KR20150056429A - Treating Method of Sewage comprising sludge and waste water using solvent extraction - Google Patents

Abstract

The present invention relates to a method for treating sewage comprising sludge and waste water using solvent extraction. The method comprises the steps of: mixing waste water and a solvent and extracting at least a part of sludge with the solvent; separating waste water and the solvent after extraction; and primarily separating the solvent and the sludge.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sludge-

The present invention relates to a method for treating wastewater containing sludge and wastewater, and more particularly to a method for treating wastewater containing sludge and wastewater using a solvent extraction method.

Under the London Convention, Korea will be prohibited from dumping the sewage sludge by 2014. Therefore, it is urgent to develop a technology that can treat sewage efficiently.

In the conventional treatment method, organic sludge, microorganisms and heavy metals present in the sewage are agglomerated / precipitated with water together with a polymer flocculant. According to this treatment method, as shown in Fig. 1, the sludge mass having a specific gravity of about 1.2 is separated / recovered.

This is because the water acts as a medium to connect the particles in a condition where the water content is 25% or more.

There are two reasons why the water content of the polymer flocculant is more than 25%. First, particles of organic sludge generally have a small particle size of less than 200 μm, so the capillary between them is too small to allow the outermost number to easily escape. The second reason is that the microorganisms present in the sewage are not destroyed. The amount of water in the microorganisms accounts for about 40% of the total water after the flocculation treatment.

For this reason, in the conventional method, only 15-20% of the water out of the 60% outermost water except the 40% body water present in the microorganism can be dehydrated through mechanical dehydration.

Therefore, there is a problem in the existing treatment method that secondary treatment such as heat treatment / dry incineration is necessary to meet the moisture content standard for recycling or landfilling treatment.

Korean Patent Registration No. 10-0371823 (disclosed on Feb. 11, 2003) Korea Patent Publication No. 2012-0120106 (disclosed on 11.01.2012)

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a sewage treatment method which can easily remove moisture from sludge using a solvent extraction method.

It is an object of the present invention to provide a method of treating wastewater containing sludge and wastewater using solvent extraction, comprising the steps of: mixing the wastewater with a solvent to extract at least a portion of the sludge with the solvent; Separating the wastewater and the solvent after the extraction; And separating the solvent and the sludge from each other.

The solvent may include a hydrocarbon-based solvent and an alcohol-based solvent of CxHy (x is 5 to 8, and y is 8 to 18).

The hydrocarbon-based solvent may be a mixture of at least two or more materials.

The alcohol-based solvent may be used in an amount of 1 to 15 parts by weight based on 100 parts by weight of the hydrocarbon-based solvent.

The method may further include diluting the sewage with additional water before the extraction.

The primary separation of the solvent and the sludge can be performed by a mechanical method.

After the primary separation step of the solvent and the sludge, secondary separation of the organic sludge and the solvent may be performed under the condition that the vaporization activity is increased.

The secondary separation can be performed at room temperature.

After the primary separation, the sludge may be further subjected to briquetting or pelletizing.

The sludge comprises a microorganism, and the solvent is capable of destroying the microorganism.

Destruction of the microorganism can be performed in the extraction step.

The solvent can be reused in the extraction step after recovery in the separation step.

The diluting, extracting and separating steps may be carried out in an enclosed closed system.

According to the present invention, there is provided a method for treating sludge which is easy to remove water from the sludge using a solvent extraction method.

1 shows the structure of an agglomerated mass obtained by a conventional sludge treatment method,
2 shows a flow of the sludge treatment method according to the first embodiment of the present invention,
FIG. 3 illustrates the extraction step in the sludge processing method according to the first embodiment of the present invention,
4 is a view illustrating a sludge / solvent primary separation step in the sludge treatment method according to the first embodiment of the present invention,
FIG. 5 illustrates a sludge / solvent secondary separation step in the sludge treatment method according to the first embodiment of the present invention,
6 shows sewage before solvent extraction in the experimental example according to the first embodiment of the present invention,
7 shows the wastewater after solvent extraction in the experimental example according to the first embodiment of the present invention,
8 shows the sludge powder obtained by the sludge treatment method in the experimental example according to the first embodiment of the present invention,
9 shows a flow of the sludge treatment method according to the second embodiment of the present invention,
10 shows POME before and after dilution in the experimental example according to the second embodiment of the present invention,
11 shows an oil recovery solvent after recovering oil and grease in an experimental example according to the second embodiment of the present invention,
12 is a view showing an organic sludge-extracted solvent in an experimental example according to the second embodiment of the present invention,
FIG. 13 is a view showing the discharged water discharged in the experimental example according to the second embodiment of the present invention,
FIG. 14 shows the sludge powder obtained by the sludge treatment method in the experimental example according to the second embodiment of the present invention.

