JP3005597B2 - Treatment of acidic wastewater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating acidic wastewater, and more particularly, to a method for treating acidic wastewater that can effectively exhibit the coagulating function of an inorganic coagulant by diluting seawater and prevent malodor.

[0002]

BACKGROUND OF THE INVENTION Heretofore, shochu wastewater has been fermented and discharged as acidic wastewater. Such shochu wastewater is often discarded without being treated in fields, and is often disposed of by evaporation or infiltration underground. However, there is a problem that the bad odor leads to deterioration of the environment of local residents. In addition, if disposed of in large quantities over a long period of time, a filtration inhibition membrane will be formed in the soil and penetration into the underground will stop, and it will be necessary to search for a new disposal site. It is difficult. For this reason, ocean dumping is being considered, but there is a problem of marine pollution. A method of incineration by an incinerator is also being studied, but there is a problem that the incineration cost is high.

[0003] In recent years, a method of directly membrane-treating shochu wastewater, which is an acidic wastewater, has been attempted. However, shochu wastewater not only has a high viscosity but also has a high content of suspended solids (ss). However, there is a problem that the film is clogged immediately.

[0004] For this reason, a method of directly biologically treating shochu wastewater is also conceivable, but it is difficult to directly biologically treat shochu wastewater having a high concentration of organic suspended solids.

[0005]

Therefore, the present inventor studied an effective pretreatment method, and tried coagulation sedimentation treatment by diluting wastewater about twice. However, it was found that the dilution effect of about 2 times and 3 times did not show the aggregation effect of the suspended suspended substance. Also, dilution with tap water is costly
It turns out.

[0006] Based on such findings, the present inventors have result of further extensive studies, depending on diluting the acidic waste water 5 times or more
And a remarkable flocculation effect was recognized, and it was found that a bad smell of wastewater could be prevented.

[0007] That is, an object of the present invention is to prevent the odor of wastewater.
And, moreover there is provided a processing method of the pretreatment capable acidic wastewater without using tap water.

[0008]

According to the present invention, there is provided a method for treating acidic wastewater, comprising the steps of: diluting acidic wastewater containing a high concentration of suspended organic substances with seawater by a factor of 5 to 20 times. In addition , shellfish incineration ash is added as an inorganic coagulant, and if necessary, a polymer coagulant is added to perform solid-liquid separation.

In a preferred embodiment, the acidic wastewater is rice,
Wheat, cereals such as buckwheat, a waste water containing potatoes residue spirits made as raw material for sweet potato, Ru der it preferably is shochu wastewater.

Hereinafter, the present invention will be described.

The acidic wastewater to which the present invention is applied has a low pH
(pH 3-6) and wastewater that cannot be subjected to biological treatment due to the high concentration of organic suspended suspended substances of 20,000 to 70,000 ppm, and wastewater that is difficult to directly apply to biological treatment and membrane treatment, for example, Waste water containing residues of distilled spirits made from grains such as rice, wheat, buckwheat, and potatoes such as sweet potatoes. Specifically, buckwheat shochu, wheat shochu,
Examples include, but are not limited to, wastewater such as potato shochu and manufacturing wastewater such as whiskey and sake.

In the present invention, before adding the inorganic coagulant to the acidic wastewater, the acidic wastewater is preliminarily 5 times or more mixed with seawater.
It is characterized by being diluted to 0 times or less. Dilution ratio is 5
If it is less than 2 times, no aggregation effect is observed, and if it exceeds 20 times, it is not preferable in terms of cost.

In the present invention, since the water is diluted using seawater, not only is the cost lower than when tap water is used, but also the versatility of the inorganic coagulant is expanded by using seawater. .

Although seawater may be used as it is, it may be used as a mixture with some industrial water, tap water, solid-liquid separation water, wastewater treatment water and the like within the scope of the present invention. If necessary, an alkali agent (eg, slaked lime) can be added to seawater.

The inorganic aggregating agent used in the present invention is the ash of shellfish.

