JPH0751668A - Purification treatment of sewage - Google Patents

Abstract

PURPOSE:To easily and inexpensively remove or decrease contamination components, such as phosphorus, in sewage and to make safety high and handling quality good by further subjecting the sewage subjected to a biological purification treatment under an aerobic condition by using shells fired by heating. CONSTITUTION:The fired shells are arranged at least at one point among a discharge path 4 from a biological treating device 3, the inside of a final settling device 5, a discharge path 6 from this settling device 5, the inside of a flocculation treating device 7 and a discharge path 8 from this flocculation treating device 7 to remove the contamination components, such as phosphate, in the treated water. The phosphate, etc., are more effectively removed if the fired shells are arranged in at least either of the discharge path 6 from the settling device 5 and the insider of the flocculation treating device 7. The shells to be used are required to be fired by heating at a high temp. of >=500 deg.C, more preferably >=1000 deg.C. The contamination component, such as phosphorus, in the sewage, are extremely effectively removed by using the fired shells described above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for purifying sewage. More specifically, the present invention relates to a method and apparatus for purifying sewage that effectively uses natural shells.

[0002]

BACKGROUND ART Biological purification treatment of sewage is widely carried out, and the activated sludge method can be mentioned as a typical example. Purification of sewage water by the activated sludge method is generally performed through a treatment process as shown in FIG. 1, and after removing sand having a large specific gravity contained in the sewage water in the sand basin 1 as necessary, First, sedimentation tank 2 (hereinafter, the sedimentation tank and the sedimentation equipment are collectively referred to as "precipitation equipment") is used to sediment and remove suspended solids (suspended materials) in wastewater, and then an aeration tank (aerobic biological treatment equipment). While aerating in 3, the activated sludge is treated under aerobic conditions to adsorb, oxidize and purify pollutants such as organic substances in the sewage, and then the treated water is passed through the discharge passage 4 to the final settler 5. A solid substance composed of activated sludge is separated into a supernatant liquid, and the supernatant liquid discharged from the final settling device 5 is processed by the coagulation processing device 7 via the discharge passage 6 and discharged from the discharge passage 8. .

In the above-mentioned biological purification treatment, it is important that the growth and activity of the organisms that purify water are kept good, and therefore, nitrogen and phosphorus, which are nutrient sources of the organisms, are maintained. Must be contained in the required amount of wastewater,
If nitrogen and phosphorus in the wastewater are insufficient, they are supplied from the outside. In the case of biological purification treatment such as the activated sludge method, organisms contained in the activated sludge absorb contaminants such as organic substances in the sewage, oxidative decomposition, and digestion by the organisms to reduce water. Purification is performed, and at the same time, nitrogen and phosphorus in sewage are digested and reduced as a nutrient source for living organisms. However, in the water discharged from aeration tanks, final settling basins, coagulation treatment equipment, etc., phosphorus is not completely removed in the form of phosphate and remains in a considerable amount. If released to such places, it may lead to nutrient enrichment in rivers, swamps, seas, etc., and may lead to abnormal occurrence of plankton and other living things, resulting in natural destruction.

[0004] Therefore, discharged water (supernatant water) obtained by precipitating and separating solid matters such as activated sludge in the final settling tank after biological purification treatment under aerobic conditions, such as slaked lime, sulphate and organic polymer, etc. It is common practice to add a flocculant to make phosphates and other components (heavy metals, trace amounts of oil, slightly residual organic matter, etc.) into insoluble coagulates, remove them by flocculation, and then discharge to rivers. It is being appreciated.

However, in the case of such a conventional method in which a flocculant such as slaked lime, vanadium sulfate, and organic polymer is added to the discharge water from the final settling tank, the phosphates contained in the discharge water are rapidly flocculated. This is convenient because it can be separated by precipitation, but since a large amount of these flocculants is supplied, they tend to remain in the treated water in large amounts, and these flocculants are constantly maintained. Since it needs to be supplied, its management and operation are troublesome and costly, and particularly when an organic polymer is used as a coagulant, there is a problem that the cost is high because it is expensive.

On the other hand, in shellfish farms and processing plants, a large amount of shells remain after the shells are taken out, but the shells are flame-retardant, extremely hard, and difficult to be decomposed or chemically decomposed by microorganisms. Therefore, it is difficult to treat by burning, compression, rot, chemical decomposition and the like, and when left as it is or discarded, it emits a foul odor due to its peculiar odor, and its handling has been difficult. From this point, it has been attempted to effectively utilize the shell for water purification, but in that case, the purpose is to use the shell as an attachment member for the habitation and multiplication of water purification organisms, It is not actively used to remove phosphorus in wastewater.

[0007]

The present inventor has many years of research on sewage treatment, preservation and improvement of natural environment, beautification, etc., and has a track record of putting many technologies into practical use for that purpose. Studies have been conducted for the purpose of developing a method capable of easily and inexpensively removing pollutant components such as phosphorus contained in discharged water discharged after biological sewage treatment, which are conventionally difficult to remove. As a result, it was found that when the above-mentioned shell, which has been difficult to handle in the past, is used as a purification material by heating and baking it in particular, contaminants such as phosphorus in water can be removed and the shell can be effectively used. Completed the invention.