The present invention relates to a method of treating wastewater containing sludge and wastewater using solvent extraction, comprising the steps of: extracting at least a part of the sludge with a solvent by mixing sewage and a solvent; Separating the wastewater and the solvent after extraction; And separating the solvent and the sludge first.

The sewage in the present invention means a mixture of wastewater and sludge. Sludge contains organic sludge, microorganisms and some minerals, and in some cases may only contain organic sludge. The scope of application of the present invention includes all wastewater including domestic wastewater, industrial wastewater, livestock wastewater and organic sludge Household wastewater can be discharged from residential facilities, public facilities, hospitals, and business facilities.

The organic sludge may be composed of food waste, manure, and the like.

In the present invention, the solvent extraction method used for metal extraction is applied to extract the sludge in the sewage as a solvent, and the outermost number of the organic sludge is easily removed in the solvent extraction process. The microorganism of the sludge is destroyed by the solvent, and the microorganism can be easily crystallized.

In the following description, it is exemplified that the sludge includes both organic sludge and microorganisms.

Hereinafter, a sewage treatment method according to the present invention will be described in detail with reference to the accompanying drawings.

2 shows a flow of the sewage treatment method according to the first embodiment of the present invention.

First, the sewage is diluted to be suitable for solvent extraction (S100). The dilution is to control the sludge concentration in the sewage taking into account the reaction ratio of the wastewater to the solvent. If the sludge concentration in the sewage is within a range suitable for the solvent extraction process, this step may be omitted. In addition, depending on the concentration of sludge in sewage, process conditions such as solvent usage can be changed in solvent extraction, and the dilution step may be omitted in this case.

In another embodiment, the sludge concentration and / or composition in the sewage can be monitored and subsequent process conditions can be varied according to the observed results. Sludge concentration and / or component observations can be made in real time.

Next, the solvent and the sewage are mixed to extract the sludge (S200). The organic solvent is used as the solvent. At this stage, solvent extraction is performed in which the organic sludge and the microorganism migrate to the organic solvent.

The organic solvent may include CxHy (x is from 5 to 8, y is from 8 to 18) hydrocarbon-based solvents and alcohol-based solvents. The hydrocarbon-based solvent may be a mixture of at least two materials, and the alcohol-based solvent may be 1 to 15 parts by weight based on 100 parts by weight of the hydrocarbon-based solvent. The specific gravity of the organic solvent may be 0.4 to 0.9, and may be 0.5 to 0.7. Organic solvents may be more volatile than water.

This process will be described in detail with reference to FIG. Organic sludge before extraction, microorganism, wastewater and organic solvent exist. When these are mixed, the organic sludge particles bind to organic solvents having lower specific gravity. Organic sludge particles whose specific gravity is lighter than water through bonding with organic solvent are separated from the surface water while moving rapidly to the organic solvent layer. In the case of microorganisms, 40% of the crystals in the microorganism are easily removed by microbial destruction by the organic solvent. The microorganisms bound to the organic solvent also migrate to the organic solvent layer.

Extraction can be carried out under turbulent conditions, and the turbulence conditions can be formed by machinery that causes a pressure difference between the inlet and the outlet, a rheological machine equipped with a baffle, a mixer, or a stirrer. Extraction can be carried out in batch or continuous reactions. In order to improve the extraction rate, a co-current multistage extraction method or a counter-current multistage extraction method may be used.

Through this process, organic wastewater sludge and microorganisms migrate to the organic solvent layer and are separated from wastewater.

