WO1994029224A1

WO1994029224A1 - Water treatment method and water treatment apparatus

Info

Publication number: WO1994029224A1
Application number: PCT/JP1994/000879
Authority: WO
Inventors: Shinpei Yamamoto; Kazuhiro Takagi; Etutami Kiyotani; Iwane Kagimoto; Shinichi Kariya; Satoshi Matumoto
Original assignee: Toyo Denka Kogyo Co., Ltd.
Priority date: 1993-06-16
Filing date: 1994-05-31
Publication date: 1994-12-22

Abstract

This invention aims at providing water treatment techniques capable of carrying out a high-performance water purifying treatment by efficiently removing a synthetic organic compound, such as a surface active agent for a detergent and components of agricultural chemicals from contaminated water having a comparatively low load of, for example, BOD. To achieve this object, a utilizable filter medium formed by depositing a substrate having a specific utilizability by the target microorganisms on a porous base material, such as charcoal, is used as the filter medium, with which contaminated water to be treated is brought into contact under aerobic conditions. Using the utilizable filter medium in this manner enables specified microorganisms having a high efficiency of removing synthetic organic contaminants to be selectively utilized, and synthetic organic compounds to be efficiently removed.

Description

Specification

Water treatment method and water treatment device

〔Technical field〕

The present invention relates to a water treatment technique, and particularly to a water treatment technique suitable for performing advanced purification treatment of sewage having a relatively low pollution load.

[Background of the Invention]

LAS (Liner Alkylbenzene Sulfonates; a surfactant used as a main component of synthetic detergents) by the activated sludge method that enables efficient water treatment of sewage with relatively high pollution loads such as sewage and industrial wastewater. It is well known that) can be effectively removed from water [for example, “Research on Water Pollution,” Vol. 5, No. 1, pp. 19-25 and Vol. 2, No. 63-72 “Study on Biodegradation of Linear Alkylbenzene Sodium Sulfonate (LAS) by Activated Sludge (I), (II); 1982] However, supply of synthetic organic compounds such as LAS and pesticides to the environment Active in the treatment of river basin rivers, which are considered to have a large specific gravity as a root, especially river water into which domestic wastewater or pesticide contaminated water flows in, because the pollution load there is too small or the daily fluctuation of the load is large. The application of the sludge method is difficult.

In addition, many examples of water treatment technologies intended for the treatment of river water are already known. These existing technologies cannot expect much effect in removing LAS. In addition, both have problems in the stable sustainability of advanced purification treatments in terms of performance degradation due to clogging and saturation of the filter media used for them. There are also many reports on the removal of LAS by adsorption using charcoal or activated carbon.However, charcoal does not have sufficient adsorption power to effectively remove LAS, whereas activated carbon has a high adsorption power but is saturated. The problem is running costs. (In other words, rivers, which are the main routes of release of harmful synthetic organic pollutants such as LAS to the environment and their removal is strongly demanded.) 11 In the treatment of water, synthetic organic pollutants are practically used. At present, there is no method that can be effectively removed at the level.

By the way, the inventors of the present application have proposed a charcoal-made microphone mouth Habi-Yu-Yat, which is excellent in microbial colonization and can be expected to improve the efficiency of biological water treatment by using it as a "filter medium". Developed (Japanese Patent Application No. 4-159177), and underwater nitrate Unlike the conventional method, which simply removes oxygen nitrogen as nitrogen gas by denitrifying bacteria, nitrate nitrogen, which is less adsorbable, is converted into highly adsorbable ammonia nitrogen, and this ammonia nitrogen is adsorbed by the adsorbent. This is a method that incorporates a process of adsorption and removal.As a result of the simultaneous use of multiple types of coexisting biological treatments, there is also a denitrification method that enables high denitrification treatment with a relatively simple facility structure. Developed earlier (Japanese Patent Application No. 4-1926533). Each of these technologies is a new technology, and the development of a water treatment system that comprehensively performs advanced water treatment by effectively utilizing these technologies remains as an issue. Therefore, the inventors of the present application proceeded with the development of a new water treatment system utilizing each of the above technologies, and obtained a water treatment apparatus described later.

First, model experiments were performed on this water treatment equipment to confirm that the intended treatment level could be sufficiently achieved, and then, in order to confirm the performance at the actual scale, the test equipment was installed on an actual river to accumulate performance data. And other tests. Analysis of the LAS in this test with the above awareness of the problems revealed that the final release of the high concentration LAS was about 0.4 mg liter in the influent water. Under running water, it was about 0.04 mg Z liter, and it was found that it had extremely good LAS removal performance.

