JPS6028894A - Treatment of night soil - Google Patents

Abstract

PURPOSE:To perform nitration and denitrification treatment with high efficiency preventing foam generation and heat generation by adding inorg. or cationic org. flocculant to night soil in the acidic region of the night soil to cause flocculation and nitrating and denitrifying the separated liquid biologically. CONSTITUTION:Night soil 7 separated from solid is charged to a first reaction tank 1 where inorg. and/or cationic org. flocculant are/is injected, and if necessary, a pH adjusting agent 9 is added to cause flocculation and growth of the floc, and the product is separated to solid and liquid in a solid/liquid separating tank 3. The separated liquid 12 is fed to a denitrification tank together with returned sludge 13 and returned nitrated liquid 14, mixed with activated sludge contg. denitrifying bacteria in the tank and denitrified. The liquid mixture after denitrification is fed to a nitration tank 5 where it is mixed with activated sludge contg. nitrate bacteria and then aerated to remove residual COD, and contained N-components are converted to NO3<-> or NO2<-> ion.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating human waste by flocculation treatment and nitrification and denitrification treatment.

Biological treatment is the mainstream in human waste treatment, and nitrification and denitrification treatment is a part of this process, but there are problems such as lack of dilution water, land shortages,
Due to stricter discharge regulations, low dilution, high load, and advanced treatment are required. However, when nitrification and denitrification are performed biologically at low dilution and high load, foaming and heat generation occur in the nitrification tank.9 In order to prevent this and ensure normal nitrification and denitrification, This method requires the addition of an antifoaming agent and a large-scale antifoaming and cooling device, which complicates the maintenance and management of the device, and poses a problem in that stable processing cannot be performed.

On the other hand, a method has been proposed in which human waste is flocculated and then subjected to aerobic biological treatment, but as the conventional method performs flocculation treatment in an alkaline region, the biodegradability of the separated liquid is poor and protein This invention is intended to solve the problems of the conventional method as described above. After coagulation treatment in an acidic region, the separated liquid is subjected to biological nitrification and denitrification treatment, which increases the biodegradability of the separated liquid and enables biological nitrification and denitrification treatment, resulting in foaming at low dilution and high load. The purpose of the present invention is to provide a method for treating human waste that can efficiently perform nitrification and denitrification treatment without causing heat generation.

This invention is a method for treating human waste, which comprises aggregating the human waste in an acidic region and then biologically subjecting the separated liquid to nitrification and denitrification treatment.

Biological nitrification and denitrification treatment involves aeration in the presence of activated sludge containing nitrifying bacteria to remove organic matter (BOD, COD) and nitrify the nitrogen content to nitrate or nitrite ions. This is a process in which denitrification is carried out by maintaining anaerobic conditions in the presence of activated sludge containing denitrifying bacteria as well as organic matter. The nitrification and denitrification reactions in this case are expressed by the following equations.

(Nitrification reaction) NH4” +1.50□→NO2-1-1-120+
2H+NO2+ 0.502→N03- (denitrification reaction) 2NO□-+6H→N2 +2H20-4-20H-2
NOs + 1DH-)N2 + 41hO+ 20H
- The denitrification reaction requires an organic carbon source as a hydrogen donor, and BOD in human waste can be used for this reaction. On the other hand, in nitrification treatment, B
Since OD must be removed, high biodegradability is required.

For this reason, in the present invention, nitrification and denitrification treatment is performed after flocculation treatment under acidic conditions.

The human waste to be treated in the present invention is raw human waste, but
Pretreatment such as SS removal and preliminary aeration to the extent of stirring is possible, and it is preferable to remove impurities in advance using a bar screen, rotary drum screen, or the like. Such raw human waste is processed without being diluted.

Human waste contains a wide variety of pollutants, which can be classified into soluble pollutants, SS pollutants, inorganic pollutants, and organic pollutants. If the SS components contained in a large amount are removed, the contamination concentration will be significantly reduced. However, if the biodegradable OD acid component is largely removed and the COD component remains, the biodegradability deteriorates and efficient biological treatment becomes impossible.

