KR20190054606A - Method for preparing composition for removing phosphorus from wastewater using oyster shell - Google Patents

Abstract

The present invention relates to a method for preparing a composition for removing phosphorus from wastewater using an oyster shell, which comprises the steps of: (a) washing oyster shells using distilled water and an organic solvent; (b) drying the oyster shells of the step (a); (c) calcining the oyster shells of the step (b); and (d) preparing the oyster shells of the step (c) as slurry. According to the present invention, a composition which is very effective in adsorbing and removing pollutants including phosphorus can be provided. In addition, when the oyster shells of the present invention is used as a raw material, the oyster shells, which are left on the seaside to cause pollution, are reduced, thereby reducing pollution of the seaside.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preparing a composition for removing phosphorus from wastewater using oyster shells,

The present invention relates to a method for producing a composition for removing phosphorus from wastewater using oyster shells.

Biological and chemical methods are mainly used to remove phosphorus, which is a pollutant, in wastewater treatment.

The biological removal mechanism consists of two or more reactors, mainly aerobic anaerobic aerobic anaerobic oxygen need for oxygen. The principle of biological elimination is to remove phosphorus by inducing phosphorus uptake and phosphorus release using the physiological characteristics of the microorganisms according to the conditions of each reactor. That is, the release of phosphorus in anaerobic condition and the excessive intake of phosphorus in aerobic condition are carried out, and the microorganisms are discharged into the system by the final precipitation.

Therefore, in order to remove phosphorus biologically, both anaerobic and exhalation conditions are necessary. In addition, external conditions such as temperature, pH, organic substance concentration, load, and residence time (SRT) necessary for growth of microorganisms also play an important role.

In particular, phosphorus present in wastewater is in the form of inorganic phosphorus (orthophosphate, polyphosphate) and organophosphate, which are classified as soluble and insoluble. Dissolving phosphorus is absorbed and removed as an essential nutrient of microbial growth, but its removal amount is only about 2% based on the dry weight, which implies the limit of biological removal. In addition, the removal efficiency varies greatly depending on the water treatment conditions, and when the water temperature falls below 15 ° C in the winter season, the removal efficiency of phosphorus is remarkably reduced, resulting in a great difficulty in operating the treatment facility.

AO method (Anoxic / Oxic process), intermittent abandonment method, and biofilm filtration method are known as biological removal water treatment methods.

On the other hand, as a chemical removal method, there is a flocculation and sedimentation method in which a coagulant of lime or aluminum salt and a metal salt (metal salt) is used to precipitate dissolved phosphorus into insoluble compound in water.

The lime as a coagulant is a method of reacting with phosphates and alkalis to generate and remove carbonate in addition to the phosphorus compound gelatin-like hydroxyapatite (Ca ₅ (OH) (PO ₄ ) ₃ ).

The metal salt coagulants include aluminum salts and iron salts, and phosphorus can be removed by precipitating in the form of aluminum phosphate (AlPO ₄ ) or ferric phosphate (FePO ₄ ) which is hardly reacted with phosphorus in water. In addition, the coagulated sedimentation method using a metal salt is a method of forming a precipitate by consuming alkaline of the wastewater, and therefore has a disadvantage in processing when the alkalinity is low.

The precipitation method using the coagulant has a disadvantage in that the phosphorus removal efficiency varies largely depending on the reaction conditions and it is difficult to maintain proper reaction conditions, and there are disadvantages such as not only the cost of the chemical agent but also the disposal cost due to the chemical sludge generation .

KR 10-1047839 B1

It is an object of the present invention to provide a method for manufacturing a composition for removing phosphorus from wastewater using an oyster shell capable of removing phosphorus contained in wastewater by a low cost and environmentally friendly method using an oyster shell.

The problem to be solved by the present invention is not limited to the above-mentioned problem (s), and another problem (s) not mentioned can be clearly understood by a person skilled in the art from the following description.

In order to solve the above problems, a method of manufacturing a composition for removing phosphorus in waste water using an oyster shell according to a preferred embodiment of the present invention comprises the steps of: (a) washing oyster shells with distilled water and an organic solvent; (b) drying the oyster shell of step (a); (c) calcining the oyster shell of the step (b); And (d) preparing the oyster shell of step (c) as a slurry.