Therefore, further analysis was conducted on which of the tanks in the water treatment system described below worked to remove LAS, and it was found that the chitosan charcoal tank had the greatest effect. Furthermore, when the mechanism of the chitosan charcoal tank effectively working for the removal of LAS was analyzed, the following mechanism was estimated.

That is, as can be seen in the above-mentioned literature, LAS is removed by adsorption and biodegradation by microorganisms in the activated sludge method, but the mechanism of adsorption and biodegradation also works in the chitosan charcoal tank. I have. Regarding this adsorption and biodegradation, chitosan charcoal has the property of excellent bacterial colonization, and the bacteria can use the chitosan attached to its pores as a supplementary nutrient source or assimilable matter. Co-metabolism action (Co-Metabol ism; the coexistence of other energy sources and nutrients that are cell-synthetic substances enables or accelerates the biodegradation of synthetic organic compounds such as LAS and pesticides for the first time. Phenomena that can be used effectively, and that the bacterial activity is stable even when the load of organic pollutants as a nutrient source fluctuates quantitatively. Tosan has a high hydrophobicity, which means it can be expected to have a high adsorption capacity due to hydrophobic adsorption.Also, by aerating the inside of the chitosan charcoal tank and supplying a sufficient amount of oxygen, a forced convection state is created in the water to be treated. Efficient LAS removal is achieved by the synergistic effect of efficient contact of the water to be treated and improvement of the adsorption opportunity.

In addition, as we proceeded with the analysis of microorganisms that actually work in LAS removal, the following facts became clear. First, chitosan charcoal was found to colonize bacteria at high density, but there were basically only two types of chitosan charcoal, indicating that chitosan charcoal has an extremely specific and selective microbial colonization function. Was. In other words, a combination of two conditions, namely, the kind of a material called chitosan and the size of the pores of a charcoal base material as pores for microorganisms to settle, selectively fix specific microorganisms, and this selective settlement It has been demonstrated practically that a particular contaminant (LAS in this example) can be efficiently treated by these microorganisms. When identified by standard identification methods, these two types of bacteria are already known and readily available, and are identified as Pseudomonas florecens biover 5, and 1-3 are identified as Pseudomonas florecens biover 5. Others could be identified as Pseudomonas put ida bioverA.

[Disclosure of the Invention]

The present invention is based on the above-described findings, and shows that the assimilable filter material represented by chitosan charcoal formed by attaching chitosan to charcoal, that is, the pore wall of the pores of the porous base material, By effectively utilizing the above-mentioned properties of the assimilable filter medium attached with assimilable materials having specific assimilation properties to the target microorganisms, at least for the depth range necessary for the microorganisms to settle in, It efficiently removes synthetic organic compounds. More specifically, Pseudomonas fluorecens b iover 5 and Pseudomonas put ida biover A are selectively established on assimilable filter media such as chitosan charcoal, and LAS is removed by these two types of bacteria. As shown in the example, the specific bacteria selectively fixed to the assimilating filter media are made to biodegrade and remove specific contaminant components with high efficiency. In order to achieve this, the water to be treated is brought into contact with the filter medium while aerobically aerobically aerated, and a forced convection state is generated in the water to be treated when contacting the filter medium. ing. The function of the assimilated material such as chitosan applied to the assimilable filter medium is to cover the spine structure on the surface of the pore wall of the base material to such an extent that it does not adversely affect microorganisms. Pore The pores must be of a degree that can at least bury the spinous structures on the pore wall surface, such as to eliminate the polarity of the pore walls and to form a supplementary nutrient source for microorganisms that settle in the pores. If necessary, it can be considered that the required amount is satisfied.

There are various methods for attaching the assimilates to the pore walls of the substrate, but the most reliable method is to immerse the substrate in a chitosan solution for a certain time, for example, in the case of chitosan. It is. As a simpler method, a method of spraying or spraying a chitosan solution on a base material is possible (in this case, uniform adhesion to the deep part of the pores may not necessarily occur, but there may be cases where microorganisms are used. This is enough for fixing. In other words, the necessary condition can be satisfied if the chitosan adheres as described above in a range where the microorganisms can be considered as “dwelling”.

