Sewage wastewater treatment system

Abstract

To provide a sewage waste water treatment system in which a coagulant in the case of purifying and treating water to be treated does not contain a metal-derived component, influence on the environment by discharged water can be suppressed, and operation cost can be reduced.SOLUTION: The sewage / wastewater treatment system comprises a first treatment tank into which water to be treated flows and in which solid-liquid separation treatment is carried out by precipitation under anaerobic conditions, a second treatment tank in which flocculation and precipitation are carried out by a bioflocculant added to the water to be treated from the first treatment tank under aerobic conditions, a third treatment tank in which anaerobic treatment is carried out and which includes a contact filter medium comprising coconut shell, a fourth treatment tank in which aeration-based aerobic treatment is carried out and which includes a contact filter medium comprising coconut shell, and a fifth treatment tank disposed downstream of the fourth treatment tank and which includes a contact filter medium comprising coconut shell and in which suspended solids are removed from the water to be treated after the aerobic treatment.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a wastewater treatment technology for purifying contaminated water (polluted water), wastewater, drainage, etc., and in particular to a wastewater treatment system in which coagulants containing metal-derived components are not used in the purification process. Hereinafter, in this specification, contaminated water, wastewater, effluent, etc. that are the subject of purification treatment may be collectively referred to as "water to be treated," and the water after the treatment in the sewage and wastewater treatment system of the present invention has been purified may be referred to as "discharge water." [Background technology]

[0002] In systems for purifying water to be treated, such as contaminated water, wastewater, and effluent, various sewage and wastewater treatment systems have been proposed in the past that do not use coagulants containing metal-derived components in the purification process.

[0003] For example, Patent Document 1 discloses a wastewater treatment system that treats water to be treated by a biological treatment method, comprising a pretreatment tank and a posttreatment tank, the pretreatment tank comprising a primary sedimentation tank and an anaerobic compartment and a first anoxic compartment as the upstream stage of a biological treatment section that carries out biological treatment on the water to be treated, and the posttreatment tank comprising a final sedimentation tank and a second anoxic compartment, an aeration compartment and a sedimentation compartment as the downstream stage of the biological treatment section.

[0004] Furthermore, Patent Document 2 discloses a wastewater treatment method including a coagulation and sedimentation treatment step in which a coagulant is added to water to be treated to generate coagulates and then precipitate them, an intermediate filtration step in which the treated water obtained in the coagulation and sedimentation treatment step is filtered, a storage step in which the treated water obtained in the intermediate filtration step is sent to an intermediate tank and stored therein, and an ultrafiltration step in which the treated water stored in the intermediate tank is filtered using an ultrafiltration membrane and the residual wastewater obtained by the filtration process is returned to the intermediate tank. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6914863 [Patent Document 2] Patent No. 6901620 [Patent Document 3] Patent No. 4683356 [Patent Document 4] Patent No. 4528988 [Patent Document 5] Patent No. 3273358 Summary of the Invention [Problem to be solved by the invention]

[0006] The purpose of this invention is to propose a sewage and wastewater treatment system that can suppress the environmental impact of discharged water because the coagulant used in the process of purifying treated water such as polluted water, wastewater, and effluent does not contain metal-derived components, and that can reduce overall operating costs, simplify the treatment process and operation, is easy to maintain, and allows the sludge recovered from sewage and wastewater treatment to be composted or used as a soil improvement material.

[0007] The sewage and wastewater treatment system of the present invention can be used as a water purification facility for waste disposal facilities, a water purification facility for cleaning recycled water in various factories, etc. The sewage and wastewater treatment system of the present invention can also be used as a public facility such as a sewage treatment facility, a water treatment facility, or a water purification facility for rivers, lakes, and marshes. [Means for solving the problem]

[0008] The inventors of the present application have previously made various proposals in the field of wastewater and wastewater treatment technology, such as a "Muddy Water Purification Apparatus" (Patent Document 3), a "Method for Separating and Treating Dioxins" (Patent Document 4), and a "Method and Apparatus for Purifying Lakes and Ponds" (Patent Document 5).

[0009] Based on these considerations, we propose a sewage and wastewater treatment system that solves the above-mentioned problems.

[0010] The inventors of the present application have discovered that the above-mentioned problems can be solved by using a bioflocculant made only from materials derived from natural sources, such as bacteria found in food that people eat and bacteria that grow in food products, as a flocculant used in the process of treating sewage and wastewater.

[0011] The present invention can be exemplified as follows. [1] a primary treatment tank into which water to be treated, which is the target of sewage and wastewater treatment, is introduced and solid-liquid separation is carried out by sedimentation under anaerobic conditions; A secondary treatment tank is disposed downstream of the primary treatment tank, and causes coagulation and precipitation under aerobic conditions by adding a bioflocculant to the treated water after the solid-liquid separation treatment flowing in from the primary treatment tank; a third treatment tank disposed downstream of the second treatment tank, which is provided with a contact filter medium including a contact filter medium made of coconut shells, and in which the treated water flowing in from the second treatment tank after the coagulation and sedimentation has occurred is subjected to anaerobic treatment; a fourth treatment tank disposed downstream of the third treatment tank, equipped with a contact filter medium including a contact filter medium made of coconut shells, in which the treated water after the anaerobic treatment flowing from the third treatment tank is subjected to aerobic treatment by aeration; a fifth treatment tank disposed downstream of the fourth treatment tank, equipped with a contact filter medium including a contact filter medium made of coconut shells, and in which suspended solids removal treatment is performed to remove suspended solids (SS) from the treated water after the aerobic treatment flowing in from the fourth treatment tank; and a sewage wastewater treatment system.

[0012] [2] A sewage and wastewater treatment system according to [1], wherein 20% to 50% of the discharged water, which is the water to be treated after the suspended solids removal treatment in the fifth treatment tank, is returned to the first treatment tank.

[0013] [3] A wastewater treatment system according to [1] or [2], in which tertiary treatment tank sludge, which is sludge produced by precipitation occurring in the tertiary treatment tank, and quaternary treatment tank sludge, which is sludge produced by precipitation occurring in the quaternary treatment tank, are collected in a sludge tank that stores raw materials for compost production.

[0014] [4] A sewage and wastewater treatment system according to [3], wherein a portion of the sludge from the tertiary treatment tank and a portion of the sludge from the quaternary treatment tank are returned to the secondary treatment tank.

[0015] [5] The wastewater treatment system according to any one of [1] to [4], wherein the bioflocculant contains powdered baking soda (sodium bicarbonate), Bacillus subtilis natto, seashell powder, and crab shell powder as blended ingredients.

