JP2012106221A - Device for treating waste water containing metal ion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for treating waste water containing metal ions, capable of continuously peeling reaction inhibitors such as hydrogen gas and magnesium hydroxide generated on a surface of a separating material mainly composed of magnesium or magnesium alloy, stably and securely bringing target waste water into contact with the magnesium surface as the separating material and separating the metal ions in the waste water continuously for a long time, when performing low-concentration waste water treatment by using the separating material.SOLUTION: In the device for continuously treating waste water containing metal ions, the separating material mainly composed of magnesium or magnesium alloy and filled within a rotating drum having a rotating shaft arranged to be inclined to the horizontal face is rolled by rotation of the drum. The separating material is regenerated by continuously peeling reactants formed on the surface of the separating material by reaction with treated waste water, and solid-liquid separation of the peeled reactants is performed.

Description

  The present invention relates to a rolling rotary drum type processing apparatus that efficiently and continuously separates and removes or separates and recovers these metal ions from wastewater containing harmful metal ions or useful metal ions.

  Wastewater from plating plants, smelters, garbage incinerators, etc. (hereinafter, unless otherwise specified, means wastewater, groundwater, aqueous solutions containing metal ions such as eluate), toxic to humans, eg mercury, lead Heavy metals such as cadmium, arsenic, chromium, copper and nickel are included. In addition, arsenic, an element that is toxic to living organisms, is usually found in groundwater such as old mine wastewater from hot water and hot air deposits, hot water from hot spring water and geothermal power plants, industrial waste, incineration ash from urban waste, and fly ash. It is also contained in electric furnace steelmaking dust and the like. In order to remove these metals, usually, a method of separating and removing metals from waste water containing metal ions or waste water from which metal ions are eluted is employed. For example, for recovering zinc, silver, gold, nickel, and chromium, which are useful and valuable industrially, usually, a method of separating and recovering metal from waste water from which these metal ions are eluted is employed.

  Conventionally, for the treatment of such waste water, there are a method in which a compound is produced by adding a neutralizing agent or a precipitating agent to precipitate and agglomerate, a method using an inorganic ion exchanger or an organic ion exchanger, and a method using an adsorbent. is there. The precipitation aggregation method separates and removes substances dissolved in waste water by depositing a hardly soluble compound such as hydroxide, sulfide or carbonate and performing solid-liquid separation. In the method using an inorganic ion or organic ion exchanger, an ionic component contained in waste water is separated by a substitution reaction with an ion of the inorganic ion or organic ion exchanger. In the method using an adsorbent, separation is performed by an adsorption phenomenon in which a substance dissolved in waste water is removed from the surface of a porous adsorbent represented by activated carbon.

  When processing a large amount of low-concentration wastewater, the precipitation aggregation method is the most widely used in the wastewater treatment field from the viewpoint of cost and the treatment of solids (sludge) generated after solid-liquid separation. Calcium-based, aluminum-based, iron-based, and magnesium-based agents are known. Among these, when a magnesium-based precipitation coagulant is used, the precipitated particles are fine, so that sludge generated after solid-liquid separation can be reduced (Non-patent Document 1).

In recent years, magnesium alloys have been used for housings such as personal computers, but recycling of magnesium alloys has become an issue. Combining the fact that the present inventors have found that various metal ions can be separated by Mg (OH) ₂ , which magnesium has changed and produced in an aqueous solution, In the waste water containing magnesium, a separation material mainly composed of magnesium or a magnesium alloy is added, pH of the waste water is neutralized by the reaction of water and magnesium, and metal ions are added to the magnesium hydroxide layer generated on the magnesium surface. We have invented a method for separating metal ions characterized by adsorbing and separating metal ions from waste water (Patent Document 1).

Schiller, J. et al. E. & Khalafalla, S .; E. : MAGNESIUM-OXIDE FOR IMPROVED HEAVY-METALS REMOVAL, Min. Eng. , Vol. 36, p. 171-173, (1984)

JP 2006-167564 A

  However, with the method of simply adding a separation material mainly composed of magnesium or a magnesium alloy, the efficiency of wastewater treatment gradually decreases due to the adhesion of hydrogen gas generated by the reaction of water and magnesium and the deposition of magnesium hydroxide on the magnesium surface. To do. Moreover, in the batch type reaction tank system, since the separating material settles at the bottom of the tank, there is a problem that the contact efficiency with the waste water is low, the waste water treatment capacity is limited, and the work efficiency is low.

