TW401379B - The treatment for the phosphoric ion acid-containing waste water - Google Patents

Abstract

It is to provide a method for the phosphoric acid-ion-containing waste water that holds the phosphoric acid-ion-removing efficiency over a long period of time. The waste water treatment method is to elute iron ions and/or aluminum ions into the phosphoric ion-containing waste water from at least a pair of electrodes containing iron and/or aluminum electrochemically in order to separate the phosphoric ions when co-precipitating with the iron ions and/or the aluminum ions. The electric conductivity of the inflow water to the electrolytic cell of the waste water treatment apparatus is below 0.3 Ms/cm and the current density is 0.05-1 Ma/cm<2>, while the distance between the electrodes is set to be 1-24 cm.

Description

V. Description of the invention (1) Technical field of the invention The present invention relates to a method for treating domestic wastewater containing phosphoric acid, such as wastewater for domestic use or wastewater for collective housing. Known technology One of the reasons for the adequate nutrition of rivers or lakes is the presence of phosphorus compounds, which is well known. In addition, many phosphorus compounds are present in domestic household wastewater. However, purification treatment is difficult. At present, effective measures cannot be taken. Various treatment devices for filling compounds have been proposed. An electrolytic dissolution method of iron is known for domestic wastewater (Japanese Patent Application Laid-Open No. 3-8 99998, co2F 3/12). This technology is a technology that allows acid-breaking ions and iron ions in the wastewater to react and then aggregates and removes them with insoluble salts such as FeP〇4 or Fe (OH) x (P〇4) y. It is installed in an electrolytic cell. After the iron electrode is energized, iron ions in the wastewater are generated. Problems to be Solved by the Invention However, there is a case of electric leakage between the floating objects flowing into the electrolytic cell and the electrodes. In addition, when a stirring terminal provided in the electrolytic cell or a stirring mechanism such as aeration is stopped or the polarity reversing mechanism of the electrode is stopped, a metal compound is deposited on the electrode surface, and leakage current between the electrodes may occur. In these cases, the phosphorus removal efficiency decreases, and stable phosphorus removal performance cannot be sustained. Therefore, it is generally thought to increase the distance between the electrodes. However, if the distance between the electrodes is increased, the specified electrolysis efficiency cannot be achieved with b unless the voltage is increased to 25V or higher (25V or lower in the electrical appliance banning system). ίΙΠΐ Page 4

The present invention is based on the idea that the ionization efficiency containing phosphoric acid is kept higher than the above-mentioned subject for a long time, and its purpose is to provide a method for treating wastewater, which can make the efficiency of phosphate ions. Means of solving the problem and / or inscriptions containing the needles: the waste water treatment method, using iron and iron in the wastewater \ Shanyi Electrochemical Method on iron and iron ions containing phosphate ions and / or &amp; Ion ions 4 'make ions in an agglomerate and kill in the form of water-based salts; it is characterized by the conductivity of the inflow water of the electrode of the electrolysis cell of 0 3mS / s wastewater treatment system electrode r = :, current density system ° 〇5 ～ lmA / c㈣ The distance between the electrodes is set to 24 cm. The method for treating wastewater containing phosphatide ions according to the present invention 'uses at least one pair of electrodes containing iron and or aluminum to electrochemically dissolve iron ions and / or aluminum ions in wastewater containing phosphate ions, and then uses phosphate ions to It is agglomerated and precipitated in the form of insoluble water salts of iron and / or aluminum; it is characterized in that the conductivity of the inflow water to the electrolytic tank installed in the wastewater treatment device is 0.3 to 1.5 mS / cm and the current density is 0.0. In the case of 5 to 05 mA / cm2, the distance between a pair of electrodes is set to 60 cm. In the method for treating wastewater containing phosphate ions of the present invention, at least one pair of electrodes containing iron and / or inscription is used to electrochemically dissolve iron ions and / or aluminum ions in wastewater containing acid ions, and then use phosphate ions. Aggregates and precipitates in the form of water-insoluble salts with iron and / or aluminum; it is characterized by the conductivity of the inflow water to the electrolytic tank installed in the wastewater treatment device

Page 5 401379 V. Description of the invention (3) In the case of 0.3 to 1.5 mS / cm and current density of 0.5 to imA / cm2, the distance between a pair of electrodes is set to 55 cm. Embodiments of the Invention The method for treating wastewater containing phosphate ions according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing a waste water treatment device according to an embodiment of the present invention. FIG. 2 is a perspective view of a part of the electrolytic cell of FIG. I, FIG. 3 is an explanatory diagram of an electrode unit, and FIG. 4 is a maximum voltage of 25V. An illustration showing the relationship between the distance L between electrodes, the current density I, and the conductivity s as a reference.