In one embodiment, the organic solvent is preferably ethyl alcohol.

In one embodiment, the step (c) may further include a step of performing a first crushing step before the step (c), and a step of crushing a second crushing step after the step (c).

In one embodiment, the step (c) is performed in an electric furnace at 800 to 1,200 ° C for 1 to 4 hours.

In one embodiment, the step (d) is preferably milled in a high-density polyethylene container to produce a slurry.

In one embodiment, the milling is preferably milled at 80-150 rpm for 30-180 minutes using alumina balls 20-30 mm in diameter.

In one embodiment, the step (d) may be performed by mixing the oyster shell of the step (c) and distilled water at a weight ratio of 1:25 to 75 by mixing.

The use of the oyster shell-forming composition for removing phosphorus in the wastewater according to the present invention has an advantage of being able to provide a composition highly effective in adsorbing and removing phosphorus contained in wastewater.

In addition, when the oyster shell is used as a raw material according to the present invention, there is an advantage that the oyster shell which is left on the shore and causes pollution is reduced, so that coastal pollution can be reduced.

1 is a flowchart illustrating a method of manufacturing a composition for removing phosphorus from waste water using an oyster shell according to an embodiment of the present invention.
2 to 4 are graphs showing hydration activity of quicklime, dolomite dust powder and calcined oyster shell.
FIG. 5 shows the results of pH analysis according to the amount of the composition prepared according to Example 1 and Comparative Example 2. FIG.
FIG. 6 is a graph showing the total phosphorus (TP) concentration measured according to the amount of slurry prepared according to Example 1 and Comparative Example 2. FIG.
7 shows the X-ray diffraction pattern of the oyster shell slurry produced according to Example 1. Fig.
FIG. 8 shows an X-ray diffraction pattern after the oyster shell slurry produced according to Example 1 was reacted with wastewater.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving it will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings.

It should be understood, however, that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. To fully inform the inventor of the category of invention. Further, the present invention is only defined by the scope of the claims.

Further, in the following description of the present invention, if it is determined that related arts or the like may obscure the gist of the present invention, detailed description thereof will be omitted.

Briefly explaining the oyster shell, the main element of the oyster shell is CaO, which can play an important role in forming a precipitate by the phosphorus and aggregation reaction contained in the wastewater.

A method for manufacturing a composition for removing phosphorus from wastewater using an oyster shell according to an embodiment of the present invention is provided.

1 is a flowchart illustrating a method of manufacturing a composition for removing phosphorus from waste water using an oyster shell according to an embodiment of the present invention.

Hereinafter, a method for manufacturing a composition for removing phosphorus from waste water using an oyster shell according to an embodiment of the present invention will be described in detail with reference to FIG.

A method for preparing a composition for removing phosphorus from waste water using an oyster shell according to an embodiment of the present invention comprises the steps of: (a) washing an oyster shell with distilled water and an organic solvent (S100); (b) drying the oyster shell of step (a) (S200); (c) calcining the oyster shell of step (b) (S300); And (d) fabricating the oyster shell of step (c) as slurry (S400).

In step (S100), the oyster shell is cleaned using distilled water and an organic solvent. In the method of manufacturing a composition for removing phosphorus from wastewater using an oyster shell according to an embodiment of the present invention,

The organic solvent may be at least one selected from the group consisting of C1 to C4 alcohols and combinations thereof, and specifically may be ethyl alcohol.

The oyster shell may be washed two to three times alternately using distilled water and an organic solvent, and the oyster shell is not limited thereto as long as it can remove the suspended substances present on the surface of the oyster shell.

In step (b) (S200) of drying the oyster shell of step (a) (S100), the method of manufacturing a composition for removing phosphorus using oyster shell according to an embodiment of the present invention.

The step of drying the oyster shell in the step (a) (S100) may be performed by far infrared ray drying or vacuum drying, but is not limited thereto.

The far-infrared ray drying may be performed using a far-infrared ray dryer at 40 to 60 ° C for 4 to 8 hours.

The vacuum drying can be performed at a temperature of -45 ° C to -40 ° C for 1 to 5 days under a high vacuum of 1 mmHg or lower.

