JP2008207062A - Electrolytic treatment apparatus and treatment method of organic matter-containing wastewater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic treatment apparatus for efficiently and continuously flocculating and separating a suspended substance contained in organic matter-containing wastewater such as coating wastewater or the like, and to provide a treatment method of organic matter-containing wastewater. <P>SOLUTION: The electrolytic treatment apparatus for performing the flocculation and separation treatment of the organic matter-containing wastewater in a treatment tank includes an air supply mechanism capable of intermittently sending air to the air jet orifices provided to the lower part of the treatment tank and a mechanism for removing the sludge floating to the upper part of the treatment tank. A flocculation and separation treatment method of the organic matter-containing wastewater is also disclosed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrolytic treatment apparatus that performs agglomeration and separation treatment of organic matter-containing wastewater containing suspension and organic matter, and a method for treating organic substance-containing wastewater.

The treatment of waste water containing organic matter containing suspended substances is usually performed as a first step, followed by agglomeration and separation treatment for removing suspended substances in the waste water, followed by treatment for decomposing harmful substances such as biological treatment and chemical treatment. .

  The coagulation separation process includes coagulant treatment in which flocculant is introduced into the wastewater and stirred to float or settle suspended solids, or oxygen or hydrogen bubbles generated by electrolysis of water by placing the electrode in wastewater. And electrolytic treatment for suspending suspended solids. Furthermore, in the electrolytic treatment, when a metal such as aluminum is used for the electrode, the metal ions are eluted from the electrode into the wastewater and react with some components in the wastewater to form a colloid to aggregate the suspended substance. Yes, the generated colloid can float and be separated by adsorbing the bubbles.

  In the agglomeration and separation treatment, the suspended and agglomerated suspended matter reaggregates in the layer and settles and deposits, which may make it difficult to remove. In addition, in the case of the electrolytic treatment apparatus, in addition to the accumulation of the suspended substance, there is a problem that the suspended substance adheres to the electrode installed in the treatment apparatus and the processing capacity is lowered.

  Patent Document 1 discloses a technique for preventing adhesion of paint or the like to the surface of an electrode plate by exchanging the anode and cathode of an electrode disposed therein at regular intervals as an apparatus for electrolytically treating paint booth wastewater or the like. ing. However, since solids such as settled paint residue are deposited on the bottom of the apparatus, the processing capacity may decrease over time. Further, when aluminum is used for the electrode, there is a concern that the surface of the aluminum reacts with a cationic substance in the waste water and becomes non-conductive when aluminum becomes a cathode.

JP-A-52-126059

An object of the present invention is to provide an electrolytic treatment apparatus and an organic matter-containing wastewater treatment method that enable continuous aggregation and separation treatment of organic matter-containing wastewater.

The present invention
1. An electrolytic treatment apparatus for performing agglomeration and separation treatment of organic matter-containing wastewater in a treatment tank, comprising a wastewater inflow pipe for supplying wastewater to the treatment tank, an air ejection mechanism provided at the lower part of the treatment tank, and intermittently in the air ejection mechanism An electrolysis apparatus comprising an air supply mechanism capable of pumping air, a sludge removal mechanism at the top of the treatment tank, and a waste water outflow pipe for discharging waste water from the treatment tank to the outside of the system,
2. An organic matter-containing wastewater treatment method in which a coagulation separation process is performed in a treatment tank of an electrolytic treatment apparatus, wherein air is intermittently ejected from an air ejection mechanism provided at the bottom of the treatment tank simultaneously with the electrolytic treatment, and the upper part of the treatment tank A method for treating waste water containing organic matter, characterized by removing sludge floated on the surface,
3. 3. The method for treating organic matter-containing wastewater according to claim 2, wherein the intermittent ejection of air is a repetition of a continuous ejection of 2 to 10 seconds and a stop of 7 to 15 times the continuous ejection time. .

According to the present invention, an air ejection mechanism that intermittently ejects air at the lower part of the processing tank is provided, and a mechanism that removes sludge that floats at the upper part of the processing tank is further provided, so that the coagulation separation process is efficiently performed. Electrolytic treatment equipment that can be treated, containing organic substances that can be continuously treated without suppressing the accumulation of suspended solids in the wastewater coagulated and deposited on the bottom of the equipment and adhesion to the electrode surface, and reducing wastewater treatment efficiency A method for treating wastewater is provided.

The electrolytic treatment apparatus of the present invention can be applied to the coagulation and separation treatment of organic matter-containing wastewater such as paint wastewater.

