced.

  For such problems, when filtering and dewatering difficult-to-filter wastewater, a flocculant (such as ferric chloride, aluminum sulfate or polyaluminum chloride) is added to the wastewater before the filtration and dewatering treatment. Suspended substances can be changed to properties that are easy to filter and dehydrate.

  On the other hand, since it is necessary to add a large amount of flocculant, there is a problem that a large amount of additive (flocculant) is required for wastewater treatment. In addition, when using a treatment method that adds a flocculant, suspended matter and a large amount of the added flocculant are recovered as waste (sludge), so that the amount of recovered waste is large. There is. Specifically, the collected waste contains a flocculant several to several tens times as many as the suspended solids.

  Moreover, as a method of filtering difficult-to-filter wastewater, there is a method (precoat method) in which the surface of the filtration filter is pre-coated with a filter aid such as diatomaceous earth or pearlite in advance, and the filter hole is blocked and blocked. (For example, refer to Patent Document 1 and Non-Patent Document 1). When using this pre-coating method, after pre-coating the filtration filter surface with a filter aid, water of difficult-to-filter drainage (treated water) is passed. Thereafter, the suspended matter collected on the surface of the filter aid pre-coated on the filter is separated by backwashing at a regular timing or after a predetermined amount of treatment, and the separated filter aid is collected. Suspended material is collected as waste.

  As described above, the precoat method is a method in which a filter aid is precoated on a filtration filter. In addition to precoating a filtration filter, a filter aid is added to wastewater, and wastewater to which a filter aid is added (treated water). ) Is filtered using a filtration filter (body feed method). Even with this body feed method, the filter hole can be blocked. Even in this body feed method, the filter aid and suspended substances are recovered as waste.

  In a method using such a filter aid, it is necessary to add a large amount of filter aid to the waste water. Therefore, there is a problem that a large amount of additive (filter aid) is required for wastewater treatment. In addition, the finally recovered waste includes a filter aid together with suspended substances. In this case as well, there is a problem that the recovered waste becomes large.

  Moreover, as shown in FIG. 6, methods other than a filtration process may be utilized for the process of a difficult-to-filter waste water. In the wastewater treatment apparatus 1 shown in FIG. 6, the wastewater is collected in the wastewater storage tank 100 and then sent to the adjustment tank 101. In the adjustment tank 101, acid, alkali, or the like is added to the wastewater sent from the drainage storage tank 100 to adjust the wastewater to a pH suitable for coagulation precipitation, and the adjusted wastewater is sent to the aggregation tank 102. In the coagulation tank 102, when a floc of suspended material is formed by adding a flocculant to the wastewater sent from the adjustment tank 101, the wastewater containing the floc is sent to the precipitation tank 103. The flocculant added here is an inorganic chemical, an organic polymer chemical, or the like, and is determined by the suspended substance contained in the waste water.

  In the sedimentation tank 103, the waste water containing floc is settled and separated. Thereafter, the sedimentation tank 103 feeds the settled floc to the concentration tank 104 and feeds the supernatant to the supernatant storage tank 105. The concentration tank 104 feeds the supernatant of the upper liquid layer formed over time to the supernatant storage tank 105. Since the supernatant liquid fed to the supernatant storage tank 105 contains a small amount of flocs, the filtration device 106 feeds the supernatant liquid from which the flocs have been removed by filtering the supernatant liquid to the neutralization tank 107. To do. Moreover, the neutralization tank 107 adjusts the water quality of the sent supernatant and discharges it as treated water.

Further, the floc concentrate from which the supernatant has been removed in the concentration tank 104 is sent to the dehydrator 108 and dehydrated to become waste. That is, when the waste water treatment apparatus 1 shown in FIG. 6 is used, the volume of waste finally recovered can be reduced by removing moisture from the waste by the dehydrator 108.
Japanese Patent No. 2106671 "Chemical Engineering Handbook, Revised 5th Edition, Chemical Engineering Association", Maruzen Co., Ltd., March 18, 1988, pages 713-715

  However, in the method using the coagulation sedimentation and dehydration process described above with reference to FIG. 6, the coagulation tank 102, the sedimentation tank 103, and the dehydrator 108 are relatively large in size, and the overall size of the waste water treatment apparatus 1 is also large. It is necessary to secure the installation location. Moreover, since it is necessary to add a large amount of flocculant to the waste water, a large amount of additive (flocculating agent) is required. In addition, even if the waste collected from the concentration tank 104 is dehydrated by the dehydrator 108, a large amount of flocculant is added to the waste water, so the amount of the suspended material added with the flocculant is the waste. (Sludge) amount.

