JPH11309304A - Precipitant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute purification treatment with a single treating tank by a method wherein aluminum polychloride and an alkali earth metal compound, further at least one constituent of a high-molecular flocculant, tannin, and a water-soluble cellulose compound as a water-soluble constituent, or those and a water-soluble silica are contained. SOLUTION: In a treatment tank 1, aluminum polychloride and a water-soluble alkaline earth metal compound, further as a watersoluble constituent, at least one of a high-molecular flocculant, tannin, and a water-soluble cellulose compound, or a precipitant containing them and a water-soluble silica are put into contaminated wastewater. After casting, they are stirred to be separated into a supernatant 13 and a precipitate 15, and when an adequent amount of the precipitate 15 is accumulated, it is exhaused by opening a precipitate exhausting valve 8 at any time. The purified water 13 being the supernatant fluid, when the precipitate 15 settles sufficiently to obtain a clearness, is exhausted by opening an exhaust valve 6 at any time. Thereby, even in the case of a comparatively much treating amount, a purification treatment can be executed by a single treating tank 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an organic matter-containing wastewater,
For example, processing emulsion adhesives, paints, emulsified oil and livestock wastewater, domestic wastewater, food processing wastewater, dyeing wastewater, factory wastewater containing malodorous components, etc., and separating organic substances to be removed as precipitates It relates to the precipitant to be removed.

[0002]

2. Description of the Related Art As a method for purifying wastewater containing contaminants such as emulsified and dispersed resins, fats and oils, pigments, dissolved dyes, and organic compounds, a purifying method utilizing the action of activated sludge and a flocculant are known. Methods of adding and coagulating and separating, and methods of adsorbing and removing contaminants are known.

[0003] Among the above-mentioned methods, the method utilizing the action of activated sludge requires a long treatment time of contaminated water due to a slow decomposition reaction of organic substances by microorganisms, and requires a large treatment layer.

In addition, it is difficult to remove particulate matter by the adsorption method, and a separate filtering means is required.

[0005] In the above method, a method of adding a flocculant to carry out flocculation and separation can effectively remove suspended particles in the form of fine particles and dissolved or solubilized organic pollutants as precipitates.

[0006]

However, the flocculant removes contaminants mainly using an electrochemical principle, and in order to make it work effectively, generally pH adjustment, addition of a decolorizing agent, It requires several steps such as the addition of a flocculant and the addition of a flocculant.If the amount of wastewater is large, a treatment tank is required for each step, requiring a large area and a large number of processing steps. There are many points to be improved.

It is an object of the present invention to provide wastewater containing organic substances, for example, emulsion adhesives, paints, emulsified oil and livestock wastewater, domestic wastewater, food processing wastewater, dyeing wastewater, and industrial wastewater containing malodorous components. To provide a precipitant that separates and removes organic substances to be treated and removed as a precipitate, and that can be purified by a single treatment layer even when the amount of treatment is relatively large. is there.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a precipitant for treating organic matter-containing wastewater in a single step, wherein the precipitant is polyaluminum chloride (hereinafter abbreviated as PAC) and a water-soluble alkaline earth metal compound. It is characterized by containing.

The combined use of a PAC and a water-soluble alkaline earth metal compound makes it possible to remove contaminants as sediments by sedimentation and separation in a single treatment tank regardless of the conditions of the contaminated water.

PAC, which is a raw material used in the present invention, is represented by the following chemical formula.

[0011]

Embedded image [Al ₂ (OH) _n Cl _6-n ] _m (1 ≦ n ≦ 5) The precipitant of the present invention further comprises at least one of a polymer coagulant, a tannin, and a water-soluble cellulose compound as water-soluble components. It is preferable to contain the components or these and water-soluble silica.

The polymer coagulant, tannin, and water-soluble cellulose compound are all ionic polymer substances, and are protected by the electric double layer to stably form the electric double layer of contaminants floating or dissolved in water. By having a function of breaking and aggregating, an adsorbing action, a pH adjusting action, and the like, the purifying action of the precipitant is enhanced.

Water-soluble silica is a compound also called silicic acid, and is represented by a chemical formula of xSiO ₂ .yH ₂ O,
It has a wastewater purifying action, such as condensing to form a porous substance and exhibiting adsorptive power.

In the above-mentioned precipitant, the PAC / water-soluble alkaline earth metal compound has a weight ratio of 8/2 to 5 /
5, and the total amount of the water-soluble component added is 5 to the total of the PAC and the water-soluble alkaline earth metal compound.
Preferably it is 15% by weight.

When the weight ratio of PAC / water-soluble alkaline earth metal compound exceeds 8/2, the concentration of alkaline earth metal ions decreases, and the cohesive strength decreases. Conversely, if the weight ratio is less than 5/5, the concentration of PAC decreases, and the cohesive strength also decreases.

If the amount of the water-soluble component is less than 5% by weight based on the total amount of the PAC and the water-soluble alkaline earth metal compound, the effect of adding these water-soluble compounds is not exhibited, and if it exceeds 15% by weight. It is not preferable because many of these compounds remain in the treated water.

The precipitant of the present invention preferably further contains at least one component selected from activated clay, acid clay, diatomaceous earth, and iron oxide as a hardly water-soluble powder component.

These substances have a high adsorptive capacity and form nuclei of aggregates formed by being aggregated by the above-mentioned precipitant,
It also has the effect of rapidly and effectively removing precipitates or removing adsorption by pollutants.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The PAC used in the present invention is preferably a powder having an Al content of 30% by weight or more in terms of Al ₂ O _3.
It may contain l ₂ O ₃ .