[0016] [6] The bioflocculant contains powdered baking soda (sodium bicarbonate) in a blending ratio of 5% to 15% by mass, shell powder in a blending ratio of 30% to 60% by mass, and crab shell powder in a blending ratio of 5% to 20% by mass, and contains 10% to 15% by mass of live natto bacteria (Bacillus subtilis natto). 5 ~10 9 CFU / g containing [5] sewage wastewater treatment system. [Effects of the Invention]

[0017] According to this invention, the coagulant used in the process of purifying treated water such as dye water, wastewater, and effluent does not contain metal-derived components, making it possible to provide a sewage and wastewater treatment system that can suppress the environmental impact of discharged water, and that can reduce overall operating costs, simplify the treatment process and operation, is easy to maintain, and allows the sludge recovered from sewage and wastewater treatment to be composted or used as a soil improvement material. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a conceptual diagram illustrating an example of the configuration of a sewage and wastewater treatment system according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] A sewage and wastewater treatment system according to one embodiment of the present invention includes a first treatment tank, a second treatment tank, a third treatment tank, a fourth treatment tank, and a fifth treatment tank, in which the treatments described below are carried out. Figure 1 shows a conceptual diagram of an example of such a sewage and wastewater treatment system.

[0020] The primary treatment tank is where the water to be treated, which is the target of sewage and wastewater treatment, flows in and undergoes solid-liquid separation through sedimentation under anaerobic conditions. This treatment takes place in the area marked "primary" in Figure 1. The primary treatment tank is the so-called initial sedimentation tank, where foreign matter is removed from the water to be treated and solid foreign matter, sediment, etc. are settled. This reduces the load on downstream treatment processes such as the secondary treatment tank.

[0021] The secondary treatment tank is located downstream of the primary treatment tank, and a bioflocculant is added to the water to be treated after solid-liquid separation from the primary treatment tank, causing coagulation and sedimentation under aerobic conditions. This treatment takes place in the area marked "secondary" in Figure 1.

[0022] The tertiary treatment tank is located downstream of the secondary treatment tank and is equipped with a contact filter medium containing coconut shells. Anaerobic treatment is performed on the treated water flowing from the secondary treatment tank after coagulation and sedimentation. This treatment takes place in the area marked "Tertiary" in Figure 1. The coconut shell contact filter medium can be composed solely of coconut shells, or it can also contain other contact filter mediums, such as shells, so that the contact filter medium in the tertiary treatment tank is composed of both coconut shells and shells. Furthermore, a "coconut shell contact filter medium" can be composed of a coconut shell contact filter medium, a shell shell contact filter medium, and a crab shell contact filter medium.

[0023] The contact filter material made of shells and crab shells in the contact filter material containing coconut shells can be made of the shell powder that is a compounding component of the bioflocculant described above, the shells used to prepare crab shell powder, and crab shells.These shells and crab shells can be powdered and used together with the contact filter material made of coconut shells to make the contact filter material made of shells and crab shells in the contact filter material containing coconut shells.

[0024] The quaternary treatment tank is located downstream of the tertiary treatment tank and is equipped with contact filter media including coconut shell contact filter media, where the post-anaerobic treatment water flowing in from the tertiary treatment tank is aerated and aerobic treated. This treatment takes place in the area marked "quaternary" in Figure 1.

[0025] The "contact filter medium including a contact filter medium made of coconut shells" placed in the fourth treatment tank can be the same as the "contact filter medium including a contact filter medium made of coconut shells" placed in the third treatment tank described above, so its explanation will be omitted.

[0026] The fifth treatment tank is located downstream of the fourth treatment tank and is equipped with contact filter media including coconut shell contact filter media, where suspended solids (SS) are removed from the post-aerobic treatment water flowing in from the fourth treatment tank. This treatment takes place in the area marked "fifth" in Figure 1.

[0027] The "contact filter medium containing a contact filter medium made of coconut shells" placed in the fifth treatment tank can be the same as the "contact filter medium containing a contact filter medium made of coconut shells" placed in the third treatment tank described above, so its explanation will be omitted.

[0028] In the above-described sewage and wastewater treatment system, 20% to 50% of the effluent, which is the water to be treated after aerobic treatment in the fifth treatment tank, can be returned to the first treatment tank.

[0029] This type of configuration is advantageous when the level of contamination of the water to be treated flowing into the primary treatment tank is high, as it reduces the level of contamination of the water to be treated in the primary treatment tank, thereby allowing the bioflocculant to react efficiently in the secondary treatment tank.

[0030] Furthermore, by adopting the above-described configuration, the effluent water returned contains a rich amount of good bacteria. Therefore, even if the level of contamination of the water to be treated flowing into the primary treatment tank is not particularly high, by adopting the above-described configuration, the effluent water containing a rich amount of good bacteria is returned to the primary treatment tank, making it possible to reduce the amount of bioflocculant used in the secondary treatment tank.

[0031] In the above-described embodiment, the amount of water returned to the primary treatment tank, ie, 20% to 50% of the discharged water, is a preferable range from the above-described viewpoint.

[0032] In any of the above-mentioned forms of sewage and wastewater treatment systems, as shown in Figure 1, the tertiary treatment tank sludge, which is sludge produced by precipitation in the tertiary treatment tank, and the quaternary treatment tank sludge, which is sludge produced by precipitation in the quaternary treatment tank, can be collected in a sludge tank that stores raw materials for compost production.

[0033] As shown in Figure 1, the tertiary and quaternary treatment tank sludge collected in the sludge tank can be dewatered and used as an additive (accelerant) for compost production at a composting facility. The tertiary and quaternary treatment tank sludge collected in the sludge tank can also be used as a soil improvement material.

[0034] In this case, as shown in Figure 1, a portion of the sludge from the tertiary treatment tank and a portion of the sludge from the quaternary treatment tank can be returned to the secondary treatment tank.

[0035] As described above, in the secondary treatment tank, coagulation and sedimentation occur due to the coagulation action of the bioflocculant added to the water to be treated after solid-liquid separation processing flowing in from the primary treatment tank. By returning to this secondary treatment tank the tertiary treatment tank sludge, which is the sludge produced by precipitation in the tertiary treatment tank, and the quaternary treatment tank sludge, which is the sludge produced by precipitation in the quaternary treatment tank, it is possible to promote stabilization of the coagulation and sedimentation action in the secondary treatment tank.

[0036] As will be described later, the coagulated sediment produced in the secondary treatment tank contains coagulated sediments of various metal components due to the function of the biocoagulant. This coagulated sediment produced in the secondary treatment tank can also be extracted from the secondary treatment tank and treated so that the coagulated and settled heavy metals meet the specified environmental standards, and can be reused as fertilizer, soil conditioner, etc. <Bio-flocculant added in the secondary treatment tank> The bioflocculant added to the secondary treatment tank can contain powdered baking soda (sodium bicarbonate), Bacillus subtilis natto, seashell powder, and crab shell powder as compounding ingredients. For example, the bioflocculant described above contains powdered baking soda (sodium bicarbonate) in a blending ratio of 5% to 15% by mass, shell powder in a blending ratio of 30% to 60% by mass, and crab shell powder in a blending ratio of 5% to 20% by mass, and contains 10% to 15% by mass of live natto bacteria (Bacillus subtilis natto). 5 ~10 9 It can be made to contain CFU / g. Here, as the powdered baking soda (sodium hydrogen carbonate), powdered baking soda (sodium hydrogen carbonate) that is generally available on the market can be used. Shell powder can be obtained by drying shells from discarded shells and pulverizing them in a powdering device (mill). Crab shell powder can be obtained by drying discarded crab shells and pulverizing them using a powdering device (mill). As the natto bacteria, commercially available edible natto bacteria can be used.

