JPS6154293A - Treatment of high concentrated organic waste water - Google Patents

Abstract

PURPOSE:To recover methane gas from the titled waste water with high efficiency in a short residence time and to reduce BOD of the waste to a prescribed value by carrying out a methane fermentation of the waste and then treating the obtd. digested waste under an anaerobic condition. CONSTITUTION:The waste is treated by carrying out the methane fermentation in a single phase or two phases to produce the methane gas and then passing the digested waste to a fixed bed type or a fluid bed type fermenter under the anaerobic condition whereby the methane gas is collected, and the waste having about 100 BOD is obtd. In the anaerobic treatment, the fixed bed of the fermenter in which a filler adhering a bacteria for the methane fermentation is packed; the fluid bed of the fermenter in which either a bacteria colony naturally adhered to a carrier or an immobilized bacteria comprised in a gel carrier is fluidized; or other fixed bed of the fermenter in which the above-mentioned immobilized bacteria is packed may be used. According to the above treating method, the waste is treated with the high efficiency in the short residence time by maintaining a concn. of a sludge in the fermenter to the prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating wastewater containing organic matter with a BODI of 0000 mg// or more (hereinafter referred to as high-concentration organic wastewater).

Conventional technology Conventionally, in order to treat high 11a degree granular wastewater, the wastewater was diluted to about BODl 000ml/1, and then the diluted wastewater was treated by an activated sludge method, or the wastewater was subjected to methane fermentation. A method is used in which methane gas is recovered, organic matter is decomposed with a BOD removal rate of 80 to 90%, and the stratified liquid is then treated by an activated sludge method (about 1,000 mg/l of BOD). was. In both cases, the water quality of the treated wastewater is determined by BOD.
It was improved to less than 200m (] /1.

Problems to be Solved by the Invention However, of the above two methods, the former method required a large amount of water for dilution.

7C The latter method has an energy advantage in that it can recover methane gas, but in the conventional methane fermentation method, the growth rate of methane-producing bacteria is slow, and if the number of days the wastewater stays in the tank is shortened, oxalic acid accumulates. and this directly or l)
Since the growth of methanogens was indirectly inhibited by lowering l-1, a retention period of 10 El to 30 days was required.

Furthermore, since all of these methods use an activated sludge method, dissolved oxygen in the aeration tank must be present at 1 to 4 mq/1, and the higher the BOD, the greater the aeration power required. The sludge ffi generated is also 0.5 to 0.7.
(MLSS)/(+ (BOD)), which made it difficult to dispose of excess sludge.

The object of the present invention is to provide a wastewater treatment method that can solve all of the above-mentioned problems.

In addition, in this specification (1), all BOD loads are BOD
MLSS refers to the concentration of suspended solids contained in the mixture of wastewater and activated sludge in aeration (a).

Means for Solving the Problems The method for treating highly concentrated organic wastewater according to the present invention
This method is characterized by subjecting organic wastewater to a methane fermentation method and then subjecting the resulting digestive fluid to anaerobic treatment.

Alcohol distillation waste liquid is a typical example of highly concentrated organic wastewater that can be used as a pest control method according to the present invention.
In addition, wastewater containing municipal waste, sewage sludge, sludge from valves, food processing wastewater, and highly concentrated organic wastewater such as human waste are of course subject to the system.

Methane fermentation methods include a two-phase methane fermentation method and a single-phase methane fermentation method, both of which can be applied to the present invention.

In this specification, the two-phase methane fermentation method refers to the separation of acid-producing bacteria and methane-producing bacteria from among the microorganisms involved in methane fermentation, and culturing them under optimal conditions. In the methane production process, the methanogens decompose specific substances to obtain lower fatty acids. The phase methane fermentation method refers to a method in which fermentation is carried out without separating microorganisms as described above.

Anaerobic treatment uses an anaerobic fixed tank or an anaerobic fluidized tank, and either methane-fermenting bacterial cells are attached to the filling material filled in the fixed tank, or adhered bacterial cells or gel-like cells are placed in a natural tube on a carrier. This is carried out by fluidizing the immobilized bacterial cells enclosed in a carrier in a fluidized tank or by filling the immobilized bacterial cells into a fixing tank. In this anaerobic treatment, the bacterial cells are reliably retained in the filler or carrier in the tank and are not washed out.

