JPH0442076B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an advanced treatment method for human waste wastewater, and more particularly to a method for decolorizing human waste at low cost. [Background of the Invention] In recent years, research into advanced treatment methods for human waste has progressed, and it has now become possible to almost completely remove organic matter. However, regarding the unique color of human urine,
The reality is that treatment technology is not perfect and even treated water from which BOD and COD have been removed cannot be discharged if it is colored.Therefore, there is a desire to develop a process that can decolorize human waste. Traditionally, the decolorization process for human waste treatment includes biological treatment equipment (centrifugal separation is used as the solid-liquid separation method), flocculation sedimentation treatment equipment, sand filtration treatment equipment + sand backwashing equipment, activated carbon adsorption treatment equipment + activated carbon backwashing equipment. (For example, Ataka Kogyo's IZ process) is known. The feature of this process is that the chromaticity of human waste is roughly removed using coagulation and sedimentation processing equipment, and the chromaticity is final processed using activated carbon adsorption treatment and sand filtration processing equipment. Sand filtration treatment equipment is provided to prevent clogging of the activated carbon adsorption treatment, and is essential equipment for this process. In addition, sand filtration treatment equipment requires sand backwashing equipment, and activated carbon backwashing equipment is also essential. In this process, the color of human waste after centrifugation is usually as high as 2,400 to 2,500 degrees, but it is reduced to 150 to 250 degrees by coagulation and sedimentation, and the color is roughly removed, and then treated with activated carbon. be done. Activated carbon treatment temporarily reduces the chromaticity to below 30 degrees, but the activated carbon quickly reaches saturation, making it impossible to reduce the chromaticity in the long term, and the activated carbon has the disadvantage of requiring early replacement. . For this reason, a method in which ozone oxidation treatment is performed in front of activated carbon treatment equipment has been adopted as a preferred method. This ozone oxidation treatment reduces the chromaticity to about 60 to 70 degrees, which reduces the load on activated carbon and has the effect of being able to obtain a chromaticity of 30 or less over a longer period of time than the above process. . However, if you try to obtain a chromaticity of 30 or less in the long term by a combination of ozone oxidation treatment and activated carbon treatment,
Because of the problem of activated carbon clogging, sand filtration equipment is required. This sand filtration treatment equipment requires a lot of ancillary equipment such as backwash equipment, which not only increases the equipment cost but also has the disadvantage of complicating maintenance. If it is returned for treatment, it has the disadvantage of increasing the load on the coagulation and sedimentation treatment equipment.
Furthermore, in order to enable continuous treatment of human waste during backwashing, it is necessary to provide a spare device for the sand filter, which has the disadvantage of increasing equipment costs. Furthermore, even if sand filtration treatment equipment is provided, ss is not completely removed, so it is inevitable that activated carbon will become clogged. Therefore, activated carbon backwashing equipment is required, resulting in high costs and the same problems as the backwashing of sand filtration equipment, such as the need to treat washing waste water. [Object of the Invention] Therefore, an object of the present invention is to provide a method for decolorizing human waste that can completely decolorize it at low equipment cost and without requiring complicated maintenance. [Means for Solving the Problems] The inventors of the present invention have made the following findings as a result of intensive studies to solve the above objects. That is, as a solid-liquid separation means after biological treatment,
Although there are various methods, we have found that the method using ultrafiltration membranes is particularly superior in terms of ease of sludge management in biological treatment, restriction of SS outflow, etc. However, when this ultrafiltration membrane was used, it was found that the chromaticity of the membrane-permeated water was as high as 500 to 600 degrees, which was even higher than the chromaticity of 150 to 200 degrees after conventional coagulation and precipitation treatment. Therefore, the present inventor performed ozone oxidation treatment as a pretreatment of activated carbon according to the conventional method, but the chromaticity was
In order to reduce human waste at 500 to 600 degrees to about 60 degrees, it is necessary to install large-scale or several ozone oxidation treatment facilities, so it does not significantly reduce costs compared to conventional processes, and it requires less equipment. It was found that there are drawbacks such as complicated maintenance. As a result of further research into a low-cost and easy-to-maintain method to eliminate these drawbacks, the inventors found a surprising result when the permeated water of the ultrafiltration membrane was treated with activated carbon adsorption without being subjected to ozone oxidation treatment. In particular, we discovered that even permeated water with a chromaticity of 500 to 600 degrees, which is higher than conventional methods, becomes completely colorless, leading to the present invention. That is, in the method for decolorizing human waste according to the present invention, human waste is received into a biological reaction tank without being substantially diluted, brought into contact with and mixed with activated sludge in the reaction tank to perform a biological reaction, and then immediately containing the activated sludge. An ultrafiltration membrane (hereinafter referred to as
