JP2001179294A - Apparatus for treating excretion wastewater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject apparatus reduced in equipment cost for providing an addition part, enhanced in the removal effect of organic matter and also having dephosphorizing effect comparable to this removal effect. SOLUTION: An apparatus for treating excretion wastewater has a pre- reaction means 3 comprising a pre-reaction tank for adding a flocculant containing a dephosphorizing agent to excretion wastewater containing excretion and septic tank sludge to apply oxidation treatment thereto, a sludge sedimentation tank 6 for separating the wastewater treated by the pre-reaction means 3 into a supernatant liquid and sludge, a dehydration means 7 for dehydrating sludge separated in the sludge sedimentation tank 6, a reaction means 8 receiving the supernatant liquid separated in the sludge sedimentation tank 6 to apply nitrification/denitrification treatment thereto and a solid-liquid separation means 9 for separating the suspension sent from the reaction means 8 into sludge and a treated liquid. In this treatment apparatus, a return means 8A for returning excess sludge generated by the reaction means 8 to the pre-reaction tank 3 or the pre-process thereof is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can stabilize septic tank sludge, improve the decomposition of organic matter in human waste, especially high molecular organic matter, generate no odor, and improve solid-liquid separation. The present invention relates to a human waste treatment apparatus capable of improving sedimentation separation by improving solid-liquid separation properties and consequently reducing the amount of sludge to be dewatered.

[0002]

2. Description of the Related Art Conventionally, human waste treatment facilities have had to complete the treatment through complicated steps for the purpose of treating a high concentration of human waste contaminants at a high level.

[0003] However, in recent years, even in distant urban areas, due to the wave of urbanization, the amount of collected urine (human waste) has rapidly decreased due to flushing of household toilets, and instead, agricultural settlement wastewater treatment facilities have been installed. The amount of the representative septic tank sludge is increasing rapidly.

[0004] The role of the human waste treatment facility is to treat human waste and septic tank sludge, and there is a need for a simplified process method corresponding to this changing situation.

The combined septic tank sludge is surplus sludge from biological wastewater treatment, and simplification of equipment can be expected by treating it together with treatment of excess sludge in a human waste treatment plant.

However, septic tank sludge has the property that its properties are not stable, the property that the dominant species of organisms differs depending on the sewage treatment method, and that the properties of surplus sludge differ.
Or, depending on the case, there is a characteristic that a toxic substance to bacterial cells is contained or a heavy metal concentration is high.

Conventionally, as a means of simplifying a human waste treatment facility,
A method has been proposed in which septic tank sludge is used as surplus sludge for urine treatment and urine is mixed and coagulated and dewatered (see Japanese Patent Publication No. 7-4598).

[0008] However, in the method described in Japanese Patent Publication No. 7-4598, the entire amount of dewatering, including excess sludge, is dehydrated. However, if such total dehydration is performed, there is a problem that the equipment becomes excessively large.
That is, it is difficult to make the dewatering operation unmanned, and because of such difficulty, if the dehydration operation is to be completed only by daytime operation, the dewatering equipment must necessarily be excessively large. In addition, if the entire amount is dehydrated as described above, the amount of the dehydrated cake naturally increases, and the treatment thereof becomes a problem. Further, there is a problem that the amount of the polymer dehydration aid must be excessively added in consideration of the maximum load in order to cope with the property change of the septic tank sludge. Furthermore, dewatered sludge contains an excessive amount of organic matter (particularly, high molecular organic matter such as protein, starch, and lipids) in urine as an excessive polymer dehydration aid. There is a problem that is easy to do. Furthermore, in recent years, guidance has been given to prohibit incineration of surplus sludge from urine treatment plants from the viewpoint of preventing environmental pollution, and treatment of surplus sludge generating odor becomes more difficult.

Therefore, as a technique for solving such a problem, it is possible to stabilize the sludge in the septic tank, to improve the decomposition of organic substances in human waste, particularly high-molecular organic substances, to improve the solid-liquid separation properties without generating odor. By improving the solid-liquid separation property, the sedimentation separation is improved, and as a result, the amount of sludge to be dewatered can be reduced, the sludge properties are stabilized, and the amount of the polymer dehydration aid added is reduced. Can be
In addition, organic matter is decomposed, and it becomes easy to perform a treatment instead of incineration such as a composting treatment of dewatered sludge, and an apparatus for treating urine wastewater is proposed in Japanese Patent Application Laid-Open No. 11-33591.