  In view of the above problems, the present invention provides a wastewater treatment apparatus that minimizes the use of additives and efficiently collects hardly filterable suspended solids in wastewater.

  The wastewater treatment apparatus according to the present invention is provided with a filter aid for a wastewater treatment tank to which wastewater containing difficult-to-filter suspended solids is fed via an inflow line, and for wastewater flowing through the inflow line or wastewater in the wastewater treatment tank. A filter aid adding means for adding the agent, a filtration device for separating the waste water after the addition of the filter aid into a mixed liquid of the suspended substance and the filter aid and treated water, and a mixed solution obtained by the filtration device Is separated into a suspended substance and a filter aid, and a filter aid recovery line for sending the filter aid separated by the separator to a filter aid recovery tank.

  ADVANTAGE OF THE INVENTION According to this invention, the usage-amount of an additive can be suppressed to the minimum, and the hardly-filterable suspended solid in waste water can be collected efficiently.

  The waste water treatment apparatus according to the present invention is an apparatus for treating difficult-to-filter waste water containing suspended substances such as sticky suspended substances and clay substances having a fine particle size. Below, the waste water treatment equipment concerning each embodiment is explained using a drawing.

<First Embodiment>
As shown in FIG. 1, the wastewater treatment apparatus 1 a according to the first embodiment of the present invention includes a wastewater treatment tank 11 to which wastewater is fed via an inflow line 10, and a filtration aid for adding a filter aid to the wastewater. An agent addition means 12, a filtration device 16 that separates the waste water containing the filter aid into a suspension material / filter aid mixture (concentrated liquid) and treated water, and a suspension material / filter aid mixture A filter aid separator 19 that separates the suspended substance and the filter aid, a suspension collection tank 21 that collects the suspended substance, and a super-agent collection tank 23 that collects the filter aid are provided. .

The wastewater treatment tank 11 is fed with wastewater containing a hardly filterable suspended substance to be treated via the inflow line 10. Further, a filter aid is also added to the wastewater treatment tank 11 from the filter aid addition means 12 through the pump 13. Filtration aid adding means 12 facilitates filtration by adding the filtration aid to the waste water treatment tank 11 so that the concentration of the filtration aid is 100 to 5000 ppm. As the super-auxiliary agent added to the waste water treatment tank 11 by the filter aid addition means 12, iron powder, magnetite particles, etc. are used instead of diatomaceous earth, perlite, etc. that have been widely used as filter aids. Further, the filter aid is a filterable material having a filtration specific resistance of about 10 ¹¹ to 10 ¹² m / kg and using a recoverable substance.

  Inside the waste water treatment tank 11, the waste water is stirred by the stirrer 14, and the filter aid added to the waste water is mixed with the waste water. The waste water mixed with the filter aid is sent to the filtration device 16 via the pump 15.

  The filtration device 16 uses a filtration filter (not shown) to separate the waste water into a mixture of suspended substances and filter aid and treated water. Since the filtration specific resistance of the filter aid is sufficiently low, the increase in the filtration differential pressure in the filtration device 16 is kept low, and the treated water from which suspended substances have been removed is discharged from the treated water line 17 from the filtration device 16. The Suspended substances and filter aids remain in the filtration device 16 after discharging the treated water. The suspended substance and filter aid remaining in the filtration device 16 are mixed with the backwash water and backwash water by backwashing using water (backwash water) or air. And supplied to the filter aid separator 19.

  The filter aid separator 19 separates the suspended substance and the filter aid from the mixed solution of the suspended substance and the filter aid supplied from the filtration device 16, and the suspension (suspended substance and backwash water). ) Is discharged to the suspension recovery tank 21 via the suspension recovery line 20, and the filter aid is discharged to the filter aid recovery tank 23 via the filter aid recovery line 22.

  For example, when the filter aid is a magnetic substance such as iron powder or magnetite having the property of being attracted to the magnet, the filter aid separator 19 uses the magnet to suspend the suspended matter as shown in FIG. And filter aid can be separated. In the filter aid separator 19 shown in FIG. 2 (a), when the mixed liquid of the suspended substance and the filter aid is supplied into the separation tank 191, the mixture is stirred by the stirrer 192. A magnet 193 is installed on the outer periphery of the separation tank 191, and the filter aid adheres to the inner wall surface of the separation tank 191 by being attracted by the magnetic force of the magnet 193. On the other hand, since the suspended matter does not have the property of being attracted to the magnetic force, the suspended matter does not adhere to the inner wall surface of the separation tank 191 and exists in the backwash water in the separation tank 191.

