JPH10174991A - Method and apparatus for treating barn drainage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the discharge of treated water and the reuse of barn washing water by a method in which after drainage from a barn being treated biologically by an activated sludge method, alkali neutralization and solid liquid separation are done, the supernatant is bleached by adding an oxidizing agent, and COD and BOD are reduced. SOLUTION: Drainage discharged from a barn is introduced into an activated sludge tank 2 through a storage tank 1 to be subjected to biological treatment by an ordinary activated sludge method. Next, the drainage is introduced into a neutralization tank 4 through a receiving tank 3 and added with alkali to neutralized pH to a weak alkaline area. The drainage is separated into solid and liquid in a sedimentation tank 5, and the separated supernatant is introduced into an acid treatment tank 7, added with the aqueous solution of an oxidizing agent such as alkali hypochlorite, and bleached to reduce COD and BOD. Moreover, the supernatant is cured in a curing tank 8 until the completion of the bleaching. In this way, even a superresitant strain can be sterilized completely to be discharged and used for washing the barn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating human wastewater discharged from a barn such as cows and pigs.

[0002]

2. Description of the Related Art Every day, a large amount of human wastewater containing manure is discharged from cattle stalls such as barns and pig stalls. This sewage has a high COD (chemical oxygen demand) and a high BOD (biochemical oxygen demand), and discharging it as it is is a cause of water pollution. Therefore, it is strictly regulated by the Water Pollution Prevention Law. Therefore, it is necessary to provide a dedicated treatment facility for excrement of human waste in livestock barn facilities.

[0003] As a method for treating such wastewater, 1) feces (solid matter) and urine are separated and put into an activated sludge tank for biochemical treatment, which is transferred to a sedimentation tank for solid-liquid separation. A method in which the separated sediment (sludge) is converted into compost and the separated supernatant is discharged or treated with soil. 2) In a state where feces and urine are mixed, the mixture is filtered with a screw press or a belt-type filter to perform solid-liquid separation, and the filtrate is introduced into an activated sludge tank to perform biochemical treatment, thereby reducing the processing load. A method of reducing the weight and improving the effect of reducing COD or BOD. 3) After the solid-liquid separation in 2) above, the filtrate is introduced into a methane fermentation tank and aerated to perform COD or BO.
A method of reducing D, followed by placing in an activated sludge tank and performing a biochemical treatment, followed by solid-liquid separation and discharge of the supernatant is employed.

[0004]

In any of the above-mentioned methods 1), 2) and 3), the treatment of human waste sewage is easily affected by the microorganism treatment capacity of the activated sludge tank.
Alternatively, it is very difficult to reduce the BOD to a concentration at which it can be discharged. Furthermore, it was almost impossible to decolorize the wastewater. An object of the present invention is to reduce the COD and BOD of human sewage discharged from a barn very efficiently, perform decolorization and sterilization, and further use the treated water as a water discharge or a wash water for a barn. And a device therefor.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the above-mentioned object was achieved by subjecting the sewage after the activated sludge treatment to a chemical treatment. The inventor has found that this can be achieved and completed the present invention.

According to the present invention, wastewater from human wastewater discharged from a livestock barn is subjected to biochemical treatment by the activated sludge method, and then neutralized by adding an alkali. Is a solid-liquid separation, and an oxidizing agent is added to the obtained supernatant to decolorize and reduce COD and BOD of the liquid.

As the oxidizing agent, it is preferable to use an aqueous solution of alkali hypochlorite, a mixed aqueous solution of alkali chlorite and alkali hypochlorite, or a mixed aqueous solution of hydrogen peroxide and alkali chlorite. In addition, a wastewater suitable for discharge can be obtained by adding a reducing agent and performing dechlorination in order to remove the oxidant remaining in the supernatant subjected to such an oxidation treatment.

Further, a part of the supernatant liquid after the neutralization is mixed with the sewage to be treated by the activated sludge method to dilute the concentration of the sewage, thereby reducing the load on the activated sludge tank and improving the treatment efficiency.
The supernatant liquid after the oxidation treatment can be discharged after being treated with a reducing agent, or can be reused as washing water for livestock before or after treatment with a reducing agent.