Examples of the water-soluble alkaline earth metal compound used as a component of the precipitant of the present invention include calcium hydroxide, magnesium hydroxide, barium hydroxide, calcium chloride, magnesium chloride and the like.

Water-soluble silica such as Toksil (manufactured by Tokuyama Soda Co., Ltd.) is commercially available.

As the polymer flocculant, a commercially available polymer flocculant can be used without any particular limitation. Generally, anionic or weak anionic resin emulsions are often used, and it is particularly preferable to use a cationic polymer flocculant which is a polycation compound.

There are tannins classified into condensed tannins and hydrolyzable tannins, but they can be used without any particular limitation, and have the effect of co-precipitating polyvalent heavy metal ions. Contributes to the purification of water. Of the tannins, the use of tannic acid is particularly preferred.

As the water-soluble cellulose compound, those which are polyvalent ionic compounds can be used without particular limitation.
Derivatives obtained by treating cellulose with maleic anhydride or the like can be exemplified, but sodium salt of carboxymethylcellulose (CMC) is preferred in terms of performance and cost.

The total amount of these water-soluble components is 100
In the case of weight%, it is preferable that each component is mixed in a range of 10 to 50 weight%, and a well-balanced purification ability is exhibited.

Activated clay, acid clay, diatomaceous earth, and iron oxide, which are powder components that are hardly soluble in water, are appropriately selected and used depending on the type of contaminated water to be treated.

It is a preferred embodiment to add sodium carbonate or potassium carbonate in addition to the above components to add a function as a pH adjuster.

In order to purify contaminated water in which oily components and resins are in an emulsified or suspended state, components such as a polymer flocculant are required. If it remains, it itself becomes a pollutant. Therefore, in the case of bad odor wastewater such as mere livestock wastewater, it may be possible to effectively settle and remove the wastewater simply by using a 2/8 to 5/5 mixture of PAC and Mg (OH) ₂ .

The amount of the precipitant used in the present invention is appropriately set depending on the concentration of the contaminated wastewater.
g. If the amount is too large as described above, it will remain in the treated water, and if it is too small, the treatment effect will be insufficient.

FIG. 1 shows an apparatus suitable for performing wastewater treatment using the precipitant of the present invention.

The treated water tank 1 is provided with a stirring blade 9 driven by a motor 11, a treated waste water inlet 3, a purified water drain 5 and a sedimentation outlet 7, and the treated waste water inlet 3 is provided with a drain valve 6 and a purification valve. Each of the water discharge ports 5 is provided with a settling discharge valve 8.

Although the precipitant of the present invention can be subjected to one-stage treatment, particularly in the case of strongly acidic or strongly alkaline wastewater,
It does not prevent providing the neutralization tank before the processing tank shown in FIG. Further, a system in which the processing wastewater is directly injected into the processing tank without providing the processing wastewater inlet 3 may be used.

The contaminated wastewater is charged with the precipitant of the present invention in the treatment tank 1 and stirred to separate into a supernatant 13 and a sediment 15, and when a considerable amount of the sediment 15 has accumulated, the sediment discharge valve is opened as needed. And discharge. When the sediment of the purified water as the supernatant is sufficiently settled and becomes clear, the drain valve 6 is opened and discharged as needed.

[0034]

Embodiments of the present invention will be described below. Example 1 A composition having the following composition was uniformly mixed to obtain a precipitant 1 of the present invention.

PAC (manufactured by Taki Kagaku) 55.0% by weight Mg (OH) ₂ 9.0 Ca (OH) ₂ 9.0 Na ₂ CO ₃ 17.0 Tannin 5.0 Water-soluble silica 3.0 Amphoteric Polymer flocculant 2.0 1000 l of wastewater containing 1% by weight as a solid content of woodworking bond CH-131 (manufactured by Konishi Co., Ltd.) as a resin emulsion is placed in a treatment tank, and the above precipitant 1 is added to 1500
g was added and stirred. After 5 minutes a clear supernatant is obtained,
When this was analyzed, the results shown in Table 1 were obtained.

[0036]

[Table 1] Example 2 A composition having the following composition was uniformly mixed to obtain a precipitant 2 of the present invention.

PAC (manufactured by Taki Chemical Co., Ltd.) 65.0% by weight Mg (OH) ₂ 8.0 CMC 6.0 Na ₂ CO ₃ 15.0 Tannin 2.0 Water-soluble silica 2.0 Amphoteric polymer flocculant 2.0 200 g of the above precipitant was added to 1000 l of drain water discharged from the compressor, and the mixture was stirred and left for 2 minutes. The supernatant was sampled and evaluated as purified water. Table 2 shows the measurement results.

[0038]

[Table 2]

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a contaminated wastewater treatment apparatus suitable for treating wastewater using the precipitant of the present invention.

Claims (4)

[Claims] 1. A precipitant for treating organic-containing wastewater in a single step, comprising polyaluminum chloride and a water-soluble alkaline earth metal compound. 2. A polymer coagulant as a water-soluble component,
The precipitant according to claim 1, wherein the precipitant contains at least one component of tannin, a water-soluble cellulose compound, or water-soluble silica. 3. The polyaluminum chloride / water-soluble alkaline earth metal compound has a weight ratio of 8/2 to 5/5,
The precipitant according to claim 1 or 2, wherein the total amount of the water-soluble component is 5 to 15% by weight based on the total of the polyaluminum chloride and the water-soluble alkaline earth metal compound. 4. The precipitant according to claim 1, further comprising at least one component selected from the group consisting of activated clay, acid clay, diatomaceous earth, and iron oxide as a powder component that is hardly soluble in water.