[0037] The above-mentioned bioflocculant can be prepared by adding the above-mentioned blended ingredients to a dry powder mixer and mixing for 0.5 to 2 hours. For example, when using a dry powder mixer that can mix 20 L in 5 minutes, 200 mL of powdered baking soda (sodium bicarbonate) weighing 4,400 g, 6,667 mL of shell powder weighing 18,000 g, 4,000 mL of crab shell powder weighing 6,000 g, and 4,000 mL of natto bacteria weighing 1,600 g (10 viable bacteria count of natto bacteria). 5 ~10 9 CFU / g) was added to a dry powder mixer and mixed for 1 hour to obtain 0.015 m of the bioflocculant of the present invention. 3 In addition, if the mixing and stirring machine is enlarged, the processing capacity can be increased, making it possible to scale up production adjustments.

[0038] The specific gravity of powdered baking soda (sodium bicarbonate) is set to 2.2 g / mL, the specific gravity of shell powder to 2.7 g / mL, the specific gravity of crab shell powder to 1.5 g / mL, and the specific gravity of natto bacteria to 0.4 g / mL, and the blending ratio of each compounding component when preparing (manufacturing) the bioflocculant of the present invention can be adjusted.

[0039] In the above case, the mixing ratio of powdered baking soda (sodium bicarbonate) is set to 5% to 15% by mass because, if the water to be purified (=water to be treated) contains oil, the oil is adsorbed by the baking soda. Also, because bicarbonate is weakly alkaline, it is used to appropriately adjust the pH of the water to be treated during the coagulation process.

[0040] The reason why the mixing ratio of shell powder is set at 30% to 60% by mass is to allow calcium carbonate (CaCO3), the main component of shell powder, to effectively adsorb heavy metals through the following mechanism: Physical adsorption: The porous structure of calcium carbonate (CaCO3), the main component of shell powder, physically adsorbs heavy metal ions. Chemical adsorption: Calcium carbonate reacts with heavy metal ions to form sparingly soluble heavy metal carbonates. Ion exchange: Calcium ions are exchanged for heavy metal ions. Shell powder is mainly composed of calcium carbonate (CaCO3), and its porous surface promotes the adsorption and coagulation of pollutants. Calcium carbonate, the main component of shell powder, is weakly alkaline, and acts as a biocoagulant to stabilize the pH during water treatment.

[0041] Furthermore, the crab shell powder content is set at 5% to 20% by mass from the viewpoint of allowing chitin and chitosan, which are the main components of crab shell powder, to effectively adsorb heavy metals through the following mechanism. Ion exchange: The amino groups of chitosan are exchanged with heavy metal ions. Chelation: Chitosan forms strong bonds with heavy metal ions, immobilizing them. Physical adsorption: The porous structure of chitin physically adsorbs heavy metal ions. As mentioned above, crab shell powder is rich in chitin and its derivative, chitosan. These components have a strong coagulating effect, effectively coagulating fine particles and suspended solids in water. Chitin and chitosan also have antibacterial properties. From these perspectives, the above-mentioned blending ratio is advantageous.

[0042] In addition, the number of live bacteria of natto (Bacillus subtilis natto) was increased to 10 5 ~10 9 The reason for using CFU / g is that the influence of EPS (Extracellular Polymeric Substances) is taken into consideration. EPS (Extracellular Polymeric Substances) produced by Bacillus subtilis natto encapsulates bacteria and organic matter in wastewater, stabilizing the flocs. Since EPS plays an important role in the formation and stabilization of flocs, the number of live Bacillus subtilis natto cells contained in the bioflocculant of the present invention is 10 5 ~10 9 CFU / g is desirable.

[0043] Bacillus subtilis natto has the ability to produce a biofilm that promotes coagulation, which allows for efficient coagulation of pollutants. Maintaining a high bacterial count also provides stable coagulation and organic matter decomposition capabilities, improving the durability of the biocoagulant and reducing the frequency of periodic re-addition. From this perspective, it is advantageous to maintain the viable cell count within the above range.

[0044] Conventional naturally derived flocculants have had varying purification effects on contaminated water containing diatoms (blue-green algae) and heavy metals, but the bioflocculant of the present invention can be more effective by changing the composition of the bioflocculant depending on the contaminated water being treated.

[0045] For example, if the contaminated water being treated is high in oil and fat and has an acidic pH, changing the blend to include more baking soda and crab shell powder will be advantageous in dealing with acidic contaminated water.

[0046] The baking soda (sodium bicarbonate) contained in this bioflocculant is slightly alkaline in water and helps adjust the pH. This creates an environment that promotes the coagulation of oil and other organic matter. Oil is heavy, so it settles down.

[0047] Additionally, baking soda (sodium bicarbonate) adjusts the pH and optimizes microbial activity, creating conditions for heavy metal precipitation.

[0048] Conventional naturally derived flocculants have had varying purification effects on contaminated water containing diatoms (blue-green algae) and heavy metals, but the bioflocculant of the present invention can be more effective by changing the composition of the bioflocculant depending on the contaminated water being treated.

[0049] In this case, changing the composition of the bioflocculant to increase the proportion of seashell powder and decrease the proportion of crab shell powder is advantageous in dealing with highly acidic contaminated water.

[0050] The baking soda (sodium bicarbonate) contained in the bioflocculant mentioned above is slightly alkaline in water, which helps adjust the pH. This creates an environment that promotes the coagulation of oil and other organic matter. Oil is heavy, so it settles down.

[0051] Additionally, baking soda (sodium bicarbonate) adjusts the pH and optimizes microbial activity, creating conditions for heavy metal precipitation.

[0052] The main component of the shell powder used in the bioflocculant mentioned above is calcium carbonate, which is alkaline. When added to the water being treated, shell powder adjusts the pH and promotes the coagulation of oil and other organic matter. The shell powder's surface also has adsorption properties, allowing it to adsorb oil. Shell powder contributes to pH adjustment and physical adsorption as calcium carbonate, and reacts with heavy metals to form insoluble compounds.

[0053] Shell powder made of calcium carbonate has a porous structure, which allows it to adsorb heavy metal ions. For example, lead (Pb 2+ ), cadmium (Cd 2+ ), copper (Cu 2+ ) and other heavy metal ions are adsorbed onto the surface of the shell powder.

[0054] In addition, when the shell powder dissolves in the treated water, calcium ions (Ca 2+ ), which reacts with heavy metal ions to form sparingly soluble precipitates. For example, Pb 2+ reacts with CaCO3 to produce a sparingly soluble precipitate called PbCO3 (cerussite).