Next, the waste water phase and the organic solvent phase are separated (S300). This process can be carried out using conventional methods of separation and separation. The separated wastewater can be used or discharged as industrial, household, or agricultural water after appropriate treatment. In another embodiment, the separated wastewater can be used for dilution (S100) of the wastewater.

On the other hand, when sewage contains heavy metals, heavy metals can also be extracted by organic solvents. In this case, since the heavy metal content of the wastewater is greatly reduced, the use of the wastewater is easy. In another embodiment, a separate organic solvent may be used to remove heavy metals in the wastewater or sludge, or a separate process may be added.

Thereafter, the sludge and the organic solvent are firstly separated (S400). The primary separation can be performed through any machine capable of solid-liquid separation such as a vacuum filter, a filter press, a belt press, a screw dehydrator, and a centrifugal dehydrator. The primary separation may be performed by a mechanical method, and a single mechanical method may be performed multiple times or a plurality of mechanical methods may be used.

This process will be described in detail with reference to FIG. The organic sludge before the primary separation and the surface of the microorganism are combined with an organic solvent. Through primary separation, most organic solvents are recovered from organic sludge and microorganisms.

Next, the organic solvent on the surface of the sludge is secondarily separated (S500).

This process will be described with reference to FIG. The secondary separation of the organic solvent can be performed at room temperature, and compressed air can be added to help recover the remaining organic solvent. Compressed air plays a role in establishing a condition for increasing the vaporization activity of the organic solvent. The compressed air collides with the organic solvent, and the organic solvent is diffused and vaporized by the collision. In other embodiments, other means of increasing the vaporization activity of the organic solvent in addition to providing the compressed air may be used.

If secondary separation of the organic solvent is performed at room temperature, energy for recovering organic solvent is saved because there is no additional energy consumption for temperature rise. In addition, when the organic solvent used is more volatile than water, the energy consumption for obtaining the final sludge is reduced as compared with the conventional process.

In another embodiment, the secondary separation may be performed at ambient temperature to 50 < 0 > C, or may utilize a vacuum.

The secondary separation can be performed in batch or continuous processes. When carried out in a continuous process, the organic solvent can be recovered while transferring the sludge to an in-tube powder transfer device in the form of an air amplifier, a tank containing a rotating body such as a fan, a blower, a cyclone, a conveyor belt or a spiral conveyor.

Sludge with a water content of less than 10% can be obtained through secondary separation.

The sludge obtained may be in powder form. Sludge can be produced in the form of briquettes or pellets and can be used as a fuel source, and can be used with coal, especially in fossil fuels such as thermal power plants and co-generation power plants. The calorific value of the sludge may be between 3500 and 5500 kcal / kg.

The organic solvent recovered in the primary separation and the secondary separation can be used again in the extraction process. A step of regenerating all or a part of the recovered organic solvent may be added, and a certain amount of the organic solvent may be replaced with a new organic solvent.

In another embodiment, the extraction efficiency of the organic solvent or the component change of the organic solvent may be observed to automatically inform the replacement time of the organic solvent. Observation of extraction efficiency or component changes can be made periodically or irregularly, and it is also possible to observe in real time. Extraction efficiency or component changes can be monitored by sampling organic solvents or remotely via instruments.

The sewage treatment described above can be performed in a closed system in which the outside and the inside are separated. In this case, the occurrence of other additional reactions is intrinsically blocked and the risk of secondary environmental pollution is reduced.

According to the present invention as described above, even microorganisms are destroyed and odor can be removed, and sludge is used as a resource, and waste treatment cost is not generated. Dewatering of the sludge is easy and energy cost for dehydration is greatly saved. In addition, the treatment of the wastewater can be carried out in a closed system, suppressing the occurrence of undesired reactions and reducing the risk of secondary environmental pollution. In addition, it does not affect the wastewater treatment efficiency of the existing sewage treatment plant, so it is easy to install the existing facility as an auxiliary device and it is also possible to replace the existing dewatering system. In addition, it is easy to equip large-capacity facilities through device-intensive processes.

Hereinafter, the present invention will be described in more detail with reference to an experimental example according to the first embodiment.

The sewage used in the experiment was collected from the U City Y sewage treatment plant and shows a turbid appearance as shown in FIG. The MLSS (mixed liquor suspended solids) was 5027 mg / L.

