JPH07112194A - Treatment with activated sludge of industrial waste water - Google Patents

Abstract

PURPOSE:To smoothly perform an activated sludge treatment of industrial waste water incorporating harmful components hindering the function of activated sludge such as sulfides and cyan compounds. CONSTITUTION:A mixture of strained lees from beer and/or strained less from bean curd or the both plus a water soluble iron salt is added to an aeration tank for activated sludge treatment of the industrial waste water containing the harmful components hindering the function of the activated sludge such as sulfides and cyan compounds. As a result, a lowered activity of the activated sludge for treating industrial waste water containing the harmful components which hinder the function of the activated sludge such as sulfides and cyan compounds is recovered in a short time and also occurrence of the undesirable treatment condition is previously suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for smoothly performing activated sludge treatment of industrial wastewater containing a cyanide and / or sulfide harmful to activated sludge.

[0002]

[0002] Industrial water discharged from coke ovens such as steel mills, chemical plants and gas plants, industrial wastewater discharged from petroleum refining plants, chemical plants such as chemicals and dyes, etc.
The pollutants indicated by D and COD are treated by the activated sludge treatment method. However, in these industrial wastewater, the amount of wastewater generated, the concentration of pollutants, etc. fluctuate significantly due to changes in the manufacturing process, types of raw materials, production volume, etc. Is not easily decomposed, bulking of activated sludge is likely to occur, and the quality of treated water is likely to deteriorate.

In particular, the low water discharged from the coke oven and the wastewater of the oil refinery contain sulfide and / or cyanide compounds which hinder the function of activated sludge, and therefore, they are associated with the fluctuation of the pollutant load. As a result, processing failure is likely to occur.

[0004]

The above-mentioned activated sludge treatment of industrial wastewater, for example, when producing coke, city gas, etc. from coal in a steel mill, chemical factory, city gas factory, etc., is discharged from the coke oven. The polluted components represented by COD, BOD, phenolic compounds, rhodan compounds, etc. are treated by the activated sludge treatment method for the safe water (gas waste liquid) and the wastewater of the oil refinery.
Although the activated sludge treatment of these industrial wastewaters is an important process that decomposes and removes most of the COD components such as phenolic compounds and rhodan compounds, it is necessary to install, manage and operate the activated sludge treatment of municipal sewage. The conditions are imitated as they are. However, since these industrial wastewaters are more complex in composition than city sewage and contain toxic components that inhibit the function of activated sludge such as cyanide compounds and sulfides, activated sludge such as city sewage is There is a limit to applying processing equipment specifications, management, operation technology, etc. as they are. For this reason, in the conventional activated sludge treatment of these industrial wastewater, a treatment failure of unknown cause is likely to occur, and when the treatment failure occurs, the recovery method is trial-and-error, and it takes 2 to 6 months for the recovery. It may take a long time.

Further, an important problem when the treatment failure occurs is that, in many cases of the treatment failure, the sludge bulking occurs and the decomposability of the rhodane compound is lowered to deteriorate the treated water quality. Rhodan compounds in this treated water are difficult to remove even by physicochemical treatment such as iron coagulation precipitation method, activated carbon adsorption method, etc. Currently, technology other than activated sludge treatment is economically and efficiently removed. Is not established. Therefore, in such a case, even if an additional treatment equipment such as an iron coagulation sedimentation method or an activated carbon adsorption method is installed after the activated sludge treatment, the rhodane compound cannot be removed by passing through this treatment equipment.