[0055] The main components of the crab shell powder used in the bioflocculant mentioned above are chitin and its derivative, chitosan. Chitin is a natural polysaccharide, and chitosan is a compound produced by its deacetylation. These compounds have the ability to efficiently adsorb heavy metal ions. Crab shell powder reacts with heavy metal ions in water as calcium carbonate to form insoluble heavy metal carbonates and hydroxides.

[0056] Chitosan has amino groups (-NH2) and hydroxyl groups (-OH), which have the ability to strongly bind with heavy metal ions. 2+ , Cd 2+ , Cu 2+ Heavy metal ions such as these are adsorbed by crab shell powder.

[0057] Chitosan can form chelates with heavy metal ions because multiple binding sites within the chitosan molecule surround the heavy metal ions to form stable complexes.

[0058] Synergistic effect of seashell powder and crab shell powder The bioflocculant described above exhibits a synergistic effect by blending seashell powder and crab shell powder.

[0059] The main mechanisms by which both seashell powder and crab shell powder remove heavy metal ions are adsorption and precipitation (in the case of seashell powder) and chelation (in the case of crab shell powder), as described above. Through these processes, the concentration of heavy metals in water is reduced, improving water quality.

[0060] A specific example of the reaction is as follows: Lead removal Shell powder: Pb 2+ + CaCO3 → PbCO3 (precipitate) Crab shell powder: Pb 2+ + Chitosan → Pb-chitosan complex Copper removal Shell powder: Cu 2+ + CaCO3 → CuCO3 (precipitate) Crab shell powder: Cu 2+ + Chitosan → Cu-chitosan complex Through these reactions, heavy metal ions are removed from the water to be treated and captured as solids.

[0061] The natto bacteria (Bacillus subtilis natto) contained in the bioflocculant mentioned above produces enzymes such as protease and amylase, which break down organic matter. In addition, the biofilm and exopolymer (EPS) produced by the natto bacteria have the effect of flocculating oil and other particles.

[0062] Enzymes such as protease and amylase produced by Bacillus natto decompose oil into small molecules, which are utilized as nutrients for microorganisms, thereby removing the oil. Additionally, due to the aggregation effect of Bacillus natto, the oil is more likely to precipitate as larger flocs. Bacillus natto forms biofilms, produces exopolysaccharides (EPS), promotes the aggregation of organic matter and SS, and has an adsorption effect on heavy metals.

[0063] The following details the mechanism of water purification when using sodium bicarbonate, Bacillus natto, shell powder, and crab shell powder, respectively, for each item. The mechanism of water purification by the bioflocculant composed of the above-mentioned formulation and composition is as follows. <BOD (Biochemical Oxygen Demand)> Functional component: Bacillus natto Bacillus natto produces enzymes that decompose organic matter and reduce BOD. When organic matter is decomposed by the enzymes of Bacillus natto, the oxygen consumption by microorganisms decreases, and BOD decreases. <COD (Chemical Oxygen Demand)> Functional components: Sodium bicarbonate, shell powder, and crab shell powder Shell powder and crab shell powder have the effect of adsorbing and aggregating oil and fat, thereby removing organic pollutants in the treated water. Sodium bicarbonate emulsifies these substances and promotes decomposition, resulting in a decrease in COD. <SS (Suspended Solids)> Functional components: Sodium bicarbonate, shell powder, and crab shell powder The use of sodium bicarbonate increases the pH of the treated water, and shell powder and crab shell powder adsorb and aggregate suspended solids, thus removing SS. <ph> The active ingredient: baking soda Baking soda (sodium bicarbonate) is weakly alkaline and neutralizes the acidic water quality of the water to be treated, adjusting it to an appropriate pH (usually within the range of 6.5 to 8.5). <Escherichia coli> Functional ingredients: Bacillus subtilis natto The antibacterial substances produced by natto bacteria inhibit the growth of coliform bacteria. The dominance of natto bacteria suppresses the activity of harmful bacteria and reduces the coliform bacteria. <Rin> Active ingredients: seashell powder, crab shell powder The calcium components of seashell powder and crab shell powder can react with phosphate to precipitate calcium phosphate, thereby removing phosphorus from the treated water. <Nitrogen> Functional ingredients: Bacillus subtilis natto Bacteria, including Bacillus subtilis natto, break down nitrogen compounds such as ammonia and nitrate and release them as nitrogen gas, thereby removing nitrogen from the treated water. <Normal hexane> Active ingredients: baking soda, seashell powder, crab shell powder The baking soda emulsifies the oil, and the seashell powder and crab shell powder adsorb and coagulate it, thereby removing normal hexane from the treated water. <Blue-green algae (diatoms)> Active ingredients: natto bacteria, shell powder, crab shell powder The enzymes produced by Bacillus subtilis natto break down the cell walls of blue-green algae and inhibit their growth, while seashell powder and crab shell powder adsorb and aggregate the algae. <Heavy metals> The bioflocculant having the above-mentioned composition and composition can remove the following heavy metals. <Lead (Pb)> Active ingredients: seashell powder, crab shell powder The calcium carbonate component in shell powder and crab shell powder is Pb 2+ It reacts with the chitosan in the crab shell powder to form PbCO3 (cerussite) and precipitate it. 2+ is adsorbed and immobilized. <Cadmium (Cd)> Active ingredients: seashell powder, crab shell powder CaCO3 in seashell powder and crab shell powder is Cd 2+ It reacts with Cd to produce poorly soluble CdCO3, which precipitates. 2+ Adsorbs. <Copper (Cu)> Active ingredients: seashell powder, crab shell powder CaCO3 in seashell powder and crab shell powder is Cu 2+ It reacts with Cu to produce CuCO3, which precipitates. 2+ Adsorbs. <Hexavalent chromium (Cr(VI))> Functional ingredients: Bacillus subtilis natto An enzyme produced by Bacillus subtilis natto reduces Cr(VI) to Cr(III), which reacts with CaCO3 to precipitate as sparingly soluble Cr2O3. <Zinc (Zn)> Active ingredients: seashell powder, crab shell powder CaCO3 in shell powder and crab shell powder is Zn 2+ It reacts with ZnCO3 to produce ZnCO3 and precipitate. 2+ Adsorbs. <Arsenic (As)> Active ingredients: seashell powder, crab shell powder As 3+ or As 5+ reacts with CaCO3 in the shell powder and crab shell powder to precipitate as a poorly soluble As compound. Chitosan adsorbs As. Mechanism of water purification by the bioflocculant mentioned above The mechanism of water purification using the bioflocculant described above is as follows. <Complex adsorption and precipitation> Shell powder and crab shell powder adsorb and precipitate harmful substances such as heavy metals, phosphorus, and nitrogen, making them more effective than removing them individually. <Microbial decomposition> Natto bacteria decompose organic matter, nitrogen compounds, and oil, thereby reducing BOD, COD, and suspended solids (SS). In addition, the production of antibacterial substances suppresses coliform bacteria. <Improvement of Effect by pH Adjustment> By adjusting to an appropriate pH range with sodium bicarbonate, the precipitation of heavy metals is promoted and the activity of natto bacteria is optimized. By multiplying the above-mentioned effects, various pollutants are removed simultaneously and the water quality is effectively improved.