Sewage and organic solvents were mixed at a ratio of 1: 0.0005 at room temperature and solvent extraction was performed under a turbulent condition for 5 minutes.

FIG. 7 shows the wastewater from which the organic solvent phase is separated after standing, showing that the sludge is sufficiently removed as compared with FIG.

FIG. 8 is a view of an organic sludge powder dried by primary and secondary separation.

Table 1 below shows the components and calorific value data of the recovered organic sludge. The high calorific value was 3,876 kcal / kg, which is the calorific value that can be fully applied to thermal power plants.

Components and calorific value of recovered organic sludge Test Items unit Results ¹⁾ Test Methods Fixed carbon % 9.2 ASTM D 5142-04 (applicable) Ash % 6.2 ASTM D 5142-04 (applicable) Volatile matter (VM) % 78.9 ASTM D 5142-04 (applicable) moisture % 3.7 ASTM D 5142-04 (applicable) Sulfur % 0.37 KS E ISO 334: 2003 (applicable) High calorific value kcal / kg 3876 KS E 3707: 2001 (applicable)

1) The remaining 1.63% is other components such as nitrogen and phosphorus.

Hereinafter, the flow of the sludge treatment method according to the second embodiment of the present invention will be described with reference to FIG.

Palm Oil Mill Effluent (POME) refers to wastewater generated when palm oil is produced in a palm oil refining facility. Due to the difficult nature of wastewater refining process, it is an environmental problem in six Southeast Asian countries that currently produce palm oil .

In Malaysia, about 172 million tons of oil are generated annually at 430 Palm Oil Mill, and the amount is increasing every year. POME has a problem that it is difficult to treat with general sewage treatment technology due to the characteristics including not only very high BOD and COD but also a large amount of Total Solids, Suspended Solids, Volatile solids and Oil & Grease.

Table 2 shows the general characteristics of POME.

General characteristics of POME (mg / L, excluding pH) Parameter Average range Regulated value
(Malaysia) pH 4.2 3.4-5.2 5-9 Biological oxygen demand (BOD) 25,000 10,250-43,750 100 Chemical oxygen demand (COD) 51,000 15,000-100,000 - Total Solids 40,000 11,500-79,000 - Suspended Solids 18,000 5,000-54,000 400 Volatile solids 34,000 9,000-72,000 N / A Oil and Grease 6,000 130-18,000 50 Ammoniacal Nitrogen 35 4-90 100

Currently, the POME treatment techniques include 1) ponding system, 2) conventional physico-chemical treatment, 3) aerobic and anaerobic digestion methods, and so on. have. However, in most cases, it is difficult to manage volatile gas capture and collection systems such as slow processing time (reservoir treatment: 45 to 60 days, aerobic & anaerobic treatment: 4 to 10 days) ), And so on, POME is not properly processed.

Meanwhile, the Sugar Mill Effluent (SME) is a term used to refer to wastewater generated during sugar production in a sugar cane refinery. It has a wastewater characteristic similar to POME.

WWF reports that 145 million tonnes of sugarcane are harvested in 120 countries each year and Brazil accounts for about 41% of the world market, producing about 60 million tonnes of sugar cane. The amount of SME generated is so large that there is no statistical value, and in many countries it is very environmentally burdensome because most of the SMEs are flowing into rivers because of the weak regulation. Table 3 shows the daily wastewater generation of a typical 2500 TCD Sugar plant.

Typical 2500 TCD Sugar plant daily wastewater discharge (m ³ / day) Source Wastewater generation (m ³ / day) Mill bearing (External cooling) 100 Hot liquid gland cooling 150 Daily cleaning and washing 100 Laboratory use 6 Domestic 90 Spray pond overflow 102 Excess condensate 200 Boiler Blow-down 75 Periodical Cleaning 75 Leakages & Stream Trap 100 Total 998

It is also reported that about 13 L of wastewater, known as vinasse, is produced when producing 1 L of bioethanol from sugarcane.

Table 4 shows the general characteristics of SMEs.

