KR20020016674A - Advanced Piggery Wastewater Treatment System - Google Patents

Abstract

PURPOSE: Provided is an advanced wastewater treatment system for livestock wastewater which contains the organic matter of high concentration, suspended solids, nitrogen, phosphorus and colors. CONSTITUTION: The advanced wastewater treatment system comprises a pre-treatment tank(2) to remove selectively ammonium and phosphorus in livestock wastewater; an anaerobic reactor(3) for denitrification of the wastewater passed from the former part by oxidative fermentation in the upper denitrification zone; a nitrification reactor(4); a post-treatment tank(6) to remove the residual nitrate of the anaerobic reactor and the nitrification reactor; and a fenton-oxidation reactor(8) to eliminate phosphorus, organic matters and colors in the wastewater treated from the former post-treatment tank and disinfect. The pre-treatment tank comprises a mixing tank and a settling tank, which enhance the denitrification efficiency by maintaining the ratio of organic matters : nitrogen of 6 : 1 by the MAP(magnesium ammonium phosphate) settling method.

Description

Advanced Piggery Wastewater Treatment System

The present invention is a pretreatment tank (2), anaerobic reaction tanks (3-1, 3-2), nitrification tank (4), to treat livestock wastewater containing a high concentration of organic matter, suspended solids, nitrogen, phosphorus and color The present invention relates to an advanced treatment system composed of a treatment reaction tank (6) and a fenton oxidation tank (8), and is a process capable of economically and efficiently removing various contaminants present in livestock wastewater.

In general, livestock wastewater contains not only high concentrations of suspended solids but also organic matter, nitrogen, phosphorus, and chromaticity. It is difficult. In addition, the conventional techniques lack the accurate technical evaluation of the removal factors of nutrients such as nitrogen and phosphorus to increase the operating cost by using excess methanol in the nitrogen removal process, and remove the phosphorus remaining after the biological treatment process In order to provide a coagulation sedimentation tank in which iron salt and a polymer coagulant are administered, not only the complexity of the process is caused but also the difficulty in selecting an optimal injection amount of the coagulant. In addition, the conventional technology is difficult to remove the additional organic matter after biological treatment, it is difficult to treat the chemical oxygen demand within the legal regulations.

Wastewater treatment method using a biological three-phase digestion process in a single reactor of the prior art (Korean Patent Registration No. 202066) is a conventional anaerobic / aerobic (A / O) process and anaerobic / quasi-anaerobic / aerobic (A2 / O) process. In order to solve the problem of nitrogen, phosphorus was removed from the anaerobic single reactor at the front end, and ammonia nitrogen was nitrified at the rear stationary stationary nitrification tank and recycled to the reactor at the front end. Not only is it difficult to do this, but it is necessary to control the alkalinity required for nitrification and to supply additional external carbon sources for denitrification. High efficiency living sewage treatment system (Korea Patent Registration No. 233565) using microbial control tank is a technology to treat home sewage, manure and livestock wastewater by anaerobic-aerobic process by culturing active microorganisms in microbial culture tank, but with high concentration of ammonia nitrogen Since it is not easy to remove nitrogen efficiently during inflow, and it is difficult to process chromaticity and residual chemical oxygen demand within legal limits, it may cause a lot of problems in the treatment process beyond the small scale purification tank. In addition, the biologically high efficiency nitrogen and phosphorus simultaneous removal system (Korean Patent Registration No. 232360) is similar to the conventional anaerobic-oxygen-aerobic process, and the removal efficiency of nitrogen and phosphorus in the wastewater is good, but microorganisms due to the high concentration of ammonia nitrogen are introduced. It is difficult to eliminate the increase of additional external carbon source, chromaticity and residual chemical oxygen demand due to inhibition of organic matter and lack of organic matter.