A part of the separated concentrated liquid is returned to the reaction tank, and the water permeated through the membrane is treated with activated carbon to decolorize it. In this specification, chromaticity refers to JIS KO102
-1985, and a value of about 30 or less indicates a transparent liquid. [Function] According to the present invention, a UF membrane is employed as a solid-liquid separation means after biological treatment, and decolorization can be achieved for a long period of time simply by the combination of this UF membrane and activated carbon. In other words, when solid-liquid separation is performed using a UF membrane, the color of night soil becomes 500 to 600 degrees, which is higher than the color of conventional coagulation-sedimentation water (150 to 200 degrees), but ozone oxidation treatment is necessary. Decolorization can be achieved over a long period of time without causing any damage. The reason for this is not clear, but color components with relatively high molecular weights (more than the predetermined molecular weight cut-off, which is membrane performance) do not pass through the membrane, and only low-molecular-weight components pass through the membrane, which is why activated carbon Since it is only necessary to adsorb components that have been homogenized to have a low molecular weight, the saturated adsorption capacity of activated carbon can be increased compared to conventional methods, and it is therefore possible to obtain transparent treated water with low chromaticity. It will be done. Furthermore, since a UF membrane is used as the solid-liquid separation means, there is no outflow of ss, so there is no clogging of activated carbon. Therefore, activated carbon backwashing equipment is not required. Further, there is no need to provide sand filtration processing equipment as pre-treatment equipment, and furthermore, there is no need to provide sand backwashing equipment. Therefore, equipment costs can be reduced,
And no complicated maintenance is required. [Specific Configuration] The present invention will be explained in detail below. Examples of the human waste to be treated in the present invention include pumped human waste (about 13,500 mg/BOD), human waste septic tank sludge (about 7,000 mg/BOD), human waste digester desorbed liquid (about 2,400 mg/BOD), and the like. Biological reaction treatment in the present invention is optional,
For example, a conventional one-stage or multi-stage aerobic and/or anaerobic biological reaction is carried out, and organic substances, nitrogen components, etc. are decomposed and removed by oxidation or reduction. In the present invention, a UF membrane is adopted as a solid-liquid separation means after biological reaction treatment, and when solid-liquid separation is performed using this UF membrane, the color of human waste becomes 500 to 600 degrees, which is the same color as that of conventional coagulation-sedimentation-treated water. degrees (150-200 degrees)
This results in a higher result. The activated carbon adsorption treatment that effectively decolorizes the water permeated through the UF membrane having high chromaticity can be performed using conventionally known treatment equipment. For example, a fixed bed type, fluidized bed type, merry-go-round type adsorption tower, etc. is filled with granular activated carbon, and water permeated through the UF membrane is passed through the adsorption tower from below or above to decolorize the water. [Example] An example of the method of the present invention will be described based on FIG. First, in Fig. 1, human waste (hereinafter referred to as the undiluted solution) collected by a vacuum vehicle or the like is received in the receiving tank 4, and the receiving tank 4 is filled with relatively large sand, stones, etc. contained in the undiluted solution. Impurities are removed by sedimentation. The stock solution in the receiving tank 4 is supplied to a rough screen 10 by a pump (not shown), and solid substances such as fibrous substances, rubber products, and other floating impurities in the human waste are removed. The separated solid substance may be disposed of by a conventional method, for example, it may be dehydrated using a dehydrator or the like and then incinerated. Next, the liquid passing through the coarse screen 10 is supplied to a so-called fine screen 12 having small openings, and inert solids (sludge) in the raw liquid are removed. This screen with small openings has openings of 0.1mm to 0.5mm to remove even relatively fine solids.
It is preferred to use a fine mesh screen. In this embodiment, the fine mesh screen 12 has a mesh opening of 0.2.
mm screen is used. By using a screen with large openings and a screen with small openings in combination as described above, it is possible to reduce the load on activated sludge and protect the ultrafiltration membrane. The solids separated by the fine screen 12 are
For example, it may be dehydrated using a conventionally known dehydrator such as a screw press and then incinerated. The stock solution that has passed through the screen is stored in a storage tank 8. In the storage tank 8, the concentration of the stock solution is made uniform. The stock solution in the storage tank 8 is supplied to the biological reaction tank 16 via the stock solution feed pump 14 that constitutes the supply means 3 . The stock solution is sent as is (substantially undiluted) to the biological reactor 16 by the pump 14. The biological reaction tank 16 has seven chambers 16A, 16B,
16C, 16D, 16E, 16F, 16G). This biological reaction tank 16 is a first tank into which the stock solution is introduced.
Pretreatment tank 18 from chamber 16A to fourth chamber 16D
and a seventh chamber 1 from which the processing liquid flows out from the fifth chamber 16E.
It is divided into a post-processing tank 20 up to 6G. Each room is separated by a vertical partition wall.