The present invention is applied to a wastewater treatment device such as a combined purification tank. This wastewater treatment device is shown in FIG. 1 and is composed of a first anaerobic filter tank A, a second anaerobic filter tank B, a biological filter tank C, a treatment water tank!), And a sterilization tank e, so that the treatment flows into each tank. The wastewater from the first anaerobic filter tank A is discharged from the disinfection tank E. And, electrolytic cell! It is provided on the circulation path L of the first anaerobic filter tank 4 after the treated water pressurized from the treated water tank D by the air pump F is returned. As shown by circles 1 to 3, the electrolytic cell 1 includes a waste water treatment chamber 4 having a waste water inlet 2 and an outlet 3, and electrodes 5, 6, which are configured to be at least partially immersed in the waste water in the treatment chamber 4. The power source 7 ′ for energizing the electrodes 5, 6 has a polarity inversion circuit for switching the polarity of the electrodes 5, 6 at a specified time and a current control circuit for controlling the current of the electrodes 5, 6 And a device 9 for aerating the air in the wastewater treatment chamber 4. Working milk

Page 6 401379 V. Description of the invention (4)-The electrodes 5, 6 can be produced from iron ion and / or aluminum ion source such as iron, iron alloy, inscription, inscription alloy or iron-inscription alloy. As shown in Figs. 2 to 3, the electrodes 5, 6 are separated by a handle in the compartment 10, and the electrode units 12 are stored only at a fixed interval. In the electrolytic cell 1, for example, ^, use a separator 13 The four groups are connected to the connector 16 by the wires 15 pulled out from the terminals 14 and fixed to the electrodes 5 and 6 by screwing or welding. In addition, a waste water inflow port 10a and an outflow port 101 are formed in the compartment 10, and an air inflow port 10C is formed. The air inflator 9 is composed of a porous air pipe 17 or air plate provided in the center of the bottom of the waste water treatment chamber 4 and an air pump (not shown) for drawing compressed air into the air pipe 17, The air pipe 17 and the air pipe 18 are connected. ~ Used in this embodiment, the air diffusing pipe 17 is provided in the center of the waste water treatment chamber 4, but it is not particularly limited in the present invention, and the water can be appropriately selected together with the outflow of the waste water to make the phosphate ion and the iron out of the waste water. Set the position of the insoluble water of the reaction product of the ion (ming ion). In addition, moving the scatter down in the waste water in the treatment chamber can also make it easy to produce convection of the waste water. In addition, in the second embodiment, the stirring of the wastewater can also improve the reactivity of iron ions. In the electrolytic dissolution method of iron (aluminum), the completed ion can adopt a conventional method, whether the current is continuous or intermittent, or pulsed =, although the amount of current is due to the acid concentration of other ions, the concentration of wastewater Flow L =, but as long as the concentration of iron ions and / or ions in wastewater / dish concentration ^

V. Explanation of the invention (5) The molar ratio (hereinafter referred to as "Fe / p") is adjusted to 1040, preferably 1.5 2.0. That is, the phosphorus in the wastewater is caused by the presence of phosphate ions to react the dish acid ions with iron ions, because FeP0 ^ Fe (0H) x (P04) y is generated and precipitated, for example, in this case, the molar ratio of Fe to P A value of 1 is sufficient, but a high phosphorus removal efficiency cannot be obtained when the molar ratio is not more than 1 when considering the efficiency. When the molar ratio becomes 4 or more, the phosphorus removal rate becomes more than 99% (the efficiency of dioxin reaches the limit), and the molar ratio is further increased. The excess iron is also released on the outflow side, which may lead to increased operating costs or environmental pollution. β «Also the conductivity of the inflow water to the electrolytic cell varies depending on the physical properties of the wastewater treatment device 'Generally it is below lmS / cm, and it is only 1. Cm when it is high, but if the conductivity is fixed, if it increases The distance between the electrodes rises, the voltage decreases, and the conductivity decreases when a fixed current is applied to the electrodes located at a fixed distance. 'Because the voltage rises, it is necessary to use the maximum voltage • B to obtain the distance L between the electrodes, the current density i, and Conductive Ω 7 = system. From FIG. 4, it is known that if the conductivity of water ^ mainly 1.41 (S1), ^ 72jS2), 0.29 (S3), and 019 (S4) is reduced, the distance between electrodes for current density 1 ^ must be reduced. In addition, for each conductivity, the regression lines are L = -56.5i + 8i.4, L = _35 5i + 5 8, L = -19.5 5 + 23. 6 and L = -13. 8i + 16.6. For the sake of ^ this, in the present invention, the electrical conductivity 5 in water is 0.3 mS / cm or less due to electricity: the dependence of the current density 1 is small, first the current density is U. 05 ~ 1 mA / cm2, Moreover, the distance L between the electrodes when the thunder pole ^ ⑽ is set to about 24 cm. The letter is about 1cra because, for example, when the aeration in the electrolytic cell stops, ‘the most about 0.5cm of deposits accumulate on the electrode surface between the two electrodes. 5. Description of the invention (6) The case is less than 1cm, 蛩. Secondly, the conductivity of 8 is the raw conductivity ^ 'It will not cause the dissolution of iron ^ ^ aa ^, ^ U · 3 ~ K5 mS / cm, because the current is dense ^ will be placed in the ^ mine group secret, for example according to sewage treatment Changes in the number of users of the device ^ iH — When the number of electrode pairs is changed from 4 to 2 pairs, the current density is divided into &quot; 5 two = 5] because the current density is the average. The distance between the electrodes is 0o ^ ft Γ Cm and 55 cm. In addition, the current density 1 is li · Dt) ~ 0.5 inA / cin2. The distance between the drop, and the wearer has been collected 丄 疋 况 11. The calculation distance is about 81 cm, but the distance is set at 2 large distances. The diameter of the inspection hole is 60 cm because the diameter of the inspection hole of the processing device is generally 2 cm. For example, when a pair of electrodes is installed and maintained, it is easy to carry out the inspection hole. In the present invention, after setting the current density and the distance between the electrodes according to the range of the conductivity of the water, the controller is used to control the current that is applied to the iron electrode, and the required iron ion dissolution amount is controlled according to Faraday's law. Thereby, the phosphorus removal efficiency can be stabilized and maintained above 70 to 80%. In addition, the treatment using the electrolytic dissolution method of iron (aluminum) in the wastewater containing phosphate ions according to the present invention uses the iron ions (aluminum ions) eluted from the electrodes to react with the phosphate ions in the wastewater to produce insoluble water-based phosphoric acid and The reaction of iron (aluminum) salts (reaction A), but hydroxide ions are present in the wastewater, and the dissolved iron ions (aluminum ions) also react with hydroxide ions (reaction B). Since reaction B is faster than reaction A, in order to capture the scaly acid ions, it is necessary to increase the electric current 'and add the dissolution amount of iron ions (ming ions). However, when calcium or manganese ions are present in the wastewater, those ions react with hydroxide ions (Reaction D). Because of this reaction j) specific iron ion (aluminum ion)