Wastewater treatment method using electrolysis to overcome the limitation of biological treatment (Korea Patent Registration No. 231331: Wastewater treatment method and wastewater treatment system using electrolysis, Korea Patent Registration No. 188231: Industrial wastewater continuous electrolytic purification treatment method and apparatus thereof Has been developed, but it is difficult to maintain and maintain periodic electrode pole exchange as well as the possibility of secondary pollution due to the addition of chemicals such as polymer flocculant and iron salt.

As described above, the conventional techniques lack the understanding of the concentration inflow method below the microbial inhibitory concentration to efficiently remove nitrogen in the livestock wastewater, and the biological treatment such as the addition of alkalinity required for nitrification and the increase of the organic carbon source required for denitrification. Not only is there a lack of research on ways to overcome the limitations of technology, but also difficult to maintain due to various process combinations.

SUMMARY OF THE INVENTION An object of the present invention is to provide a high level livestock wastewater treatment system, which is excellent in pollutant treatment efficiency, stable in operation, and low in operation cost, while solving the problems of the prior art described above. This object is achieved by pretreatment to remove some of the biologically difficult phosphorus and nitrogen and to significantly increase the organic / nitrogen ratio to induce subsequent denitrification-nitrification reactions. In addition, the oxidized nitrogen remaining after the denitrification-nitriding reaction is fed to methanol denitrification reactor along with the organic material source to reduce the nitrogen gas, and phosphorus, color and organic matter remaining after the above treatment process are fentonized. Treated water can be produced as follows.

1 includes a pretreatment tank 2, an anaerobic reactor 3-1, 3-2, a nitrification tank 4, a post treatment reactor 6, and a fenton oxidation tank 1 according to the present invention. Schematic diagram of a livestock wastewater advanced treatment system.

Explanation of symbols for the main parts of the drawings

1: solid-liquid separation tank 2: pretreatment tank

3-1: acid formation zone in anaerobic reactor

3-2: Denitrogen Zone in Anaerobic Reactor

4: nitrification tank 5: precipitation tank

6: post treatment reactor

7: External carbon source supply tank for denitrification

8: Fenton Oxidation Tank

Advanced livestock wastewater treatment system according to the present invention consists of pretreatment tank (2), biological denitrification-nitridation tank (3-1, 3-2, 4), post-treatment reaction tank (6) and fenton oxidation tank (8). .

The pretreatment according to the invention optionally removes ammonia nitrogen and phosphorus in the livestock waste water, which can lead to subsequent nitrification and denitrification continuous reactions in the acid fermentation and denitrification tanks. In the after-treatment reactor (6), the nitric oxide remaining in the front end is easily reduced to nitrogen gas through a media-filled denitrification reactor that is small in volume and easy to maintain, and then phosphorus, color and As a process that can achieve additional organic removal, water quality that satisfies the current legal regulations can be achieved.

In the following, the present invention is described in more detail with reference to FIG. 1.