[0006] The fungus that decomposes this rhodane compound (rodan-decomposing bacterium) has a remarkably slower proliferative property than the fungus that decomposes phenol and the like. If the function deteriorates, it takes 20 to 60 days for the function to recover to the state before the shock after removing these shocks, and during this period, the COD and the rhodan concentration of the treated water remain high. Has been revealed.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides activated sludge treatment of industrial wastewater by adding beer squeezer and / or tofu squeezer (okara) to an aeration tank for activation. Activated sludge treatment method of industrial wastewater characterized by performing sludge treatment Activated sludge treatment method of industrial wastewater according to the above invention wherein squeezed beer and / or tofu squeeze and water-soluble iron salt are added Method for treating activated sludge of industrial wastewater according to the first or second invention, which contains harmful components that inhibit sludge function The above-mentioned third, wherein the harmful components are wastewater containing a reducing sulfur compound such as a cyanide compound and / or a sulfide. Activated sludge treatment method for industrial wastewater according to the invention The activated sludge treatment process for industrial wastewater according to each of the first to fourth inventions, wherein the industrial wastewater is an ammonium hydroxide (gas waste liquid) generated from a coke oven. Method: Activated sludge treatment method of industrial wastewater according to the fifth aspect of the present invention, which comprises performing and recovering activated sludge treatment of cheap water in which treatment failure has occurred Squeezing beer and / or tofu squeezing powder and ferric iron alone or second It is constituted by the method for treating activated sludge of industrial wastewater according to the sixth invention, wherein a water-soluble iron salt obtained by combining an iron salt and a ferrous salt is added.

[0008]

The inventors have already established a treatment technique suitable for treating industrial wastewater, for example, ammonium hydroxide, in which harmful components that inhibit the function of activated sludge include cyanide compounds and / or reducing sulfur compounds such as sulfides. However, I was able to deal with the poor processing to some extent.

In the present invention, the conventional method is further improved so that the activated sludge treatment of industrial wastewater containing harmful compounds that inhibit the function of the activated sludge containing a reducing sulfur compound such as a cyanide compound and / or a sulfide is unsuccessful. Then, we have completed the technology to recover in a significantly shorter time than the conventional method.

That is, industrial wastewater containing harmful compounds that inhibit the function of activated sludge, such as cheap water discharged from a coke oven and wastewater of an oil refinery, contains cyanide compounds and / or reducing sulfur compounds such as sulfides. In the activated sludge treatment, a treatment disorder is likely to occur due to a shock due to a component that inhibits the function of the activated sludge or a shock due to an abnormal pH. This is because these shocks significantly reduce the number of bacteria that make up the activated sludge and also decrease the activity. Therefore, in order to recover the processing disorder to the normal processing state, first, the bacteria reduced by shock must be grown to recover the state when the normal processing was performed.

The most general method for recovering the untreated activated sludge to a normal state is to remove the cause of the untreated treatment and manage the pH, temperature and DO of the activated sludge under appropriate conditions. .

However, activated sludge is an aggregate of various bacteria, and it is conceivable that the properties of each bacterium are quite different. For example, as described above, the growth rate of the rhodanic acid-degrading bacterium is very slow, which is about 1/40 of that of bacteria degrading phenolic compounds. Therefore, for example, in order to recover the disorder of the activated sludge treatment of the ammonium hydroxide in a short period of time, it is necessary to promote the growth rate of a slow-growing bacterium such as a rhodane-degrading bacterium.

The conventional disorder recovery method merely controls the conditions of activated sludge treatment, that is, temperature, pH, dissolved oxygen (DO), etc. and expects natural growth of bacteria. Takes a long time as explained above.

The inventors of the present invention have activated sludge of industrial wastewater containing harmful compounds that inhibit the function of activated sludge typified by wastewater such as cheap water and oil refineries containing cyanide compounds and / or reducing sulfur compounds such as sulfides. In order to recover the treatment disorder in a short period of time, a study was conducted on a method of promoting the growth of bacteria, in particular, a rhodane-degrading bacterium to restore the treatment disorder in a short period of time.

In general, bacteria are trace amounts of vitamins,
It is known that the growth rate is promoted in the presence of enzymes, phytic acid and the like. The inventors measured the growth rate of bacteria by adding vitamins, enzymes, phytic acid, etc. to the aeration tank of the activated water sludge treatment, and as a result, in the case of Rhodan-degrading bacteria as an example, the growth rate was higher than that without addition. Was promoted about 2 to 5 times. From these results, it is conceivable that if a problem occurs in the activated sludge treatment, the addition of vitamins, enzymes, phytic acid, etc. will recover the problem in a short period of time.

Therefore, as a result of adding these to the activated sludge treatment in which a malfunction actually occurred, recovery of poor decomposition of the rhodane compound took 20 to 60 days in comparison with the conventional method, but vitamins, It was recovered in 7 to 10 days by adding enzymes, phytic acid and the like.

