JPH0342957B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for treating wastewater generated from a waste incinerator (hereinafter referred to as waste incinerator wastewater). In recent years, much of municipal waste has been disposed of by incineration, but in addition to the heavy metals contained in the waste, non-metals such as boron, fluorine, arsenic, and hydrogen chloride are disposed of in the chimney. are emitted and cause air pollution. For this reason, a commonly used method is to wash the incineration gas with an alkaline aqueous solution such as caustic soda or caustic potash. This process generates cleaning wastewater (usually called smoke washing wastewater), and in the smoke washing wastewater,
Because it contains heavy metals such as mercury, cadmium, lead, zinc, chromium, and copper, as well as boron, fluorine, and arsenic, it cannot be discharged into rivers as is. On the other hand, after incinerating garbage, the cinders are washed with acid and then neutralized with an alkaline aqueous solution.The washed ash wastewater also contains heavy metals and boron, which can cause water pollution. Similar to the above-mentioned smoke washing wastewater, this cannot be discharged into rivers or the like. Therefore, various studies have been conducted regarding the heavy metals contained in wastewater from garbage incinerators in line with the tightening of wastewater regulations, and at present, almost no technology has been established regarding the treatment methods. ing. For example, the smoke washing wastewater mentioned above is treated by sequentially performing coagulation-sedimentation treatment, overtreatment, and adsorption treatment with a chelate resin for mercury adsorption. Treatment is performed after coagulation treatment, followed by tertiary treatment using a two-stage chelation method in which adsorption treatment is performed using a chelate resin for mercury adsorption, and then the mercury is sometimes discharged into rivers, etc. (Japanese Patent Laid-Open No. 124763/1983, Publication No. 124764 (1982), Japanese Unexamined Patent Publication (Kokai) No. 57-
15886 and Japanese Unexamined Patent Publication No. 57-53286).
However, in such conventional methods, the target is the removal of heavy metals contained in smoke washing wastewater, and although these can be completely removed, arsenic, fluorine, and
No consideration has been given to boron at all, and it is not possible to completely remove it. All of these non-metals are recognized to be toxic, so they must be treated to below regulatory values when discharged into rivers, etc. Among them, boron, especially boric acid and its salts, is cheap, so it is used in many applications including glass.
It is widely used in fields such as additives, preservatives, dye manufacturing, pigments, catalysts, cosmetics, and photography, and is often mixed in household garbage and industrial waste, but its phytotoxicity has recently been investigated. It has been reported that if it exceeds 2 ppm, it inhibits plant growth. Therefore, when water containing a high concentration of boron is used as agricultural water, it is predicted that various harmful effects will be caused to agricultural crops, and boron wastewater regulations are expected to become even stricter in the future. In fact, it is necessary to treat boron to 1 to 2 ppm or less according to the wastewater standards set by the Kyoto Prefectural Ordinance. However, even if waste incinerator wastewater is treated by the conventional method described above, it is difficult to completely remove harmful non-metals such as boron to below the above-mentioned regulatory values. In view of these circumstances, the present inventors have conducted extensive research with the aim of providing a method for treating wastewater from waste incinerators that can completely and efficiently remove not only heavy metals but also harmful non-metals such as boron. As a result, the inventors discovered that the above object could be achieved by treating pretreated wastewater with a combination of specific chelate resins, and completed the present invention. That is, the present invention provides a method for treating wastewater generated from a garbage incinerator with a chelate resin, including a pretreatment step of coagulating and precipitating the contents in the wastewater and separating solid and liquid, and treating the pretreated wastewater with an aminopolyol group. A method for treating waste incineration plant wastewater is characterized by comprising a step of bringing a chelate resin containing sulfur into contact with a chelate resin containing sulfur and a ligand. In order to treat garbage incinerator wastewater with the present invention, first, the heavy metals contained in the wastewater are coagulated and precipitated.
Solid-liquid separation is necessary. for that purpose,
For example, the pH of wastewater can be changed to caustic soda, caustic potash,
After adjusting the pH to a range of 8 to 12 using hydroxides of alkali metals and alkaline earth metals such as slaked lime,
This may be carried out by an alkali coagulation precipitation method in which an inorganic flocculant and a polymer flocculant are sequentially mixed. Examples of the inorganic flocculant used here include ferric chloride, aluminum sulfate, polyaluminum chloride, barium chloride, ferric sulfate, aluminum sulfate, and sodium sulfide. In addition, as a polymer flocculant,
For example, materials mainly composed of polyacrylamide and sodium polyacrylate are used, and specific examples include Unifloc UF-105 (Unitika product), Sumifloc FA-30, 40, 50 (Sumitomo Chemical Co. product), Sunpoly (manufactured by Sankyo Kasei Co., Ltd.), Sunfrost (manufactured by Sanyo Kasei Co., Ltd.), and Hiset (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.). The amount of flocculant added at this time is not necessarily constant depending on the wastewater, but usually the amount of inorganic flocculant added is 50 to 500 per 1 part of wastewater.