When we measured the B OD/CODor ratio, which is one indicator of biodegradability, the biodegradability of raw human waste was 0.31, which was poor, and even if it was flocculated in an alkaline range, it was only improved to about 0.41. And biodegradability is not good. On the other hand, when molecular weight fractionation was performed on polluted components of raw human urine, the BOD/C0Dcr ratio was 0.0 for molecular weights below 20,000.
It was found that the biodegradability was extremely good. When we investigated a method of increasing biodegradability through flocculation treatment, we found that the BODZCODCr ratio was approximately 041 at pH 1'0, 063 at pH 6.5, and 0.80 at pH 4.5, indicating that the pH of flocculation treatment is in the alkaline range. It was found that the biodegradability is low in the case of the acidic region, but the biodegradability is high in the case of the acidic region, and there is no elution of proteins, fats, etc., and biological nitrification and denitrification treatment is possible.

In general, the BOD/T-N ratio in the nitrification and denitrification treatment of night soil is said to be about 6 for the nitric acid type and 18 for the nitrite type, but the BOD/T-N ratio of the separated liquid when flocculation treatment is performed in an acidic region.
The ratio is about 1.57, which is significantly lower than the above value.

However, flocculation treatment removes only the SS and polymeric B O1), leaving the low-molecular 130D that is easily utilized by denitrifying bacteria, as well as removing SS components, resulting in high sludge activity. It was found that the nitrification and denitrification treatment was carried out extremely efficiently due to the following reasons:

The flocculant used in the flocculation treatment may be either an inorganic flocculant or an organic flocculant, but it is also possible to use both in combination. Inorganic flocculants include aluminum chloride, polyaluminum chloride, aluminum sulfate, iron chloride (Ill), iron sulfate (Ill), iron chloride (rin), iron sulfate IL+, kotsubarasu chloride, polyferric chloride, polyferric sulfate, etc. The use of one or more species is possible.

Examples of organic flocculants include aminoalkyl acrylate or aminoalkyl methacrylate homopolymers or copolymers with acrylamide or other monomers, Mannich-modified or Hoffmann decomposition products of polymers containing acrylamide or methacrylamide as a structural unit, and polyamides. Polyamine, polyvinylimidacillin, polyethyleneimine, polydialkyl diallyl ammonium 6
Cationic organic flocculants such as salts can be used, and it is possible to use one type or several types of these.

When these inorganic flocculants and/or cationic organic flocculants are added to human waste and stirred in an acidic region, flocculation occurs and flocs are generated. At this time, in order to grow flocs, it is preferable to further add a nonionic or anionic organic flocculant and stir. Examples of nonionic or anionic organic flocculants include polyacrylamide, polyacrylamide partial hydrolyzate, and sodium polyacrylate.

In the case of inorganic flocculants, the amount of flocculant added is 0 for human waste.
．． 1 to 0.5'Mt%, 100 to 300 my/l for cationic organic flocculants, and about 50 to 150 m9711 for nonionic or anionic organic flocculants added later for floc growth. The ← ÷ ÷ acidic range when performing aggregation treatment is pH less than 7,
If the pH of raw human waste is within this range, there is no need to adjust the pH, but if it is outside this range or if you want to adjust it to a specific value within this range, add a pH adjuster such as hydrochloric acid. . The stirring conditions and other aggregation conditions may be the same as those for normal aggregation treatment.

The flocs generated by coagulation are separated by solid-liquid separation. As the solid-liquid separation means, a settling tank, a pressurized flotation tank, a dehydrator, a concentrator, etc. can be used. As a dehydrator, a belt press, a filter press, a centrifugal dehydrator, a screw press, a vacuum dehydrator, etc. can be used, and as a concentrator, a wedge wire screen, a rotary screen, etc. can be used.

Since the branch 1 liquid separated by solid-liquid separation has good biodegradability, nitrification and denitrification treatment can be performed without dilution. In this case, even without dilution, foaming and heat generation do not occur during aeration, and B
OD is sufficiently removed and nitrification and denitrification can be performed efficiently. Dilution here refers to intentional use of industrial water, river water,
It refers to mixing seawater, treated water, etc. with a separated liquid, and it prevents contamination of the system with defoaming water during aeration, seal water from pumps, cooling water, miscellaneous water, etc., P liquid from sludge dewatering, and cleaning waste water from dehydrators. Returns within the system are permitted.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 and FIG. 2 are system diagrams showing another embodiment of the present invention, respectively, in which 1 is a first reaction tank, 2 is a second reaction tank,
6 is a solid-liquid separation tank, 4 is a denitrification tank, 5 is a nitrification tank, and 6 is a solid-liquid separation tank.