[0009] The present invention also provides a wastewater storage tank from which feces in human wastewater discharged from a livestock barn are removed, an activated sludge tank for biochemically treating the wastewater led from the storage tank, and an activated sludge tank derived from the activated sludge tank. A neutralization tank for adding alkali to the liquid after the treatment to neutralize the solution, a sedimentation tank for solid-liquid separation of the precipitate formed in the discharged liquid of the neutralization tank, and an oxidizing agent added to the supernatant introduced from the sedimentation tank This is a treatment device for livestock barn sewage, comprising an oxidation treatment tank.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. The drawings show the flow sheet of the invention,
Human waste sewage discharged from a barn is removed by filtering and separating feces (solids) contained therein by a known method such as a screw press or a belt-type filter, and then the sewage (liquid) is stored in a storage tank 1. Introduce. The sewage in the storage tank 1 is guided to the activated sludge tank 2 and is subjected to biochemical treatment such as aeration treatment by a usual activated sludge method. The pH of the wastewater after this treatment is 4-5,
The COD is about 1,000 to 2,000 mg / l, and the BOD is about 50 to 70 mg / l. Next, the wastewater is transferred to receiving tank 3
When the alkali is further introduced into the neutralization tank 4 and neutralized to a weakly alkaline region having a pH of 7 to 8 by precipitation, a precipitate is rapidly formed. As a result of elemental analysis, this precipitate contains a large amount of Ca,
It contains a considerable amount of K and a small amount of Cl, S, Mg, Fe and the like. In addition, it contains a large amount of protein as organic matter. The discharged liquid of the neutralization tank containing the precipitate is led to the settling tank 5 to perform solid-liquid separation. The sedimentation rate of the precipitate is about 60% by volume of the supernatant liquid after 1 hour, and about 40% by volume of the precipitate. In this case, the sedimentation rate can be promoted by adding ferric chloride. The sediment can be sent to the fermenter 6 in the fertilizer production process, and fermented by adding, for example, "sawdust" and air to be fertilized. A part of the supernatant liquid can be returned from the sedimentation tank 5 to the storage tank 1 to dilute the sewage concentration, reduce the load on the activated sludge tank 2 and improve the treatment capacity.

The supernatant is introduced into an oxidation treatment tank 7, where an aqueous solution of an oxidizing agent such as alkali hypochlorite is added to perform decoloration and reduce COD and BOD. When an aqueous solution of alkali hypochlorite (effective chlorine: about 13% by weight) is used as an oxidizing agent, the amount of addition depends on the concentration of organic substances in the supernatant.
It is 0.1 to 10% by volume, preferably 0.5 to 5% by volume, based on the treatment liquid. When the addition amount is small, not only the time is required for decolorization but also the decolorization may not be performed. In addition, when the amount of addition increases, the decolorization becomes faster but the cost increases, and the amount of the reducing agent used for dechlorination as a post-treatment increases.

Next, the wastewater to which the oxidizing agent such as alkali hypochlorite is added is led to the curing tank 8 and the process is waited until the decoloring is completed. Usually, the decolorization is completed in about 2 hours after the addition in an amount of 1 to 2% by volume. When discharging the decolorized wastewater, excess chlorine such as alkali hypochlorite is dechlorinated using a reducing agent such as sodium sulfite, hydrogen peroxide, and sodium thiosulfate. The wastewater subjected to such treatment is decolorized and COD
To about 80 mg and BOD to about 3.6 mg. When alkali chlorite is used in combination as an oxidizing agent, the deodorizing effect is enhanced. The oxidizing agent added to the wastewater has a bactericidal effect, and it can be determined that the wastewater using alkali hypochlorite or the like completely kills super-resistant bacteria found in a pig farm in the UK. In addition, the wastewater after the oxidation treatment can be used as washing water in the livestock barn besides the discharge.

[0013]

【Example】

Example 1 Wastewater treated with activated sludge at a pig farm in Ehime Prefecture was 1,000 m
1 was collected and used for a decolorization test. The composition of the wastewater after the activated sludge treatment is as follows. pH = 4.8-5.3, COD = 1.250 mg /
1, BOD = 58.7 mg / l, T-N = 1,37
0 mg / l, TP = 594 mg / l, qualitative analysis with fluorescent X-ray Calculated as K content 100 Ca 70.2 Cl 23.7 P 21.7 S 15.5 Mg 3.0 Si 2.3 NMR In the analysis of organic substances, many proteins were detected.

In order to remove the composition as a precipitate,
10 ml of a 10% by weight aqueous solution of caustic soda was added with stirring to adjust the pH to 7.3. The sedimentation rate is as follows. This amount of sedimentation indicates a state in which the floc-like suspended matter is gradually tightened and settles, and the supernatant becomes large.

[0015] 600 ml of the supernatant was taken out and subjected to elemental analysis of the liquid and the precipitate in the same manner. Analysis of liquid composition COD = 578 mg / l, BOD = 21 mg / l,
TN = 1,310 mg / l, TP = 77.6 mg
/ L, calculated as K content 100 Cl 21.8 Ca 10.3 S 8.4 P 3.0 Na 1.7 Si 1.2 Mg 1.0 Analysis of precipitate composition Calculated as Ca content 100 P 38 0.2K25.5Cl7.3S5.2Mg2.4Fe2.4Si1.4Zn1.0Al1.0Na0.9Cu0.35Ti0.07 Proteins Many detected

Next, an aqueous solution of sodium hypochlorite (effective chlorine concentration 13% by weight) was added to the supernatant 11 by 0.5% by volume.
1%, 1.5% and 2% were added, and the decolorizing effects were compared.