In the present invention, organic substance-containing wastewater is industrial wastewater, agricultural wastewater, domestic wastewater, etc. discharged from factories or business establishments, and particularly includes paint wastewater. Examples of the paint wastewater include a paint line for automobiles and various industrial products, a paint booth water in a sheet metal factory, and a drainage containing paint components from a paint manufacturing factory. For example, if an example of the waste_water | drain of the painting line of a motor vehicle is given, about 1-100g of deposits, TOC1,000-15,000mg, and about 1-10,000mg of organic solvents are contained in 1L of wastewater. Further, COD _{Mn is} 1,000 to 10,000 mg / L, and BOD is 1,000 to 5,000 mg / L. Here, TOC means total organic carbon, COD _Mn means chemical oxygen demand, and BOD means biochemical oxygen demand.

  The organic wastewater containing organic matter can be subjected to biological treatment or chemical treatment as it is when it has a small amount of insoluble solids. However, when it contains a large amount of solids such as resins, pigments, and curing agents, it can be added with a flocculant or electrolyzed. It is preferable to perform solid separation by a treatment or the like to remove the solid content.

  As the flocculant, for example, inorganic flocculants represented by aluminum sulfate, polyaluminum chloride, ferric chloride and the like, low molecular flocculants such as surfactants, anionic, nonionic or cationic polymer flocculants, etc. These can be used alone or in combination of two or more according to the type of waste water.

  Electrolytic treatment is performed by putting an electrode in wastewater, passing an electric current, adsorbing pigments and resins in the wastewater using fine bubbles of oxygen and hydrogen generated by the electrolysis of water, and buoyancy of the bubbles to release these substances. It is a method to float the flocculate and collect it on the surface of waste water. In addition, when a metal such as aluminum is used for the electrode, metal ions may elute from the electrode into the wastewater and react with some components in the wastewater to form a colloid. The colloid adsorbs the bubbles. Therefore, it is possible to float and separate. In the electrolytic treatment, an electrolyte is usually charged and dissolved in supplied wastewater, and a plurality of electrodes are arranged in the water tank at appropriate intervals, and electricity is passed between the electrodes to perform electrolysis. As the electrode, an aluminum electrode is preferably used as the anode, and an iron or stainless steel electrode is preferably used as the cathode. It is preferable to use sodium nitrate, sodium chloride, or the like as the electrolyte. In some cases, the waste water can be coagulated and separated more effectively by combining the electrolytic treatment and the treatment with the flocculant.

  The electrolysis apparatus of the present invention relates to an apparatus for performing the agglomeration separation process. Hereinafter, the electrolytic apparatus of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a side view showing an embodiment of the electrolysis apparatus of the present invention, and FIG. 2 is a front view. An organic matter-containing wastewater is caused to flow into the treatment tank 1 through a wastewater inflow pipe 2. Although organic matter-containing wastewater is not shown in the figure, it can be made to flow in from a painting facility outside the system using a pump or the like. The amount of inflow can be determined in consideration of the treatment capacity of the wastewater treatment apparatus such as the type and concentration of organic matter contained in the wastewater and the size of the treatment tank. The position of the wastewater inflow pipe is preferably installed above the center in the height direction from the bottom surface to the top surface of the treatment tank.

  In the treatment tank 1, a coagulation separation process is performed in which the solid content suspended in the organic matter-containing wastewater is floated or settled. 3 and 4 in the figure indicate a pair of electrodes of a cathode and an anode, respectively. In the electrolytic treatment apparatus of the present invention, the number of electrodes is not particularly limited. Further, a flocculant as described above may be added during operation of the electrolytic treatment apparatus.

  In the figure, 5 is an air pipe, and 6 is an air ejection hole. Here, an air pipe having an air ejection hole is cited as the air ejection mechanism, but it is not particularly limited. Instead of the air ejection hole, a slit or a fine mesh may be used. In the figure, an air pipe fixed to the bottom of the treatment tank is shown, but it may be movable. Although not shown in the drawing, pressurized air is sent to the air pipe 5 from an air supply mechanism outside the system, and the air is ejected from the air ejection hole 6 as bubbles into the organic matter treatment wastewater. As an air supply mechanism that supplies air to the electrolytic treatment apparatus of the present invention, an air pump that can control the amount and time of air ejection can be used. Alternatively, air may be supplied to the air pipe via a valve capable of controlling high-pressure air supplied from an air compressor or the like. The shape, number and size of the air ejection holes are not particularly limited. The diameter immediately after the ejection of the bubbles to be ejected into the organic waste water is preferably 0.01 mm or more and 10 mm or less, and preferably 0.1 mm or more and 6 mm or less from the viewpoint of preventing sedimentation of suspended substances in the treatment tank. Therefore, it is preferable to arrange circular holes with a diameter of 5 mm or less at equal intervals.