Step 1 for attaching bacterial cells in the tank! As the Jt IJ, a net-like object, an annular object, a saddle-like object, etc. made of plastic, metal, ceramic, etc. are used, and specific examples thereof include a Raschig ring, a Stedman backing, and a Barnador.

Vermiculite, sand, activated carbon, etc. are used as carriers for natural attachment of bacterial cells.

Immobilization of the bacterial cells is carried out as follows using a known entrapping method in which the bacterial cells are wrapped in a gel-like carrier.

That is, after a predetermined volume of bacterial cells is mixed with an aqueous solution of a gel base, the mixed liquid is cooled or brought into contact with a gelling agent, and the resulting gel is formed into particles or films of a desired size. When polyacrylamide is used as an IC or gel substrate, an acrylamide monomer, a crosslinking agent, a polymerization accelerator, and a polymerization initiator are added to a solution containing bacterial cells of a predetermined fn to polymerize the 7-mer to form an IC gel. Above) Shape as shown. As the gel base, carrageenan, sodium alginate, polyvinyl alcohol, polyacrylamide, polyurethane, etc. are used, as the gelling agent, potassium chloride, calcium chloride, magnesium chloride, etc. are used, and as the crosslinking agent, N, N- Methylenebisacrylamide etc. are used, and β-
Dimethylaminopropionitrile or the like is used, and potassium persulfate or the like is used as a polymerization initiator.

Effects of the Invention The method for treating high-concentration effluent wastewater according to the present invention performs anaerobic treatment after methane fermentation, so it does not solve the problems mentioned at the beginning, namely, treating high-concentration effluent wastewater. It is possible to completely eliminate the problems of requiring a large amount of water for dilution, requiring a large amount of aeration power to maintain a high dissolved oxygen level, and having to be careful about how to dispose of excess sludge.

Therefore, according to the method of this invention,
The sludge fJ degree in the treatment tank is maintained at a predetermined value, and the wastewater W is
Even during the i-retention time, methane gas can be recovered and BOD can be reduced.

EXAMPLES Next, examples of the present invention will be shown to illustrate the effects of the present invention.

Example 1 First, the configuration of a two-phase methane fermentation apparatus will be described. In the accompanying drawing, the acid generation tank (2) installed on the downstream side of the wastewater storage tank (1) is a mechanically stirred fermenter with an actual volume of 1.51 cm, and the agitator (3) and temperature and a pH control display device (4). Acid generation tank (2)
The methane generation tank (6) installed on the countercurrent side of the tank via the sedimentation tank (5) is a fluidized bed type fermenter with an actual volume of 1.51, and is a small-diameter fermenter with a jacket (7) for heat retention. Flow part (8
) and a large-diameter settling section (9
), the flow section (8) is equipped with a temperature and pH 1 control display device (10), and the sedimentation section (9) is equipped with a cylindrical gas display device for separating light gas from the fermentation liquid. A separating member (11) is internally played.

The wastewater containing Utsukumite stored in the wastewater storage tank (1) is
The organic acid-containing liquid that is supplied to the acid generation tank (2) by the pump (12) and produced in the circulation tank (2) is sent to the settling tank (3) by the pump (13). and sedimentation 4tJ (3)
The supernatant liquid is supplied to the bottom of the methanogen tank (6) by a pump (14), and the fermentation liquid flows out from the top by overflow. Also, a part of the fermentation liquid is taken out from the top and circulated to the bottom by a pump (15). And the acid generation tank (
2) and the gas content m generated in the methane generation tank (6) are each measured using a wet gas make (1G) (1γ).

In the above two-phase methane fermentation device, methane production is 4! f
An anaerobic tank (19) was installed on the downstream side of f (6) via a flow m adjustment tank (21) and a pump (18). Same species (
Reference numeral 19) is a fixed bed type fermenter with an actual volume of 1/1, and the gas content generated is measured with a wet gas meter (20). In the anaerobic treatment tank (19), there are a number of cylindrical fillers (diameter 2Qmm) made of plastic mesh wire structures.

