JPH09271795A - Household waste water treating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To treat both urine and various kinds of waste water generated at a household in a sufficiently less space by adding an equipment for membrane separation to an existing single treating septic tank. SOLUTION: This system is provided with an embedded and installed aeration septic tank 1, an auxiliary tank 5 installed at a high place, and a membrane separation device 8 installed on the ground lower than the position of the auxiliary tank 5, and a liquid to be treated is successively circulated via the aeration type septic device 1, the auxiliary tank 5 and the membrane separation device 8, and the purified water filtered and separated in accordance with this circulation is discharged from the membrane separation device 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a domestic wastewater treatment system used for purifying domestic wastewater generated at home.

[0002]

2. Description of the Related Art The present situation of the treatment of domestic wastewater in areas where sewerage is not complete is as follows: For wastewater in the kitchen or bathroom, the aeration-type septic tank (independent treatment septic tank) buried in the residential land is used to treat the human waste. Most of the cases without treatment are discharged into the gutter (more than 7 million units in Japan), and the miscellaneous wastewater discharged into the gutter flows into rivers and lakes, pollutes the water source, and drinks. This leads to lower water quality and higher costs associated with advanced treatment at water purification plants. In recent years, it has been requested that each household also purify the domestic wastewater generated from each household.

[0003]

The above-mentioned aeration-type septic tank, in the aeration chamber, adsorbs and metabolizes organic matter in human urine by microorganisms (activated sludge) under aerobic conditions to proliferate a group of microorganisms and grow them. The liquid is introduced into the sedimentation separation chamber, the supernatant liquid by sedimentation is discharged, the sludge that has precipitated is returned to the aeration chamber, and the excess sludge is taken out to the outside. In order to improve the performance of this aeration type septic tank, a septic tank in which a membrane module is immersed in an aeration chamber and membrane separation is used instead of the above precipitation separation has been proposed. It is considerably larger than a septic tank and requires a wide installation space. Moreover, replacing the single treatment septic tank with the combined treatment septic tank requires a great deal of cost. Therefore, there are many problems in the purification treatment of gray water as well as human waste by adopting the combined treatment septic tank in each home.

An object of the present invention is to add domestic wastewater and domestic wastewater generated at home to an existing single treatment septic tank with a facility for membrane separation, and to treat the domestic wastewater with a sufficiently small installation space. To provide a processing system.

[0005]

A domestic wastewater treatment system according to the present invention is installed in a buried aeration-type septic tank, an auxiliary tank installed at a high place, and installed on the ground lower than this auxiliary tank. The liquid to be treated is sequentially circulated through the aeration-type septic tank, the auxiliary tank, and the membrane separation device, and the purified water filtered and separated by this circulation is discharged from the membrane separation device. The configuration is characterized by. In the operation of the system, the on-off valve provided in the purified water extraction pipe of the membrane separation device is opened only when the water level in the aeration-type septic tank exceeds a predetermined water level to activate the filtration operation of the membrane separation device. When, the liquid is circulated, but the filtration operation is stopped,
The membrane surface of the membrane separation device can be washed by flushing with the circulating flow. Alternatively, the membrane separation device may be provided with an air diffuser to clean the membrane surface with a bubble flow.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing a domestic wastewater treatment system according to the present invention. In FIG. 1, 1 is an aeration-type septic tank (single treatment septic tank) buried underground, which includes an anaerobic chamber 11 that separates contaminants in the introduced wastewater and stabilizes the wastewater by anaerobic decomposition, and activated sludge by aeration. And an aeration chamber 12 for promoting a decomposition process. 2 is an air diffuser provided in the aeration chamber 12, and 21 is a blower for supplying air to the air diffuser 2. Reference numeral 3 is a drain pipe for introducing all the wastewater from the home (human waste and miscellaneous wastewater in the kitchen or bathroom) into the aeration type septic tank 1, and 4 is a water level sensor for detecting the water level in the aeration type septic tank 1. 5 is an auxiliary tank installed at a high place,
It can be installed on the balcony or roof of the building. 6
Is a pipe from the aeration type septic tank 1 to the auxiliary tank 5, and 7 is a pump.

Reference numeral 8 is a membrane separation device installed at a position lower than the auxiliary tank 5, and reference numeral 9 is a pipe from the auxiliary tank 5 to the stock solution inlet of the membrane separation device 8. The membrane separation device 8 is installed right above the ground so that the water level difference in the pipe 9 is as large as possible, and the membrane surface differential pressure required for filtration acts on the membrane separation device 8 due to the water level difference. Reference numeral 13 is a filtrate outflow pipe of the membrane separation device 8, and 14 is an opening / closing valve provided in the pipe 13.
In the above description, the effective volume of the aeration type septic tank 1 is given by the volume from the bottom surface to the wastewater inlet 111, and the effective volume of the auxiliary tank 5 is given by the volume from the bottom surface to the overflow outlet 51. Therefore, the capacity of the entire system is increased by the effective capacity of the auxiliary tank 5 as compared with the case of the aeration type septic tank alone.

