KR20180109776A - Manufacturing method of oyster cell removing phosphorus in waste water - Google Patents

Abstract

The present invention relates to a method for manufacturing calcined oyster shells for removing phosphorus from wastewater. The present invention relates to a method for manufacturing oyster shells for removing phosphorus from wastewater, comprising the step of: washing and drying oyster shells to remove saline and foreign substances from oyster shell surfaces; crushing the washed and dried oyster shells to a particle diameter of 0.5-1 cm; and calcining the oyster shells through the crushing step at 900°C for 2 hours.

Description

Technical Field [0001] The present invention relates to a method of manufacturing oyster shells for removing phosphorus from wastewater,

The present invention relates to a method for manufacturing a water treatment oyster shell capable of removing phosphorus from wastewater to inhibit the generation of a green alga.

Eutrophication is a phenomenon caused by an increase in the inflow of nutrients to the lake, and as a result, the algae grow rapidly and are often called the green tide (Algal bloom, Water bloom) In other words, green tide is a phenomenon in which a large amount of floating algae proliferate in eutrophicated lakes or slow-flowing streams, and the water color changes significantly to green.

In Korea, the water pollution caused by the eutrophication of the lake has been a major problem nationwide. This problem is caused by the increase of the livestock wastewater, agricultural runoff, domestic sewage and factory wastewater due to rapid commercialization, It is caused by the rapid growth of algae and aquatic plants due to excessive inflow of nutrients.

It is expected that the increase of atmospheric carbon dioxide concentration and the rise of water temperature will continue in the future due to global warming. Therefore, it is expected that the occurrence of green algae will become worse in the future. Therefore, it is necessary to prevent eutrophication of hoso and river and develop an efficient greenhouse treatment system.

According to the Korean Intellectual Property Office (KIPO), patent applications related to avian control technology have more than doubled in five years since 2010, demonstrating a growing interest in the development of avian control technology. However, about 84% of the patent applications were focused on 'preventive technology' that suppresses the generation of green algae by removing nitrogen and phosphorus contained in the bottom / wastewater flowing into the river. In advanced countries such as the United States, Canada, the United Kingdom, and Japan, which focused on these 'preventive technologies', the recognition of the system by prevention technology has been recognized recently as the harmful effects of fish, animal wastes, Technology 'is being spurred.

In Korea, on the other hand, there is a lack of 'post-elimination technology' efforts compared to 'preventive technology'. As in Korea, 'post-elimination technology' is still in the advanced stage in developed countries.

On the other hand, oyster aquaculture in Korea is causing a lot of oyster shelling, which leads to pollution of coastal fisheries, problems of shared sleep management, and damage to natural landscape. It is necessary to study treatment method and recycling of oyster shell which is a fish waste.

The inventor of the present invention has long studied the method of recycling the oyster shell when removing phosphorus from wastewater as one of the post-elimination techniques for suppressing the occurrence of the green tide, and after completion of trial and error, the present invention has been completed.

The present invention provides a method for efficiently removing phosphorus from wastewater using a calcined oyster shell.

It is another object of the present invention to provide a method for manufacturing oyster shells for removing phosphorus from wastewater which provides conditions such as optimum baking temperature and baking time at the time of baking oyster to improve the phosphorus removal efficiency in wastewater during baking of oyster shells.

On the other hand, other unspecified purposes of the present invention will be further considered within the scope of the following detailed description and easily deduced from the effects thereof.

In order to solve the above problems, a first aspect of the present invention is a manufacturing method for manufacturing a calcined oyster shell for removing phosphorus from wastewater,

Washing and drying the oyster shell to remove foreign substances from the salt and oyster shell surfaces;

Crushing the oyster shell having been washed and dried to a particle size of 0.5 cm to 1 cm;

And calcining the oyster shell through the crushing step at 900 ° C for 2 hours.

And removing phosphorus from the wastewater.

Wherein the firing comprises:

Nitrogen (N ₂ ) atmosphere.

Wherein the firing comprises:

The oyster shell having been subjected to the pulverizing step may be put into a cylindrical rotary furnace having a predetermined inclination to advance the calcination.

A second aspect of the present invention is a method for removing phosphorus by injecting an oyster shell sintered in wastewater,

A method for removing phosphorus from wastewater using an oyster shell fabricated by the method of any one of claims 1 to 3, wherein the oyster shell is injected with 50 g of oyster shell per liter of wastewater.

The effect of the present invention is clear. According to the present invention, it is possible to efficiently remove phosphorus from wastewater by using a calcined oyster shell.

In addition, it is possible to improve phosphorus removal efficiency in wastewater by using calcined oyster shells by specifically showing conditions at oyster shell firing.

On the other hand, even if the effects are not explicitly mentioned here, the effect described in the following specification, which is expected by the technical features of the present invention, and its potential effects are treated as described in the specification of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a method of manufacturing oyster shells for removing phosphorus from wastewater according to an embodiment of the present invention.
It is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, an embodiment of the oyster shell manufacturing method for removing phosphorus from wastewater according to the present invention will be described.