Regarding the mechanism described above that functions in the present invention, it is a fact that it was actually known that the assimilable filter medium made of chitosan-treated charcoal exhibits preferable characteristics, but from the principle derived from this fact, Naturally, a material having a porous structure similar to that of charcoal, for example, a porous mineral, or a sponge-like material that has been subjected to chitosan processing may be used as a base material, so that the same effect may be obtained. In addition, polysaccharides such as chitosan are particularly preferred as the assimilation substances to be attached to the base material. Anything that can satisfy the requirements of having a function as a supplementary nutrient source that functions for metabolism, etc., and having hydrophobicity can be used sufficiently. Since the shape and size of the pores in the porous substrate can also contribute to the fixing specificity, in addition to the fixing specificity depending on the type of the material, the type of the material and the type of the substrate By appropriately selecting the combination, the selective fixation of microorganisms can be further enhanced. Therefore, not only LAS, but also synthetic organic compounds such as pesticide components, which are the same as LAS, can be selectively fixed to specific microorganisms that efficiently decompose them. It is thought that a similar removal mechanism can be effectively exerted.

Such water treatment equipment is based on the properties of assimilable filter media such as chitosan charcoal. The mechanism described above can effectively remove LAS and other synthetic organic compounds, but has the following additional features. In other words, biodegradation can be used more effectively than a system that removes LAS or the like only by adsorption after the general treatment, for example, using activated carbon or the like. In addition, since it can be performed together with the processing of the B〇D component, the system can be simplified and the cost can be reduced.

The present invention also provides a water treatment device capable of performing the above-described efficient removal of synthetic organic compounds as well as advanced treatment of BOD components, etc., by filling a filter medium for removing suspended solids and the like. A denitrification tank provided with a pre-treatment tank, an adsorbent layer filled with bacterial assimilates, and an adsorbent layer filled with an adsorbent capable of adsorbing ammonium nitrogen. Provided is a water treatment apparatus including a chitosan charcoal tank filled with chitosan charcoal, a dephosphorization tank filled with an adsorbent capable of adsorbing phosphorus, and a finishing tank filled with charcoal.

The main treatment functions in each tank of this water treatment device are as follows. In addition to these main treatments, various treatment functions are mixed depending on the types of the filter media and the like which are additionally filled in each tank. Each of these processes is a biological process, and these processes are combined with ancillary processes to realize advanced processes.

In the pretreatment tank, BOD components (organic substances) are decomposed together with the removal of loose solids (SS).

In the denitrification tank, nitrate nitrogen is converted to ammonia nitrogen and nitrogen gas (N ₂ ) and removed by three types of processes in which nitrate nitrogen coexists under highly anaerobic conditions provided by the assimilate layer. More specifically, advanced anaerobic conditions are formed in the material layer by immersing the material in water and consuming oxygen by aerobic bacteria that temporarily breed using the material. The conversion to ammonia nitrogen is based on the anaerobic conditions in the assimilation layer and the biological activity of bacteria that have nitrate reducing ability that breeds using assimilation, and the advanced anaerobic conditions in the assimilation layer, It proceeds by purifying chemicals with high reduction levels. These reducing processes _{_{N 0 3 - → N 0 2}} - → N 2 0 → NH 4 - shown as. On the other hand, conversion to nitrogen gas (N ₂₎ is done by denitrifying bacteria breeding by utilizing the anaerobic conditions contribute product in well assimilated Monoso, N 0 ₃ - + 5 H (hydrogen donor)-0.5 N ₂ +2 H ₂ O + OH—. As described above, the ammonium nitrogen generated in the assimilable material layer travels to the adsorbent layer as it travels on the water stream in which the amount of dissolved oxygen is reduced by passing through the assimilable material layer, and at the same time as the adsorbent layer. Is adsorbed without being redissolved in the adsorbent. On the other hand, nitrogen gas is released into the atmosphere.

In the chitosan charcoal tank, the synthetic organic compounds such as LAS described above are removed together with the decomposition of BOD components.In the dephosphorization tank, dephosphorization is performed by adsorption with an adsorbent, and in the finishing tank, decolorization and deodorization are performed. At the same time, final removal of SS and decomposition of B 0 D component are performed.

Various arrangements are possible for the arrangement order of each tank in the water treatment apparatus as described above. For example, from upstream to downstream, a pretreatment tank, a denitrification tank, a chitosan charcoal tank, a dedicated aeration tank, a deaeration tank Arranging in the order of the phosphorus tank and the finishing tank is a preferable example from the viewpoint of each treatment.

