JP2015058401A - Wastewater treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wastewater treatment apparatus which recovers metals in wastewater by a simple treatment process.SOLUTION: In a wastewater treatment apparatus which recovers metals by a simple treatment process, hardly biodegradable substances contained in wastewater are degraded to easily degradable substances by air added with low-concentration ozone, the easily degradable substances are treated and metals contained in the wastewater are adsorbed and precipitated by biological treatment in a membrane separation activated sludge tank 7, and only the precipitated metal fine particles are recovered.

Description

  The present invention relates to treatment of biologically incurable organic wastewater containing metal and metal recovery.

  At present, reducing industrial waste, separating and reusing industrial waste, or not releasing industrial waste to the natural world is an important theme from the viewpoint of ecology and is a corporate issue in the 21st century. In particular, rare metals and precious metals have a depletion problem, and recovery from waste is important.

  Among these industrial wastes, there are various fluids containing the objects to be removed. These are expressed in various words such as sewage, drainage, and waste liquid. Hereinafter, a substance that is a substance to be removed in a fluid such as water or chemicals will be referred to as drainage.

  These waste water is reused by removing the object to be removed by an expensive filtration device or the like, and the waste water becomes a clean fluid. Further, the separated objects to be removed or those that cannot be filtered are treated as industrial waste. Waste may contain metals, and useful metals are further recovered. The waste water containing these useful metals includes waste water containing biodegradable substances. In this case, further decomposition treatment is performed.

  As a conventional method for treating biologically difficult-to-decompose organic wastewater, accelerated oxidation treatment with addition of chemicals such as ozone and hydrogen peroxide is performed. In the accelerated oxidation treatment, an excessive drug is added to decompose the biodegradable substance, the remaining drug is rendered harmless, and the biological treatment is performed later (for example, refer to Patent Documents 1 and 2). Thereafter, metals such as platinum contained in the waste water are converted into chlorides using a crystallization reaction (see, for example, Patent Document 3) or recovered as metal fine particles by a microorganism that reduces metal ions (for example, Patent Document). 4).

Japanese Patent No. 372512 JP 2002-166275 A Japanese Patent No. 3479483 JP 2013-13403 A

  In such a conventional technique, when metal ions or metal complexes are contained in the biologically degradable wastewater, crystallization of recovering metal ions or metal complexes after oxidative decomposition of the hardly decomposable substance with a chemical such as ozone, etc. Therefore, the wastewater treatment process becomes complicated, and the efficiency of recovering metals, metal ions, and metal complexes is low. In addition, metals are often contained in sludge and recovered in a low content, and incineration is necessary to recover from sludge at a high concentration.

  Then, this invention solves said subject and it aims at providing the waste_water | drain processing apparatus which collect | recovers the metals in waste_water | drain by a simple processing process.

  And in order to achieve this object, in the present invention, a decomposition tank for decomposing a biologically difficult-to-decompose wastewater containing metal with ozone-added air to obtain decomposition water; A membrane separation activated sludge tank for obtaining concentrated water containing sludge, a sedimentation separation tank for obtaining a supernatant liquid by settling sludge in the concentrated water, and a separation part for recovering metal from the supernatant liquid by a separation part. This is a featured wastewater treatment device. This achieves the intended purpose.

  ADVANTAGE OF THE INVENTION According to this invention, without performing the complicated process and control for collect | recovering metals, a metal can be collect | recovered and the effect of making a collection | recovery process easy can be acquired.

Configuration diagram of platinum-containing biodegradable wastewater treatment apparatus of Embodiment 1 of the present invention

  The waste water treatment apparatus according to claim 1 of the present invention is a decomposition tank for decomposing biodegradable waste water containing metal by ozone-added air to obtain decomposition water, and reducing metal from the decomposition water as fine particles by microorganisms. A membrane separation activated sludge tank for obtaining concentrated water containing metal-containing sludge, a sedimentation separation tank for obtaining a supernatant liquid by settling sludge in the concentrated water, and a separation part for recovering metal from the supernatant liquid by a separation part. Is.

  Thereby, there exists an effect that waste water treatment and the collection | recovery of the metal in waste water can be performed efficiently with a simple processing apparatus and a collection process.

  Further, the wastewater treatment apparatus according to claim 2 continues the recovery of the metals without reducing the amount of microorganisms adsorbing the metals by returning the sludge settled in the sedimentation separation tank to the membrane separation activated sludge tank. There is an effect that can be done.

  Moreover, the waste water treatment apparatus according to claim 3 has an effect of supplying the organic matter necessary for biological treatment by returning the residual treated water from which the metal has been recovered to the membrane separation activated sludge tank.