  Therefore, if the valve 201 is opened and the valve 211 is closed while the filter aid is attached to the inner wall surface of the separation tank 191, the suspension (suspension material and backwashing) is passed through the suspension recovery line 20. Water) can be recovered in the suspension recovery tank 21. In addition, after the suspended substance is discharged from the separation tank 191, if the valve 201 is closed and the valve 211 is opened so that the magnetic force of the magnet 193 is not applied to the separation tank 191, the filter aid recovery line 22 is opened. The filter aid can be collected in the filter aid collection tank 23. For example, when the magnet 193 is an electromagnet, the power source of the magnet 193 may be turned off.

  Further, when the filter aid is a substance having a large specific gravity, the filter aid separator 19 can separate the suspended substance and the filter aid using a liquid cyclone as shown in FIG. . In the example shown in FIG. 2B, the suspension recovery line 20 is connected to the upper part of the separation tank 191, and the filter aid recovery line 22 is connected to the lower part. In the separation tank 191, the mixed liquid of the suspended substance and the filter aid is swirled, the suspended substance is floated by centrifugation and discharged from the suspension collection line 20, the filter aid is settled, and the filter aid collection line is collected. 22 is discharged.

  The filter aid recovered in the filter aid recovery tank 23 is circulated to the filter aid addition means 12 through the filter aid circulation line 25 by the pump 24 and reused.

  In FIG. 1, the filter aid is added from the filter aid addition means 12 to the wastewater in the wastewater treatment tank 11, but the filter aid is added to the wastewater flowing through the inflow line 10 that supplies wastewater to the wastewater treatment tank 11. May be added.

  As described above, in the waste water treatment apparatus 1a, a filter aid can be added to the waste water to easily separate suspended substances from difficult-to-filter waste water, and a mixed liquid of suspended substances and filter aids can be used. Since the filter aid can be recovered by separating it into a suspended substance and a filter aid and the filter aid can be reused, the amount of additive used can be reduced. Also, instead of using the mixed liquid of suspended solids and filter aid obtained by filtration as waste, only the suspension is recovered from the mixed liquid and made into waste. Can do. Furthermore, since the wastewater treatment apparatus 1a is not configured to add a flocculant, a large-sized agglomeration tank or sedimentation tank is unnecessary, and the installation location can be reduced compared to a wastewater treatment apparatus that requires agglomeration sedimentation. .

<Second Embodiment>
As shown in FIG. 3, the wastewater treatment apparatus 1 b according to the second embodiment of the present invention adds a release agent to the filter aid separator 19 as compared with the wastewater treatment apparatus 1 a described above with reference to FIG. 1. The difference is that a release agent adding means 26 is provided.

  The suspended substances contained in the wastewater have different surface charges and hydrophilic / hydrophobic states depending on the type, and may be adsorbed on the surface of the filter aid. Further, when the suspended substance is adsorbed on the surface of the filter aid and its peelability is poor, the separation may be difficult even if the suspended substance and the filter aid are separated by the filter aid separator 19.

  Thus, when it is difficult to separate the filter aid and the suspended matter, the suspended matter may be adsorbed on the filter aid collected in the filter aid collection tank 23. Therefore, the suspended substance adsorbed on the filter aid together with the filter aid by the filter aid adding means 12 may flow into the waste water treatment tank 11 again.

  If suspended substances accumulate in the wastewater treatment apparatus 1b and circulate together with the filter aid, problems such as a short backwash interval in the filter device 16 or the need to replace the filter aid arise. In FIG. 4, the backwashing timings a1 to a7 when the suspended substance is adsorbed on the filter aid and the peelability of the filter aid and the suspended substance is poor, and the filter aid and the suspended substance are separated. The timing of backwashing b1 to b7 when the property is good is compared. In this way, when the filter aid and the suspended substance are poorly peelable, the backwash interval is shorter than when the thinness is good, and eventually the filter aid needs to be replaced. I understand that

  The stripping agent adding means 26 adds a stripping agent for stripping the suspended matter adsorbed on the filter aid to the filter aid separator 19 in order to improve the separation efficiency between the suspended matter and the filter aid. As the release agent added by the release agent adding means 26, for the purpose of changing the surface potential of the filter aid, for example, a chemical such as sulfuric acid, hydrochloric acid or sodium hydroxide may be used for the purpose of removal by pH adjustment. Alternatively, warm water may be used for the purpose of peeling due to surface alteration due to an increase in liquid temperature, and can be determined according to the properties of the suspended substance and the filter aid.