In FIG. 1, removed human waste 7 is introduced into the first reaction tank 1,
Here, an inorganic flocculant and/or a cationic organic flocculant 8 is injected, and if necessary, an inorganic H regulator 9 is injected and stirred to perform a flocculation reaction, and then in a second reaction tank 2, a nonionic flocculant is An anionic organic (flocculant) is injected and stirred to grow flocs, and solid-liquid separation is performed in the solid-liquid separation tank 6.

The flocculated sludge 11 in the solid-liquid separation tank 6 is discharged, and the separated liquid 12 is introduced into the denitrification tank 4 together with the return sludge 13 and the return nitrification liquid 14, where it is mixed with the activated sludge containing denitrifying bacteria in the tank to remove oxygen. Denitrification treatment is performed by gently stirring in a shut-off state. Here, denitrifying bacteria that reduce nitric acid or nitrite ions in the returned nitrification liquid to nitrogen using BOD in the separated liquid as a hydrogen donor are dominant9, and the nitrogen component in the separated liquid is removed.

The denitrified mixed liquid is introduced into the nitrification tank 5, mixed with activated sludge containing nitrifying bacteria, and aerated to remove residual BOD and nitrify the nitrogen components to nitrate or nitrite ions. do.

A part of the nitrified mixed liquid is returned to the denitrification tank 4 as a return nitrification liquid 14, and the remaining part is solid-liquid separated in the solid-liquid separation tank 6. The separated liquid in the solid-liquid separation tank 6 is either discharged as it is as treated water 15 or is reused after being subjected to tertiary treatment.

A portion of the separated activated sludge 16 is returned to the denitrification tank 4 as return sludge 13, and the remainder is discharged as surplus sludge 17.

Although the flocculated sludge 11, excess sludge 17, and tertiary treated sludge can be treated individually, when they are mixed, the flocculated sludge 11 contains a large amount of fibrous material, so that the dewaterability is improved. These sludges can be processed by digestion, drying, incineration, composting, etc.

In FIG. 2, the denitrification tank 4 and the nitrification tank 5 are followed by a second denitrification tank 4a, a second nitrification tank 5a, a sixth denitrification tank 4b, and a re-nitrification tank 4a so that the denitrification and nitrification processes are repeated in multiple stages. 11ψ
An air tank 18 is provided, and the separated liquid 12 is sent to the denitrification tank 4 and the second
The nitrification liquid 14 is dispensed into the denitrification tank 4a and returned to the second nitrification tank 5.
The structure is the same as that shown in FIG. 1, except that the water is returned to the denitrification tank 4 from a. Since nitrification and denitrification are performed in multiple stages here, the denitrification efficiency is high, and the organic matter 19 that does not contain nitrogen such as methanol is finally collected in the filtration denitrification tank 4b.
is injected for denitrification, and the remaining substances are removed in the re-aeration tank 18.

In the above nitrification and denitrification process, the nitrification liquid is returned and denitrified by the denitrification process.
In order to utilize Bol) as a hydrogen donor, the device #
Specifically, the denitrification tank 4 is arranged at the front stage, and the nitrified liquid is returned from the nitrification tank 5 at the rear stage. Therefore, the apparatus may be configured to have a nitrification tank in the front stage and a denitrification tank in the rear stage. The treatment method shown in Figure 2 is suitable for removing nitrogen at a high rate, and when performing more advanced treatment, it can be modified depending on the treatment goal, such as increasing the number of stages of nitrification and arsenic denitrification. It is possible.

In the present invention, the separated liquid that has been flocculated in an acidic region is subjected to nitrification and denitrification treatment, so the separated liquid has high biodegradability and protein,
There is no elution of fat, etc., so BOD removal in the pre-nitrification stage is sufficient, and nitrification treatment is possible, and foaming occurs during aeration at this time.