mg, and the polymer flocculant may be added in the range of 1 to 10 mg. This alkali coagulation and precipitation treatment method is performed using a method known per se, and is not limited in any way to the equipment and operating method. In addition to the alkali coagulation-precipitation method, a coagulation-precipitation method using sodium sulfide, a coagulation-precipitation method using apatite, and a coagulation-precipitation method using a water-soluble heavy metal scavenger can also be used. In addition to the various precipitation treatments described above, flotation treatment, dehydration treatment, and overtreatment may also be performed in order to perform solid-liquid separation. For this solid-liquid separation operation, a method known per se is applied, and there are no restrictions on the apparatus or operation method. Next, in the present invention, the pretreated wastewater is brought into contact with a chelate resin having an aminopolyol group and a chelate resin having sulfur as a ligand. The order of contact at this time may be either carried out first, but it is usually preferable to contact the chelate resin having an aminopolyol group and then the chelate resin having sulfur as a ligand. A known method is applied to the contacting operation itself, and is not particularly limited, but if the pH of the pretreated wastewater is adjusted to a range of 2 to 10, preferably 5 to 9,
This is advantageous because harmful non-metals such as boron and heavy metals such as cadmium and mercury can be efficiently treated. In addition, when contacting with the column method, the space velocity (hereinafter referred to as SV) should be set at 0.5~
20 1/Hr, particularly preferably in the range of 1 to 10 1/Hr. As the chelate resin having a polyamino alcohol group used in the present invention, for example, a chelate resin having a chelate group represented by the following general formula () or () is suitable. (However, _R1 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and n represents an integer of 1 to 6.) (However, R ₂ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.) In the formula (), R ₁ is particularly a methyl group,
An ethyl group is preferred, and n is preferably 4;
R ₂ in formula () is preferably a hydrogen atom or a methyl group. In addition, as the resin matrix, styrene,
Preferable examples include divinylbenzene copolymer, phenol/formalin resin, and epoxy resin. Preferred specific examples of these chelate resins include Amberlite IRA-743 (styrene/divinylbenzene copolymer, manufactured by Rohm & Haas), and phenol resins (specially Gansho 56-81475, 57-
28655). In order to produce a phenolic resin having a chelate group of formula () or () in the phenol nucleus, for example, phenols,
It may be produced by three-dimensionally crosslinking aldehydes, aminopolyalcohols, and aliphatic polyamines. For example, a PVC column (inner diameter 13 mmφ) filled with 60 ml of a phenolic resin having a chelate group represented by the formula
= 7.0) at a rate of 120ml per hour,
Even after 40 hours, the leaked concentration of boron was maintained at 0.1mg/, and heavy metals other than mercury were completely removed. Next, once the resin is saturated, heavy metals other than boron and mercury can be eluted from the resin by treatment with a 1-5% by weight mineral acid aqueous solution. As the mineral acid, hydrochloric acid, sulfuric acid, nitric acid, etc. are used, but sulfuric acid is particularly preferred. Furthermore, after eluting heavy metals other than boron and mercury,
It can be regenerated by washing with 1 ml of water and neutralizing with 4 to 10% by weight aqueous alkaline solution. The chelate resin having sulfur as a ligand used in the present invention includes a chelate resin having a functional group such as a thiourea derivative or a dithiocarbamate derivative and a resin matrix such as polyphenol or polystyrene, and a chelate resin having a thiourea derivative on activated carbon. Examples include adsorbents carrying sulfur-containing compounds such as dithiocarbamic acid derivatives, and specific examples include Uniselect UR-2200H and 120H (manufactured by Unitika), Sumikylate Q-10R (manufactured by Sumitomo Chemical),
Eporus-Z-7 (manufactured by Miyoshi Oil Co., Ltd.), chelate
MA (manufactured by Hokuetsu Tanso Co., Ltd.), ALM-125 (manufactured by Nippon Soda Co., Ltd.)
etc. can be mentioned. These resins are not normally subjected to regeneration treatment, and can be replaced and used as needed when they reach saturation. According to the present invention, it is possible to completely remove harmful non-metals such as boron from wastewater from garbage incinerators, which was previously difficult, and also completely and reliably remove heavy metals such as cadmium and mercury. can be removed to below the wastewater standard value. Next, the present invention will be specifically explained using examples.
In addition, % in Examples and Reference Examples represents weight %. Reference example 1 Phenol 29.1g, 37% formalin 25.0g, N
A mixture of 60.0 g of -methyl-D-glucamine and 10 g of water was heated and stirred at 80°C for 2 hours to obtain an initial product. To this initial product, 56.1 g of 22% caustic soda aqueous solution, 11.2 g of ethylenediamine, and 100 g of 37% formalin were added and stirred at 30°C for 1 hour.
While cooling to 5-20℃, add 33.9g of resorcin for 22 hours.
% caustic soda aqueous solution and 113 g of 37% formalin were added and stirred at 20°C to obtain a viscous reaction solution. When this reaction solution is subjected to pearl polycondensation using perchlorethylene as a solvent in a conventional manner,
180 g of crosslinked three-dimensional resin in the form of small spheres was obtained. After washing this resin with water, neutralizing it with 4.0% hydrochloric acid, and then treating it with a 4.0% caustic soda aqueous solution, washing the resin sufficiently with water until the phenolphthalein becomes colorless, it becomes a blackish brown resin. Got something for 50 metsushi. Example 1 Smoke washing wastewater (raw water) from a municipal waste incinerator A was adjusted to pH 11.0 with a 24% caustic soda aqueous solution, 300 mg of ferric chloride was added to 1 part of the raw water, and the mixture was allowed to stand for 30 minutes. After adjusting the pH to 11.0 again with a 24% caustic soda aqueous solution, 2 mg of Uniflocker UF-105 (manufactured by Unitika Co., Ltd.) was added to 1 part of the raw water and allowed to stand for 30 minutes. Next, separate this supernatant and PH with 30% sulfuric acid.
It was adjusted to 7.0 and used as a stock solution. When we analyzed this raw water solution, it was found that general heavy metals were almost completely removed to below the wastewater standard value.
Boron had not been removed at all, and cadmium and mercury had not fallen below standard values. Next, this water-flowing stock solution was added to the resin obtained in Reference Example 1.
A PVC column with an inner diameter of 13 mm filled with 60 ml and a PVC column with an inner diameter of 13 mm filled with 60 ml of Uniselect UR-2200H (manufactured by Unitika) were arranged in series, and liquid was passed through at SV = 2. The results are shown in Table 1. As is clear from Table 1, all harmful metals and heavy metals, including boron, were completely removed to below the wastewater standard values.