[0010]

SUMMARY OF THE INVENTION Japanese Patent Application Laid-Open No. H11-3359
In No. 1, an addition unit for adding a flocculant to human wastewater containing raw human waste and septic tank sludge is provided, and then a pre-reaction means for oxidizing the human wastewater is provided. By directly adding a flocculant to the means, it was found that not only the equipment cost for providing the addition section was reduced, but also the effect of removing organic substances was improved and the effect of dephosphorization was equivalent, and the present invention was reached.

[0011]

The apparatus for treating human wastewater according to the present invention, which solves the above-mentioned problems, comprises a reaction prior to oxidation treatment by adding a coagulant containing a dephosphorizing agent to wastewater containing human waste and septic tank sludge. A pre-reaction means comprising a tank, a sludge settling tank for solid-liquid separating wastewater treated by the pre-reaction means into a supernatant liquid and sludge, a dewatering means for dewatering the sludge separated in the sludge settling tank, Reaction means for introducing the supernatant liquid separated in the sludge settling tank to perform nitrification denitrification treatment, and solid-liquid separation means for solid-liquid separation of the suspension sent from the reaction means into sludge and treatment liquid, And a return means for returning excess sludge generated by the reaction means to the pre-reaction means or the preceding step.

In a preferred embodiment of the present invention, the solid-liquid separation means is a membrane separation means, and after the membrane separation means, there is activated carbon treatment means for decolorization.

Further, in a preferred embodiment of the present invention, the coagulant comprises two types, a coagulant containing an iron component and a coagulant containing a silica component.

[0014]

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

The human wastewater to be treated according to the present invention contains at least human waste and septic tank sludge, and the septic tank sludge can contain a combined septic tank sludge. In the present invention, human wastewater composed of septic tank sludge or human waste may include miscellaneous wastewater.

FIG. 1 is a block diagram showing an example of an embodiment of the present invention, and FIG. 2 is a block diagram showing another example of the embodiment of the present invention.

FIGS. 1 and 2 show an example of receiving both night soil and septic tank sludge. In FIG. 1, reference numeral 1 denotes first pretreatment means for introducing septic tank sludge and removing contaminants; 2 is a second pretreatment means for introducing human waste to remove impurities.

The first and second pretreatment means 1 and 2 are composed of sand,
It is a means for removing contaminants such as stones, paper, fibers, rubber products, hair, and other debris, and the configuration is not limited.

The first and second preprocessing means 1 and 2 may be provided separately, but one may be shared.

In the present invention, reference numeral 3 denotes a pre-reaction means comprising a pre-reaction tank, and the pre-reaction means 3 reacts the human wastewater prior to the subsequent biological treatment (nitrification and denitrification treatment). Specifically, the organic matter contained in the human wastewater is oxidatively decomposed by the pre-reaction to lower the liquid viscosity and improve the solid-liquid separation property. In addition, high molecular organic matter is oxidatively decomposed by the pre-reaction to suppress malodor. In addition, the pre-reaction causes an environment in which one or two or more aerobic bacteria or facultative anaerobic bacteria occupy the dominant species, suppresses anaerobicization of the septic tank sludge, and stabilizes the properties.

As a pre-reaction means for performing such oxidation treatment, as shown in FIG. 2, a pre-reaction tank 301 is provided, and urine wastewater is drawn out from the pre-reaction tank 301 by a circulation pump 302 to the outside, and the pre-reaction is performed again. A preferred example is a method in which air is mixed into the circulation line by providing an air mixing unit 303 in the process of returning to the tank 301, and air is mixed into human wastewater in the pre-reaction tank 301.

Although not shown, a method is also preferable in which an air diffuser is provided in the pre-reactor 301, air is supplied to the diffuser, and air is mixed into the human wastewater in the pre-reactor 301.

4 is a facility for adding a coagulant containing an iron component, and 5 is a facility for adding a coagulant containing a silica component.

The present invention is characterized in that a flocculant is added directly to the pre-reaction tank. It has been found that such a configuration improves the effect of removing organic substances as compared with a case where the coagulant is added to and mixed with human wastewater and then oxidized in the pre-reaction tank.

The cause is considered as follows.

The organic matter is adsorbed and stored by the activated sludge and then decomposed. The effect of the decomposition treatment is increased when more organic matter is adsorbed on the activated sludge in the preceding adsorption step. Such adsorption occurs during the initial contact of the human wastewater with the returned activated sludge. That is, the first adsorption occurs before the pre-reaction tank. Activated sludge that performs this initial contact adsorption may have various bacterial cells. At this stage, there is a case where there is no effect even if the coagulant adding section is provided and the coagulant is added. In addition, since the pH and the charge state of the wastewater fluctuate, the effect of the coagulant-added portion may not be exhibited. On the other hand, in the present invention, since the flocculant is added to the aerated pre-reaction tank, the effect of the flocculant can be sufficiently exhibited, and the treatment effect of the organic matter is improved.