[0064] The bioflocculant with the above-mentioned formulation and composition is added to treated water such as polluted water, wastewater, and drainage to exhibit a water purification function. Also, since it does not contain metal-derived components, the impact on the environment is suppressed when the purified water is discharged.

[0065] The bioflocculant with the above-mentioned formulation and composition exhibits the same purification performance as the conventionally used flocculant containing metal-derived components and can similarly flocculate and precipitate metals contained in polluted water. [[ID=X16]]

[0066] Since the bioflocculant with the above-mentioned formulation and composition does not contain metal-derived components, there is no secondary pollution even when the purified water is discharged, and the impact on the environment due to the discharge of the purified water is suppressed.

[0067] The bioflocculant with the above-mentioned formulation and composition is composed of natural-derived materials (sodium bicarbonate, natto bacteria, shell powder, crab shell powder) and has the following advantages compared to metal-based flocculants. <Cost Reduction> Since it does not use metal-derived components, raw material costs can be procured at a low price and processing (drying and pulverization) is easy. As a result, the overall operation cost can be reduced. In particular, sodium bicarbonate is inexpensive and easily available, and shellfish and crab shells can be easily, inexpensively, and stably supplied by reusing those discarded by manufacturing companies. <Reduction of Impact on Environment> Because it does not use metal-derived components, harmful effects on the environment can be significantly reduced. In particular, even if the purified water is discharged, there is no secondary pollution, which reduces the environmental impact of discharging the purified water, making sustainable water purification possible. <Replacement for conventional flocculants> The bioflocculant with the above-mentioned formulation and composition functions satisfactorily as a replacement for conventional metal-based flocculants. In particular, effective flocculation and precipitation are possible through microbial activity and pH adjustment, and the bacteria contained in the bioflocculant proliferate, so the amount added can be reduced compared to metal-based flocculants, which can significantly contribute to reducing the environmental impact. <Ease of maintenance> By using the bioflocculant with the above-mentioned formulation and composition, the flocculant used in the process of purifying treated water such as dye water, wastewater, and effluent does not contain metal-derived components, making it possible to provide a sewage and wastewater treatment system that can suppress the environmental impact of discharged water, reduces overall operating costs, simplifies the treatment process and operation, is easy to maintain, and makes it possible to compost the sludge recovered from sewage and wastewater treatment or use it as a soil improvement material. <Coagulation and sedimentation treatment in the secondary treatment tank where bioflocculants are added> In the secondary treatment tank located downstream of the primary treatment tank, as described above, a bioflocculant is added to the water to be treated after solid-liquid separation processing flowing in from the primary treatment tank, and a process that causes coagulation and precipitation is carried out under aerobic conditions. In this case, the various effects described above can be achieved by adding and using the above-mentioned powdered bioflocculant of this embodiment in a volume range of 0.5 mL to 30 mL per 1,000 liters of water to be treated after solid-liquid separation processing flowing in from the primary treatment tank.

[0068] The specific gravity of powdered baking soda (sodium bicarbonate) is 2.2 g / mL, meaning that 1,000 g of powdered baking soda (sodium bicarbonate) corresponds to a volume of approximately 454.55 mL of powdered baking soda (sodium bicarbonate). The specific gravity of seashell powder is 2.7 g / mL, meaning that 3,000 g of seashell powder corresponds to a volume of approximately 1,111.11 mL of seashell powder. The specific gravity of crab shell powder is 1.5 g / mL, meaning that 1,000 g of crab shell powder corresponds to a volume of approximately 666.67 mL of crab shell powder. The specific gravity of natto bacteria is 0.4 g / mL, meaning that 1,000 g of natto bacteria corresponds to a volume of approximately 2,500 mL of natto bacteria.

[0069] Adding the bioflocculant naturally causes flocculation and precipitation, but the powdered bioflocculant can be stirred at the same time as being added so that it is sufficiently dispersed in the water to be treated after solid-liquid separation that flows into the secondary treatment tank from the primary treatment tank. The stirring time can be, for example, about 30 seconds.

[0070] The powdered bioflocculant is sufficiently dispersed in the treated water after solid-liquid separation process that flows from the primary treatment tank into the secondary treatment tank, allowing each component contained in the bioflocculant to perform the functions described above.

[0071] In other words, the sodium bicarbonate contained in the bioflocculant adjusts the pH, creating conditions that optimize microbial activity and create conditions for the precipitation of various metals.

[0072] In addition, the shell powder contained in the bioflocculant contributes to pH adjustment and physical adsorption as calcium carbonate, reacting with the various metals mentioned above in the treated water to form insoluble compounds, which are then precipitated and removed from the treated water.

[0073] The crab shell powder contained in the bioflocculant reacts as calcium carbonate with the various metal ions mentioned above in the water being treated, forming insoluble metal carbonates and hydroxides, which then settle and precipitate, and are removed from the water being treated.

[0074] The Bacillus subtilis natto contained in the bioflocculant forms a biofilm and produces exopolymers (EPS) that help flocculate organic matter and suspended solids (SS). It also has the effect of adsorbing various metals.

[0075] In this way, after the powdered bioflocculant is added to the treated water that has undergone solid-liquid separation and flows into the secondary treatment tank from the primary treatment tank, the water is separated into flocculated sediment that settles to the bottom of the secondary treatment tank and the treated water after flocculation and sedimentation has occurred within 3 to 10 minutes.

[0076] In this way, the secondary treatment tank can be called a stirring and settling tank, where sodium bicarbonate and shell powder adjust the pH while forming and precipitating calcium phosphate, and the activity of Bacillus subtilis natto promotes the coagulation of suspended solids (SS) and organic matter.

[0077] The residence time of the water to be treated that has been subjected to the solid-liquid separation treatment and flows in from the first treatment tank in the secondary treatment tank where the treatment described above is carried out can be set to 1 to 4 hours. <Anaerobic treatment in the tertiary treatment tank> In the tertiary treatment tank located downstream of the secondary treatment tank, the water to be treated that flows in from the secondary treatment tank and after coagulation and sedimentation occurs is subjected to anaerobic treatment. As described above, the tertiary treatment tank is equipped with a contact filter containing a contact filter made of coconut shells, so the anaerobic treatment of the water to be treated that flows in from the secondary treatment tank and after coagulation and sedimentation occurs is carried out under the condition that the tertiary treatment tank is equipped with a contact filter containing a contact filter made of coconut shells.

[0078] The tertiary treatment tank, which can be called an anaerobic digester, can also be configured to denitrify nitrate (convert it into nitrogen gas).

[0079] In other words, under anaerobic conditions, denitrifying bacteria produce nitrate (NO3 - ) into nitrogen gas (N2) and release it into the atmosphere. - → NO2 - → NO → N2O → N2This removes nitrogen from the water being treated.