The advanced livestock wastewater treatment system according to the present invention separates the incoming livestock wastewater into solid-liquid separation (1) and enters the pretreatment tank (2). In the pretreatment tank (2), a mixing tank and a precipitation tank are mixed by adding magnesium salt and inorganic phosphorus components. It adjusts the amount of chemicals to remove about 40-60% of ammonia nitrogen depending on the characteristics of livestock wastewater. This MAP (Magnesium Ammonium Phosphate) precipitation method removes only ammonia nitrogen from the livestock wastewater and induces struvite formation by using MgCl ₂ as a magnesium source to reduce the inhibition of high concentration ammonia nitrogen. Way. In general, in the MAP method, the struvite form precipitates rapidly within 30 minutes at a high value of pH 10 or more, but in the case of livestock wastewater, the pH value is about 8.0-8.5 so that a small amount of NaOH can control the pH. In addition, the generated sediment has a high value as a slow-acting fertilizer can be recycled as a fertilizer can reduce the treatment cost of the sludge. In the prior art, since most of the conventional technology is introduced into the biological nitrogen removal process without any pretreatment except solid-liquid separation, the organic matter / nitrogen ratio is less than 3: 1, which not only provides a factor of process deterioration in the subsequent denitrification process but also a large amount of denitrification. It needs an organic source. However, in the case of the present invention, organic matter / nitrogen can be maintained at least 6: 1 or higher, and further nitrogen removal rate of 75% or more can be achieved in a subsequent nitrogen removal process. During the biological nitrogen removal process consisting of the subsequent anaerobic reactors (3-1, 3-2) and nitrification tank (4), the anaerobic reactor (3) was operated in the range of 10-40 ° C. and stable in the acid formation zone (3-1). The denitrification zone (3-2) at the top of the reactor, which can induce hydrolysis and acid fermentation reactions, is a medium-filled composite reactor exhibiting denitrification. The nitrification reactor 4 is composed of an activated sludge process and is composed of three or more stages for efficient nitrification. If the above reaction characteristics are maintained, the amount of organic matter consumed for denitrogenation after complete nitrification can be reduced by about 50% compared with the case of no pretreatment. Maintenance costs can be greatly reduced. In general, when the nitrified treated water is recycled to the denitrification tank (3-2) in the range of 3-5 times the inflow flow, it is possible to further achieve a total nitrogen removal rate of 75-80% based on the pretreated water. In addition, through the above-described pretreatment, there is a big advantage that it is possible to exclude the addition of additional alkalinity causing material required for the nitrification of ammonia nitrogen in the livestock wastewater. In general, livestock wastewater contains higher alkalinity than wastewater, but shows about 50-60% of theoretical alkalinity due to high ammonia nitrogen concentration in the influent. In the present invention, even when the above-mentioned treatment process is operated efficiently, about 200-250 mg / l of nitrate nitrogen is discharged at the 2,000 mg / l inflow concentration in the high concentration livestock wastewater, so that an additional denitrification tank is inevitable. Ceramic-filled post-treatment reactor (6) was installed to minimize the land area, and the denitrification tank (6) introduced organic carbon source and returned symbol water together into the lower part of the reactor for denitrification by heterotrophic microorganisms. Digestion occurs to reduce nitrified nitrogen to harmless nitrogen gas. Through the above treatment process, most pollutants can be treated within the legal limit, but in the case of phosphorus and trace chemical oxygen demand (COD) and chromatic color which can be aesthetically indispensable, follow-up treatment is necessary. In the present invention, the Fenton oxidation tank (8) was introduced.

Hereinafter, the Example of this invention is described. However, the following examples are only preferred examples of the present invention to aid in understanding the present invention, and the present invention is not limited by these examples.

<Example>

In order to evaluate the wastewater treatment system according to the present invention, first, manure-separated pig wastewater containing relatively little solids was applied. The livestock wastewater is divided into the scrape type barn which is a manure separation type and the slurry type barn which is the manure consolidation type according to the type of barn, but in the case of the slurry type livestock wastewater with a relatively high concentration, the water quality of the sewage type piglet can be easily As the target wastewater can be achieved, a manure separation type scraper-type piglet was selected. In the pretreatment test of the present invention, ammonia degassing, MAP precipitation test, zeolite adsorption, etc. may be performed to initially reduce the nitrogen concentration in the livestock wastewater, but in the case of ammonia degassing, it may cause odor and secondary pollution, and in the case of zeolite, ammonium ion As the adsorption capacity was limited, the MAP precipitation method was selected, which can use by-products as slow fertilizer as well as stable treatment efficiency.

In addition, the following analysis method was used about the following example.

PH: pH meter (glass electrode method, Coring 120, TOA HM71)

Alkalinity: CaCO ₃ titration method

SS (suspended solids): Total amount of suspended solids dried for 2 hours in a drying oven at 103-105 캜 using a GF / C filter.