  Moreover, the waste water treatment apparatus according to claim 4 has an effect that metal having a high specific gravity can be efficiently separated by using a centrifugal separator in the separation section.

  Moreover, the waste water treatment apparatus of Claim 5 has the effect that it can isolate | separate efficiently even the metal used as a fine particle by using a microfiltration membrane for a separation part.

  Moreover, the waste water treatment apparatus of Claim 6 has an effect that biological sludge can be separated when the pore diameter of the microfiltration membrane used in the separation section is 0.4 μm or less.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
As shown in FIG. 1, the wastewater treatment apparatus includes a decomposition tank 2 for decomposing biologically degradable wastewater 1 containing metal by ozone-added air 4 to obtain decomposition water 6, and metal from decomposition water 6 by microorganisms. Membrane separation activated sludge tank 7 that obtains concentrated water 14 containing metal-containing sludge by reducing as fine particles, sedimentation separation tank 15 that sediments sludge in concentrated water 14 to obtain supernatant liquid 17 and concentrated water 14, and separation unit A separation unit 18 for recovering metal from the supernatant liquid 17 is provided.

  The decomposition tank 2 includes a decomposition tank diffusion tube 3 through which ozone-added air 4 is diffused. In the membrane separation activated sludge tank 7 into which the cracked water 6 obtained from the decomposition tank 2 is introduced, the floating sludge 8 is stored, and the activated sludge tank aeration pipe 9 that diffuses air 10 is installed at the bottom. Furthermore, it comprises an immersion membrane unit 12 for sucking filtered water 13 from the concentrated water 14.

  The operation | movement which collect | recovers metals from the waste_water | drain 1 of a biodegradable waste water treatment apparatus in the said structure is demonstrated.

  When the wastewater 1 is supplied to the decomposition tank 2, the decomposition tank 2 introduces ozone-added air 4 from the decomposition tank aeration pipe 3 and generates ozone-containing bubbles 5. Biodegradable substances can be decomposed into biodegradable easily degradable substances.

  The bubble diameter of the ozone-containing bubbles 5 may be in the range of the ordinary membrane separation activated sludge method, but is preferably several μm to several mm in order to improve the contact efficiency with the biologically indegradable substance.

  The ozone concentration of the ozone-added air 4 is preferably set to a concentration of 0.1 ppm in the upper space of the decomposition tank 2.

  When the TOC (total organic carbon concentration) of the wastewater 1 is 1000 mg / L, the biodegradable substance can be decomposed if it is about 15 ppm. When ozone dissolves in the waste water 1, it decomposes and disappears directly, so there is no dissolution in the decomposed water 6. When the pH of the wastewater 1 is in the acidic or alkaline region, it is efficient by adjusting the pH in the subsequent treatment by making the decomposition tank 2 neutral.

  Next, the decomposed water 6 that has become an easily decomposable substance by ozone is sequentially sent to the membrane separation activated sludge tank 7.

  The decomposed water 6 is decomposed by microorganisms contained in the floating sludge 8 in the membrane separation activated sludge tank 7. In this decomposition process, the organism can adsorb and reduce the metals contained in the waste water 1.

  In the membrane separation activated sludge tank 7, air 10 is diffused by the activated sludge tank aeration pipe 9 installed at the bottom, and aerobic treatment is performed. The air 10 becomes bubbles 11 of a predetermined size by the activated sludge tank diffuser tube 9 and rises in the submerged membrane unit 12. The air bubbles 11 serve as an oxygen supply source of the floating sludge 8 made of an aggregate of microorganisms and have a function of preventing the accumulation of the floating sludge 8 on the surface of the submerged membrane unit 12. The adsorbed and reduced metals are stored in the microorganisms of the floating sludge 8 or discharged as fine particles from the floating sludge 8 and dispersed.

  At this time, metal fine particles such as platinum deposited by biological treatment are dispersed together with the floating sludge 8 in the membrane separation activated sludge tank 7.

  The submerged membrane unit 12 installed vertically above the activated sludge tank diffuser 9 discharges filtered water 13 by sucking the inside. Since the particle size of the metal particles such as the floating sludge 8 and precipitated platinum is several hundred nm to several μm, the pore diameter of the membrane usually used in the membrane separation activated sludge method is 0.25 μm to 0.4 μm. There is little discharge | emission from the separation activated sludge tank 7, and it concentrates in the tank. Usually, it can be concentrated to about tens of thousands mg / L as the suspended sludge concentration.

  In order to further simplify the treatment process, the decomposition tank 2 and the membrane separation activated sludge tank 7 may be shared. In the case of common use, the ozone concentration of the ozone-added air 4 is changed to a concentration that does not affect the floating sludge 8. The concentration to be changed is preferably such that the ozone concentration in the upper space of the membrane separation activated sludge tank 7 is 0.1 ppm or less.