[0080] Nitric acid (NO3 - Denitrifying bacteria, which convert carbon dioxide (CO₂) into nitrogen gas (N₂) and release it into the atmosphere, are widespread in nature. In the wastewater and wastewater treatment system of the present invention, denitrifying bacteria are present in the water to be treated, which is the target of purification treatment, and they grow by utilizing organic matter and nutrients present in the water to be treated. In the wastewater and wastewater treatment system of the present invention, solid-liquid separation treatment by sedimentation is carried out in the primary treatment tank, which is placed under anaerobic conditions. The tertiary treatment tank is also placed under anaerobic conditions. Under these anaerobic conditions, the denitrifying bacteria present in the water to be treated are allowed to grow as described above.

[0081] In addition, in the primary treatment tank and the tertiary treatment tank, which are placed under anaerobic conditions, denitrifying bacteria can be actively added to the water to be treated.

[0082] The contact filter material that contains coconut shell contact filter material, for example, the contact filter material that is only made up of coconut shell contact filter material, or the contact filter material that is made up of coconut shell contact filter material and other contact filter material, for example, the contact filter material that is made up of shell or crab shell contact filter material, all of these contact filter materials have porous structure and large surface area.Therefore, it physically captures and adsorbs suspended solids (SS) and various metal ions mentioned above.In this way, the contact filter material that contains coconut shell contact filter material that is arranged in the tertiary treatment tank can be called a physical filter.

[0083] Contact filter media, including those made from coconut shells, also support biofilms, promoting the biosorption of the various metals mentioned above through microbial activity. They serve as a support for the growth of aerobic and anaerobic microorganisms. For example, microorganisms form biofilms on the surfaces of contact filter media made from coconut shells, seashells, and crab shells, allowing the nitrogen removal process to proceed efficiently. That is, denitrifying bacteria form biofilms on the surfaces of contact filter media, including those made from coconut shells, allowing the denitrification reaction to proceed efficiently.

[0084] The contact filter media, including the coconut shell contact filter media described above, are not particularly limited in shape or form as long as they have a porous structure and a large surface area, and various shapes and forms such as powder, fiber, pellet, granule, honeycomb, and paper can be used as coconut shell contact filter media, seashell contact filter media, and crab shell contact filter media.

[0085] The contact filter material made of shells and crab shells in the contact filter material containing coconut shells mentioned above can use the shell powder that is a compounding component of the bioflocculant mentioned above, the shells used to prepare crab shell powder, and crab shells.These shells and crab shells can be powdered and used together with the contact filter material made of coconut shells mentioned above to make the contact filter material made of shells and crab shells in the contact filter material containing coconut shells.

[0086] Shell powder and crab shell powder, which are used as other contact filter media, can each exhibit the purification functions described above as being exerted by the shell powder and crab shell powder, which are compounding ingredients of the bioflocculant.

[0087] In this way, the tertiary treatment tank can be called an anaerobic digestion tank, where anaerobic conditions are maintained and the use of contact filter media, including coconut shell contact filter media, maintains biofilm activity, allowing the adsorption and capture of the various metals mentioned above. Furthermore, some of the metals mentioned above may precipitate as sulfides under anaerobic conditions. For example, they may precipitate as iron sulfide.

[0088] In the tertiary treatment tank, which can be called an anaerobic digester, phosphorus-accumulating bacteria (PAOs) dissolve the phosphorus that has accumulated inside their cells under anaerobic conditions. At this stage, the phosphorus dissolves again in the treated water, but is then taken up again by the phosphorus-accumulating bacteria (PAOs) during aerobic treatment in the subsequent quaternary treatment tank, which will be described later.

[0089] The contact media, including the coconut shell contact media described above, in the tertiary treatment tank, which can be called the anaerobic digester, acts as a support for the microorganisms and supports the effective activity of the PAOs.

[0090] Phosphate-accumulating bacteria (PAOs) are widely distributed in nature and play an important role in water treatment processes such as sewage treatment.

[0091] In the wastewater treatment system of the present invention, phosphorus-accumulating bacteria (PAOs) exist in the water to be treated, which is the target of purification treatment, and they grow by utilizing the organic matter and nutrients present in the water. As described above, the wastewater treatment system of the present invention intentionally switches between anaerobic and aerobic conditions to create conditions favorable for the growth of phosphorus-accumulating bacteria (PAOs). In the tertiary treatment tank where the above-mentioned treatment is carried out, the residence time of the water to be treated that flows in from the secondary treatment tank and has undergone coagulation and sedimentation can be set to 0.5 to 1 hour.

[0092] <Aerobic treatment in the quaternary treatment tank> In the fourth treatment tank located downstream of the third treatment tank, the water to be treated after anaerobically treated flowing in from the third treatment tank is subjected to aerobic treatment by aeration. As described above, the fourth treatment tank is equipped with a contact filter containing a contact filter made of coconut shell, so the aerobic treatment of the water to be treated after anaerobically treated flowing in from the third treatment tank is carried out in the fourth treatment tank equipped with a contact filter containing a contact filter made of coconut shell.

[0093] The contact filter material containing coconut shells that is provided in the fourth treatment tank is the same as the contact filter material containing coconut shells that is provided in the third treatment tank described above, so its description will be omitted.

[0094] In the fourth treatment tank, which can be called an aerobic decomposition tank, contact filter media including contact filter media made from coconut shells are installed, and the treated water that has undergone anaerobic treatment and flows in from the third treatment tank is subjected to aerobic treatment through aeration.

[0095] If blue-green algae (diatoms) are mixed into the treated water that flows in from the tertiary treatment tank after anaerobic treatment, the inhibitory effect of the Bacillus subtilis natto, which is mixed into the bioflocculant that was added in the secondary treatment tank, and the physical removal effect of contact filter media, including contact filter media made from coconut shells, can be expected, and the removal of blue-green algae (diatoms) will be promoted by the activity of aerobic microorganisms due to aeration.

[0096] In addition to the purification process described above using baking soda, natto bacteria, seashell powder, and crab shell powder, which are contained in the bioflocculant added to the secondary treatment tank, aeration is also combined with contact filter media, including contact filter media made from coconut shells, to achieve multi-stage and comprehensive water purification, resulting in a high purification effect.

[0097] In the fourth treatment tank, which can be called an aerobic decomposition tank, the formation of biofilms is promoted by using contact filter media, including contact filter media made from coconut shells, under aerobic conditions through aeration, and the microorganisms on the surface of the contact filter media, including contact filter media made from coconut shells, adsorb and capture the various metal ions mentioned above, thereby facilitating their removal.

[0098] As mentioned above, phosphorus is removed from the treated water by aerobic treatment in a quaternary treatment tank equipped with a contact filter medium containing coconut shells (Bio-P process).

[0099] Under aerobic conditions, phosphorus-accumulating bacteria (PAOs) accumulate phosphorus within their cells, which is then used as energy in the decomposition of organic matter.

[0100] Specifically, aeration is performed in the quaternary treatment tank, which is equipped with contact filter media including coconut shell contact filter media, to maintain aerobic conditions and promote the activity of phosphorus-accumulating bacteria (PAOs).