  In the present invention, the air ejection is not performed continuously but intermittently. The ejection time per one time of air is preferably 2 seconds or longer and 10 seconds or shorter, more preferably 3 seconds or longer and 6 seconds or shorter. When the ejection time is shorter than 2 seconds, suspended substances may settle and accumulate in the treatment tank, and the treatment capacity may be reduced. When the ejection time is longer than 10 seconds, the waste water is excessive in the treatment tank. There is a risk that the waste water will splash outside the device.

  Furthermore, the stop time after the ejection of the air is preferably in the range of 5 to 20 times the ejection time after the ejection is completed, and more preferably in the range of 10 to 14 times. Although it is related to the above-mentioned one ejection time, if it is shorter than 5 times the ejection time, the wastewater may foam excessively in the treatment tank, and the wastewater may be scattered outside the apparatus. In the treatment tank, suspended substances may precipitate and accumulate, and the processing capacity may be reduced.

  In the present invention, the ejection speed of air into the treatment tank can be appropriately determined according to the size of the treatment tank, the type of waste water to be treated, and the like. Usually, the jetting speed of air is preferably in the range of 10 to 80%, more preferably 20 to 60% with respect to the capacity (volume) of the treatment tank in terms of the amount of air jetted for 1 minute. Within range. If the air ejection speed is lower than the above range, the aggregate may not be sufficiently lifted, and if it is too high, the suspended state of the waste water in the treatment tank may continue and the aggregation separation process may not be performed.

  Reference numeral 7 in the figure denotes an apparatus for removing sludge that has floated by the aggregation classification process. The sludge can be removed as follows, for example. By installing a large spatula adjacent to the processing tank at the upper part of the processing tank and periodically moving it in the direction of the arrow, sludge can be removed outside the processing apparatus via the trap 8. The removed sludge can be solid-liquid separated by centrifugation or filtration and treated. Normally, the solid content may be incinerated or crushed after drying and used as an aggregate for building materials. The liquid component can be mixed with treated water that has been subjected to the electrolytic treatment of the present invention, which will be described later, to perform biological treatment or chemical treatment. In the present specification, the sludge treatment apparatus that removes sludge that has been levitated by a spatula that performs reciprocating movement has been described. It may be a device for removing sludge.

  9 in the figure indicates a discharge pipe for discharging treated water out of the system from the treated layer. Although not shown in the figure, the waste water after the coagulation and separation treatment can be discharged using a pump or the like. Further, a filter such as a wire mesh may be installed at the opening of the discharge pipe inside the processing tank for the purpose of preventing the suspended substance from flowing out of the system. The position of the drain pipe 9 is preferably installed below the center in the height direction from the bottom surface to the top surface of the treatment tank. In the electrolytic treatment apparatus of the present invention, the waste water discharged from the discharge pipe 9 is one in which the solid content has been removed by agglomeration separation treatment, and usually biological treatment or chemical treatment is further performed to remove harmful substances such as organic matter. Can be disassembled.

  In the figure, reference numeral 10 denotes a discharge pipe for discharging slurry generated by precipitation of suspended substances in the lower part of the treatment tank in the course of treatment of organic matter-containing wastewater. The opening in the treatment tank can be opened and closed. Although not shown in the figure, the slurry containing a large amount of suspended solids can be discharged out of the system by a slurry pump. The discharged slurry can be treated in the same manner as the removed sludge. Or you may make it flow in into a processing tank again from the said waste-water inflow pipe.

  In the case where the electrolytic treatment apparatus of the present invention is operated while being periodically stopped for inspection, maintenance, etc., the removal of the slurry is scraped and removed when the electrolytic treatment apparatus is stopped without using a slurry pump. May be. In that case, the bottom of the treatment tank can be inclined.

  Next, a method for treating organic wastewater using the electrolytic treatment apparatus of the present invention will be described. The treatment method of the present invention is used for coagulation and separation treatment of organic matter-containing wastewater such as paint wastewater, and the organic matter-containing wastewater is continuously flowed into the treatment tank of the electrolytic treatment apparatus, and the treated wastewater is continuously supplied. To exhaust. During operation of the electrolytic treatment apparatus, air is intermittently ejected from the air ejection holes provided in the apparatus. Air is ejected from an air pump installed outside the processing tank through an air pipe connected to an air ejection hole. In the method for treating organic matter-containing wastewater according to the present invention, air is ejected intermittently into the treatment tank by repeating a cycle in which the ejection of air is stopped for a certain time after air is ejected for a certain time. The air ejection time and the subsequent stop time may be provided with an ejection stop time within the range of 5 to 20 times the ejection time after air is ejected within the range of 2 to 10 seconds as described above. preferable. Even if the state of the waste water staying in the tank changes by intermittently ejecting air, the pressure and speed of the ejected air will decrease the processing capacity, such as sudden foaming and significant sedimentation of suspended solids. Can be prevented without adjusting.

