KR20060091084A - Treatment method for livestock waste water including highly concentrated organic materials - Google Patents

Abstract

The present invention relates to a method for treating livestock wastewater containing a high concentration of organic matter. More specifically, the method for treating livestock wastewater of the present invention includes organic pollutants including BOD (biological oxygen demand) generating substance, COD (chemical oxygen demand) generating substance, SS (floating substance), etc. dissolved in the livestock wastewater. The first step is to remove the suspended solids above a certain size by passing a high density vibrating screen to greatly reduce the pollutant load, and then first dissolve and oxidize. After secondary flocculation, contaminants were separated by pressurized flotation or fine screen filtered, and the oxidized separated water was passed through a mechanical tower filled with ceramic media in two stages, and the polymer was changed into a water quality of pH 7-8 with a neutralizing agent. It is composed of the step of removing the remaining organic matter by injection, followed by microbial treatment in three stages, followed by precipitation and final discharge.

The livestock wastewater treatment method of the present invention composed of the above steps is useful in treating a large quantity of water due to higher processing efficiency than the general wastewater treatment process in the first stage of pretreatment, and can be prevented quickly when a load occurs, and the pretreatment of the first stage Due to the high processing efficiency in the process, it is possible to significantly reduce the load during the three-step microbial treatment, which is very economically advantageous.

Livestock Wastewater, Vibrating Screen, Oxidizer, Pressurized Flotation, Micro Screen, Ceramic Media Tower

Description

Treatment method for livestock waste water including highly concentrated organic materials}

1 is a simplified flow chart (Flow-Sheet) of the method for treating livestock wastewater of the present invention.

2 is a block diagram of a method for treating livestock wastewater according to a preferred embodiment of the present invention.

The present invention relates to a method for treating livestock wastewater containing a high concentration of organic matter. More specifically, the method for treating livestock wastewater of the present invention includes organic pollutants including BOD (biological oxygen demand) generating substance, COD (chemical oxygen demand) generating substance, SS (floating substance), etc. dissolved in the livestock wastewater. The first step is to reduce the pollutant load by passing through a high density vibrating screen to remove suspended solids above a certain size, and then the first dissolution and oxidation. After the secondary flocculation treatment, contaminants are separated by pressurized flotation or fine screen filtered, and the oxidized separated water is passed through a mechanical tower filled with ceramic media in two steps, and the water quality discharged from this is neutralized (pH7-8). It is composed of the step of injecting, removing the remaining organic matter, and again after the microbial treatment in three steps to precipitate the final discharge.

Livestock wastewater contains high concentrations of organic matter with BOD concentrations of 12,000 to 50,000 mg / L and SS concentrations of 20,000 to 30,000 mg / L.

In general, the organic material treatment method of livestock wastewater includes a long-term aeration method for storage aeration in a microbial tank for a long time, and a standard activated sludge method for treatment with a second aerobic microorganism after the first pressure flotation treatment. However, the long-term aeration method is difficult to diagnose early and prevent a lot of site demand and microbial load, and there is a costly economic burden of large aeration tank and sump facilities. In addition, the standard activated sludge method has a limited removal rate of contaminants during the first flotation treatment, and the variation in removal rate is large so that microorganisms are loaded when a high concentration of organic matter is removed into the post-treatment aeration tank to obtain stable treated water. There is a disadvantage that can not be.

In addition, many farmhouses have difficulty in treating livestock wastewater, and most farmers compost wastewater, or wastewater, which is difficult to treat, is charged with a wastewater consignment treatment company to pay a high cost. In particular, since the entrusted wastewater is a large amount of ocean dumping, there is a need for a method of treating livestock wastewater that can protect the natural environment and reduce the burden of economic operation and wastewater treatment of farmers.

Therefore, the present inventors have studied to solve the above problems, and after the high concentration livestock wastewater is passed through a vibrating screen to remove particulate suspended solids, the filtrate is first eluted and oxidized. Secondary flocculation treatment is used to separate contaminants into pressure flotation or filter with a fine screen, then pass through a ceramic filter tower, change to weak alkaline water, and inject a polymer flocculant to remove dissolved residual organic material and treat it as a microorganism. In this case, it was found that the removal efficiency of the contaminants in the pretreatment process can process a large quantity and significantly reduce the cost of the microbial treatment facility, and completed the present invention.