Oyster shells are composed mainly of CaCO ₃ , organic substances are attached between layer structures and have a complex structure, and the shiny side of the inner surface of oyster shell is composed of SiO 2. The major component of the oyster shell is CaCO ₃ as the main component with 93.5%, and Na, Mg, Si, etc.

When these oyster shell thereby firing, the CaCO ₃ is formed with a porous body consisting of CaO and CaCO _3. As CaCO ₃ changes to CaO, CO ₂ is generated, and the generated CO ₂ is reduced and the total mass is reduced.

The porosity of the CaO / CaCO ₃ porous body formed by firing the oyster shell forms Ca ^{2 +} and OH ^- on the surface in the aqueous solution and reacts with PO ₄ ^{3 -} P in the wastewater to form crystalline form of hydroxyapatite (Ca _{10 4} ) ₆ (OH) ₂ ) and removing it from the wastewater, phosphorus can be removed from the wastewater.

The reaction formula is as follows.

^{_{10Ca 10 + 6PO 4 + 10OH -}} <-> Ca 10 (PO 4) 6 (OH) 2

As described above, the present invention relates to a method for manufacturing oyster shells which can remove phosphorus most efficiently, using a property that a fired oyster shell can remove phosphorus from wastewater.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a method of manufacturing oyster shells for removing phosphorus from wastewater according to an embodiment of the present invention.

Referring to FIG. 1, a method of manufacturing oyster shells for removing phosphorus from wastewater includes washing and drying, crushing, and calcining.

Salinity may remain in the oyster shell, and the salt remaining in the oyster shell may interfere with the phosphorus removal, so it is desirable to remove such salt. In addition, foreign substances attached to the surface of the oyster hinder CaCO ₃ from being calcined with CaO.

Thus, the present invention includes washing and drying oyster shells to remove foreign matter from the salt and oyster shell surface remaining on the oyster shell.

The crushing step is a step of crushing the oyster shell having been washed and dried to a particle diameter of 0.5 cm to 1 cm. When the size of the oyster shell is increased, the size of the space between the different oyster shells is increased, so that there is wastewater which does not reach the surface of the oyster shell, and the removal efficiency of phosphorus in the waste water using the oyster shell may be lowered.

In addition, if the oyster shell size is too small, the time taken for the wastewater to escape from the space between the oyster shells becomes too long, resulting in low economic efficiency.

Therefore, preferably, the size of the grain size of the oyster shell is preferably 0.5 cm or more and 1 cm or less. When the size of the oyster shell is 0.5 cm or more and 1 cm or less, the wastewater passes through the oyster shell while sufficiently contacting the oyster shell surface.

The calcining step is to calcine the oyster shell through the crushing step at 900 ° C for 2 hours. Oyster shells were sintered at various temperatures and times in order to obtain the optimal temperature and time for effectively removing phosphorus from the oyster shell.

Table 1 below shows the mass reduction rate at 1, 2, and 3 hours at 800 ° C, 900 ° C, and 1000 ° C, respectively.

division Temperature (° C) 800 900 1000 Time (Hr) One 12.7 26.6 34.1 2 25 54.1 47.5 4 27.2 45.6 44.3

As described above, when the oyster shell is fired, the mass of CaCO ₃ , which constitutes most of the oyster shell, is changed to the CaO / CaCO ₃ porous body. The greater the mass loss rate, and so a large amount CaO / CaCO ₃ of the porous body is produced, wherein generating the CaO / CaCO ₃ porous body is to be used to remove the phosphorus from an aqueous solution. Therefore, the greater the mass reduction rate, the greater the phosphorus removal efficiency in wastewater.

The weight reduction rate of the oyster shell was 45 ~ 50% when the firing time was longer than 2 hours, and the difference in weight reduction rate was not significant even when the firing time was increased. The weight reduction rate was increased (about 34%) when the calcination was performed at 1000 ° C for 1 hour, but the weight reduction rate was lower than that at calcination at 900 ° C for 2 hours or more Similarity can be confirmed. In addition, when the firing time is 4 hours, the weight reduction rate tends to be slightly lower than that when the firing is performed for 2 hours.

As can be seen from Table 1, when the oyster shell was calcined at 900 ° C for 2 hours, the highest mass reduction rate was observed. In other words, the most efficient firing for removal of phosphorus from wastewater proceeds.

On the other hand, the step of baking the oyster shell can proceed under a nitrogen atmosphere. Nitrogen is injected into the calcining furnace where the calcination proceeds, and the oyster shell is calcined under a nitrogen atmosphere. Oyster shell firing under nitrogen atmosphere showed larger mass reduction rate than oyster shell firing under oxygen atmosphere.