The effect of the dephosphorizing agent is different from the case where the dephosphorizing agent is previously added to the adding section only by adding the dephosphorizing agent in the pre-reaction tank completely in an oxidizing atmosphere. I knew it wasn't. Therefore, it is more advantageous to directly add the dephosphorizing agent to the pre-reaction tank because the addition section is not provided since the equipment cost can be reduced.

Examples of the coagulant containing an iron component include ferric polysulfate (polyiron), ferric chloride and the like. The coagulant containing the iron component functions as a dephosphorizing agent when added to human wastewater.

As the coagulant containing a silica component, first, a solution of an inorganic salt containing a silica component and a magnesium component can be used. For example, a mixed solution of a silicate and a magnesium salt can be used.

Secondly, as the flocculant containing a silica component, it is also preferable to use a silica-based flocculant obtained from a silica-based raw material composed of a composite crystal mineral and an amorphous mineral of silica. As such a silica-based flocculant, there is a method in which blast furnace slag or the like is dissolved in a reducing acid or a neutral acid, preferably diluted sulfuric acid. As a specific example of the dissolving method, see Japanese Patent No. 255859.
The method described in No. 1 is exemplified. In addition, as a coagulant containing a silica component, a crystalline mineral containing a silica component, for example, trade name "Mineral Panny" can be used.

Third, as a coagulant containing a silica component, thirdly, a soil compact mainly composed of humus can be used.

The amount of the coagulant containing the silica component is preferably in the range of 1.0 to 200 mg / l as silica with respect to the mixed liquid of night soil, septic tank sludge and excess sludge.

The coagulant containing a silica component includes silica (Si
O ₂ ), calcium, magnesium, and aluminum are contained as main components, and these components contribute to coagulation of human waste and septic tank sludge and dominance of useful bacteria.

In the present invention, when polyiron, which is usually used as a coagulant containing an iron component, is used, if sludge is separated without passing through the pre-reaction means 3, the reaction will take place in a reducing atmosphere. However, there is a problem that polyiron does not function as a flocculant. That is, if air is not supplied, the atmosphere becomes a reducing atmosphere. In the reducing atmosphere, iron easily forms a complex with an organic substance and does not form iron phosphate.

On the other hand, if the pre-reaction treatment is performed by the pre-reaction means 3 as described above, it is in an oxidized state and oxidatively decomposes organic substances so that an iron complex is not formed. Therefore, polyiron functions as a flocculant, The dephosphorization effect is further improved. Further, in the present invention, the equipment cost is greatly reduced as compared with the case where the dephosphorization means after nitrification denitrification is separately provided.

When a coagulant containing the above-described silica component is used in combination as the coagulant, useful facultatively anaerobic bacteria (specifically, Bacillus sp.) Become dominant species in the pre-reaction tank. In addition, it becomes difficult for anaerobic bacteria and spoilage bacteria to survive. Therefore, even sludge having strong anaerobic properties, such as septic tank sludge, is a preferred embodiment since the properties are stabilized by facultative anaerobic useful bacteria becoming the dominant species. Since the above-mentioned useful bacteria are excellent in decomposability of high-molecular organic substances (proteins, starch, lipids, etc.), the reaction does not proceed in the anaerobic direction, which also makes it difficult for the anaerobic bacteria and spoilage bacteria to survive. It can prevent putrefaction odor.

In the present invention, the capacity of the pre-reaction tank is determined by the amount of water when human wastewater is continuously introduced (in the present invention, the amount of water is equal to the amount of mixed liquid of human waste and excess sludge consisting of human waste and septic tank sludge). It is preferable that the retention time is between 1 day and 3 days. An environment where not more than one day not only suppresses fluctuations in the load of human wastewater, but also one or two or more of the bacteria contained in the human wastewater are facultatively anaerobic or oxidized. Because you can make it. If the capacity is too large, the cost will increase, so it is within 3 days, preferably within 2 days.

After the pre-reaction treatment by the pre-reaction means 3, the sludge sedimentation tank 6 for solid-liquid separation of the treated waste water into a supernatant liquid and sludge, and a dewatering means 7 for dewatering the sludge separated in the sludge sedimentation tank 6 And

As the sludge settling tank 6, an ordinary gravity settling tank can be used. In the present invention, since the solid-liquid separation property of the sludge is improved, in the sludge settling tank 6, the supernatant liquid and the sludge are clearly separated. Accordingly, the amount of sludge to be dewatered in the dewatering means 7 is reduced as a result.