2Q mm in length and 200 m 2 /m 3 in specific surface area) were filled randomly.

Alcohol distillation waste liquid is used as the highly concentrated organic wastewater, and this egg water is passed through the acid generation tank (2) and then into the methane generation tank (6), where it is subjected to two-phase methane fermentation according to a conventional method, and then into the anaerobic treatment tank ( 19) Anaerobic place 1! gshita.

The alcohol distillation waste liquid is 280% molasses from the Philippines.
24 using a medium consisting of (]// and urea 1.1/1.
Time Alcohol Fermentation (Ichikawa Sukka OV Ihis Cereviche 38 CG 1) ar OIll V CoScer
evisiae I F OO224), the fermented liquid was boiled for about 4 hours to scatter the alcohol, and the waste liquid (BOD33000m (+
// ).

The treatment results are shown in Table 1 below.

[Leaving space below] Table 1 As is clear from Table 1, the water quality of highly concentrated organic wastewater was determined to be BOD 53,000 mg// with a total tli retention period of 4.4 days.
11 Qm O/1 ni'A:r could be improved from 1 to 1, and 0.671 methane could be recovered per g BODl.

Example 2 As anaerobic treatment 1 (19), a fluidized bed fermentor with 1/actual volume was used, and Example 2 except that 10V% of vermiculite was filled as a carrier in the same type of container (19). The same operation as 1 was repeated.

The fluidized bed type treatment tank has the same 1111 structure as the methane generation tank (6).

The treatment results are as shown in Table 2 below.

(Leaving space below) Table 2 As is clear from Table 2, the water quality of highly concentrated organic wastewater was
1(+'//) to approximately 100 m0//, and 0.641 ml of methane could be recovered per gram of BOD.

Example 3 Example 1 except that a 4-bed fluidized bed fermentation tank with an actual volume of 11 was used as the anaerobic treatment tank (19), and 30 V% of immobilized methane-fermenting bacteria enclosed in sodium alginate gel was filled. The same operation was repeated.

The methane-fermenting bacteria were immobilized using the sodium alginate gel in the following manner. That is, the meso-temperature digested sludge from the sewage treatment plant was
g/l alcohol distillation waste, temperature 37℃, pH 7-8
100 m of the obtained acclimated sludge was concentrated to 20 m
After 1 m and 1 min, this concentrated sludge was mixed with 18 Qm of a sterilized 2% sodium alginate aqueous solution kept at a temperature of 40°C, and the mixed solution was dropped into a 0.1 M calcium chloride aqueous solution of 1,51 m. . In this way, a goose-like gel with a diameter of about 4 mm containing methane-fermenting bacteria was formed.

The treatment results are shown in Table 3 below.

(Leaving space below) Table 3 Example 4 Except that instead of two-phase methane fermentation, single-phase methane fermentation was performed using only the methane production tank (6) of the two-phase methane fermentation device shown in the attached drawing. Then, the same operation as in Example 3 was repeated.

The treatment results are shown in Table 4 below.

(Margin below) Table 4

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view of a two-phase methane fermentation apparatus used in Examples 1 to 3. (2)... Acid production 1ff, (6)... Methane production tank, (19)... Anaerobic treatment tank. 4 people other than above

Claims (2)

[Claims] (1) A method for treating high-concentration organic wastewater, which comprises treating the high-concentration organic wastewater by a methane fermentation method, and then subjecting the obtained digestive fluid to anaerobic treatment. (2) Using an anaerobic fixation tank or anaerobic fluidization tank, methane-fermenting bacteria are attached to the filling material filled in the fixation tank, or they are fixed by attaching the bacteria naturally attached to the carrier or by enclosing them in a gel-like carrier. 2. The method according to claim 1, wherein the digestive fluid is subjected to anaerobic treatment by flowing the cultured bacterial cells in a fluidized tank or by filling the immobilized bacterial cells in a fixed tank.