In order to treat domestic wastewater with the wastewater treatment system according to the present invention, all of the human waste and sewage generated at home are introduced into the aeration-type septic tank 1, and the anaerobic chamber 11 separates contaminated matters and sewage. Stabilize the organic matter in the aeration chamber 12 under the aerobic condition by the air from the air diffuser 2 by adsorbing and metabolically decomposing the organic matter in the sewage with microorganisms (activated sludge), and proliferating the microbial group, and mixing this activated sludge. The liquid is sent to the auxiliary tank 5 by the pumping pump 7, and the water level difference energy of the mixed solution flowing down the auxiliary tank 5 is washed to wash the membrane surface of the membrane separation device 8 and the drop pressure based on the water level difference. The membrane separation device 8 is caused to carry out a filtration operation, and the mixed solution whose sludge concentration has been concentrated by the filtration is returned to the aeration-type septic tank 1. Thereafter, the above is repeated to accelerate the decomposition of the activated sludge and to filter only the amount of introduced wastewater. Yo Continue to release the generated purified water. In this case, the surplus activated sludge is taken out in a timely manner and the sludge concentration is maintained at an appropriate concentration.

In the above, a predetermined level lower than the drainage inlet 111 is defined as the detection level of the water level sensor-4,
Only when the water level is higher than this level, the valve 14 of the filtrate extraction pipe 13 of the membrane separation device 8 can be opened to discharge the filtrate. With the discharge of the filtrate, when the water in the activated sludge water passes through the membrane, the activated sludge adheres to the membrane surface, and the filtration flux gradually decreases. However, for the water level below the water level sensor-detection level, the valve 14 of the filtrate extraction pipe 13 is closed, the filtration operation of the membrane separation device 8 is stopped,
The action of cleaning the membrane surface by the mixed liquid flowing down the auxiliary tank 5 overruns the action of adhering the activated sludge to the membrane surface, and the membrane surface is cleaned, so that the filtration flux is high. Can be guaranteed. Therefore, by alternately repeating filtration and cleaning, a good filtration flux as a whole can be guaranteed, and efficient purification can be performed.

In the above, the membrane separation device is provided with an air diffuser capable of blowing a flow of bubbles on the membrane surface, and the membrane surface is constantly washed with the flow of bubbles while the membrane separation device is constantly operated by opening the valve of the filtrate extraction pipe. It is also possible to use the shunt pipe 22 of the air supply pipe to the air diffuser pipe 2 of the aeration type septic tank 1 as shown in FIG. 1 for supplying the air to the air diffuser pipe.

In the present invention, it is desirable to use a thin type (installation area of 0.4 m ² or less) for the membrane separation device, which requires a small installation space. 2 (a) and FIG. 2 (b) [a cross-sectional view taken along line (b) in FIG. 2 (a)] shows an example of a flat sheet membrane element used in this thin membrane separation device, with hollow spaces at both ends. Frame body 81 having a support portion 811
Separation membranes 82, 82 (ultrafiltration membranes, microfiltration membranes, etc.) are attached to (usually plastic) with an adhesive or fusion, and a filtrate liquid channel material 83 (for example, plastic) between the separation membranes 82, 82. The filtered water generated by passing the solvent in the raw water through the membrane reaches the inside of the hollow spacer 811 on one side through the filtered liquid flow path member 83, and the filtered liquid take-out pipe 8
It will be leaked from 12.

FIG. 3A is a side view showing the thin membrane separation device used in the present invention, and FIG. 3B is a sectional view taken along the line RO in FIG. 3A. In FIG. 3A and FIG. 3B, 84 is a thin vessel,
A partition wall 841 that is open at the bottom divides the raw water inflow chamber 851 and the flat membrane module storage chamber 852. Reference numeral 80 denotes a flat sheet membrane module housed in a flat sheet membrane module storage chamber 852. As shown in FIG. 4, a plurality of flat sheet membrane elements described above are stacked and a spacer portion 811 is provided between the flat sheet membrane elements. Holds the gap a, and these gaps a, ... Are used as raw water passages. The flat membrane elements are integrated with each other by bolts and angles, but the bolts and angles are not shown. In FIG. 3, reference numeral 86 denotes a vessel lid plate, and 8
7, ... Connection hoses 88, which are provided in a liquid-tight manner on the cover plate 86,
Is a liquid collecting pipe connected to the filtrate extracting pipe 811 of the flat membrane module 80, and 89 is a filtrate extracting pipe. Reference numeral 891 is a raw water inflow pipe provided in the vessel 84, and 892 is a concentrated raw water outflow pipe.