  The present invention has been made in view of such circumstances, such as hydrogen gas and magnesium hydroxide generated on the surface of the separation material when performing low-concentration wastewater treatment using the separation material mainly composed of magnesium or a magnesium alloy. Metal ion-containing wastewater treatment equipment that continuously peels reaction-inhibiting substances, can stably and reliably contact the target wastewater with the magnesium surface, and can separate the metal ions in the wastewater continuously for a long time. The purpose is to provide.

  The configuration of the present invention that meets the above-mentioned object is that the separation material mainly composed of magnesium or magnesium alloy filled in the apparatus rolls with rotation in the rotating drum, and collides with each other or the rotating drum wall. It is characterized by exfoliating insoluble compounds such as magnesium hydroxide containing gas generated on the surface and metal ions to be separated, continuously renewing highly reactive metallic surfaces, and continuously separating metal ions .

  Further, the configuration of the present invention is a form in which two or more sections separated by a partition wall having a water passage hole in the separation material filling portion are continuous, and drainage is performed by lengthening the flow path of drainage passing through the treatment apparatus. In addition to improving the probability of contact with the separating material, the multi-stage reaction tank avoids mixing of the waste water on the upstream side with a high concentration of metal ions and the treatment waste water on the downstream side with a low concentration of metal ions. It is characterized by separation processing.

  Further, the structure of the present invention is provided with protrusions and irregularities on the inner wall of the rotating drum, and efficiently rolling a separation material mainly composed of magnesium or a magnesium alloy filled in the apparatus, so that the gas generated on the surface and the object to be separated are separated. It is characterized in that an insoluble compound such as magnesium hydroxide containing metal ions is efficiently peeled off, and a highly reactive metallic surface is reliably continually regenerated, and metal ions are continuously separated.

  In addition, the structure of the present invention includes a metal or ceramic hard body together with a separation material mainly composed of magnesium or a magnesium alloy filled in the apparatus, and the separation material and the hard body roll together with rotation in the rotating drum. By mutual collision, the gas generated on the surface and the insoluble compounds such as magnesium hydroxide containing the metal ions to be separated are efficiently peeled off to ensure that a highly reactive metallic surface is continuously born and continuously It is characterized in that metal ions are separated.

  In the present invention, by adopting the above-described configuration, when performing low-concentration wastewater treatment using magnesium or a magnesium alloy as a separation material, reaction inhibitors such as hydrogen gas and magnesium hydroxide generated on the surface of the separation material are continuously added. Therefore, the target drainage can be brought into contact with the magnesium surface, which is a separating material, stably and reliably, and the metal ions in the drainage can be separated continuously for a long time.

  As the magnesium or magnesium alloy separating material used in the present invention, it is possible to use magnesium scrap which is expected to generate a large amount in the future, which is significant in terms of economy and environmental load. As the magnesium alloy, any magnesium alloy may be used as long as it contains 50% or more by mass%. Based on the ASTM symbol, AZ31C, AZ61A, AZ80A, AZ91D, AM50A, AM60B, AM100A, EZ33, ZE41, QE22A, WE54A, Alloys such as WE43, ZK51A, ZK60A, and ZK61A are listed.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS A rolling rotary drum type waste water treatment apparatus according to an embodiment embodying the present invention will be described below with reference to the drawings to provide an understanding of the present invention.

  The waste water treatment apparatus in the present invention is a waste water that can efficiently and continuously separate or remove metal ions by passing waste water such as waste water containing metal ions, ground water, and eluate through a rotating drum. It is a processing device.

  As shown in FIG. 1, the waste water treatment apparatus according to the present invention is a rotary drum apparatus having a rotary drum 10 that is disposed in a state where the rotation axis is inclined with respect to a horizontal plane. The treated wastewater injection hole 11 for injecting the treated wastewater into the rotating drum 10 from above and the end surface inclined to the lower side of both end faces of the rotating drum 10 on the end surface which is the upper side A treated wastewater discharge hole 12 for discharging wastewater from below to the rotating drum 10 is provided, and a solid-liquid separation device 13 for separating the treated wastewater discharged via the rotating drum 10 into solid and liquid.