[0101] In the quaternary treatment tank, which can be called the aerobic digester, decomposition of organic matter and partial processing of nitrogen (nitrification) proceeds. This mechanism is based on the aerobic conditions where ammonia (NH3) and ammonium ions (NH4 + ) is converted into nitrate (NO3 - ) The nitrification reaction is + → NO2 - → NO3 - is.

[0102] In this way, ammonia and ammonium ions are converted into nitric acid by nitrifying bacteria, and the nitrifying bacteria form a biofilm on the surface of contact filter media, including contact filter media made from coconut shells, thereby efficiently promoting the nitrification reaction.

[0103] Nitrifying bacteria (such as Nitrosomonas and Nitrobacter) are also widely found in nature. In the wastewater treatment system of the present invention, nitrifying bacteria (such as Nitrosomonas and Nitrobacter) are present in the water to be treated, which is the target of purification treatment, and grow by utilizing organic matter and nutrients present in the water to be treated. The retention time of the anaerobically treated water flowing in from the tertiary treatment tank in the fourth treatment tank where the above-mentioned treatment is carried out can be set to 1 to 2 hours.

[0104] <Nitrogen removal through anaerobic treatment in the tertiary treatment tank and aerobic treatment in the quaternary treatment tank> As described above, nitrogen is removed by anaerobic treatment in the tertiary treatment tank, which is equipped with a contact filter medium including a contact filter medium made from coconut shells, and by aerobic treatment in the quaternary treatment tank, which is equipped with a contact filter medium including a contact filter medium made from coconut shells. That is, in the anaerobic decomposition tank (tertiary treatment tank), denitrifying bacteria convert nitrate into nitrogen gas, and in the aerobic decomposition tank (quaternary treatment tank), nitrifying bacteria convert ammonia into nitrate. Through these processes, nitrogen is removed from the treated water, improving its quality. Contact filter media, including the coconut shell contact filter media mentioned above, promote the growth of microorganisms and the formation of biofilms, providing an ideal environment for nitrogen removal along with the physical removal of suspended solids (SS).

[0105] <Suspended solids removal treatment in the fifth treatment tank> A fifth treatment tank is located downstream of the fourth treatment tank, and suspended solids (SS) are removed from the aerobic treated water flowing in from the fourth treatment tank. The treated water is then discharged after being treated in the fifth treatment tank. The fifth treatment tank can also be equipped with a contact filter medium containing coconut shell contact filter medium similar to that installed in the third and fourth treatment tanks described above. In this case, in the fifth treatment tank, which is equipped with contact filter media including contact filter media made from coconut shells, suspended solids removal treatment is performed on the treated water that has undergone aerobic treatment and flows in from the fourth treatment tank. The contact filter material containing coconut shells that is provided in the fifth treatment tank is the same as the contact filter material containing coconut shells that is provided in the third treatment tank described above, so its description will be omitted. The fifth treatment tank can be called a final settling tank, where the biofilms and sediments produced in the third treatment tank (anaerobic digestion tank) and fourth treatment tank (aerobic digestion tank) finally settle and suspended solids (SS) are removed.

[0106] <Summary of water purification by the wastewater and wastewater treatment system of the present invention> According to the wastewater treatment system of the present invention, the removal of various metals described above is achieved through a combination of chemical precipitation, adsorption, and biological processes. The shell powder reacts with the various metals to form insoluble compounds, and the Bacillus subtilis natto and the contact filter medium containing coconut shell adsorb the various metal ions. These processes effectively remove various metals from the treated water, improving the water quality.

[0107] Phosphorus removal is achieved through a combination of chemical precipitation and biological processes. Shell powder promotes calcium phosphate precipitation, and the activity of phosphorus-accumulating bacteria (PAOs) in the aerobic and anaerobic digesters achieves biological phosphorus removal. Contact media, including coconut shell contact media, act as a support for microorganisms, increasing the efficiency of the aerobic and anaerobic processes. This integrated approach achieves effective phosphorus removal and improved water quality.

[0108] The treated water undergoes primary purification using baking soda, natto bacteria, shell powder, and crab shell powder, followed by secondary purification by aeration using contact filter media including contact filter media made from coconut shells, and tertiary purification by anaerobic decomposition.Finally, the treated water passes through contact filter media including contact filter media made from coconut shells, and can be discharged as effluent that meets environmental standards.

[0109] With these advantages, the present invention not only solves the problems of the past, but also brings many benefits in terms of environmental protection, cost reduction, and waste recycling, making it a technology that contributes to building a sustainable society.

[0110] The following describes examples of the present invention, but the present invention is not limited to the above-described embodiments or the examples described below, and can be modified in various ways within the technical scope understood from the claims. [Example]

[0111] <Preparation of bioflocculant> The bioflocculant to be added in the treatment in the secondary treatment tank of the sewage and wastewater treatment system of the present invention was prepared as follows. The following ingredients were added to a dry powder mixer and mixed for 1 hour to obtain 6 kg of bioflocculant. Powdered baking soda (sodium bicarbonate): 0.8 kg (363.64 mL) (Commercially available powdered baking soda (sodium bicarbonate) "Product name: Baking Soda, Japanese-made baking soda") Shell powder: 3 kg (1,111.11 mL) (Scallops and oyster shells that would otherwise be disposed of are dried and then powdered in a powder mill) Crab shell powder: 1 kg (666.67 mL) (The shells of king crab and snow crab that would otherwise be disposed of are dried and powdered in a powder mill.) Bacillus subtilis natto: 1kg (2,500mL) (Commercially available natto bacteria (Bacillus subtilis natto) "Product name: Sarasara Kinkatsu Natto Powder". The number of live bacteria of natto bacteria (Bacillus subtilis natto) is 10 5 ~10 9 (CFU / g equivalent.) [Example]

[0112] <Purification treatment by the sewage and wastewater treatment system of the present invention> 1.0 ton of water to be treated (wastewater from an industrial waste and rubble intermediate treatment facility) was flowed into the first treatment tank that constitutes the sewage and wastewater treatment system of the present invention, and solid-liquid separation treatment was carried out in the first treatment tank, followed by coagulation and sedimentation treatment in the second treatment tank, followed by anaerobic treatment in the third treatment tank, followed by aerobic treatment in the fourth treatment tank, followed by suspended solids removal treatment in the fifth treatment tank.

[0113] The retention time in the first treatment tank was 60 minutes, the retention time in the second treatment tank was 30 minutes, the retention time in the third treatment tank was 60 minutes, the retention time in the fourth treatment tank was 60 minutes, and the retention time in the fifth treatment tank was 30 minutes.

[0114] In the treatment in the secondary treatment tank, 6 kg of the bioflocculant of the present invention prepared in Example 1 was added, and after addition, stirring treatment was carried out for 30 seconds.

[0115] The contact filter media, including the contact filter media made of coconut shells, installed in the third, fourth and fifth treatment tanks, are 1 m 3 In the case where the contact filter medium containing coconut shells is composed of coconut shell contact filter medium and other contact filter medium such as shell powder or crab shell powder, the amount of the contact filter medium containing coconut shells is 0.5 kg. 3 For the tank, 0.4 kg of contact filter media made from coconut shells and 0.1 kg of contact filter media made from shell powder were used to form a "contact filter media containing contact filter media made from coconut shells."