As the incinerated ash of shellfish, incinerated ash obtained by incinerating shellfish at a temperature of about 1000 to 1800 ° C. in an incinerator is used. Examples of the shellfish include scallops, abalone, clams, clams, corals, clams, oysters, green shells and the like. The shellfish may be incinerated with the contents, or may be incinerated with the shell alone. The shellfish before incineration may contain seaweed and the like. In the present invention, incinerated ash can be used as it is, but fine powder from which impurities have been removed by sieving can also be used.

[0017]

In the present invention, shellfish which are inorganic coagulants
It is preferable to mix powdered or finely divided activated carbon into the incinerated ash .

In the present invention, a polymer flocculant can be added as required. As the polymer flocculant, any of anionic, cationic and nonionic polymers can be used, and they are used in powder or liquid form.

In the present invention, the inorganic coagulant and the powdery polymer coagulant can be used by mixing them in a predetermined ratio in advance. It is also preferable that these mixtures are formed into pellets.

Next, in order to carry out the treatment method of the present invention, a mixing tank (which can be replaced with a static mixer),
A slow stirring tank (not required), a sedimentation tank (alternative with other solid-liquid separation means) can be used, and the acidic wastewater is first diluted with seawater before or in the mixing tank. Next , shellfish incineration ash is added and mixed as an inorganic coagulant to start coagulation, a polymer coagulant is added if necessary, then coagulation is grown in a slow stirring tank, and solid-liquid separation is performed in a sedimentation tank.

The treated water subjected to the solid-liquid separation is sent to post-treatment biological treatment or membrane treatment. The biological treatment and the membrane treatment are not particularly limited, and various methods can be used. One feature of the present invention is that such post-processing is enabled. That is, by using the treatment of the present invention as a pretreatment, a treatment process for acidic wastewater can be completed.

The agglomerated sludge of the shochu wastewater obtained by the treatment method of the present invention can be effectively used as animal feed or organic fertilizer for agriculture as it is or after being dried by dehydration.

[0024]

[Function] Even if an inorganic coagulant is added as it is to acidic wastewater containing a high concentration of organic suspended solids, it does not show coagulability, but by diluting it with seawater 5 to 20 times,
Cohesiveness develops . Such effects are remarkable when the acidic wastewater is shochu wastewater. Further, it was confirmed by experiments that a flocculation reaction caused by seawater dilution was more effective in preventing bad smell than tap water dilution.

Therefore, according to the treatment method of the present invention, malodor is effectively prevented, and acidic wastewater containing a high concentration of organic suspended solids and having a low pH is pretreated at low cost, and biological treatment and membrane treatment are carried out. Treatment is also possible, and a treatment process for acidic wastewater can be established.

[0026]

EXAMPLES The effects of the present invention will be illustrated below with reference to examples of the present invention.

Example 1 (Production of shellfish incineration ash) Shellfish attached to an intake pipe of a thermal power plant were incinerated at a temperature of 1200 ° C. or more in an incinerator without being sorted. Take out the obtained incineration ash and leave it as it is,
Assume “A”. In addition, what was obtained by sieving the obtained incinerated ash to about 200 mesh is referred to as “B”.

[0028]

(Wastewater) As wastewater, acidic wastewater (shochu wastewater) discharged from Company U (Kyushu) was used. The acid wastewater was fermented and had a pH of 4.7. Further, it had a bad odor, a high viscosity, and contained a large amount of organic suspended substances (ss550,000 ppm to 60,000 ppm).

(Experimental Method) 25 ml of waste water was put in a 500 ml beaker, and seawater was added to a predetermined dilution ratio. Next, rotate 150r with a stirrer
While stirring at pm, the incineration ash and the polymer flocculant were added in predetermined amounts, and stirring was continued for 1 minute. Next, the stirring speed was changed to 30 rpm and the mixture was stirred for 5 minutes.
After standing for a minute, the cohesiveness was examined.