401379 V. Description of the invention (7) The reaction B with the hydroxide ion preferentially suppresses the reaction b, and the iron ion (mine ion) is effectively used for the reaction A with the phosphate ion. In addition, the sentence ions and short ions also react with the dish acid ions to form water-insoluble salts, which contribute to the phosphate ions. '' Therefore, in the present invention, 'addition of calcium ions or manganese ions suppresses the reaction B between iron ions (ming ions) and hydroxide ions, and also enables efficient reaction between iron ions (ming ions) and phosphate ions A . Thereby, the flux can be reduced, power can be saved, and the elution amount of iron or aluminum can be reduced. — The wastewater treatment device of the present invention is as shown above 'and can be particularly effectively used for general domestic wastewater. Therefore, it can be used alone, but it can be combined with other purification systems such as activated sludge method, membrane separation method, and anaerobic / aerobic gas circulation method to be used as a comprehensive wastewater purification system for domestic and collective housing. It can also be used in a large-scale treatment system (excrement treatment plant). Next, the present invention will be described based on examples, but the present invention is not limited to these examples. Example In the iron electrolytic dissolution wastewater treatment device shown in FIG. 1, a high-purity iron plate is used on four pairs of electrodes immersed in the wastewater, and the conductive system of water flowing into the electrolytic tank is about 1 roS / cm. , Set the distance between the electrodes to 25 cm each. In addition, the electrode was electrolyzed with two poles under a constant monitoring voltage, and the polarity reversal time was controlled to 1 hour. In addition, ‘let the domestic wastewater containing phosphorus concentration of 3 to 5 mg / l flow in from the inflow inlet at 1200 liters / day, and set the circulating flow rate in the treatment device to 6000

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Claims (1)

___Announcement VI. Scope of patent application ~~ · — i .. i. A method for treating wastewater containing phosphate ions, using at least one pair of electrodes containing iron and / or aluminum to electrochemically treat wastewater containing phosphate ions. After dissolving iron ions and / or aluminum ions, phosphoric acid ions are used to aggregate and precipitate in the form of insoluble water salts of iron and / or aluminum. Among them, the conductivity of the inflow water to the electrolytic tank installed in the wastewater treatment device is In the case of 0.3 mS / cm or less and a current density of 0.05 to lmA / cm2, the distance between a pair of electrodes is set to 24 cm. 2. —A method for treating wastewater containing phosphate ions, using at least one pair of electrodes containing iron and / or aluminum to electrochemically dissolve iron ions and / or aluminum ions in wastewater containing phosphate ions, and then use the phosphate ions Aggregates and precipitates in the form of insoluble water salts with iron and / or aluminum; among them, the conductivity of the inflow water to the electrolytic tank installed in the wastewater treatment device is 0.3 ~ 1.5mS / cm, and the current density is 0.05 ~ In the case of 0.5 mA / cm2, the distance between a pair of electrodes is set to 60 cm. 3. —A method for treating wastewater containing phosphate ions, using at least one pair of electrodes containing iron and / or inscriptions to electrochemically dissolve iron ions and / or aluminum ions in wastewater containing phosphate ions, and then use phosphate ions 3m ~ 1. 5mS / cm 、 电 密 系 0. In the form of agglutination and precipitation of insoluble water and iron and / or aluminum; wherein the conductivity of the inflow water to the electrolytic tank provided in the waste water treatment device is 0. 3 ~ 1. Case of 5 to lmA / cm2 'Set the distance between a pair of electrodes to 55 cm. Page 14