In addition, since the dephosphorization in the water treatment apparatus as described above has a relatively low correlation with other treatments and the degree of freedom in the treatment order is high, the adsorbent for dephosphorization is overlapped with the filler in another tank. When the dephosphorization tank is integrated with other tanks, it is particularly structurally simple to integrate the dephosphorization tank with the chitosan charcoal tank. Above is preferred.

In addition, in the water treatment apparatus as described above, one of the tanks was paired with L and two of them, and both tanks were provided with a common sludge pit, and the sludge was poured into one tank from above. If the water to be treated is allowed to flow into the other tank from below via a sludge pit, a forced downward flow and an upward flow can be generated in both tanks. It is more preferable because the contact efficiency can be increased.

When a downward flow and an upward flow are generated in this way, a partition plate for partitioning the two tanks forming a pair is formed so as to protrude sufficiently high with respect to a normal water level state, and the filling material in the tanks is formed. It is more preferable that the water level in the upstream tank be higher than the water level in the downstream tank when the water permeability of the tank decreases. In other words, the downflow pressure and the upflow pressure can be increased by the water level difference between the upstream side and the downstream side, so that the water flow resistance due to the sludge (biofilm and attached matter) accumulated on the surface of the packing material and the gaps between them Which can be countered by this It is also possible to prevent sludge degradation and to remove sludge appropriately by this high-pressure water flow, thus eliminating the need for periodic sludge removal work such as backwashing. .

[Brief description of drawings]

FIG. 1 is a sectional view of a water treatment apparatus according to one embodiment of the present invention.

FIG. 2 is a plan view of the water treatment apparatus of FIG.

FIG. ₃ is a sectional view taken along the arrow SA ₃ —SA ₃ in FIG.

Fig. 4 is a cross-sectional view of the denitrification tank.

FIG. 5 is a graph showing LAS data in the water treatment apparatus according to the embodiment of the present invention.

[Mode for Carrying Out the Invention]

Hereinafter, examples of the present invention will be described.

Water treatment apparatus in this embodiment is a sea urchin designed Example I with the capacity of about 5 O m ³ days on average, as shown in FIGS. 1 to 3, the total length of about 1 lm, a width of about 3. 5 m The inside of a casing formed of concrete in a rectangular parallelepiped with a height of about 2.2 m is almost evenly divided by the main partition wall W into five first to fifth five blocks Ba to Be. ~ Be has a structure in which necessary tanks are set.

The first block B a is entirely a sedimentation tank 1. The sedimentation tank 1 is used to settle and remove relatively large suspended solids from the water to be treated, and has a flow straightening tube 2 at the upstream end and a flow straightening tube 3 at the downstream end. The others are empty. In other words, the water to be treated that flows into the sedimentation tank 1 from the inflow path P is made to flow downward by the inflow rectifying tube 2, flows toward the bottom of the sedimentation tank 1, and moves gently in the tank. After that, it flows out from the outlet 3t of the outflow rectifier 3 to the second block Bb. The residence time of the water to be treated in the sedimentation tank 1 during this period is about four hours, and during this residence, relatively large suspended matters are settled and removed.

A sludge pit Db having a predetermined depth is formed in the second block Bb: a perforated bottom plate 4b is provided so as to float above the bottom of the casing, and is erected in the center of the perforated bottom plate 4b. A pretreatment tank 6 and a denitrification tank 7 are formed by being partitioned by a partition plate 5b. Therefore, both tanks 6 and 7 are in communication via sludge pit Db, and the water to be treated is After flowing down in the treatment tank 6, it flows into the denitrification tank Ί through the sludge pit Db as an ascending flow.

The pretreatment tank 6 is filled with a porous filter medium (not shown) made of plastic. The filter medium filters the SS and decomposes and removes the B0D component by microorganisms settled on the filter medium. .

The denitrification tank 7 is for removing nitrogen dissolved in the water to be treated in the form of nitric acid, and as shown in FIG. 4, a material layer 8 and an adsorbent layer 9 are provided in a stacked state.

The assimilable material layer 8 is formed by filling a dead body of a plant, which serves as a nutrient source for the bacteria and provides a favorable place for the bacteria, with a density that allows appropriate water permeability. Specifically, for example, the core layer is made by shredding the core of a traditional tatami mat, a dead branch or a firewood of shiitake mushrooms into an appropriate size between the skin layers 8 s using straw as a straw-like structure. It is formed by filling as 8 c. The assimilate layer 8 is highly anaerobic by being immersed in the water to be treated as described above, and under these anaerobic conditions, the three types of coexisting processes described above cause the nitrate-containing ammonia gas and nitrogen gas to flow. The nitrogen gas is adsorbed and removed by the adsorbent layer 9, while the nitrogen gas is released into the air.