  The rotating drum 10 is constituted by a reaction tank divided into a plurality of partitions by a partition wall 14, and a separating material 15 mainly composed of magnesium or a magnesium alloy is loaded into at least one section thereof. As shown in FIG. 2, the partition wall 14 has at least one water passage hole 16 provided with a mesh member having an opening diameter large enough to prevent the purification material from passing therethrough. The separating material 15 rolls by the rotation of the rotating drum 10, and the separating material 15 is regenerated by continuous peeling of reactants formed on the surface of the separating material 15 by reaction with the wastewater to be treated.

  The rotating mechanism of the present invention is not particularly limited as long as it can rotate while controlling the rotating drum. For example, a roller rotating in contact with the lower portion of the rotating drum is suitable. When the rotating drum 10 is rotated by an external driving force such as a roller 17 and drainage is poured from the injection hole 11, the drainage proceeds while contacting the separating material 15 in the rotating drum 10 according to the inclination of the rotating drum 10, and the discharge hole 12 It goes out of the rotating drum 10 more. At this time, since insoluble compounds such as magnesium hydroxide generated with the separation reaction in the tank are also discharged together, the wastewater to be treated is solid-liquid separated by the solid-liquid separation device 13.

  The solid-liquid separation device is provided downstream of the discharge hole of the rotary drum device, and can be provided as an integral type with the rotary drum device or as an individual type. As the solid-liquid separation method, known solid-liquid separation methods such as precipitation separation, flotation separation, centrifugation, membrane separation and the like can be used.

  The shape of the separating material used in the present invention is not particularly limited, and includes, for example, magnesium or magnesium alloy powder, flakes, and granules. Since the surface of magnesium is remarkably high in activity, the smaller the size of the separation material, the higher the separation characteristics, but there is a tendency to lose reactivity in a short period of time. A material is preferred. In addition, since the metallic surface is renewed when the separating materials collide with each other or the rotating drum wall, the separating materials adhere to each other in the reaction tank and are not easily formed with a lump (lumb). Preferably there is.

  In the present invention, the state of separation of metal ions varies depending on the type and concentration of metal ions and the pH of the waste water containing the metal ions. The magnesium or magnesium alloy, which is the main component of the separation material, reacts with water, and the magnesium ion is generated, so that the separation reaction proceeds. Therefore, the pH is preferably in the acidic region, but also in the neutral region and the alkaline region. Separation is possible by the reaction between the separating material and water.

  In addition, the diameter of the rotating drum, the rotating speed, the tilt angle of the rotating drum, and the filling amount of the separating material when performing the waste water treatment including metal ions are not particularly limited, but the filled separating material is sufficiently rolled by rotation. It is desirable to set the conditions to

  Moreover, the water flow rate at the time of performing the waste water treatment containing metal ions can be arbitrarily set according to the metal ion concentration in the waste water to be treated, the rotating drum diameter, the rotating drum inclination angle, and the separation material filling amount.

Next, examples carried out for confirming the effects of the present invention will be described.
Example 1: Drainage was collected from a washing process of a nickel plating line during nickel separation and recovery operation, and metal ion separation was attempted using the wastewater treatment apparatus of the present invention. In the wastewater treatment apparatus of this example, the inside of the rotating drum having a diameter of 354 mm and a length of 310 mm was divided into six sections, which was inclined by 15 degrees with respect to the horizontal plane and rotated at a speed of 23 rpm.

  The highest compartment has the role of drainage injection hole and buffer tank, and the treated wastewater passes through the four reaction tanks below it and passes through the discharge port installed in the lowest compartment. Go out. Of the four compartments, 800 g of magnesium alloy was put into one compartment for wastewater treatment. The magnesium alloy used here is AZ91D having a relatively well-shaped chip shape (about 1 × 1 × 4 mm). The wastewater to be treated is acidic (pH = 2.5) and is continuously injected directly into the rotating reaction tank at a flow rate of 150 ml / min without adjusting the pH, and outside the rotating drum via the reaction layer in the rotating drum. The treated waste water to be poured was subjected to solid-liquid separation with a filter paper (5A).