Next, an Example is given and this invention is demonstrated more concretely.
1. Preparation of model wastewater A model wastewater was prepared by diluting a water-based paint (metallic color) for automobile topcoat to a solid content of 2% by mass with tap water. This model wastewater includes an acrylic resin and a melamine resin as organic substances, and an aluminum flake pigment or titanium dioxide-coated mica pigment as a glittering pigment as a pigment component.
2. Using an electrolytic processing apparatus (anode: aluminum, cathode: iron) having an electrolytic processing volume of 6 L, the model wastewater prepared in 1 was subjected to coagulation separation.
(Standing treatment)
First, the drainage hole of the treatment tank was closed, and 5 L of model wastewater was injected into the tank for 1 hour of electrolytic treatment.
(Continuous electrolytic treatment)
After the stationary treatment, continuous operation was repeated in which the model wastewater was injected into the treatment tank at a flow rate of 20 ml / min for 2 minutes and stopped for 1 minute. The sludge that floated to the top was discharged out of the system using a scraping device. When sludge accumulated in the treatment tank, the operation of the apparatus was stopped as necessary and physically discharged out of the system. Waste water was discharged using a pump connected to the drain hole so that the amount of waste water staying in the treatment tank would not increase or decrease. The conditions for the discharge were a 2-minute outflow and a 1-minute stop at a flow rate of 14 ml / min. The treatment was performed for 24 hours under the above conditions.
(Example)
From the air ejection hole at the lower part of the treatment tank, the air flow rate was adjusted to a flow rate of 2 L / min using an air pump capable of controlling the air flow rate, and air was intermittently ejected. The air was repeatedly ejected for 5 seconds and stopped for 60 seconds. The discharged wastewater was clear with suspended solids removed throughout the treatment time. The sludge accumulated on the bottom surface was cleaned only once 12 hours after the start of the treatment.
(Comparative Example 1)
From the air ejection hole at the lower part of the treatment tank, the flow rate was adjusted to 2 L / min in the same manner as in Example, and air was continuously ejected. The discharged waste water was cloudy and the removal of suspended solids was insufficient.
(Comparative Example 2)
The treatment was carried out without closing the air ejection hole and blowing out air. The discharged wastewater was transparent at the beginning of continuous operation with the suspended solids removed, but began to become cloudy after about 2 hours. Since the sludge accumulated on the bottom surface increased, it was necessary to clean the sludge after 5 hours and then clean it every 2 hours thereafter.
(Comparative Example 3)
Air was continuously ejected from the air ejection hole at the bottom of the treatment tank by adjusting the flow rate to 0.15 L / min. The discharged waste water was transparent at the beginning of operation with the suspended solids removed, but began to become cloudy after about 4 hours. Since the amount of sludge accumulated on the bottom surface increased, it was necessary to clean the sludge after 8 hours and then clean it every 4 hours.

The electrolytic treatment apparatus and organic matter-containing wastewater treatment method of the present invention can be applied to agglomeration and separation treatment of organic matter-containing wastewater such as paint wastewater.

It is a schematic diagram of the front surface of the electrolytic treatment apparatus of the present invention. It is a schematic diagram of the side surface of the electrolytic treatment apparatus of the present invention.

Explanation of symbols

1. 1. Processing tank 2. Waste water inflow pipe Cathode 4. Anode 5. Air tube 6. Air ejection hole 7. 7. Sludge removal device Trap 9. Waste water discharge pipe10. Slurry discharge pipe

Claims (3)

An electrolytic treatment apparatus for performing agglomeration and separation treatment of organic matter-containing wastewater in a treatment tank, a wastewater inflow pipe for supplying wastewater to the treatment tank, an air ejection mechanism provided in the lower part of the treatment tank, and intermittently in the air ejection mechanism An electrolytic treatment apparatus comprising an air supply mechanism capable of pumping air, a sludge removal mechanism at an upper part of the treatment tank, and a waste water outflow pipe for discharging waste water out of the treatment tank. An organic matter-containing wastewater treatment method in which a coagulation separation process is performed in a treatment tank of an electrolytic treatment apparatus, wherein air is intermittently ejected from an air ejection mechanism provided at the lower part of the treatment tank simultaneously with the electrolytic treatment, and the upper part of the treatment tank A method for treating organic matter-containing wastewater, characterized by removing sludge floated on the surface. The method for treating organic matter-containing wastewater according to claim 2, wherein the intermittent ejection of the air is a repetition of a continuous ejection of 2 to 10 seconds and a stop of 7 to 15 times the continuous ejection time. .

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