[0017] However, if this method is applied to the treatment failure of the actual equipment, a large amount of vitamins, enzymes, phytic acid, etc. are required, and there is a problem in terms of cost, and practical application is quite difficult. Therefore, the inventors focused on beer squeeze cake and tofu squeeze cake (okara) as a substance containing vitamins, enzymes, and phytic acid, which is inexpensive and available in large quantities, and uses this for the refined water and refinery plants. Vitamin, enzyme, phytic acid were added when sprayed to the aeration tank of the activated sludge treatment of industrial wastewater containing harmful compounds that inhibit the function of activated sludge represented by wastewater containing cyanide compounds and / or reducing sulfur compounds such as sulfides. It was found that the same effect as when it was done can be obtained.

The activated sludge treatment of industrial wastewater containing harmful compounds that inhibit the function of activated sludge typified by wastewater such as cheap water and oil refineries contains cyanide compounds and / or reducing sulfur compounds such as sulfides. When the treatment becomes unsuccessful, activated sludge bulking (swelling) occurs, sludge floats and flows out in the sludge settling tank, and the activated sludge flows out into the treated water, causing deterioration of the treated water quality. In addition, this bulking had no proper method for recovery, and thus it took a long time to recover. However, in the present invention, beer squeeze cake and / or tofu squeeze cake and water-soluble iron salt, for example, ferric iron salt alone, or ferric iron salt and ferrous iron salt are added to activated bulk sludge that has caused such bulking. It was clarified that the recovery was made early by adding the aqueous solution of the iron salt which was combined with.

The bulking recovery mechanism is considered as follows. Beer squeeze cake and / or tofu squeeze cake has a large amount of the skin of grain, which is a raw material of rice, wheat, soybean, etc. When activated sludge adheres to the skin, and when a water-soluble iron salt coexists, the skin on which the activated sludge adheres due to the aggregating action of iron salt, especially ferric iron, has good sedimentability. It seems that bulking will be recovered in a short period of time by forming various flock. Therefore, instead of the water-soluble iron salt, a coagulant that does not adversely affect the activated sludge, such as polyaluminum chloride or a polymer coagulant, can be used.

[0020]

EXAMPLES Next, examples of the present invention will be described. (Example 1) Beer squeezing residue was aerated in the aeration tank for the activated sludge treatment in which the rhodan compound of the ammonium hydroxide became poorly decomposed.
About 30 to 60 g per m ³ was constantly added per day. As a result, the decomposability was recovered from about 5 to 7 days after the addition of squeezed beer, and the decomposability was recovered almost completely after 7 to 10 days. In addition, when the squeeze residue of beer was not added, recovery of the decomposability of the rhodane compound required about 20 to 60 days or more. From this, the squeeze of beer is
It was revealed that the rhodane compound has an action of promoting recovery of degradability.

(Example 2) As a result of adding 500 to 600 g of beer squeeze per 1 m ³ of the aeration tank to the aeration tank of the batch activated sludge treatment for culturing the rhodanic acid-decomposing bacteria, the concentration of the rhodane compound was 300 mg / l. (As SCN)
The aqueous solution of was decomposed within 24 hours. It should be noted that, without adding squeezed beer, it took 96 hours or more to completely decompose the aqueous solution having the same concentration. From this, it was clarified that the squeeze cake of beer had an action of activating the rhodane-decomposing bacteria.

(Example 3) Ammonia component (sulfide, cyanide)
The inhibition of the function of sulfite ion (NO ^{2 −} ) caused by rhodane-decomposing bacteria caused by over-aeration of the activated sludge treatment with amniotic water was improved by the addition of squeezed beer.

That is, the rhodane-decomposing bacterium is added to the rhodane compound solution 1
00 mg / l (as SCN) was added, and 500 to 600 mg / l of beer squeezed residue was added and shake culture was performed. As a result, sulfide was 15 mg / l (as S ^2- ) or cyanide ion was 10 mg. / l, or a sulfite ion 20mg / l (as NO ^2-) thiocyanate compound that may be added are completely degraded within 24 hours. When no beer squeeze is added, S ^2- is 10 mg / l, CN ^- is 10 mg / l, or NO ^2- is 15 mg / l.
The rate of decomposition of rhodan when adding 1 is 38%,
35% and 53%. From this, the functional inhibition of the rhodane-degrading bacterium by S ²⁻ , CN ⁻ and NO ^{2 −} was improved by the addition of beer squeezing residue.