In the method of manufacturing a composition for removing phosphorus from waste water using an oyster shell according to an embodiment of the present invention, the step (c) (S300) is a step of calcining the oyster shell of the step (b) (S200).

The step (c) (S300) may be performed in an electric furnace at 800 to 1,200 ° C for 1 to 4 hours, and specifically, in an electric furnace at 1,000 ° C for 2 hours.

The step (c) (S300) may further include a second crushing step (S300) followed by the first crushing step (C) (S300).

The primary crushing step may be performed by filtering the crushed oyster shell so that the particle size of the crushed oyster shell is 100 μm or less. The secondary crushing step may be performed by the same method, but the particle size of the crushed oyster shell Is not more than 75 mu m.

The smaller the particle size of the crushed oyster shell is, the larger the surface area is, and the reactivity of the causal agent contained in the wastewater can be increased.

In step (d) (S400), the oyster shell of step (c) (S300) is prepared as a slurry in the method for producing a composition for removing phosphorus from wastewater according to an embodiment of the present invention .

The step (d) (S400) may be performed by milling in a high-density polyethylene container to prepare a slurry.

The milling can be performed at 80 to 150 rpm for 30 to 180 minutes using alumina balls having a diameter of 20 to 30 mm, and specifically, at 160 rpm at 108 rpm using alumina balls having a diameter of 25 mm.

The milling may also be a wet milling.

The oyster shell of step (c) S300 and the distilled water may be mixed and milled at a weight ratio of 1:25 to 75 in step (d) (S400). More specifically, step (c) Distilled water can be mixed and milled at a weight ratio of 1:50.

The use of the oyster shell-forming composition for removing phosphorous waste according to the present invention has an advantage that it is possible to provide a composition highly effective for adsorbing and removing phosphorus contained in wastewater.

In addition, when the oyster shell is used as a raw material according to the present invention, there is an advantage that the oyster shell which is left on the shore and causes pollution is reduced, so that coastal pollution can be reduced.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples. However, the following examples and experimental examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Preparation of materials

In the present invention, wastewater was collected from Geum River near Okcheon, Korea. Eutrophication materials were prepared by adding ₁₁ g of K ₂ HPO ₄ and 5 g of NH ₄ NO ₃ to 5,000 ml of distilled water at a molar ratio of 1: 1 in order to sufficiently cultivate the eutrophication material.

Next, 500 ml of the solution was mixed with 5,000 ml of distilled water to prepare a diluted solution.

The diluted solution was incubated for 7 days in an incubator equipped with a continuous fluorescent lamp of 3,000 lux for 12 hours at a temperature of 30 DEG C for 12 hours and then dark for 12 hours.

The oyster shells used in the present invention were collected in a temporary shelter near the seaside near Geoje Island in Korea.

Example 1: Preparation of oyster shell slurry

The oyster shell was washed with distilled water and ethyl alcohol to remove impurities on the surface and dried in an oven at 100 ° C for 1 hour.

Dried oyster shells were crushed using a bowl and sieved to prepare oyster shell fine powders of 100 μm or less.

The oyster shell fine powder was calcined in an electric furnace at 1,000 DEG C for 2 hours and then pulverized with a mortar to obtain an oyster shell fine powder of 75 mu m or less.

Oyster shell slurry was prepared from the second pulverized oyster shell fine powder by using a wet ball mill method in a high density polyethylene (HDPE) vessel.

The wet ball mill was prepared by charging 10 g of the secondarily pulverized oyster shell powder and 500 g of distilled water into a container made of HDPE and then ball milling at 108 rpm for 2 hours using an alumina ball having a diameter of 25 nm to prepare an oyster shell slurry.

Comparative Example 1

The composition was prepared in the same manner as in Example 1 except that calcium oxide was used.

Comparative Example 2

The same procedure as in Example 1 was carried out except that dolomite dust powder was used to prepare a composition.

Experimental Example 1: Component analysis

Untreated oyster shells, burnt lime and dolomite powder were analyzed by X-ray fluorescence analysis to analyze the components of the oyster shell.

Table 1 below shows the results of X-ray fluorescence analysis of untreated oyster shell, burnt lime and dolomite dust powder.