【table】

[Table] Example 2 Amberlite instead of the resin obtained in Reference Example 1
60ml of IRA-743 (manufactured by Rohm and Haas)
The operation was exactly the same as in Example 1, except for using the following. The concentrations of the treated water at a liquid flow rate of 30 to 40/-R were as shown in Table 2.

[Table] Example 3 The operation was exactly the same as in Example 1 except that the smoke washing wastewater (containing 15 ppm of boron) from the B municipal waste incinerator was used. The results are shown in Table 3. As is clear from Table 3, all harmful metals and heavy metals, including boron, were completely removed to below the wastewater standards.

【table】

[Table] Comparative Example 1 Liquid was passed through the column in exactly the same manner as in Example 1 except that a commercially available iminodiacetic acid type chelate resin was used instead of the resin obtained in Reference Example 1. the result,
Although all heavy metals were treated to below the wastewater standards,
Harmful non-metals such as boron cannot be treated at all, and in particular the boron concentration in the treatment solution is 27ml/
It was hot.

Claims (1)

[Claims] 1. A method of treating wastewater generated from a garbage incinerator with a chelate resin, which includes a pretreatment step of coagulating and precipitating the contents in the wastewater and separating solid and liquid, and treating the pretreated wastewater with an aminopolyol. A method for treating wastewater from a garbage incinerator, comprising the step of bringing a chelate resin having a group into contact with a chelate resin having a sulfur group and a chelate resin having a sulfur group. 2. The treatment method according to claim 1, wherein the chelate resin having an aminopolyol group is a chelate resin having a chelate group represented by the following general formula () or (). (However, _R1 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and n represents an integer of 1 to 6.) (However, R ₂ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.)