(Experimental Results) Each acidic wastewater was diluted with seawater to a dilution factor of 5, 10, 15, and 20 times. Incineration ash "A",
When the cohesion was examined for "B", the coagulation effect was confirmed in each case. Higher agglutination was shown when the dilution was 10 times or more than the 5 times dilution. No aggregation effect was observed when the dilution ratio was 3 times.

[0032] In addition, the Tsu line a similar experiment with 10-fold diluted with tap water as dilution water.

Furthermore, when the incineration ash “A” and “B” were examined for cohesion in the case of no dilution, no coagulation effect was observed in any case.

Further, when a sensory test was conducted on the effect of preventing the offensive odor, the odor of the wastewater was eliminated in the case of dilution with seawater, but a little odor remained in the case of dilution with tap water.

Example 2 Treatment method: 900 ml of seawater and 100 ml of wastewater were put into a 2 liter beaker, and 10 g of the above incinerated ash “A” was added while stirring with a stirrer at a rotation speed of 150 rpm, and then a polymer flocculant was added. 5 ml (0.2% solution) was added and stirring was continued for 1 minute.
Next, the rotation speed of the stirrer was changed to 30 rpm, and the mixture was stirred for 5 minutes, and then left standing for 30 minutes to examine the properties of the supernatant water.

Treatment method: 900 ml of seawater and 90 ml of wastewater are put into a 2 liter beaker, 10 g of the above incinerated ash “A” is added while stirring with a stirrer at a rotation speed of 150 rpm, and then 5 ml of a polymer flocculant (0.2 ml). % Liquid) and stirring was continued for 1 minute. Next, the rotation speed of the stirrer was changed to 30 rpm, and the mixture was stirred for 5 minutes, and then left standing for 30 minutes to examine the properties of the supernatant water.

Treatment method: 900 ml of seawater and 90 ml of wastewater are put into a 2 liter beaker, 15 g of the above incinerated ash “A” is added while stirring with a stirrer at a rotation speed of 150 rpm, and then 5 ml of a polymer flocculant (0.2 ml). % Liquid) and stirring was continued for 1 minute. Next, the rotation speed of the stirrer was changed to 30 rpm, and the mixture was stirred for 5 minutes, and then left standing for 30 minutes to examine the properties of the supernatant water.

Table 1 shows the dilution ratio of seawater, the concentration of the incinerated ash “A” added to the wastewater, and the concentration of the polymer flocculant added to the wastewater.

[0039]

[Table 1]

(Experimental Results) The results of the experiments are as shown in Table 2.

[0041]

[Table 2]

[0042] As Table 2 or et al is clear, 10 by seawater
In the treatments at 1-fold and 11- fold dilution, good coagulation effects were observed, and in particular, a significant phosphorus removal effect was observed.

[0043]

According to the present invention, the odor of wastewater can be prevented,
Moreover, pretreatment can be performed without using tap water. Especially with seawater dilution, it can be diluted at lower cost than tap water.
You . Such effects are remarkable when the acidic wastewater is shochu wastewater.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-64-75097 (JP, A) JP-A-63-166496 (JP, A) JP-A-2-52091 (JP, A) JP-A-6-62091 121981 (JP, A) JP-A-52-140484 (JP, A) JP-A-8-299966 (JP, A) JP-A-51-141457 (JP, A) JP-A-48-47162 (JP, A) JP-B-39-28178 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 1/52-1/56 B01D 21/01

Claims (3)

(57) [Claims] 1. A acidic waste water containing a high concentration of organic suspended suspended solids was diluted to less than 20 times 5 times or more at sea, and an inorganic coagulant
A method for treating acidic wastewater, comprising adding incinerated ash of shellfish and, if necessary, adding a polymer flocculant to perform solid-liquid separation. 2. The acidic wastewater according to claim 1, wherein the acidic wastewater is a wastewater containing a residue of distilled liquor made from grains such as rice, wheat, buckwheat, and potatoes such as sweet potatoes. Processing method. 3. The method for treating acidic wastewater according to claim 2, wherein the wastewater is shochu wastewater.