Accordingly, an object of the present invention is to provide a method for treating livestock wastewater which can reduce the installation cost of a microbial tank (aeration tank) with high treatment efficiency in the pretreatment process.

In order to achieve the above object, the livestock wastewater treatment method of the present invention is (1) primary elution and oxidation after passing the livestock wastewater solution through a high density vibration screen. Separating into a second flocculation process; (2) passing the oxidized separated water through a ceramic filter tower and changing it into a weak alkaline water, and then injecting a polymer coagulant to remove residual organic matter; And (3) precipitating and then finally discharging the microbial treatment.

Hereinafter, the present invention will be described in more detail at each step.

Livestock wastewater treatment process of the present invention is a livestock wastewater (collecting tank)-screen (vibration screen)-primary reaction tank-pressurized flotation tank (or fine screen)-secondary reaction tank-ceramic media tower-tertiary reactor-primary precipitation tank -Aeration tank (microbial tank)-Secondary sedimentation tank-Discharge, consisting of a brief flow chart (Flow-Sheet) is shown in Figure 1 below, the configuration of the livestock wastewater treatment process according to an embodiment of the present invention is shown in Figure 2 .

(1) Primary elution and oxidation of livestock wastewater through a high density vibration screen. Separation by secondary flocculation.

The livestock wastewater collected in the sump is passed through a high density vibration screen, preferably a 120 mesh vibration screen, to remove particulate suspended solids. At this time, the removal rate of the suspended solids is different depending on the quality of each farm and waste water, but when passed through a vibration screen of 120 mesh (mesh) is about 15-25%. Next, 199.2 to 1000 ppm of a coagulant such as ferrous sulfate (FeSO ₄ ) or ferric chloride (FeCl ₃ ) was added to the filtrate to cause primary elution, and then sulfuric acid (H ₂ SO ₄ ) Is added to maintain the pH of the wastewater at 1-2, and then an organic oxidizing agent, preferably potassium permanganate (KMnO ₄ ), is administered at 30 to 1000 ppm to oxidize and remove the organic matter in the water. The reason for adding sulfuric acid is because the livestock wastewater is in an alkaline state, so the oxidation reaction rate is slow, so that the oxidation reaction is performed quickly by making it an acidic water quality state. The concentration of the oxidizer (KMnO ₄ ) depends on the concentration of the raw wastewater, but 0.5 ppm of BOD-generating material can be removed per ppm of the oxidant. At this time, the smell and color of the wastewater unique may be partially removed.

Next, an alkaline agent (neutralizing agent) such as caustic soda (NaOH) or calcium hydroxide (Ca (OH ₂ )) is added thereto to neutralize or weakly alkalinize to pH 7-8, and then secondary agglomerate with a polymer flocculant to pressurize the tank (or Microliquid separation). Here, it is preferable that the micro screen has a body size of about 250 mesh.

In the above process, the removal rate of the entire pretreatment process is about 87%, and solid-liquid separation of the livestock wastewater is performed.

The pressure flotation process is a process of separating contaminants by introducing the condensed reaction wastewater of the primary reaction tank into the precipitation tank, and the principle thereof is as follows. That is, as shown in FIG. 2, pressurized water diverges into the atmosphere by inserting pressurized water, that is, water in which microbubbles are pressurized and dissolved in a portion of a pipe flowing into the pressurization tank from the first reaction tank. At the same time, microbubbles are generated due to the difference in atmospheric pressure, and one or several bubbles are attached to the coagulated oxidized agglomerated substance (Floc) to precipitate and separate. At this time, the attached contaminant is removed by the rotating scraper (Skimer) at the top, and the unattached contaminant is precipitated and separated. The water in the middle layer is completely separated, and it flows into the secondary reaction tank, is transferred to the machine tower, into the tertiary reaction tank, passes through the reaction and enters the first precipitation tank, and after the final microbial treatment (aeration tank), the sewage is passed through the sedimentation tank. Will be released.

As the oxidizing agent, potassium permanganate (KMnO 4) is preferable, and the use of the oxidizing agent oxidizes the dissolved organic material and forms a flocculated material, so that the separation between the water and the suspended matter becomes clear. At this time, the concentration of the oxidizing agent is generally determined by using Jar Test, which is introduced to determine the amount of chemicals in the reaction tank, thereby preventing excessive sludge generation and maintaining good preservation of treated water quality, and reducing the consumption of chemicals. .