[0116] The coconut shells used in the contact filter media made from coconut shells were fibrous, and the shell powder used in the contact filter media made from shell powder was made by washing and drying discarded shells and crushing them to pieces of approximately 5mm to 5cm.

[0117] The numerical values ​​of each item under consideration for the treated water flowing into the primary treatment tank, the numerical values ​​of each item under consideration after solid-liquid separation treatment in the primary treatment tank, the numerical values ​​of each item under consideration after coagulation and sedimentation treatment in the secondary treatment tank, the numerical values ​​of each item under consideration after anaerobic treatment in the tertiary treatment tank, the numerical values ​​of each item under consideration after aerobic treatment in the fourth treatment tank, and the numerical values ​​of each item under consideration after suspended solids removal treatment in the fifth treatment tank are as shown in Table 1 below.

[0118] The numbers in the "Inflow Value" column are the numerical values ​​of each item under consideration in the treated water that was inflowed into the primary treatment tank, and the numerical values ​​after primary treatment, secondary treatment, tertiary treatment, quaternary treatment, and quintal treatment are the numerical values ​​of each item under consideration after solid-liquid separation treatment in the primary treatment tank, after coagulation and sedimentation treatment in the secondary treatment tank, after anaerobic treatment in the tertiary treatment tank, after aerobic treatment in the quaternary treatment tank, and after suspended solids removal treatment in the fifth treatment tank, respectively.

[0119] [Table 1] In Japan, water quality environmental standards are set based on the Basic Environment Law. These are the Ministry of the Environment's discharge standards for rivers and lakes (Water Quality Environmental Standards Based on the Basic Environment Law of Japan), and they include the following major standards. The general standard items are as follows:

[0120] BOD (Biochemical Oxygen Demand) Rivers: 1-10 mg / L, Lakes and ponds: 1-3 mg / L COD (Chemical Oxygen Demand) Rivers: 1-8 mg / L, Lakes and ponds: 1-3 mg / L SS (Suspended solids amount) Rivers: 25-50 mg / L, Lakes and ponds: 5-30 mg / L pH Rivers, lakes and marshes: 6.5~8.5 Coliform count Rivers, lakes and marshes: 1,000 particles / 100 mL or less Heavy metals and other harmful substances Lead (Pb) Rivers, lakes and ponds: 0.01 mg / L or less Cadmium (Cd) Rivers, lakes and ponds: 0.01 mg / L or less Copper (Cu) Rivers, lakes and ponds: 1.0 mg / L or less Hexavalent chromium (Cr(VI)) Rivers, lakes and ponds: 0.05 mg / L or less Zinc (Zn) Rivers, lakes and ponds: 0.5 mg / L or less Arsenic (As) Rivers, lakes and ponds: 0.01 mg / L or less Other criteria oil Rivers, lakes and marshes: Not visible to the naked eye Total phosphorus Rivers: 0.1 to 1.0 mg / L, Lakes and ponds: 0.02 to 0.1 mg / L Total Nitrogen Rivers: 0.4 to 1.5 mg / L, Lakes and ponds: 0.1 to 1.0 mg / L Factory wastewater regulations More detailed regulations are in place for wastewater from factories and businesses, including the following standards: pH: 5.8 to 8.6 BOD: 30 mg / L or less (varies depending on industry and size) COD: 160 mg / L or less (varies depending on industry and size) SS: 100 mg / L or less Oil content: No floating oil can be visually confirmed These standards are set out in the Ministry of the Environment's Water Pollution Control Act and related regulations.

[0121] As shown in Table 1 above, the values ​​after 5th treatment, i.e., the values ​​for each item under consideration after suspended solids removal treatment in the 5th treatment tank (BOD, COD, SS, pH, total phosphorus, total nitrogen) all met the standards.

[0122] Based on the results of the study shown in Table 1, when the wastewater treatment system of Example 2 contains E. coli, oil, lead (Pb), cadmium (Cd), copper (Cu), and arsenic (As) as shown in Table 2 below, a computer simulation was performed to determine how these values ​​would decrease when the wastewater treatment system of Example 2 of the present invention is used for treatment. The results are shown in Table 2 below.

[0123] [Table 2] The simulation results showed that the above-mentioned standards would be met for E. coli, oil, lead (Pb), cadmium (Cd), copper (Cu), and arsenic (As).< / ph>

Claims

1. a primary treatment tank into which water to be treated, which is the target of sewage and wastewater treatment, is introduced and solid-liquid separation is carried out by sedimentation under anaerobic conditions; A secondary treatment tank is disposed downstream of the primary treatment tank, and causes coagulation and precipitation under aerobic conditions by adding a bioflocculant to the treated water after the solid-liquid separation treatment flowing in from the primary treatment tank; a third treatment tank disposed downstream of the second treatment tank, which is provided with a contact filter medium including a contact filter medium made of coconut shells, and in which the treated water flowing in from the second treatment tank after the coagulation and sedimentation has occurred is subjected to anaerobic treatment; a fourth treatment tank disposed downstream of the third treatment tank, equipped with a contact filter medium including a contact filter medium made of coconut shells, in which the treated water after the anaerobic treatment flowing from the third treatment tank is subjected to aerobic treatment by aeration; a fifth treatment tank disposed downstream of the fourth treatment tank, equipped with a contact filter medium including a contact filter medium made of coconut shells, and in which suspended solids removal treatment is performed to remove suspended solids (SS) from the treated water after the aerobic treatment flowing in from the fourth treatment tank; and a sewage wastewater treatment system.

2. The sewage and wastewater treatment system according to claim 3, wherein 20% to 50% of the discharged water, which is the treated water after the suspended solids removal treatment in the fifth treatment tank, is returned to the first treatment tank.

3. A sewage and wastewater treatment system as described in claim 1 or 2, wherein tertiary treatment tank sludge, which is sludge produced by precipitation occurring in the tertiary treatment tank, and quaternary treatment tank sludge, which is sludge produced by precipitation occurring in the fourth treatment tank, are collected in a sludge tank that contains raw materials for compost production.

4. 4. The sewage and wastewater treatment system according to claim 3, wherein a portion of the sludge in the tertiary treatment tank and a portion of the sludge in the quaternary treatment tank are returned to the secondary treatment tank.

5. 2. The wastewater treatment system according to claim 1, wherein the bioflocculant contains powdered baking soda (sodium bicarbonate), Bacillus subtilis natto, seashell powder, and crab shell powder as blended components.

6. The bioflocculant contains powdered baking soda (sodium bicarbonate) in a blending ratio of 5% to 15% by mass, shell powder in a blending ratio of 30% to 60% by mass, and crab shell powder in a blending ratio of 5% to 30% by mass, and contains 10% live natto bacteria (Bacillus subtilis natto). 5 ~10 9 10. The sewage and wastewater treatment system of claim 1, comprising:

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