Heat generation is prevented. In addition, the coagulation process removes SS and deodorizes it, and since there is no inflow of SS components, the activated sludge that is generated is mostly made up of highly active bacterial cells, and B.
OD removal, nitrification, and denitrification activities become higher. In addition, the flocculation process removes PSS and polymeric BOD, leaving BOD that is bioavailable, resulting in an extremely high removal rate of organic matter and nitrogen, making it possible to perform low dilution, high load, and advanced treatment. becomes.

Next, examples and comparative examples of the present invention will be described.

EXAMPLE The treatment was carried out according to the treatment method shown in FIG. First, polyferric sulfate was added to the human waste that had been removed using a rotary screen.
00m9/l was added and stirred, and the cationic organic flocculant (
Copolymer of aminoalkyl methacrylate 30'C and acrylamide, [η], .-:r4L
NO* = 1 i, s (al/g), = + oide equivalent (vL 1.8 meq/g) 200 m9/l was added, stirred, agglomeration treatment 1 ~ at pH 4,5, and centrifuged. The BOD of is 4,870 m9/1.
B OD/T -N ratio is 1.57, COI) M is 1
, 800 mg/A.

This separated liquid was subjected to biological nitrification and denitrification treatment at Muki Station.

At this time, the amount of returned sludge is 6 times, the amount of nitrified liquid returned is 30 times,
The total residence time in the denitrification tank and nitrification tank is 6 days. The amount of COCol in the treated water was 2201l197g, the TN removal rate was 95%, and almost no foaming or heat generation was observed in the nitrification tank.

The above separated liquid was diluted twice and subjected to the same treatment.The COI of the treated water was 130In9/1. The TN removal rate was 89%.

Comparative Example 1 When the sediment-removed human waste of the example was diluted twice without flocculation treatment and subjected to biological nitrification and denitrification treatment under the same conditions as the example, the CODMn of the treated water was 400 my//J ,T-
The N removal rate was 85%. Foaming in the shattered nitrification tank was so intense that, unless an antifoaming agent was added, the foam would overflow and make operation impossible. The foaming state was not uniform and changed over time, and 50 to 6 GOm9/l of a silicone antifoaming agent was required to suppress the foaming to a level that caused no actual damage.

Comparative Example 2 50% iron sulfate (11) was added to the excreta of the example as Fe.
0my/IJ, 2,000mg/l of slaked lime was added to make pi(10), flocculation treatment was performed, solid-liquid separation was performed, and the separated liquid was adjusted to pH 7.5 with hydrochloric acid, and biologically incubated under the same conditions as in the example. When nitrification and denitrification treatment was performed, CO of the treated water was
DMn is 310n evening/1. The TN removal rate was 90%.

The above results show that the treatment method of the present invention can efficiently remove organic matter and nitrogen, and is advantageous in terms of measures against foaming and heat generation in the nitrification tank.

[Brief explanation of the drawing]

1 and 2 are system diagrams showing different embodiments of the present invention, respectively, in which 1 is a first reaction tank, 2 is a second reaction tank, 6 is a solid-liquid separation tank, and 4 is a desorption tank. A nitrogen tank, 5 a nitrification tank, and 6 a solid-liquid separation tank. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Patent Attorney Sei Yanagihara

Claims (5)

[Claims] (1) A method for treating human waste, which comprises aggregating the human waste in an acidic region and then biologically subjecting the separated liquid to nitrification and denitrification. (2) The method for treating human waste according to claim 1, wherein the flocculating treatment is performed by adding an inorganic flocculant and a cationic organic flocculant. (3) The flocculation treatment is performed by adding an inorganic or cationic organic flocculant and stirring, and then adding a nonionic, anionic or anionic organic flocculant and stirring. Human waste disposal blade 1. (4) The method for treating human waste according to any one of claims 1 to 6, wherein the biological nitrification and denitrification treatment is performed without diluting the separated liquid. (5) The method for treating human waste according to any one of claims 1 to 4, wherein the biological nitrification and denitrification treatment is carried out repeatedly in multiple stages.