As the polymer coagulant used in the above treatment step, an anionic polymer coagulant is preferable, and the amount thereof is generally determined by the Jar Test introduced to determine the amount of chemicals in the reactor.

On the other hand, sulfuric acid is used to maintain the pH of the wastewater at 1 to 2, and when the sulfuric acid is injected, the oxygen is instantaneously generated so that it is sprayed with a bubble generating spray device.

(2) passing the oxidized separated water through a ceramic filter column and changing it to a weak alkaline water quality, and then injecting a polymer coagulant to remove residual organic matter.

The contaminant separated through the above process is introduced into the secondary reactor. At this time, the separated water is treated with sulfuric acid to maintain a pH of 1-2. This is passed through a machine column filled with ceramic media, and the water quality is changed to neutral or weakly alkaline with pH 7-8, and a polymer coagulant is added to remove the undissolved organic matter from the tertiary reactor. . The flocculated material with polymer coagulant flows into the primary settling tank and is separated by forced precipitation.

The neutralizing agent and the polymer coagulant used in step (2) are the same as the specific examples in step (1).

(3) after the microbial treatment to precipitate and finally discharge.

After passing through the pretreatment process of steps (1) and (2), the pretreated supernatant is collected in a preliminary collection tank (flow control tank) and introduced into the microbial tank (aeration tank), and then the organic matter is removed by aerobic microorganisms and the microbial community ( The floc) is finally settled (secondary settling tank) and discharged to the stream and recycled to the cleaning water in the house.

On the other hand, the sedimentation sludge of the contaminants collected at the lower part of the pressure flotation tank (or fine screen) and the first and second settling tank is discharged to the lower part and flows into the concentration tank to treat dehydration cake, and the filtrate is returned to the sump tank. Is returned.

The method of treating livestock wastewater of the present invention consisting of the steps of (1) to (3) is capable of treating a large quantity due to the high treatment efficiency of step (1), and significantly reduces the load during microbial treatment of the post-treatment process. It is very economically advantageous because it can reduce the size of facility and the site of facility aeration tank.

Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited only to these examples.

In the following examples, the amount of raw water (livestock wastewater) used in each experiment was 500 ml / min x 10 hr (300 L / day), and the experiment operation time was 10 hours. The pollutants to be removed were biological oxygen demand (BOD) and suspended solids ( SS).

First, in the following examples, the separation of the pressurized flotation and the fine screen filtration are described together in one embodiment, unless it is a separate embodiment. When all the other conditions are the same, the pressurized flotation separation or the fine screen (250Mesh) filtration is performed. Note that there is no difference in the degree of removal of contaminants.

EXAMPLE

The stock solution (livestock wastewater) with the concentration of biological oxygen demand of organic pollutants of about 20,500ppm and the concentration of suspended solids of about 18,000ppm is passed through a vibrating screen (SUS304 120Mesh) to remove particulate suspended solids. Ferric chloride (FeCl3) as a coagulant was prepared at a concentration of 1,000 ppm and injected into the reactor to dissolve the suspended solids. Next, sulfuric acid 746.2 ~ 1,000ppm was added to the filtrate to maintain a pH of 1 ~ 2, and then 30ppm of organic peroxide oxidant potassium permanganate (KMnO ₄ ) was added to oxidize the organic matter. Next, neutralize it with caustic soda to pH 7 ~ 8, and add 150 ppm of A.Floc (A-101, Sein Corp.) as a polymer coagulant (Anion Type) to separate floc and pressurized flotation (or fine screen). The primary organics were separated by filtration (SUS304 250Mesh). The results are shown in Table 1 below.

As can be seen in Table 1, the concentration of the primary oxidation treated water was reduced by 87% compared to the concentration of the original wastewater.

Such high efficiency removal of contaminants is possible by injecting an appropriate amount of chemicals, and by adding sulfuric acid to maintain the pH of 1 ~ 2 while injecting sulfuric acid to increase oxidation efficiency, high concentration of organic matter oxidation is carried out by injecting potassium permanganate (KMnO4). I think it is because.

Meanwhile, the upper and lower sludges (or fine screen filtered sludges) separated from the pressure flotation were transferred to a concentration tank and dewatered, and the dehydration filtrate was introduced into the collection tank and the second reaction tank again. Dehydrated cakes are transported to the composting facility in the workplace for composting.