  Next, the concentrated water 14 is extracted from the bottom of the membrane separation activated sludge tank 7 and stored in the sedimentation separation tank 15. The concentrated water 14 is separated into a settled sludge 16 and a supernatant liquid 17. Deposited metal fine particles such as platinum are dispersed without being settled and mixed in the supernatant liquid 17. In addition, since the sedimentation sludge 16 settled in the sedimentation separation tank 15 still has organisms in which metals are accumulated, it is returned to the membrane separation activated sludge tank 7. This return enables stable treatment without reducing the suspended sludge concentration in the membrane separation activated sludge tank 7.

  In addition, when the organism is killed and self-digested, the metal fine particles can be recovered and the efficiency is high. Generally, activated sludge microorganisms are said to change generations within a few days to weeks, and die. Dozens of hours. For this reason, the organisms holding the metal are killed and self-digested, so that the metal fine particles are deposited. In the normal membrane activated sludge method, the propagated microorganisms are discharged as surplus sludge. However, there is a high possibility that the surplus sludge contains metals. When the metals contained in the waste water 1 are precious metals such as precious and expensive platinum, sludge is not discarded as much as possible, and it is more efficient if platinum can be recovered with high purity.

  The supernatant liquid 17 that has settled and separated is further fed to a separation unit 18 where it is separated into residual treated water 19 and sludge 20 containing metal. The separation unit 18 can be a centrifuge or a microfiltration membrane device. Since there is a possibility that metals that could not be separated remain in the residual treated water 19, it is further returned to the membrane separation activated sludge tank 7 and the treatment to become metal fine particles is continued. By returning the settled sludge 16 and returning the residual treated water 19, the remaining metals can be made into metal fine particles, and the recovery rate can be improved. When the metals are noble metals such as platinum, the higher the recovery rate, the more effective. When the filtered water 13 includes drainage regulation targets such as nitrogen, it is easy to carry out these treatments.

  When a centrifugal separator is used for the separation unit, a metal having a relatively high specific gravity can be efficiently separated. Further, when a microfiltration membrane is used for the separation part, even a metal that becomes a fine particle having a particle diameter of several nm can be efficiently separated.

  In this way, by adding simple processing steps such as ozone aeration and sedimentation separation, it is possible to easily recover the noble metal even by the membrane separation activated sludge method.

  Conventionally, it has been necessary to carry out complicated processing for recovering metals, but according to the present invention, metals are easily and efficiently recovered through simple recovery steps using ozone, biological treatment, and separation devices. be able to.

  The wastewater treatment apparatus according to the present invention can recover precious metals by a simple treatment composed of ozone, biological treatment, and separation equipment, and is very energy saving because it uses microorganisms. For this reason, the present invention can be applied to a wide range of water resources such as water and sewage, middle water, and well water from the electronic and automobile industries.

DESCRIPTION OF SYMBOLS 1 Wastewater 2 Decomposition tank 3 Decomposition tank aeration pipe 4 Ozone addition air 5 Ozone containing bubble 6 Decomposed water 7 Membrane separation activated sludge tank 8 Floating sludge 9 Activated sludge tank aeration pipe 10 Air 11 Bubble 12 Immersion membrane unit 13 Filtration water 14 Concentrated water 15 Sedimentation separation tank 16 Sedimentation sludge 17 Supernatant liquid 18 Separation part 19 Residual treated water 20 Sludge

Claims (6)

Decomposition tank for decomposing biodegradable wastewater containing metals with ozone-added air to obtain decomposed water, and membrane separation activity for obtaining concentrated water containing metal-containing sludge by reducing metals from the decomposed water as fine particles by microorganisms A wastewater treatment apparatus, comprising: a sludge layer; and a sedimentation tank for collecting a sludge in the concentrated water to obtain a supernatant, and a solid-liquid separator for recovering metal from the supernatant by a separation unit. The wastewater treatment apparatus according to claim 1, wherein sludge settled in the settling separation tank is returned to the membrane separation activated sludge tank. The wastewater treatment apparatus according to claim 1, wherein the residual treated water from which the metal has been recovered in the solid-liquid separation tank is returned to the membrane separation activated sludge tank. The wastewater treatment apparatus according to claim 1 or 3, wherein a centrifugal separator is used for the separation unit. The wastewater treatment apparatus according to claim 1 or 3, wherein a microfiltration membrane is used for the separation part. 6. The waste water treatment apparatus according to claim 5, wherein the pore size of the microfiltration membrane used for the separation part is 0.4 μm or less.

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