JP2015116523A - Wastewater treatment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sludge treatment device which is compact, which reduces running cost, and which saves maintenance.SOLUTION: A wastewater treatment system comprises: a biological treatment tank having two or more tanks for performing biological treatment of wastewater; a solid-liquid separator for separating the wastewater treated in the biological treatment tank; and a mesh-like woven cloth bag. The sludge separated by the solid-liquid separator is filled in the mesh-like woven cloth bag by transfer means, and in the bag, dewatering and drying of the sludge are performed.

Description

  The present invention relates to wastewater treatment using a biological tank, and a method and apparatus for treating sludge produced by biological treatment.

  Organic wastewater treatment at sewage treatment plants and business establishments is performed by oxidative decomposition treatment using microorganisms such as activated sludge. A general waste water treatment system is mainly composed of a water treatment system that purifies water by a biological tank and a sludge treatment system that separates and disposes surplus sludge. In this water treatment process, microorganisms (bacteria, protozoa, etc.) consume organic substances in water as energy sources necessary for biological activities, and mainly decompose into carbon dioxide and water, but some of them are used for the growth of microorganisms. Is also used. That is, organic substances in water are basically decomposed and released out of the processing system, but a part of them is retained in the system as a growth of microorganisms.

In wastewater treatment, normally, such excessively grown microorganisms are drawn out of the system as surplus sludge, and the inside of the biological tank is maintained at an appropriate concentration for operation. In the process, after being concentrated and dehydrated, it is landfilled or incinerated as industrial waste.
The conventional wastewater treatment system combines a water treatment system and a sludge treatment system, so the equipment configuration is complex, and it is necessary to manage the concentration of biological tanks and to treat a large amount of excess sludge frequently. Is a complicated problem, and many countermeasure techniques have been proposed.

  The biological treatment method that can be operated easily is not the suspended activated sludge method (biological suspension method) in which microorganisms are cultured directly in water, but the fixed activated sludge method (biological fixation method) that uses a carrier to immobilize organisms on its surface. Since the concentration control of the biological tank is not necessary, it has been increasingly used in recent years, and various types of carriers as in Patent Document 1 have been invented. ing.

  As a method for reducing the generation amount of excess sludge, it is known that the biofixation method described above has a smaller generation amount of excess sludge than the biological suspension method. In particular, it is known that a plurality of biological treatment tanks equipped with a biological fixing carrier are connected in multiple stages to form a multistage biological tank, and the waste water is pushed out to cause a food chain effect and further suppress the generation of excess sludge. It has become.

In addition, as described in Patent Document 2, many attempts have been made to reduce the volume of surplus sludge generated by the self-digestion phenomenon of microorganisms to reduce the processing effort of surplus sludge.
As a method of easily dewatering, drying and discarding the generated excess sludge, as described in Patent Document 3, flocculant is added to the sludge to form a flock, and the mesh bag is filled and suspended. For example, a method of performing solid-liquid separation by dropping only moisture outside the bag body is proposed.

JP 2000-15278 A JP 2008-18304 A JP 2007-44621 A

  However, even in the conventional fixed biological method such as the above-mentioned Patent Document 1, surplus sludge is generated. Therefore, the equipment configuration requires a sludge treatment system such as a filter press, a belt press, and a screw press. Due to the complexity of the configuration, there were significant problems in operation management and maintenance.

  Similarly, in the wastewater treatment system with enhanced sludge volume reduction effect as described in Patent Document 2, chemical management is complicated, and a complex sludge treatment system is required as in Patent Document 1, and the equipment configuration is Due to the complexity, there were major problems in operation management and maintenance.

  In the sludge treatment method utilizing the mesh bag as in Patent Document 3, since the sludge containing moisture is heavy, when the bag is filled with a large amount of sludge and suspended, the bag is ruptured. There is a limit to its own priority capacity, and as a result, the frequency of sludge disposal becomes frequent, so there is a disadvantage that it can be applied only to a small-scale wastewater treatment system.

  Therefore, the present invention solves the problem of such a conventional wastewater treatment system, and aims to reduce the sludge treatment apparatus in a small size, low running cost, and maintenance.

That is, this invention provides the following waste water treatment systems.
1. A biological treatment tank comprising two or more tanks for biological treatment of wastewater, a solid-liquid separator for separating wastewater treated in the biological treatment tank, and a cloth bag woven in a mesh shape, A wastewater treatment system comprising transport means for filling sludge separated by a separation device into a cloth bag woven in a mesh shape, wherein sludge is dehydrated and dried in the cloth bag.
2. 2. The wastewater treatment system according to 1 above, wherein at least one of the biological treatment tanks is a contact oxidation tank using a fixed carrier or a fluid carrier.
3. 2. The wastewater treatment system according to 1 above, wherein the solid-liquid separation device is a pressure levitation device.
4). 2. The wastewater treatment system according to 1 above, wherein the solid-liquid separation device is a sand filtration device.
5. 2. The wastewater treatment system according to 1 above, wherein the solid-liquid separation device is a drum type screen device.
6). 2. The waste water treatment system according to 1 above, wherein the solid-liquid separation device is a disk-type screen device.
7). 2. The waste water treatment according to 1 above, wherein at least two cloth bags woven in a mesh shape are disposed, and the separated sludge can be alternately filled, dehydrated, dried, and disposed of with a cycle of disposal. system.
8). 2. The wastewater treatment system according to 1 above, comprising a photovoltaic power generation system or a wind power generation system as a necessary power supply.
9. A storage power generation system is provided, wherein surplus electricity generated from the power generation system is stored, and when the power generated from the power generation system is insufficient, the electricity required for the wastewater treatment system is supplied from the power storage system. The waste water treatment system according to 8 above.