[0017]

[Table 1] Regarding the above display, +5: brown to +1: weak yellow,-
-: Slightly colored, 0: colorless (color is not visually confirmed)

In Table 1, sodium hypochlorite aqueous solution 2
The remaining effective chlorine concentration after adding volume% is 1 in 48 hours.
It was 00 mg / l. COD after oxidation treatment = 78 mg
/ L, BOD = 3.6 mg / l. The results of elemental analysis of this liquid are as follows. Calculated as K content 100 Cl 68.1 Ca 7.8 S 5.9 Na 3.9 P 1.8 Si 0.92 Mg 0.64

Example 2 1,000 ml of the supernatant liquid neutralized in Example 1 was collected, and this solution was added to an aqueous sodium chlorite solution (effective chlorine concentration: 2).
(5% by weight) and 5 ml of an aqueous sodium hypochlorite solution (effective chlorine concentration: 13% by weight) were added, and chlorine dioxide was released from the sodium chlorite to perform a decolorization test. After 10 hours, hydrogen peroxide was added to reduce free chlorine dioxide and residual chlorine, resulting in completely decolorized wastewater. Also, the odor of the wastewater was completely removed.

Example 3 The treatment of human waste sewage discharged from a piggery was carried out according to the flow sheet shown in FIG. 5m ^{3 of} sewage from which feces have been removed (COD
= 15,000-20,000 mg / l, BOD = 2
(8,000 to 38,000 mg / l), the supernatant after the neutralization treatment was added, and the mixture was diluted about 2-fold in a storage tank.
= 8,000-10,000 mg / l, BOD = 17,
2,000 to 25,000 mg / l. When this wastewater was subjected to aeration treatment in an activated sludge tank, the treated wastewater had a COD of 500 to 600 mg / l and a BOD of 38 m.
g / l, pH = 4-5.5. Next, this solution was sent to a neutralization tank, a 48% by weight aqueous sodium hydroxide solution was added to adjust the pH to 7 to 8, and a suspension containing the generated precipitate was sent to a settling tank to perform solid-liquid separation. After 2 hours, separating the precipitate and supernatant (supernatant / precipitation volume ratio = about 6/4), a portion of the supernatant 6 m ³ back to the reservoir described above, the remainder to oxidation treatment tank Sodium hypochlorite aqueous solution (effective chlorine concentration 13
% By weight) was added to the supernatant, and after 3 hours, the liquid color became more colorless than yellow, and the COD at this time was 4%.
0 mg / l, BOD = 3 mg / l. The liquid contained 95 ppm of residual chlorine, which was completely dechlorinated by adding sodium sulfite as a reducing agent in a regulating tank to obtain wastewater that could be discharged as it was.

[0021]

According to the present invention, as compared with the case where the human wastewater discharged from the livestock bar is simply treated by the activated sludge method as in the past, a neutralization step and an oxidation treatment step are added thereto. It can be a wastewater that can be discharged directly with much lower COD and BOD. In particular, by adding an oxidizing agent, it is possible to almost completely decolorize, and since it has a bactericidal effect, it can be used as washing water in livestock barns,
The environment is improved, which is effective in preventing the occurrence of various bacteria and diseases. The precipitate generated in the neutralization step can be used as fertilizer.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing a processing method of the present invention.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI C02F 11/00 C02F 11/00 C (72) Inventor Ryutaro Ieku 291 Shintani-cho Ko, Ozu City, Ehime Prefecture (72) Inventor Yasuhiko Takashima 1247-1 Kitayoshida-cho, Matsuyama-shi, Ehime

Claims (8)

[Claims] 1. A wastewater discharged from a livestock sewage from which feces have been removed is biochemically treated by an activated sludge method, and then neutralized by adding an alkali. A method for treating livestock sewage, comprising separating an supernatant and adding an oxidizing agent to the obtained supernatant to decolorize the solution and to reduce COD and BOD of the solution. 2. The treatment method according to claim 1, wherein a part of the supernatant liquid after neutralization is mixed and diluted with sewage to be treated by an activated sludge method. 3. The treatment method according to claim 1, wherein the supernatant liquid after the oxidation treatment is discharged or reused as washing water in the livestock barn. 4. The treatment method according to claim 1, wherein the oxidizing agent is alkali hypochlorite. 5. The method according to claim 1, wherein the oxidizing agent is an alkali hypochlorite or an alkali chlorite. 6. The method according to claim 1, wherein the oxidizing agent is hydrogen peroxide and alkali chlorite. 7. The processing method according to claim 1, wherein a reducing agent is added to the supernatant after the oxidation treatment to remove the remaining oxidizing agent. 8. A storage tank for sewage from which feces in human wastewater discharged from a livestock house have been removed, an activated sludge tank for biochemically treating sewage introduced from the storage tank, and a treatment introduced from the activated sludge tank. A neutralization tank for adding an alkali to the post-solution to neutralize the solution, a sedimentation tank for solid-liquid separation of the precipitate formed in the effluent of the neutralization tank, and an oxidation for adding an oxidizing agent to the supernatant liquid guided from the sedimentation tank A livestock barn sewage treatment apparatus comprising a treatment tank.