  As described above, in the wastewater treatment apparatus 1b, when suspended substances are adsorbed on the filter aid and the peelability is poor, the release agent is added, so that the filter aid is not required to be replaced or the number of times of replacement is reduced. Can do. Moreover, since the waste water treatment apparatus 1b has the same configuration as the waste water treatment apparatus 1a, it is possible to reuse the filter aid, reduce the amount of additive used, and the amount of waste. In addition, since the coagulation sedimentation treatment is not performed, the installation location can be reduced.

<Third Embodiment>
As shown in FIG. 5, the wastewater treatment apparatus 1 c according to the third embodiment of the present invention has a suspension in the suspension collection tank 21 as compared with the wastewater treatment apparatus 1 a described above with reference to FIG. 1. The difference is that a dehydrator 27 for dehydration is connected.

  The dehydrator 27 dehydrates the suspension supplied from the suspension collection tank 21 via the pump 28.

  In addition to suspended substances recovered from the waste water, the suspension includes liquid that has not been discharged as treated water and backwash water. Therefore, by removing moisture from the suspension, it becomes possible to recover only the suspended substance as waste.

  As described above, in the wastewater treatment apparatus 1c, the waste material obtained by dehydrating the suspension with the dehydrator 27 is used as the waste material, so that the final waste volume can be reduced. Moreover, since the waste water treatment apparatus 1c has the same configuration as the waste water treatment apparatus 1a, it is possible to reuse the filter aid, reduce the amount of additive used, and reduce the amount of waste. In addition, since the coagulation sedimentation treatment is not performed, the installation location can be reduced.

It is a figure explaining the composition of the waste water treatment equipment concerning a 1st embodiment. It is a figure explaining an example of a filter aid separator. It is a figure explaining the structure of the waste water treatment equipment which concerns on 2nd Embodiment. It is a figure explaining the peelability and backwashing of a filter aid. It is a figure explaining the structure of the waste water treatment equipment which concerns on 3rd Embodiment. It is a figure explaining the structure of the conventional waste water treatment equipment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a-1c ... Waste water treatment apparatus 10 ... Inflow line 11 ... Waste water treatment tank 12 ... Filter aid addition means 13 ... Pump 14 ... Stirrer 15 ... Pump 16 ... Filtration apparatus 17 ... Treated water line 18 ... Backwash line 19 ... Filtration aid Agent separator 191 ... Separation tank 192 ... Stirrer 193 ... Magnet 20 ... Suspension recovery line 201 ... Valve 21 ... Suspension recovery tank 22 ... Filter aid recovery line 221 ... Valve 23 ... Filter aid recovery tank 24 ... Pump 25 ... Filter aid circulation line 26 ... Release agent addition means 27 ... Dehydrator 28 ... Pump

Claims (4)

A wastewater treatment tank to which wastewater containing difficult-to-filter suspended solids is sent through an inflow line;
The flow through the inlet line against the drainage of waste water or the wastewater treatment tank, a filter aid adding means for adding a filter aid to react to a magnetic force to a concentration of 100 to 5000 ppm,
A filtration device for separating the waste water after the addition of the filter aid into a mixed liquid of suspended solids and filter aid and treated water;
A container to which the mixed liquid is supplied; a stirrer for stirring the mixed liquid in the container; and a magnet disposed on an outer periphery of the container; When separating the turbid substance and the filter aid, a magnetic force is applied to the container, the filter aid is collected on the inner wall of the container, and only the suspended substance is discharged from the container. A separator that discharges the filter aid from the container in a state in which no magnetic force is applied therein,
A filter aid recovery line for sending the filter aid separated by the separator to a filter aid recovery tank;
A wastewater treatment apparatus comprising:   The wastewater treatment apparatus according to claim 1, further comprising a circulation line for circulating the filter aid recovered in the recovery tank to the filter aid addition means.   A release agent that changes the surface potential state of the filter aid or changes the surface temperature of the filter aid to peel off the suspended material adhering to the filter aid to the mixture of the suspended material and the filter aid. The wastewater treatment apparatus according to claim 1, further comprising a release agent adding means to be added.   The wastewater treatment apparatus according to any one of claims 1 to 3, further comprising a dehydrating unit that dehydrates the suspended substance separated by the separator.

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