In the dewatering means 7, a polymer dehydration aid is used, but when the sludge properties are stabilized, there is an effect that the amount of the polymer dehydration aid added can be reduced.

Further, the dewatered sludge (cake) is an environment in which organic matter is decomposed and sludge in which useful bacteria are predominantly present.
There is an effect that composting of dewatered sludge can be easily performed, and processing instead of incineration can be easily performed.

Further, in the present invention, since there is a return means 8A for returning excess sludge generated in the reaction means described later to the pre-reaction means 3 or the preceding step, dehydration and pre-treatment of the excess sludge are performed. The dewatering of the mixed septic tank sludge generated at the same time can be simultaneously performed, and the cost of the dewatering equipment can be reduced.

The separated liquid separated by the dehydrating means 7 is sent to the reaction means 8 for reprocessing.

The reaction means 8 following the sludge settling tank 6 is mainly constituted by a nitrification and denitrification treatment tank, and the constitution of the nitrification and denitrification treatment tank is not particularly limited.

In the present invention, the presence of the pre-reaction means 3 promotes the oxidative decomposition of organic substances, thereby reducing the load of organic substances in the nitrification and denitrification treatment tank and without increasing the viscosity. Stable processing becomes possible.

When a flocculant containing a silica component is used, a treatment system is formed such that the useful biota is dominated by useful microorganisms or useful bacteria. Bacteria become the dominant species, the biota is stable, and stable processing is possible.

Numeral 9 denotes a solid-liquid separating means. As the solid-liquid separating means, a gravity sedimentation type sedimentation tank or a membrane separating means can be adopted, and may be selected according to the requirements of the properties of the processing liquid. In this example, a case where a membrane separation unit is employed will be described.

[0048] The membrane separation means is a means for solid-liquid separation of the suspension (activated sludge) sent from the reaction means 8, and as described above, the treatment of the nitrification and denitrification treatment tank in the reaction means 8 is stabilized. Thereby, clogging of the film is reduced, the effect of recovering the film flux by washing is stabilized, and the film treatment can be stabilized.

The type of the membrane used for the membrane separation means may be any of an ultrafiltration membrane, a microfiltration membrane, a reverse osmosis membrane, etc. It may be installed outside. Further, the type of the membrane may be any of a flat membrane and a tubular membrane.

The activated sludge is separated into a permeate and a concentrated sludge by the membrane separation means. The concentrated sludge is returned to the reaction means 8 and a part thereof is returned to the pre-reaction means 3 as the excess sludge as described above. You.

The permeate separated by the membrane separation means is subjected to further advanced treatment if necessary. For example, the decolorization treatment is performed in the activated carbon treatment means 10 as shown in the figure, and the treated water is reused or discharged.

[0052]

An embodiment of the present invention will be described. The present invention is not limited by such embodiments.

Embodiment 1 Using the treatment apparatus shown in FIG. 1 (a block diagram showing an example of the apparatus of the present invention), the wastewater containing pretreated sludge and urine is returned from the reaction means 8 to the wastewater. The surplus sludge thus obtained was mixed and introduced into the pre-reaction tank. The mixing ratio of night soil, septic tank sludge, and excess sludge was set as night soil: septic tank sludge: excess sludge = 3: 6: 1.

The properties of the mixed solution introduced into the pre-reaction tank were as follows. The analysis method was in accordance with JIS K-0102.

PH 7.1 BOD 5,290 mg / L COD 4,200 mg / L SS 7,270 mg / L T-N 1,580 mg / L T-P 210 mg / L

The coagulant added in the pre-reactor was a polyiron and silica-based coagulant. The silica-based flocculant used had the following composition.

SiO ₂ 10,000-12,000 ppm Al ₂ O ₃ 1,600-2,600 ppm CaO 600-1,000 ppm MgO 600-1,200 ppm

The amount of the coagulant added was 0.1% by volume of polyiron,
The silica-based flocculant was 1.0 Vol%. The residence time in the pre-reaction tank was 2 days.

Under the above conditions, a comparative experiment was performed between the case where the pre-reaction tank was installed and the case where the pre-reaction tank was not installed. In addition, when the pre-reaction tank was installed, a comparison was made between the case where the flocculant was added in the addition section and the case where the coagulant was directly added to the pre-reaction tank. In each case, the supernatant of the sludge settling tank was analyzed to compare the treatment effects. In addition, SV ₃₆₀ and SV ₁₂₀₀ were measured in order to compare the sedimentation property of the sludge in the sludge settling tank. Table 1 shows the results.