  The present invention suppresses the amount of excess sludge to a minimum by a multi-stage biological treatment process having two or more biological treatment tanks, and because the amount of excess sludge is small, a bag body that could not be used for a large-scale system By combining the used sludge treatment, it is possible to provide a wastewater treatment system with an extremely simple equipment configuration. Furthermore, since it is a system with low power consumption by combining biological treatment and natural filtration drying of excess sludge, it becomes possible to construct a smart plant by combining with natural energy such as sunlight.

The schematic diagram of the waste water treatment system of this invention.

Embodiment examples of the wastewater treatment system of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram of a wastewater treatment system of the present invention. The main components are biological treatment tanks, solid-liquid separation tanks, and mesh fabric bags, and sewage is decomposed and digested by microorganisms in a multistage biological treatment tank equipped with two or more biological treatment tanks. Minimize. By storing the wastewater after the biological treatment in the separation tank of the solid-liquid separator, the excess sludge is precipitated and separated, and the supernatant is discharged out of the system as treated water.

  The sludge separated by the solid-liquid separator is once separated into a sludge tank, and then filled into a cloth bag woven in a mesh shape. Thereby, moisture can be removed, dehydrated and dried from between the meshes by the weight of sludge water.

  Wastewater that can be applied to this system includes wastewater that contains organic matter that can be decomposed by living organisms, and includes a wide variety of wastewater such as domestic wastewater, food factory wastewater, chemical factory wastewater, and pharmaceutical factory wastewater. Moreover, even if the waste water contains toxic substances for microorganisms or the like that digest organic substances, the system can be treated by removing the toxic substances in advance by pretreatment.

  After removing the solid matter contained in the raw water of organic wastewater such as domestic wastewater and factory wastewater treated by this system, it is temporarily stored in the raw water adjustment tank. In this raw water adjustment tank, the hydrogen ion concentration of the wastewater is adjusted to a neutral range of about PH 6 to 8 by adding an acidic or alkaline neutralizing agent, and then introduced into the biological treatment tank. When a large amount of solid matter is contained in the waste water, it is common to perform pretreatment by a separation device applying physical and chemical principles such as a pressurized flotation device and remove the solid matter in advance.

  Such a biological treatment tank includes a diffuser pipe and an air pipe for air supply inside, and has a structure capable of sending air into the biological tank. The air diffuser is intended to supply oxygen to aerobic microorganisms, and it is required to increase the dissolution rate in water as much as possible, but at the same time, the surface of the air diffuser is not blocked by the propagation of microorganisms. Consideration is also an important requirement. Various types of diffuser tubes such as a fine diffuser tube that prioritizes oxygen dissolution efficiency and a coarse diffuser tube that prioritizes blocking resistance by microorganisms can be used.

  Among the biological treatment tanks configured in two or more stages, at least one tank is a catalytic oxidation tank using a fixed carrier or a fluid carrier. Such a biological treatment tank is provided with a space partitioned by partition walls made of concrete, plastic, metal, etc., and is composed of two or three tanks by placing the partition walls in one tank. The flow of drainage from the tank to the tank is always unidirectional and flows by overflowing the upper side of the partition wall or communicating between the tanks on the lower side of the partition wall.

  Specifically, MBBR (Moving Bed Bio Reactor) using a fluid carrier, RBC (Rotating Bio Contactor) using a rotating disk, and MSABP (registered trademark) which is a multi-stage biological treatment tank of Aquarias can be used. .

  The biological tank using the carrier is fixed in the tank without flowing out of the tank because bacteria adhere to the surface of the carrier, so that the age of the sludge becomes high. By increasing the age of sludge, there is a merit that the ability to decompose into persistent organic substances increases. In addition, although the microbial membrane formed on the carrier surface is composed of aerobic bacteria, the back side of the microbial membrane has a low oxygen concentration, so facultative anaerobes have settled, and a variety of microbial membranes Will progress. It is thought that facultative anaerobes and aerobic bacteria prey on each other. As a result, the merit that sludge is reduced in the microbial membrane is expressed.