220-602ppm of sulfuric acid (H ₂ SO ₄ ) is added to the separated water introduced from the above-mentioned first pressure flotation tank (or fine screen) to maintain a hydrogen ion concentration (pH) of 1-2, and the ceramic filter tower Passed. Ceramic media (diameter 3mm, unit weight 1.3) is known to change the water quality to water quality of weak alkaline water by contacting a certain residence time (3Min) and has the effect of improving the turbidity of the water quality. 1000 mL (1,300 g) of media is required per 400 mL of water, and the amount of minute flow should be submerged in the container when calculating the ceramic media filler.

After neutralization by adding caustic soda, a neutralizer, to the water conversion water from the ceramic media tower, 150ppm of anion type A.Floc (A-101, manufactured by Sein Corp.) was forced to precipitate the pollutants in the secondary precipitation tank. After separation, the filtrate was sent to a post-treatment microbial tank (aeration tank) and finally discharged after aerobic microbial treatment and tertiary sedimentation. The results are shown in Tables 2 and 3 below.

As can be seen from the results in Table 2, the hydrogen ion concentration of the water treated with the neutralized treatment of the separated water was maintained at 1 to 2 to pass through the ceramic media charging tower, and the water quality was neutral or weak with an alkaline agent (neutralizing agent). The removal rate of the residual organic matter was increased by coagulating the residual organic matter after changing the water quality to alkaline. In particular, flocculation not only increased the flocculation effect by using anionic polymer coagulant, but also enhanced the reaction of soluble organic substances in water.

As can be seen in Table 3, the influent water flowing into the microbial tank (first, second aeration tank) has a low concentration of contaminants since most of the high concentration of contaminants have already been removed in the pretreatment step. Therefore, the pollutant load is low, which is suitable for the activation conditions of microorganisms, and it is economically possible because a large microbial tank is not required. In addition, the final effluent after the above-mentioned microorganism treatment was able to stably treat the contaminants of the livestock wastewater below the acceptable standard value in the Water Environment Conservation Act.

As described above, the livestock wastewater treatment method according to the present invention is useful in treating a large amount of daily water because the pretreatment process, which is the first stage of the treatment facility, has much higher treatment efficiency and better separation and precipitation than the general wastewater treatment process. When load occurs, it can be prevented in a short time, and the high processing efficiency in the first pretreatment can significantly reduce the load in the microbial treatment, which is the post-treatment process, to reduce the size of the aeration tank and reduce the site requirements.

Claims (9)

(1) The livestock wastewater solution is passed through a vibrating screen to remove particulate suspended solids, and then coagulant is administered to the filtrate to elute organic contaminants, and sulfuric acid (H ₂ SO ₄ ) is added to adjust the pH of the wastewater to 1-2. Acidifying with, followed by oxidizing the organics by the addition of an oxidizing agent, neutralizing with an alkaline neutralizing agent, and then coagulating and separating the oxidized and separated particulate matter with a polymer coagulant; (2) adding sulfuric acid to the separated water separated in step (1) to acidify the pH to 1-2, then passing it through a mechanical tower filled with ceramic media and changing the pH to 7-8 with an alkaline neutralizer. Injecting and separating the precipitate; And (3) after the treatment of the supernatant separated in step (2) microorganisms, the step of sedimentation into a microbial community (floc) and finally discharged. The method of claim 1, wherein the size of the body of the vibrating screen is about 120 mesh. The method of claim 1, wherein the flocculant is ferrous sulfate (FeSO ₄ ) or ferric chloride (FeCl ₃ ). The method of claim 1, wherein the oxidizing agent is potassium permanganate (KMnO4). The method of claim 1, wherein the ceramic column is filled with a ceramic filter having a diameter of 3 mm is filled with 1000 mL (1,300 g) per 400 mL of the treated water. The method of claim 1, wherein the separating in the step (1) is a step of agglomeration of the oxidatively separated particulate matter with a polymer flocculant to separate the resultant into a pressurized flotation. The method of treating livestock wastewater according to claim 1, wherein the separating in step (1) is a step of coagulating the oxidatively separated particulate material with a polymer flocculant and filtering the fine screen. The method of treating livestock wastewater according to any one of claims 1 to 6, wherein the polymer coagulant is an anionic polymer coagulant. The method of claim 7, wherein the size of the body of the microscreen is about 250 mesh.

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