The adsorbent layer 9 is formed by filling a gravel-like adsorbent of a mineral substance such as zeolite (zeolites) or bamicularite, which has a high ability to adsorb ammonia nitrogen. It has a two-layer structure with a large L, a layer 9 m made of an adsorbent, and a small L of size 9 n made of an adsorbent.

The third block Bc is the first chitosan charcoal tank 10 for the decomposition of B0D components by aerobic biological treatment, and forms a sludge pit Dc at the bottom. Perforated bottom plate for 4. A chitosan-treated charcoal (not shown) treated with chitosan on the perforated bottom plate 4c is laminated and the chitosan charcoal layer is treated in the tank by air supply means 11c. The air rate is set to be strong enough to cause forced convection in the water. Since chitosan charcoal easily floats on water, an adsorbent for ammonia nitrogen adsorption is placed on it as a weight.

Chitosan charcoal obtained by the following treatment is used. The charcoal used was a mixed charcoal of hardwood and conifer at a ratio of 8: 2, which was crushed in the size of 5 to 1 Omm.

Chitosan is a pale yellow-white powder having a deacetylation degree of 70% or more [Koyo Chemical Sanko SK-400 (trademark) by Koyo Chemical Co., Ltd.:! It was used.

For the adhesion, an immersion method under the following conditions was used.

Chitosan solution; dissolve 1% chitosan in 5% acetic acid solution

Immersion conditions: normal temperature, normal pressure

Immersion time: 24 hours

Drying conditions: 50 to 60 ° C for 8 to 16 hours

A comparison test was conducted on the adsorption power of this chitosan charcoal to LAS with ordinary charcoal (oak charcoal, Akamatsu charcoal) and activated carbon. As a result, the relationship between the adsorption powers is as follows: activated carbon> chitosan charcoal> Akamatsu charcoal> oak charcoal for LAS 10 and LAS 11, and activated carbon> chitosan charcoal> oak charcoal> Akamatsu for LAS 12-LAS14 It was charcoal. The difference in adsorption power between LAS 10 and LAS 12 is relatively large, and chitosan charcoal has several times higher adsorption power than ordinary charcoal. As described above, chitosan charcoal itself has excellent adsorption power to LAS, but such excellent adsorption power may cause various characteristics of chitosan charcoal and forced convection as described above. It is thought that excellent LAS removal ability will be realized by cooperation of aeration conditions.

The fourth block Bd is almost equally divided by a partition plate 5d erected from the bottom of the casing, and the upstream side is a second chitosan charcoal tank 12 and the downstream side is a tank 13 for aeration. The second chitosan charcoal tank 12 is basically the same as the first chitosan charcoal tank 10 except that its size power is about half. On the other hand, the dedicated aeration tank 13 is for supplying oxygen to the water to be treated, and is similarly empty as the sedimentation tank 1, and the air supplied by the air supply means 1 1d diffuses into the water to be treated. It is made easy.

The fifth block Be has the same structure as the second block Bb, and is provided with a dephosphorization tank 14 and a finishing tank 15. The dephosphorization tank 14 has a main purpose of adsorbing and removing phosphorus, and also serves to supplementarily adsorb and remove ammonia nitrogen. An adsorbent (not shown) for adsorbing phosphorus and an adsorbent for adsorbing ammonia nitrogen are used. Adsorbent (not shown) filled in layers Have been. On the other hand, the finishing tank 15 is filled with ordinary charcoal (not shown), and the charcoal is used for decolorization and deodorization, while filtering fine SS and performing final biological treatment. You.

Here, each of the partition plates 5b, 5d, and 5e in the second block Bb, the fourth block Bd, and the fifth block Be is more than the normal water level state (the state in FIG. 1). It is formed so as to protrude higher. This is intended to raise the water level of the upstream tanks higher than the water level of the downstream tanks in response to the increase in water flow resistance caused by the accumulation of sludge on the filter media and chitosan charcoal in each tank. As a result, a reduction in water permeability can be prevented and a constant backwashing effect can be achieved.

As shown in Fig. 2, a sludge collection pipe 16 is provided along the casing, and the sludge is collected from the sludge collection pipe 16 at any time via branch pipes facing each block. I can do it. Although not shown, each block is entirely covered with a lid to prevent rainwater intrusion and sunlight irradiation.