[0060]

[Table 1]

As can be seen from Table 1, it can be seen that the settling of sludge is greatly improved by installing the pre-reaction tank. In addition, the values of BOD and COD were significantly reduced, because BOD and COD were decomposed by a biological treatment reaction by forced aeration, and as a result, it was confirmed that the liquid viscosity was also reduced.

Further, when the coagulant is added directly to the pre-reaction tank, it can be seen that the effect of removing BOD and COD is further improved.

[0063]

As described above, according to the present invention, the provision of a pre-reaction tank stabilizes the septic tank sludge, improves the decomposition of organic substances in human waste, especially high-molecular organic substances, and does not generate a bad odor. It can improve the liquid separation property, improve the solid-liquid separation property, improve the sedimentation separation, consequently reduce the amount of sludge to be dewatered, stabilize the sludge properties, and polymer dehydration The addition amount of the auxiliary agent can be reduced, and the organic matter is decomposed, so that not only the decomposed sludge can be easily replaced with incineration such as composting, but also the cost for providing an additional portion can be reduced. In addition, it is possible to provide an apparatus for treating urine wastewater in which the effect of removing organic substances is improved and the effect of removing phosphorus is equivalent.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of an embodiment of the present invention.

FIG. 2 is an explanatory view showing an example of a pre-reaction tank.

[Explanation of symbols]

 1: First pretreatment means 2: Second pretreatment means 3: Prereaction means 4: Addition equipment for coagulant containing iron component 5: Addition equipment for coagulant containing silica component 6: Sludge settling tank 7: Dewatering means 8: reaction means 8A: return means 9: solid-liquid separation means 10: activated carbon treatment means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 9/00 503 C02F 9/00 503D 504 504A (71) Applicant 000219314 Toray Engineering Co., Ltd. 3-4-1-18 Nakanoshima-ku, Ward (Mitsui Building No. 2) (71) Applicant 000004123 Nippon Kokan Co., Ltd. 1-1-2 Marunouchi, Chiyoda-ku, Tokyo (72) Inventor Hitoshi Yano 5-6 Tsukiji, Chuo-ku, Tokyo No. 4 Mitsui Engineering & Shipbuilding Engineering Co., Ltd. Environmental Business Division (72) Inventor Kazuo Ikeda 8-4-6 Nishikasai, Edogawa-ku, Tokyo ST Nishi-Kasai Building Water Treatment Engineering Division Mitsui Engineering & Shipbuilding Co., Ltd. Environmental Business Division (72) Inventor Junichi Baba 2-233 Kinrakuji-cho, Amagasaki City, Hyogo Prefecture Takuma Plant Co., Ltd. (72) Inventor Hiromichi Okada 1-1-1 Sonoyama, Otsu-shi, Shiga Prefecture Toga Engineering Co., Ltd.Shiga Plant Town 1-1 Nihon Kokan Co., Ltd. Engineering Laboratory Water System Laboratory F-term (reference) 4D015 BA12 BA19 BA23 BB08 BB16 CA03 CA12 DA13 DA16 DA19 DA32 DA34 DA35 FA01 FA02 FA12 FA15 FA17 FA22 FA26 4D040 DD03 DD18 4D062 BA12 BA19 BA23 BB08 BB16 CA03 CA12 DA13 DA16 DA19 DA32 DA34 DA35 FA01 FA02 FA12 FA15 FA17 FA22 FA26

Claims (3)

[Claims] 1. A pre-reaction means comprising a pre-reaction tank for adding a coagulant containing a dephosphorizing agent to wastewater containing human waste and septic tank sludge and oxidizing the wastewater, and a supernatant liquid comprising the wastewater treated by the pre-reaction means. Sludge sedimentation tank for solid-liquid separation into sludge and sludge, dehydration means for dewatering the sludge separated in the sludge sedimentation tank, and reaction means for introducing the supernatant liquid separated in the sludge sedimentation tank and performing nitrification and denitrification treatment And solid-liquid separation means for solid-liquid separating the suspension sent from the reaction means into sludge and treatment liquid, and returning excess sludge generated by the reaction means to the pre-reaction means or the preceding step. An apparatus for treating human wastewater, comprising: 2. The wastewater treatment apparatus according to claim 1, wherein the solid-liquid separation means is a membrane separation means, and an activated carbon treatment means for decolorization is provided after the membrane separation means. 3. An apparatus for treating human waste wastewater according to claim 1, wherein said coagulant comprises two types: a coagulant containing an iron component and a coagulant containing a silica component.