The mass reduction rate when the oyster shell was calcined at 900 ° C for 2 hours under oxygen atmosphere was 45.1%, which is much smaller than the mass reduction rate of 54.1% under nitrogen atmosphere. That is, it is possible to further increase the phosphorus removal efficiency in the wastewater by proceeding the oyster firing step in the nitrogen atmosphere when the oyster shell is fired.

In the present invention, experiments were carried out in various cases in order to confirm whether or not the oyster shell is calcined to increase the phosphorus removal efficiency of the oyster shell when the weight is reduced by changing the CaCO ₃ to the CaO / CaCO ₃ porous body.

Table 2 below shows the phosphorus removal efficiency when the oyster fired at 800 ° C for 1 hour, 2 hours and 4 hours was changed to 10 g, 25 g, and 50 g per 1 liter of wastewater containing phosphorus.

division Injection amount (g / L) 10 25 50 Hour (Hour) One 8.7 12.5 14.4 2 7.3 13.6 18.2 4 9.2 15.6 16.5

Table 3 shows the phosphorus removal efficiency when the oyster shell calcined at 900 ° C for 1 hour, 2 hours and 4 hours was changed to 10 g, 25 g and 50 g per 1 liter of wastewater containing phosphorus.

At the same dose of oyster shell, the removal rate of phosphorus according to firing time shows a similar tendency, and as the injection amount increases, the removal rate of total phosphorus increases. Overall, the removal rate is below 20%, which is inappropriate for use in phosphorus removal from wastewater.

division Injection amount (g / L) 10 25 50 Hour (Hour) One 5.5 20.2 21.1 2 49.2 55 86.5 4 8.4 43 64.5

Table 4 shows the phosphorus removal efficiency when the oyster shell calcined at 1000 ° C for 1 hour, 2 hours and 4 hours was changed to 10 g, 25 g and 50 g per 1 liter of wastewater containing phosphorus.

division Injection amount (g / L) 10 25 50 Hour (Hour) One 10.6 25 31.7 2 30.3 55.2 71 4 15 39 62

As shown in Tables 2 to 4, when the oyster shell is fired at 900 ° C for 2 hours, the removal efficiency is the highest. When the oyster shell calcined at 900 ° C for 2 hours is injected 50g per 1L of wastewater, phosphorus removal efficiency is 86.5% at maximum.

Referring to Tables 1 to 4, it is possible to confirm the optimum phosphorus removal efficiency by calcining the oyster shell at 900 ° C for 2 hours through the weight reduction rate and the phosphorus removal rate according to the firing temperature and firing time of the oyster shell.

On the other hand, in the sintering step of the present invention, the oyster shell subjected to the pulverizing step is charged into a cylindrical rotary furnace having a predetermined angle of inclination, and the sintering is progressed.

 The reason why the oyster shell is put into the cylindrical rotary furnace and baked is because the oyster shell inserted into the inside of the cylindrical rotary furnace rotates and the large amount of oyster shell can be evenly baked at the same temperature.

In addition, the cylindrical rotary shaft at this time is formed to be inclined at a certain angle, and the oyster shell angle is applied from the upper part to move downward along the cylindrical rotary shaft by gravity by itself. The firing processing of the oyster shell can be continuously performed through the inclined cylindrical rotary furnace.

By controlling the inclination angle of the cylindrical rotary furnace at this time, the baking time of the oyster shell can be controlled. That is, if the inclination angle is increased, the oyster shell in the cylindrical rotary furnace moves quickly and the baking time is shortened. If the inclination angle is lowered, the oyster shell in the cylindrical rotary furnace slowly moves and the baking time becomes longer.

By controlling the tilt angle, the firing time of the oyster shell can be controlled and the firing process can be continuously performed.

The scope of protection of the present invention is not limited to the description and the expression of the embodiments explicitly described in the foregoing. It is again to be understood that the present invention is not limited by the modifications or substitutions that are obvious to those skilled in the art.

Claims (1)

CLAIMS 1. A method for removing phosphorus from wastewater using a calcined oyster shell,
The fired oyster shells,
Washing and drying the oyster shell to remove foreign substances from the salt and oyster shell surfaces;
Crushing the oyster shell having been washed and dried to a particle size of 0.5 cm to 1 cm; And
Calcining the oyster shell through the crushing step at 900 ° C for 2 hours,
Wherein the firing comprises:
(N ₂ ) atmosphere, and the oyster passing through the crushing step is put into a cylindrical rotary furnace having a predetermined angle of inclination to carry out calcination. Through the calcination, CaCO ₃ , which is the main component of oyster shell, CaCO _{3 &lt;} / RTI &gt; porous body to be used for removal,
Which is manufactured by the oyster shell manufacturing method,
Characterized in that phosphorus is removed from the wastewater by using the calcined oyster shell produced by the oyster shell manufacturing method, and oyster shell of 50g is injected per 1L of wastewater.
How to remove phosphorus from wastewater.

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