Component analysis result SiO ₂ Al ₂ O ₃ FeO ₃ CaO MgO K ₂ O Na ₂ O TiO MnO P ₂ O ₅ Igloss quicklime 0.11 0.03 0.09 55.54 0.20 0.03 &Lt; 0.02 <0.01 0.01 0.01 43.79 dolomite 0.06 0.04 0.18 31.27 21.81 0.03 &Lt; 0.02 0.01 0.07 0.01 46.37 Oyster shell 0.45 0.12 0.06 53.66 0.26 0.06 0.55 <0.01 0.07 0.16 44.56

As shown in Table 1, the quicklime contains a large amount of CaO and a small amount of SiO ₂ and MgO, and dolomite showing the chemical composition of CaMg (CO ₃ ) ₂ contains Ca as well as Mg as a main component .

As a result of the analysis, it was confirmed that oyster shell and lime were similar, and Ca was contained at a high concentration, and oyster shell was identified as chemical composition similar to that of quicklime, so that the reactivity with oyster shell was similar to that of quicklime Can be confirmed.

Experimental Example 2: Reactive analysis

In order to confirm the reactivity of the calcined oyster shell in solution, the hydration activity was measured over time and shown in Figs. 2 to 4.

2 to 4 are graphs showing hydration activity of quicklime, dolomite dust powder and calcined oyster shell.

Referring to Figs. 2 to 4, all three species show an exothermic reaction in which the temperature increases with time, but all three species show different hydration activity patterns.

The quicklime showed rapid hydration activity in a short time and was observed up to a maximum temperature of 70 ° C. The dolomite dust powder gradually increased to 600 ° C. and reached 48 ° C. The calcined oyster shell was very slow in hydration activity, The maximum temperature was not reached.

In conclusion, it can be seen that the quicklime and oyster shell have similar composition and particle size through the analysis of the components, but they show different hydration activity due to some other elements such as Si and Na in both samples.

Experimental Example 3: pH Analysis

In order to observe the pH change of wastewater, the amount of oyster shell slurry prepared according to Example 1 was varied, and the wastewater was added.

In addition, dolomite dust powder produced according to Comparative Example 2 was used as a comparative example.

FIG. 5 shows the results of pH analysis according to the amount of the composition prepared according to Example 1 and Comparative Example 2. FIG.

Referring to FIG. 5, it can be seen that the pH increases as the amount of slurry prepared according to Example 1 and Comparative Example 2 increases.

The pH of the wastewater charged with 5.0 g / L of the oyster shell slurry prepared according to Example 1 was 11.7, and the pH was steadily increased until the slurry was added at 12.5 g / L.

The reason why the pH is increased as the oyster shell slurry prepared according to Example 1 is increased is that Ca (OH) ₂ contained in the slurry is present as Ca ²⁺ ions and OH ^- ions in the solution, Ca ²⁺ ions included in the water phase react with CO ₂ or CO ₃ ^2- ions to cause aggregation reaction or react with nitrogen ions and phosphorus ions present in the wastewater. This causes the pH to increase to 13 due to the increase of OH ^- ions.

When the pH of wastewater to which the slurry prepared according to Comparative Example 2 was added and the oyster shell slurry prepared according to Example 1 were compared within the entire range, the wastewater slurry prepared according to Example 1 was added to the wastewater Can be explained for two reasons.

First, Mg (OH) ₂ contained in the slurry prepared according to Comparative Example 2 has a lower solubility than the oyster shell slurry Ca (OH) ₂ prepared according to Example 1, and therefore exhibits a low OH ^- concentration in the wastewater, Value.

Also, based on Le Chatelier's principle, in a parallel reaction, if a change in the concentration of the reactant or product occurs, the reaction proceeds toward the reaction to maintain the parallel state.

According to this principle, Ca (OH) ₂ as well as Mg (OH) slurry of Comparative Example 2 consisting of ₂ is due to Ca (OH) ₂ has a higher solubility in Mg (OH) ₂ is Mg ²⁺ and OH ^- ionized The pH of the solution into which the slurry prepared in accordance with Comparative Example 2 is added exhibits a lower pH than the wastewater to which the oyster shell slurry prepared according to Example 1 is added.

As a result, it was confirmed that the oyster shell slurry prepared according to Example 1 can promote a better solidification reaction than the slurry prepared according to Comparative Example 2.