That is, the present invention is a method for purifying sewage, characterized in that sewage that has been biologically purified under aerobic conditions is further treated with heated and fired shells.

Further, the present invention relates to a sewage purification treatment apparatus equipped with an aerobic biological treatment apparatus, and if necessary, a precipitation apparatus and / or an agglomeration treatment apparatus, in which treated water is discharged from the biological treatment apparatus. The heated and fired shells are arranged in at least one of the path, the inside of the settling device, the discharge path of the treated water from the settling apparatus, the inside of the aggregating apparatus and the discharge path of the treated water from the aggregating apparatus. It is a purification treatment device for sewage.

In the present invention, the type of sewage to be treated is not particularly limited, and examples thereof include various industrial wastewater, business wastewater, domestic wastewater, marsh lakes, rivers, ponds, sea water, and the like. The content of sewage is not particularly limited.

The activated sludge method is widely known as a method for biologically purifying sewage under aerobic conditions. However, the aerobic biological purification treatment in the present invention is performed by the activated sludge method. Without limitation, any of the conventionally known aerobic biological purification treatment methods can be adopted, and in addition to the activated sludge method, for example, aeration type oxidation pond method (aeration type lagoon method), biofilm method,
A sprinkling filter method, a biological stabilization pond method, a rotating plate method, a contact aeration method, etc. may be adopted. At that time, the shape of the biological processing device,
The structure, scale, incidental equipment, etc. are not particularly limited and may be any. Among the above-mentioned biological purification methods, it is preferable to carry out by the activated sludge method, and as the activated sludge method in that case, for example, standard activated sludge method, complete mixing method, dispensing method, oxidation groove method, pure oxygen Method, super deep aeration method, etc. can be adopted.

The conditions for the biological purification treatment are not particularly limited, and it is preferable to select the optimum conditions as appropriate according to the type of sewage, the purification treatment method, the scale and structure of the device, and the like.
Then, the wastewater may be directly introduced into the above-mentioned biological treatment equipment as it is, or if necessary, a sand basin and / or a first sedimentation basin (first sedimentation equipment) may be provided upstream of the aerobic biological treatment equipment. It may be treated with these devices and then introduced into the biological treatment device. When the wastewater is a concentrated wastewater such as molasses drainage during alcohol fermentation or yeast production, human waste drainage, etc., install an anaerobic biological treatment device upstream of the aerobic biological treatment device. The sewage may be biologically treated under anaerobic conditions to reduce the concentration of pollutants (BOD or COD), and then biologically purified under aerobic conditions.

Then, the sewage treated under aerobic conditions by the biological treatment apparatus is preferably led to a settling apparatus to remove activated sludge and other solid matters contained therein, and then,
Further, if necessary, the treated water is subjected to a coagulation treatment with a coagulation treatment device and then the treated water is discharged. In the present invention, the discharge passage from the biological treatment device, the inside of the precipitation device, the discharge passage from the precipitation device, the coagulation treatment device The heat-fired shells (hereinafter referred to as "fired shells") are arranged in at least one of the inside and the discharge path from the coagulation treatment device.

The location of the baked shells will be described with reference to FIG. 1. The discharge passage 4 from the biological treatment device 3, the inside of the final settling device 5, the discharge passage 6 from the precipitation device 5, and the coagulation treatment device 7 , And at least one of the discharge passages 8 from the coagulation processing device 7 are arranged with burned shells to remove contaminants such as phosphate contained in water.

In this case, it is desirable to arrange the calcined shells in at least one of the discharge path 6 from the settling device 5 and the inside of the coagulation processing device 7 because it is possible to more effectively remove phosphates and the like. Even if the fired shells are arranged in all of the discharge passage 4 from the biological treatment device 3, the settling device 5, the discharge passage 6 from the precipitation device 5 and the inside of the coagulation treatment device 7, or the discharge passage 4 and the precipitation device. It may be arranged on only one of the insides of 5.

[0016] The shell in this case may be any shell of shellfish that lives in seawater, freshwater, or a mixed area of seawater and freshwater. Examples thereof include shells such as shellfish, turban shells, and mill shells, and those that can be obtained in large quantities and constantly at shellfish farms and processing plants are preferable.
The shells may be used alone or in combination of two or more.

The shell used in the present invention is 500
It is necessary to be heated and calcined at a high temperature of ℃ or more, preferably 1000 ℃ or more, and by using the calcined shell, contaminants such as phosphorus in the sewage can be removed very effectively. The mechanism has not been fully clarified yet, but the ability to release calcium ions from the shell is increased by heating and baking the shell at high temperature, and the calcium ion and phosphate ion released in water are bound to each other. And insoluble calcium phosphate is produced,
Alternatively, it is presumed that the phosphate ion adsorbing ability of the shell is increased and the phosphate ion in water is adsorbed and removed.