The processing liquid in each chamber is sequentially transferred from the first chamber 16A to the seventh chamber 16G by a conventionally known method.
The method for feeding the processing liquid may be an overflow method or, as shown in FIG. 2, a combination of an overflow and an underflow method. 17A is a partition wall for overflow, and 17B is a partition wall for underflow. If it is configured as shown in FIG.
The first chamber 16A, which is set to be aerobic, is supplied to the second chamber 16E, which is set to be anaerobic.
The processing liquid is transferred to the chamber 16B by overflow, and the processing liquid is transferred from the bottom from the second chamber 16B and fourth chamber 16D, which are set to be anaerobic, to the third chamber 16C and fifth chamber 16E, which are set to be aerobic. It can be moved. Further, the biological reaction tank 16 may be provided with a defoaming spray 50 as shown in FIG. In this case, a baffle plate 52 may be further provided near the overflow part of the partition plate 51 of each chamber, and a defoaming spray 50 may be provided between the baffle plates. This configuration prevents bubbles from flowing into adjacent rooms. Returning to FIG. 1, in the pre-treatment tank 18, the first
The chamber 16A and the fourth chamber 16D are connected to the circulation pump 22.
It is connected by a circulation pipe 24 via. On the other hand, the storage tank 8 is connected to the circulation pipe 24 on the suction side of the circulation pump 22. Therefore, the stock solution from the storage tank 8 is sent to the biological reaction tank 16 at a flow rate Q while being mixed with the circulating treatment solution. In the first chamber 16A, an aeration injector (trade name: Mitsui-Beyer injector type aeration device) 26 is installed at the tip of the circulation pipe 24 to introduce air when inserting the mixture of stock solution and circulating fluid. It is being This aeration injector 26 makes it possible to fragment the aeration air and improve the efficiency of stirring the room. Furthermore, the circulation pump 22 circulates a maximum of 120Q of processing liquid. In this embodiment, the cycle is approximately 40Q. The stock solution inserted into the activated sludge tank 16 passes through each chamber while sequentially overflowing from the first chamber 16A together with the circulating fluid, and reaches the seventh chamber. 2nd room 16
B, 3rd room 16C, 4th room 16D, 6th room 16F
and aeration devices 30, 31, 3 which are normally used to supply air to the seventh chamber 16G, respectively.
2, 36, and 38 are installed. The amount of air supplied to these aeration devices can be adjusted independently. 1st room 16A, 5th room 16E
is maintained in an anaerobic atmosphere, and the second chamber 16B and the third chamber
The chamber 16C, the fourth chamber 16D, the sixth chamber 16F, and the seventh chamber 16G are maintained in an aerobic atmosphere. In the supply process, when the stock solution is supplied to the pre-treatment tank, it is not limited to being supplied to one chamber.
For example, when the chamber is divided into three or more as shown in FIG. 2, the first chamber and the third chamber may be supplied at the same time. Each chamber of the post-processing tank 20, like the pre-processing tank, may be divided into any number of chambers as long as it is plural, and can be arbitrarily and independently set to a relatively aerobic or anaerobic atmosphere. It is preferable. Furthermore, as in this embodiment, it is preferable that the last chamber and the second to last chamber for supplying the treatment liquid in the latter treatment tank to the ultrafiltration device are set to be aerobic. In this case, sticky anaerobic bacteria are not allowed to proliferate immediately before the ultrafiltration membrane, which prevents the filtration performance from decreasing due to the adhesion of these bacteria to the ultrafiltration membrane, and makes it easier to clean the membrane. The number of times can be reduced. In the biological reaction tank 16, the human waste is effectively processed into activated sludge in the front stage tank 18 and the rear stage tank 20 by a combination of an anaerobic atmosphere and an aerobic atmosphere. The seventh chamber is connected to an ultrafiltration device 42 via a pipe 39 and a circulation pump 40. The UF membrane used in the ultrafiltration device 42 has a molecular weight cutoff of 1000.
A range of 3,000,000 to 3,000,000 is used. In this example, polyacrylonitrile with a molecular weight cutoff of 15,000
A UF membrane of 20,000 to 20,000 (Iris manufactured by Rhone-Poulenc) is used. The treated liquid is passed through the UF membrane in a cross-flow manner, and is separated into membrane-permeated water and concentrated liquid. The concentrated liquid is sent from the ultrafiltration device 42 to the pre-stage tank 1.
6's fourth chamber 16D and the seventh chamber 16G of the latter stage tank 18
A return pipe 46 is provided for returning the product to the factory. A surplus sludge pipe 4 is connected to a return pipe 46 for discharging the remainder of the concentrated liquid as surplus sludge to the outside of the system.