General characteristics of SME (mg / L, except pH) Parameter range pH 6.5-8.8 Dissloved Oxygen 0-2.0 Biological oxygen demand (BOD) 300-2,200 Chemical oxygen demand (COD) 1,360-2,000 Total Solids 870-1,950 Total dissolved Solids 400-1,650 Suspended Solids 220-790 Chlorides 18-40 Sulphate 40-70 Oil and Grease 60-100

The present invention is also useful for the processing of POME and SME, and FIG. 9 shows a flow for POME and SME processing.

The second embodiment for the POME and SME processing adds an oil / grease recovery step (S150) in comparison with the first embodiment.

In the oil / grease recovery step (S150), oil and grease residues contained in POME and SME are separated / recovered, and an extraction method using an oil recovery solvent can be used. The oil recovery solvent can be an organic solvent, which is specially formulated and the organic solvent containing oil and grease is recovered. The recovered organic solvent can be used as an energy source of oil itself and can be separated from oil and grease by a special separation device such as a heating / coagulation recovery device or a membrane separation membrane, and can be used again in the extraction process .

The total retention time of the process according to the present invention can be as short as 4 to 10 days, 45 to 60 days, in a short time (about 1 to 2 hours) It is an efficient and economical process that can separate and recover grease, and can also be used as an energy source.

Hereinafter, the present invention will be described in more detail with reference to experimental examples according to the second embodiment.

Experiments were performed on POME with an MLSS concentration of 57,400 (mg / L). POME and oil recovery solvent were mixed at a room temperature of 1: 0.0005 in a volume ratio of 5 min. Then, POME and organic solvent were mixed at a ratio of 1: 0.0005 at a room temperature for 5 minutes under a turbulent condition, and then the solvent phase and the aqueous phase were separated.

FIG. 10 shows the POME before and after the dilution in the experimental example according to the second embodiment of the present invention, and FIG. 11 shows the POME after the recovery of oil and grease in the experimental example according to the second embodiment of the present invention. FIG. 12 is a view showing a solvent in which organic sludge has been extracted in an experimental example according to a second embodiment of the present invention, and FIG. 13 is a graph showing the results of the final treatment of the experimental example according to the second embodiment of the present invention FIG. 14 is a view showing the sludge powder obtained by the sludge treatment method in the experimental example according to the second embodiment of the present invention.

As can be seen from the results in this experimental example, the POME can be effectively treated by the present invention.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation and that those skilled in the art will recognize that various modifications and equivalent arrangements may be made therein. It will be possible. Accordingly, the true scope of protection of the present invention should be determined only by the appended claims.

Claims (13)

A method of treating wastewater comprising sludge and wastewater using solvent extraction,
Mixing the sewage and the solvent to extract at least a portion of the sludge with the solvent;
Separating the wastewater and the solvent after the extraction;
And separating the solvent and the sludge. The method according to claim 1,
The solvent may be,
CxHy (x is from 5 to 8, y is from 8 to 18) hydrocarbon-based solvent and alcohol-based solvent. 3. The method of claim 2,
Wherein the hydrocarbon-based solvent is a mixture of at least two substances. The method of claim 3,
Wherein the amount of the alcohol-based solvent is 1 to 15 parts by weight based on 100 parts by weight of the hydrocarbon-based solvent. The method according to claim 1,
Before the extraction,
Further comprising adding water to the sewage to dilute it. The method according to claim 1,
Wherein the primary separation of the solvent and the sludge is performed by a mechanical method. The method according to claim 6,
After the primary separation step of the solvent and the sludge,
Further comprising the step of secondarily separating the organic sludge and the solvent under the condition of increasing the vaporization activity. The method according to claim 1,
Wherein the secondary separation is performed at room temperature. The method according to claim 1,
After the primary separation,
Further comprising the step of briquetting or pelletizing the sludge. The method according to claim 1,
Wherein the sludge comprises microorganisms,
Wherein the solvent is capable of destroying the microorganism. 11. The method of claim 10,
Destruction of the microorganism may be caused by,
Wherein the step (b) is performed in the extraction step. The method according to claim 1,
The solvent may be,
Wherein the waste water is recovered in the separation step and then reused in the extraction step. The method according to claim 1,
Characterized in that said dilution, extraction and separation steps are carried out in an enclosed closed system with the outside.

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