The calcined shell may be uncrushed whole or crushed, but is approximately 1 mm.
It is preferable to use a crushed product having a size of about 40 mm, especially about 5 mm to 30 mm. At that time, the pulverization may be carried out at any stage before or after the calcination, but calcination after the pulverization is preferable. The baked shell used in the present invention is
By the burning treatment, decomposition and removal of organic components such as proteins remaining on the shell that cause the propagation of spoilage bacteria and the generation of odor, carbonization and removal of moisture, and drying are also performed. At the same time, there is no offensive odor and the quality is stable and good.

At that time, the baked shells may be arranged in a separated granular form by spraying on the above-mentioned places, or a bag made of a water-permeable net or cloth, a plastic having holes, a metal, a wood. It may be placed in the above-mentioned location by filling a water-permeable container, basket or the like with the baked shell and placing it in the above-mentioned location, or by hardening the baked shell into an appropriate size with a binder or the like and placing it in the above-mentioned location. Good. From the viewpoints of easy handling, easy placement in a predetermined place, and easy removal from the placement place, it is convenient to fill the bag, basket, or other container before use. When arranging the baked shells, it is necessary to adjust the arrangement position and the amount to be used so that the original treatment of the device and the flow of water are not significantly hindered.

Although not limited thereto, a specific example of the arrangement of the baked shells will be described with reference to the drawings. When the baked shells A are arranged in the discharge paths 4, 6, 8 and the like, as shown in FIG. a)
As shown in FIG. 2, the entire discharge passage may be filled and arranged, or as shown in FIG. 2B, it may be arranged only below the discharge passage.

When the calcined shells are placed inside the settling device 5 and the coagulation processing device 7, the calcined shells A are located slightly above the bottom surface of the device as shown in FIG. 3 (a).
It is convenient to arrange so that it does not mix with the sediment deposited on the bottom of the device. Further, when a large particle size is used as the baked shell A, for example, as shown in (b) of FIG. 3, the baked shell A has a hole or the like near the bottom surface of the precipitation device 5 or the processing device 7 through which the precipitate can pass. It is also possible to provide a plate (shelf) 9 on which the shell A is placed and to place the baked shell A there.

In the present invention, the discharge passage 4, the precipitation device 5, the discharge passage 6, the coagulation treatment device 7 and / or the baking shell placed in the discharge passage 7 and, if necessary, the inside of the biological treatment device 3 are baked. Unsealed shells may be placed, in which case the unfired shells become a habitat for organisms having a water purification function and can promote the growth, proliferation and habitation of the organisms, and the conventional handling The amount of shells that has been difficult to use increases, which will contribute to the effective use of the shells.

Furthermore, in the present invention, when the discharged water from the settling device is coagulated in the coagulating device by using the coagulant such as van sulphate soil, slaked lime and organic polymer described above, a calcined shell is used. It is also possible to reduce the amount of use of these flocculants.

[0024]

According to the present invention, by effectively utilizing the shell, which has conventionally been regarded as one of the sources of pollution as useless waste, contaminants such as phosphorus in wastewater can be easily and inexpensively removed. Or it can be reduced. The calcined shell used in the present invention does not generate an offensive odor and is derived from a natural product, and thus has high safety and good handleability. Further, according to the present invention, it is possible to reduce the amount of flocculating agents such as van sulphate soil, slaked lime, and organic polymers that have been conventionally used, or to avoid the use thereof, which is also greatly effective in preventing pollution. Contribute.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a typical flow sheet for biological purification treatment of sewage.

FIG. 2 is a diagram showing an example in which a baked shell is arranged in a discharge path in the present invention.

FIG. 3 is a diagram showing an example in which a baked shell is arranged inside a precipitation device or an aggregating treatment device in the present invention.

[Explanation of symbols]

 A Baked shell 1 Settling basin 2 First settling basin (first settling device) 3 Biological treatment device 4 Discharge path 5 Precipitator 6 Discharge path 7 Coagulation processing device 8 Discharge path 9 Dish (shelf)

Claims (3)

[Claims] 1. A method for purifying sewage, characterized in that sewage that has been biologically purified under aerobic conditions is further treated with heated and baked shells. 2. A biological treatment device treats wastewater under aerobic conditions, and then, if necessary, guides it to a precipitation device to remove precipitates, and further, if necessary, a coagulation treatment with a coagulation device. Then, in the method for purifying sewage, which comprises discharging treated water, a treated water discharge passage from a biological treatment device, an inside of a sedimentation device, a treated water discharge passage from a sedimentation device,
A method for purifying sewage, which comprises arranging heated and fired shells in at least one of the inside of the aggregating apparatus and the discharge path of the treated water from the aggregating apparatus. 3. An aerobic biological treatment device, and if necessary, a wastewater purification treatment device equipped with a sedimentation device and / or a coagulation treatment device, in which the treated water is discharged from the biological treatment device and the sedimentation is performed. Sewage characterized by arranging heated and fired shells in at least one of the inside of the apparatus, the discharge path of treated water from the sedimentation apparatus, the inside of the coagulation processing apparatus and the discharge path of treated water from the coagulation processing apparatus. Purification equipment.