Figure 5 shows the data of LAS in the above-mentioned combined water treatment system. As can be seen from the figure, a large variation in the amount of LAS was observed in the first chitosan charcoal tank 10, and the excellent LAS removal ability of the first chitosan charcoal tank 10 can be known. In particular, comparing the LAS removal capacity in the chitosan charcoal tank by comparing the force with which a considerable amount of biological treatment occurs in the pretreatment tank 6 and the finishing tank 15 and the change in LAS amount in these tanks. Understand the excellence.

[Industrial applicability]

As described above, the present invention makes it possible to selectively use specific microorganisms by effectively utilizing the characteristics of assimilable filter media. It can efficiently remove synthetic organic pollutants such as LAS, and can greatly contribute to the conservation of water quality in the basin.

In addition, the water treatment apparatus of the present invention is composed of a denitrification tank and a chitosan charcoal tank with high treatment efficiency as a core, and a pretreatment tank, a dephosphorization tank, and a finishing tank are combined in a complex manner. Advanced water treatment combined with phosphorus can all be performed more efficiently by biological treatment. Therefore, this can be used, for example, for purification treatment of small rivers where municipal wastewater is drained as it is, to preserve the water quality environment in harmony with nature. Can greatly contribute to c

Claims

The scope of the claims

(1). In a water treatment method in which a treatment target water is brought into contact with a filter medium on which microorganisms have been fixed to perform a purification treatment, at least micro-organisms inhabit at least as pores of pores covered by a porous base material as a filter medium. Using the assimilable filter medium attached with assimilable material having specific assimilation properties to the target microorganisms in the depth range necessary for the process, and contacting the assimilable filter medium with the water to be treated under aerobic conditions A water treatment method characterized in that the water treatment is performed.

(2) The water treatment method according to claim 1, wherein charcoal is used as the porous substrate.

(3). The water treatment method according to claim 1 or claim 2, wherein the assimilable substance is chitosan.

(4) The water treatment method according to any one of claims 1 to 3, wherein a forced convection state is generated in the water to be treated upon contact with the assimilable filter medium.

(5). The water treatment method according to any one of claims 1 to 4, wherein the microorganisms that settle on the assimilable filter medium are bacteria belonging to the genus Pseudomonas.

(6). The water treatment method according to claim 5, wherein the bacterium belonging to the genus Pseudomonas is Pseudomonas fluorecens biover 5 and / or Pseudomonas put ida biover A.

(7) A water treatment apparatus for use in the water treatment method according to claim 1, wherein at least a depth range necessary for microorganisms to inhabit the pore walls of the pores of the porous base material. Use an assimilable filter medium to which an assimilable material as a specific assimilant is attached to the microorganisms, and let the water to be treated pass through the treatment tank filled with this assimilable material while aerating it. A water treatment apparatus comprising a treatment zone.

(8). The water treatment apparatus according to claim 7, wherein a forced convection state is generated in the water to be treated in the treatment zone.

(9). The water treatment apparatus according to claim 7 or claim 8, wherein bacteria of the genus Pseudomonas are established on the assimilable filter medium.

(10). The water treatment apparatus according to claim 9, wherein the bacterium belonging to the genus Pseudomonas is Pseudomonas fluorecens biover 5 or Pseudomonas put ida bioover A.

Q1). Adsorption filled with an adsorbent capable of adsorbing ammonia nitrogen while providing a pretreatment tank filled with a filter medium for removing suspended solids etc. A denitrification tank in which the material layer is continuously provided on the material layer, a chitosan charcoal tank filled with chitosan-treated charcoal, a dephosphorization tank filled with an adsorbent capable of adsorbing phosphorus, and a charcoal tank. A water treatment device equipped with a filled finishing tank.

(12). The water treatment apparatus according to claim 11, which is arranged in the order of a pretreatment tank, a denitrification tank, a chitosan charcoal tank, a dephosphorization tank, and a finishing tank from the upstream side to the downstream side.

(13). Two tanks are paired for any one tank, and a sludge pit is provided in common for both tanks, and the water to be treated that has flowed into one tank from above is inserted into the other tank via the sludge pit. The water treatment device according to any one of claims 11 and 12, wherein the water is supplied from below.

Q). A partition plate that separates the two tanks that make a pair is formed so as to protrude sufficiently higher than normal water level, and the water level of the upstream tank when the water permeability of the packing material in the tank decreases. 14. The water treatment apparatus according to claim 13, wherein the water level is higher than a water level in a downstream tank.