(Embodiment 4) In the bulking state,
³⁰ to 60 g of beer squeezing powder per day in an aeration tank for activated sludge treatment of annoying water that has been in poor condition due to degradation of the rhodane compound, etc., water-soluble iron salt As a solution, an aqueous solution of ferric chloride was constantly added. As a result, it usually took about 30 days to more than half a year to recover bulking, but after adding beer squeezing powder and iron chloride, the sedimentation property became good from about 7 to 10 days, and after addition,
The bulking condition was completely recovered in 15 to 20 days. or,
The degradability of the rhodan compound improves 5-10 days after addition,
It was completely recovered after 10 to 20 days.

Example 5 About 50 mg / l (a of sulfide)
s S ^{2 ‐} ) wastewater from an oil refinery including s S ^{2 −} ) is treated while supplying it according to the temporal change in the amount of wastewater generated in the factory, resulting in activated sludge in a bulking state, resulting in COD and SS of treated water. The concentration became significantly higher. In this activated sludge treatment, squeezed tofu (okara) and water-soluble iron salt were not added.

Therefore, about 50 g of tofu squeeze debris was added to this activated sludge aeration tank per 1 m ³ of the aeration tank per day.
An aqueous solution of ferric chloride and ferrous sulfate as a water-soluble iron salt was added daily at 30 to 50 g (as iron ions) for about 30 days every day. The sedimentation property of the activated sludge was improved from about 10 days after the addition of the squeeze cake of tofu and the water-soluble iron salt, and the bulking state was completely recovered 15 to 20 days after the addition.

Thereafter, the addition of the squeeze cake of tofu and the water-soluble iron salt is reduced once every two months, once every two days, once every five days, once every ten days, and finally every ten days. As a result of adding tofu squeeze cake and water-soluble iron salt once, bulking did not occur and good treated water quality was obtained.

As described above, when the tofu squeeze cake and the water-soluble iron salt are added to the activated sludge treatment which tends to cause bulking at regular intervals, the occurrence of bulking is suppressed and a stable and good activated sludge treatment becomes possible. became.

[0029]

As described above, the present invention provides a sulfide,
When processing industrial wastewater containing harmful components that inhibit the function of activated sludge such as cyanide compounds by the activated sludge treatment method, squeeze of beer and / or squeeze of tofu in the aeration tank of activated sludge treatment, or squeeze of beer By adding the dregs and / or tofu squeezed residue and the water-soluble iron salt, it is possible to recover the processing troubles such as the occurrence of bulking of activated sludge and the poor decomposition of polluted components of wastewater in a short period of time, and to add these at all times. It has become possible to suppress the processing failure of.

Claims (7)

[Claims] 1. An activated sludge treatment of industrial wastewater, which comprises adding beer squeeze cake and / or tofu squeeze cake (okara) to an aeration tank to perform activated sludge treatment. Sludge treatment method. 2. The method for treating activated sludge of industrial wastewater according to claim 1, wherein the squeezed dregs of beer and / or the squeezed dregs of tofu and a water-soluble iron salt are added. 3. The method for treating activated sludge of industrial wastewater according to claim 1, wherein the industrial wastewater contains harmful components that inhibit the function of activated sludge. 4. The waste water containing the harmful compound as a reducing component such as a cyanide compound and / or a reducing sulfur compound such as a sulfide.
(3) The method for treating activated sludge as described in the industrial wastewater. 5. The method for treating activated sludge of industrial wastewater according to any one of claims 1 to 4, wherein the industrial wastewater is an ammonium hydroxide (gas waste liquid) generated from a coke oven. 6. The method for treating activated sludge of industrial wastewater according to claim 5, wherein the activated sludge treatment of the poor water in which the treatment failure occurs is performed and recovered. 7. A squeeze cake of beer and / or a tofu squeeze cake and a ferric salt alone, or a water-soluble iron salt obtained by combining a ferric salt and a ferrous salt is added. Activated sludge treatment method for industrial wastewater.