  FIG. 3 shows changes over time in the ion concentration and pH of the treated water collected through the wastewater treatment apparatus of this example. The wastewater to be treated before injection was pH = 2.5, Ni concentration = 105 ppm, Mg concentration = 3.5 ppm, but after reaction with Mg alloy in the reaction tank, Ni was ICP (Inductively Coupled) from the beginning of sampling. (Plasma, inductively coupled plasma) emission spectroscopic analysis was below the detection limit, and it was revealed that all Ni ions were removed from the wastewater to be treated. Moreover, although about 60 L of washing waste water was continuously injected into the reaction tank, all the treated water had a Ni concentration below the detection limit, and it was confirmed that the removal reaction was stably occurring. Therefore, in the rolling type, insoluble compounds such as magnesium hydroxide containing the gas generated on the surface of the Mg alloy hydration reaction and the metal ions to be separated are peeled off to create a highly reactive metallic surface. It was shown that metal ions could be continuously separated.

  The pH of the treated water was as high as 9.25 from the beginning of the reaction, and after that, there was a tendency to stabilize at about 8.9, although the pH value slightly decreased. In addition, the Mg concentration in the treated water increases significantly to 120.4 ppm, and soon stabilizes at about 100 ppm. This is because the Mg alloy surface immediately after injection of the wastewater to be treated is almost 100% metallic, so the activity is strong and the dissolution of Mg, the generation of hydrogen gas, and the increase in OH ion concentration accompanying the hydration reaction are fast. It is. After that, a reaction layer mainly composed of Mg (OH) 2 is formed on the Mg alloy surface, so that the activity itself becomes weak, but the reaction layer is peeled off due to collision between Mg alloy chips due to rolling, so that the metallic property It is thought that the surface of this appears and the reaction continues stably.

Comparative Example 1 (Comparative Example of Example 1)
This comparative example is a comparative example of Example 1. As in Example 1, wastewater collected from the cleaning process of the nickel plating line in operation was used as wastewater to be treated.

  The same waste water treatment apparatus as that in Example 1 was used. However, the wastewater to be treated was passed through without rotating the rotating drum. The Ni ion concentration of the treated water collected through the wastewater treatment apparatus was below the detection limit by ICP in the initial collection, but several ppm of Ni ions were detected after 500 ml treatment, and 10 ppm or more Ni after 1000 ml treatment. It became an ion concentration, and the tendency which the Ni ion density | concentration which remains in a treated water without increasing gradually with the increase in a processing amount increased was shown. In this case, Ni ions in the wastewater to be treated that are initially injected by the surface reaction of the separation material are separated and removed, but the separation material does not roll, so that the reaction product that accumulates on the surface of the separation material as the reaction proceeds It is considered that the separation performance gradually decreases due to the stable presence of the film without peeling.

It is front sectional drawing which shows the rolling type rotary drum type processing apparatus concerning the structure of this invention. It is sectional drawing which shows the II-II cross section of FIG. The figure which shows the time change of the treated water density | concentration at the time of continuously treating nickel plating waste_water | drain with the rolling type rotary drum type processing apparatus of this invention using the separation material which has a magnesium alloy as a main component in the example of nickel separation removal. It is.

10: Rotating drum 11: treated wastewater injection hole 12: treated wastewater discharge hole 13: solid-liquid separator 14: partition 15: separation material mainly composed of magnesium or magnesium alloy 16: water passage hole 17 on the partition: Driving roller

Claims (4)

A rotating drum in which a rotation axis is inclined with respect to a horizontal plane, a wastewater injection hole to be treated provided on an end surface which is inclined to the upper side of both end surfaces of the drum, and an inclined surface in both end surfaces of the drum The treated wastewater discharge hole provided in the lower end surface, the rotating shaft provided in the axial direction of the drum, the drive mechanism for rotating the rotary drum, and the downstream of the treated wastewater discharge hole And a solid-liquid separation device provided in
Magnesium or magnesium alloy loaded as a separating material in the rotating drum is rolled by rotating the drum,
Regenerating the surface of the separation material by peeling the reaction product formed on the surface of the separation material by reaction with the wastewater to be treated,
Metal ion content characterized in that metal ions adsorbed to the solid reaction product on the surface of the separated separation material are separated or removed by solid-liquid separation of the wastewater to be treated discharged from the rotating drum Wastewater continuous treatment equipment.   2. The continuous treatment apparatus for metal ion-containing wastewater according to claim 1, further comprising a partition wall having water passage holes for dividing the inside of the rotary drum into a plurality of sections.   The continuous treatment apparatus for metal ion-containing wastewater according to claim 1 or 2, wherein protrusions and / or irregularities are provided on the inner wall of the rotating drum.   The continuous treatment apparatus for metal ion-containing wastewater according to claim 1, wherein a hard body is mixed together with a separating material loaded in the rotary drum.