In this membrane separation apparatus, the activated sludge water flowing down from the above-mentioned high place auxiliary tank 5 due to the water level difference is inverted at the bottom of the vessel, and the gaps a, ... The water in the activated sludge water passes through the membrane while passing through the concentrated liquid extraction pipe 892 and returned to the aeration-type septic tank, and between the elements of the flat membrane module, and the filtration generated by the passage. Water is filtered water extraction pipe 8
It is discharged from 9 to the gutter. In this case, in FIG. 1, only when the water level in the aeration-type septic tank 1 is equal to or higher than the water level sensor-detected water level, the valve 14 of the filtrate extraction pipe of the membrane separation device 8 is opened to perform the filtration operation, and the water level sensor- When the water level is below the detected water level, the valve 14 of the filtrate extraction pipe is closed and the membrane separation device 8
It is also possible to stop the filtration operation of (3) and allow the activated sludge water to pass through the gaps between the flat sheet membrane elements to promote the membrane surface cleaning. In addition, as shown in (b) of FIG.
It is also possible to provide an air diffusing tube 220 directly below the cell and wash the membrane surface with a bubble flow at regular intervals (for example, every 10 minutes for 1 minute) or at all times.

[0014]

[Example] As the aeration type septic tank, a single treatment septic tank for a family of 5 was used. The daily miscellaneous drainage of a family of 5 is set to 1 m ^3, and the effective volume of the auxiliary tank is 0.1 m ³ for this drainage.
Was used. As the membrane separation device, those shown in (a) of FIG. 3 and (b) of FIG. 3 were used, and the flat membrane module of the membrane separation device had a membrane with a daily average filtration flux of 0.2 m. ³ /
m ² / day microfiltration membrane with 5 elements
A device having a height of 640 mm, a width of 1030 mm and a thickness of 13 mm was used, and the dimensions of the entire membrane separation device were 800 mm in height, 1100 mm in width and 150 mm in depth. The effective membrane area of this membrane separation device was slightly larger than 5 m ² , and the possible filtration flux per day was more than 1 m ³ , and the above waste water was sufficiently purified. The low area of the membrane separator is 0.165m.
^{Since the} width is as narrow as ² and the height is 1 m or less, it can be arranged in contact with the outer wall of the building, and the space required for installing the membrane separation device was hardly required.

[0015]

In the domestic wastewater treatment system according to the present invention, in order to purify not only human waste but also wastewater, the volume is increased by installing an auxiliary tank, and the separation capacity is increased by installing a membrane separator. Although it is increasing, since the auxiliary tank is installed at a high place above the ground, it is not necessary to actually use the residential land for installing the auxiliary tank, and since the auxiliary tank can be made sufficiently thin, the residential area occupation rate of the entire system Can be extremely reduced (about 50% of the combined treatment septic tank). In addition, since the existing urine septic tank that has been independently treated can be used as an aeration septic tank, the initial cost can be reduced (about 70% of the combined septic tank).

[Brief description of drawings]

FIG. 1 is an explanatory view showing a domestic wastewater treatment system according to the present invention.

FIG. 2 (a) is a perspective view showing a flat membrane element of a membrane separation device used in the present invention, and FIG. 2 (b) is a cross section taken along the line of FIG. 2 (a). It is a figure.

3 (A) is a plan view showing a membrane separation device used in the present invention, and FIG. 3 (B) is a cross-sectional view taken along line FIG. 3 (A).

FIG. 4 is a perspective view showing a flat membrane module of a membrane separation device used in the present invention.

[Explanation of symbols]

 1 Aeration-type septic tank 2 Diffuser pipe 3 Drain pipe 4 Water level sensor-5 Auxiliary tank 7 Pump 8 Membrane separation device 13 Purified water extraction pipe 14 Open / close valve 220 Diffuser pipe

Claims (3)

[Claims] 1. An aeration-type septic tank installed buried, an auxiliary tank installed at a high place, and a membrane separation device installed on the ground lower than the auxiliary tank, and liquids to be treated are sequentially supplied. A domestic wastewater treatment system characterized by being circulated through an aeration-type septic tank, an auxiliary tank, and a membrane separation device, and the purified water filtered and separated by this circulation being discharged from the membrane separation device. 2. The domestic wastewater treatment system according to claim 1, wherein an opening / closing valve provided in the purified water extraction pipe of the membrane separation device is controlled to be opened / closed by a water level sensor provided in an aeration type septic tank. 3. The domestic wastewater treatment system according to claim 1, wherein the membrane separation device is provided with an air diffuser for cleaning the membrane surface with a bubble flow.