Experimental Example 4: Reaction analysis of causal

The amount of slurry prepared according to Example 1 and Comparative Example 2 was increased, and the total phosphorus (TP) concentration was measured after being put into wastewater, and is shown in FIG.

FIG. 6 is a graph showing the total phosphorus (TP) concentration measured according to the amount of slurry prepared according to Example 1 and Comparative Example 2. FIG.

6, the total phosphorus (TP) decreased as the amount of slurry prepared according to Example 1 and Comparative Example 2 increased. In particular, the amount of oyster shell slurry produced according to Example 1 was 7.5 g / L The amount of total phosphorus (TP) is reduced rapidly, and phosphorus of all concentrations is removed. On the other hand, it was confirmed that the amount of the slurry prepared according to Comparative Example 2 did not affect the amount of 5 g / L, and the concentration of total phosphorus (TP) dropped rapidly after that. This indicates that Comparative Example 2 Ca ²⁺ ions is insufficient in the slurry according to fail to combine all of phosphorus in the wastewater.

Experimental Example 5: Structural Analysis

7 shows the X-ray diffraction pattern of the oyster shell slurry produced according to Example 1. Fig.

FIG. 8 shows an X-ray diffraction pattern after the oyster shell slurry produced according to Example 1 was reacted with wastewater.

CaO, which is a major element of oyster shell, is wet - milled and is present as Ca (OH ^- ).

Referring to FIGS. 7 and 8, Ca ²⁺ ions in the oyster shell slurry produced according to Example 1 react with PO ₄ ^3- in the wastewater to form Ca ₃ (PO ₄ ) ₂ and Ca ₅ (PO ₄ ) ₃ OH And all the diffraction peaks for Ca (OH) ₂ after the reaction with the wastewater were not detected, but a new peak of Ca ₅ (PO ₄ ) ₃ OH corresponding to hexagonal P63 / m was detected at around 32 ° . In other words, it was confirmed that all Ca ions were precipitated by binding with phosphate ion (PO ₄ ^3- ).

On the other hand, as shown in Figures 7 and 8, is that the X- ray diffraction pattern analysis, the content of the result calcite increased in proportion to the amount of Ca ²⁺ ions to the slurry prior to PO ₄ ³ CO ₂ or CO ₃ ^2- and reaction ^- &lt; / RTI &gt;

The use of the oyster shell-forming composition for removing phosphorous waste according to the present invention has an advantage of being able to provide a composition highly effective in adsorption and removal of contaminants including phosphorus.

In addition, when the oyster shell is used as a raw material according to the present invention, there is an advantage that the oyster shell which is left on the shore and causes pollution is reduced, so that coastal pollution can be reduced.

Although the present invention has been described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications may be made without departing from the scope of the present invention. Do.

Therefore, the scope of the present invention should not be construed as limited to the embodiments described, but should be determined by the scope of the appended claims, as well as the claims.

It is to be understood that the foregoing embodiments are illustrative and not restrictive in all respects and that the scope of the present invention is indicated by the appended claims rather than the foregoing description, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

S100: washing the oyster shell
S200: step of drying oyster shell
S300: Step of calcining oyster shell
S400: Step of making oyster shell as slurry

Claims (7)

(a) washing the oyster shell with distilled water and an organic solvent;
(b) drying the oyster shell of step (a);
(c) calcining the oyster shell of the step (b); And
(d) preparing the oyster shell of step (c) as a slurry.
The method according to claim 1,
The organic solvent may include,
Ethyl alcohol. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt;
The method according to claim 1,
The step (c)
(C) a step of first crushing before the step (c)
Wherein the step (c) further comprises a second pulverization step after the step (c).
The method according to claim 1,
The step (c)
Wherein the pretreatment is carried out in an electric furnace at 800 to 1,200 DEG C for 1 to 4 hours.
The method according to claim 1,
The step (d)
Wherein the slurry is milled in a high-density polyethylene container to produce a slurry.
6. The method of claim 5,
Preferably,
And milling the slurry at 80 to 150 rpm for 30 to 180 minutes using alumina balls having a diameter of 20 to 30 mm.
The method according to claim 1,
The step (d)
Wherein the oyster shell of step (c) and distilled water are mixed at a weight ratio of 1:25 to 75 and milled.

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