8 are branched. The treated liquid in the downstream treatment tank (chamber 7) is supplied to the ultrafiltration device 42, where the treated liquid is highly concentrated as a concentrated liquid and repeatedly sent back to the front and downstream treatment tanks to remove any impurities in the treated liquid. Decomposable organic substances are also decomposed to high concentrations (MLSS 6000 to 25000 ppm) by activated sludge repeatedly or over long periods of time. The ultrafiltration device 42 is connected to activated carbon adsorption equipment 44 via a membrane permeated water pipe 43. A membrane-permeated water return pipe 45 for returning part of the membrane-permeated water to the seventh chamber is branched from the membrane-permeated water pipe. In this embodiment, the activated carbon adsorption equipment 44 uses a fixed bed type adsorption tower filled with granular activated carbon. The water flow rate (sv) of activated carbon can be within the conventionally known range, but it can be completely reduced to ss with the UF membrane installed in front of the activated carbon.
is removed, so it is possible to achieve a higher sv than with normal activated carbon treatment. After reducing the chromaticity of the membrane-permeated water and removing organic dissolved substances such as BOD and COD in the activated carbon adsorption equipment 44, the water is discharged as treated water. Although there are almost no bacteria such as Escherichia coli in the treated water due to the synergistic effect with the membrane treatment, chlorine or the like may be used to disinfect the water in order to kill bacteria such as Escherichia coli that have invaded from outside the system. [Experimental Example] Experimental Example 1 The following experiment was conducted using the apparatus shown in FIG. Human urine was received in the storage tank 8, and the concentration was adjusted without dilution, and this was used as a stock solution. The supply rate of this stock solution was set at 300/day (Q), and as a result of supplying it to a biological reaction tank for treatment, and performing solid-liquid separation using a UF membrane, the composition of the membrane-permeated water was as follows. (Composition of membrane permeate water) BOD 20mg/ COD 250mg/ ss trace Chromaticity 550 degrees As a result of treating the above membrane permeate water with activated carbon, the composition of the final treated water was as follows. (Composition of activated carbon treated water) BOD 10mg / COD 27mg / ss trace Chromaticity 9 degrees Comparison Experimental Example 1 In Experimental Example 1, as shown in the flow below, a centrifuge was used as a solid-liquid separation means after the biological reaction, and then the separation After the liquid was subjected to coagulation and sedimentation treatment and then sand filtration treatment, activated carbon treatment was continued for one month. Initially, the results shown in the table below were obtained, but after one week, the sand filter became clogged and it became impossible to continue operation. Therefore, the process was continued by backwashing the sand, but after a month, the activated carbon became clogged and it became impossible to continue the process.

[Table] [Effects of the Invention] According to the present invention, a UF membrane is employed as a solid-liquid separation means after biological treatment, and decolorization can be achieved for a long period of time simply by the combination of this UF membrane and activated carbon. I can do it. In other words, when solid-liquid separation is performed using a UF membrane, the color of night soil becomes 500 to 600 degrees, which is higher than the color of conventional coagulation-sedimentation water (150 to 200 degrees), but ozone oxidation treatment is necessary. Decolorization can be achieved over a long period of time without causing any damage. Furthermore, since a UF membrane is used as the solid-liquid separation means, there is no outflow of ss, so there is no clogging of activated carbon. Therefore, activated carbon backwashing equipment is not required. Further, there is no need to provide sand filtration processing equipment as pre-treatment equipment, and furthermore, there is no need to provide sand backwashing equipment. Therefore, equipment costs can be reduced,
And no complicated maintenance is required. Furthermore, according to the present invention, since an ultrafiltration membrane is adopted as a solid-liquid separation means after a biological reaction, it is necessary to consider the sedimentation property of sludge in a settling tank, which has conventionally been adopted as a solid-liquid separation means for biological treatment. is gone,
In addition, it has become possible to physically control the sludge concentration in the biological reaction tank, and therefore the activated sludge concentration in the reaction tank can be increased, making it possible to operate under high load and at high concentration.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing one embodiment of the method of the present invention, and FIGS. 2 and 3 are schematic sectional views showing other examples of the processing tank. 4... Receiving tank, 8... Storage tank, 10... Coarse screen, 12... Fine screen, 16...
Biological reaction tank, 42... ultrafiltration device, 44... activated carbon adsorption equipment.

Claims (1)

[Claims] 1. Human waste is received into a biological reaction tank without being substantially diluted, contacted and mixed with activated sludge in the reaction tank to perform a biological reaction, and then the suspension containing the activated sludge is immediately mixed with membrane permeated water and concentrated liquid. A method for decolorizing night soil, which comprises sending the water to an ultrafiltration membrane that separates it into two parts, returning a part of the separated concentrated liquid to the reaction tank, and decolorizing the membrane-permeated water by treating it with activated carbon.