  By configuring the biological treatment tank in two or more stages, the priority species of the organism will change from bacteria to protists and metazoans from the front to the rear, and the organic matter in the wastewater is decomposed by a wide variety of microorganisms. And purified. By configuring the food chain, surplus sludge is efficiently self-digested and sludge volume reduction can be achieved. In the case of a multistage biological treatment apparatus (MSABP: registered trademark), the aeration tank containing the diffuser tube and the biological carrier is multistaged to 8 to 12 stages to reproduce the food chain in the biological treatment tank, and biological treatment Can be implemented efficiently.

In addition, a biological floating activated sludge tank and a biological fixed activated sludge tank can be used in combination.
Following the biological tank, a solid-liquid separation device is installed to separate a small amount of microbial membrane flowing out from the biological tank and the treated water. Various systems such as a screen, a sand filtration device, a coagulation sedimentation device, and a pressurized flotation device can be applied to the solid-liquid separation device. The microbial membrane separated from the solid-liquid separation device is sent to a cloth bag woven in a mesh shape to further remove moisture.

  The pressure levitation device generally uses a polymer flocculant and can be separated from water by agglomerating fine organisms and solids to form a floc. It is done. When the required water quality of the treated water is relaxed, a drum type screen or a disk type screen that does not use a polymer flocculant is selected.

  Microbial membranes are fragile and easily mixed with water and colloids, so separation from water may be difficult. In such a case, it is common to add a polymer flocculant to fill the microbial membrane before filling the cloth bag woven in a mesh shape. There are various types of polymer flocculants such as anionic, nonionic, cationic, and bipolar, and an appropriate one is selected according to the properties of waste water and sludge.

The cloth bag woven in a mesh shape is made of Geotextile, which is a water-permeable fabric having a three-dimensional structure. The mesh usually has an opening of 0.1 to 1 mm, and when the sludge is introduced, only moisture is discharged, and the sludge forms a sludge cake on the surface of the mesh. It can be performed. The material is made of synthetic fiber, such as polypropylene or polyester fiber.
Specific examples include Geotube (registered trademark) manufactured by Tencate, and Eco tube (registered trademark) manufactured by US Fabric.

  At least two cloth bags are arranged. Microbial residues and excess sludge separated in the solid-liquid separation tank are drawn into the sludge tank, and sludge separated by the transfer means such as pump means is filled in one of the cloth bags. When the sludge is filled in the cloth bag, the sludge is transferred by switching to the other cloth bag, and during that time, dewatering, drying and disposal are performed. By alternately performing this, the cycle of filling, dewatering, drying, and disposal can be continuously performed.

  The wastewater dehydrated in the cloth bag is not discharged as it is, but is returned to the raw water adjustment tank and biological treatment is performed again. Microbial flocs are made of organic viscous substances, and because the body of microorganisms contains a large amount of organic matter, the water filtered by Geottile cloth bags is a wastewater with relatively high pollution. . Therefore, the waste water dehydrated in the cloth bag is not discharged out of the system as it is, but is returned to the raw water adjustment tank and biological treatment is performed again.

  As a power supply necessary for this system, a solar power generation system or a wind power generation system is provided. The power storage system further includes a surplus electricity generated from the power generation system, and when the electricity generated from the power generation system is insufficient, the power storage system supplies the necessary electricity to the wastewater treatment system. Can do.

  Since wastewater from food factories contains a large amount of organic matter that is highly degradable by living organisms, a large amount of excess sludge is generated along with the wastewater treatment, which makes the operation of wastewater treatment facilities and excess sludge treatment very complicated. It was. In addition, there are many small factories in the industry, and there is a problem that a space for installing a conventional wastewater treatment system cannot be secured. The present invention is an invention that solves the above-described problems, and is suitable mainly for food factories and the like.

Claims (9)

  A biological treatment tank comprising two or more tanks for biological treatment of wastewater, a solid-liquid separator for separating wastewater treated in the biological treatment tank, and a cloth bag woven in a mesh shape, A wastewater treatment system comprising transport means for filling sludge separated by a separation device into a cloth bag woven in a mesh shape, wherein sludge is dehydrated and dried in the cloth bag.   The wastewater treatment system according to claim 1, wherein at least one of the biological treatment tanks is a contact oxidation tank using a fixed carrier or a fluid carrier.   The wastewater treatment system according to claim 1, wherein the solid-liquid separator is a pressure levitation device.   The wastewater treatment system according to claim 1, wherein the solid-liquid separation device is a sand filtration device.   The wastewater treatment system according to claim 1, wherein the solid-liquid separation device is a drum type screen device.   The wastewater treatment system according to claim 1, wherein the solid-liquid separator is a disk-type screen device.   It is characterized in that at least two cloth bags woven in a mesh shape are arranged, and provided with a transfer means capable of alternately transferring the separated sludge to the cloth bags, and a cycle of filling, dehydrating, drying and disposal can be rotated. The wastewater treatment system according to claim 1.   The wastewater treatment system according to claim 1, comprising a solar power generation system or a wind power generation system as a necessary power supply.   A storage power generation system is provided, wherein surplus electricity generated from the power generation system is stored, and when the power generated from the power generation system is insufficient, the electricity required for the wastewater treatment system is supplied from the power storage system. The waste water treatment system according to claim 8.