BOD ₅ : BOD measurement after 5 days

CODcr: Titration, K ₂ Cr ₂ O ₇ Closed Reflux

TKN: Determination of Organic Nitrogen and Ammonia Nitrogen (Micro Kjeldahl Method)

NH ₄ ⁺ -N: distillation and titration (Nonorganic Kjeldahl Method)

NO ₂ ^-- N: Colorimetric Method (λ = 543 nm)

NO ₃ ^-- N: Brucine-sulfate Method (λ = 410 nm)

TP (Total Phosphorus Content): Stannous Chloride Method (λ = 690 nm)

PO ₄ ^3- -P: Stannous Chloride Method (λ = 690 nm)

<Example 1>

Typical scraper-type pig wastewater with chemical oxygen demand 5,000-6,000 mg / l, biological oxygen demand 3,000-3,500 mg / l, ammonia nitrogen 1,500-2,200 mg / l, alkalinity 6,000-8,000, solids content 851 mg / l, pH 8.5 Was reacted for 2 hours at room temperature in an acrylic 20 L pretreatment tank, at which time 1714 mg / l magnesium and 2213 mg / l phosphorus were administered to remove 1000 mg / l of ammonia (based on molar concentration. Molar concentration equal to ammonia concentration, ie Mg ²⁺ : NH ₃ -N: PO ₄ ³ -P = 1: 1: 1). An acrylic anaerobic reactor equipped with a thermostat and an effective volume of 5.4 ℓ, a composite anaerobic reactor having a UASB (upflow anaerobic sludge blanket) type and an anaerobic filter (AF) type at the bottom, wherein the pretreatment tank is Coarse wastewater was introduced and operated at 20-25 ° C. in an organic volume load range of 0.5-1.0 kg COD / m ³ · day. Subsequently, it was introduced into a nitrification tank equipped with a thermostat (made of acrylic material, effective volume of 10L) and operated at a nitrogen volume load of 0.2-0.4 kg N / m ³ · day at about 25 ° C., followed by 2.5L of An acrylic aftertreatment reactor was filled with a ceramic carrier (Tricycle Vaporizer Co., Ltd.), and 0.79 g of methanol as a carbon source per liter of nitrate tank effluent was added to the aftertreatment reactor and allowed to react at room temperature. It was operated in the nitrogen volume load range of -1.0 kg / Nm ³ · day. Finally, 500 mg / l of iron salt and 750 mg / l of hydrogen peroxide were injected into the 1-liter Fenton oxidizing tank made of acrylic and operated for 2 hours or less, and the COD concentration at this time was 500 mg / l. As a result, a final product of 35 mg / l COD (80% removal) and 0.15 mg / l TP (99% removal) was obtained.

Comparative Example 1

The experiment was carried out in the same manner as in Example 1 except that the pretreatment step was excluded and 2.37 g of methanol as carbon source per liter of nitrate tank effluent was added to the aftertreatment reactor.

Experiments with a pretreatment process as in Example 1 and experiments without a pretreatment process as in Comparative Example 1 were performed several times, taking the products before entering the aftertreatment reactor and comparing the total nitrogen amounts in Table 1 below. Indicated.

Total Nitrogen Content in Nitrifier Effluent (mg / ℓ) If there is pretreatment process Without pretreatment maximum 905 1,605 Average 352 989 at least 135 789

According to the present invention, it is possible to achieve stable and excellent total nitrogen removal rate by removing some of phosphorus and nitrogen which are difficult to treat biologically in livestock waste through MAP pretreatment and greatly increasing organic / nitrogen ratio to induce subsequent denitrification-nitrification reaction. Can be. In addition, the oxidized nitrogen remaining after the denitrification-nitriding reaction is fed to methanol denitrification reactor along with the organic material source to reduce the nitrogen gas, and phosphorus, color and organic matter remaining after the above treatment process are fentonized. Treated water can be produced as follows.

Claims (3)

a) pretreatment tank for selectively removing ammonia nitrogen and phosphorus in livestock wastewater; b) an anaerobic reactor for acidifying the object to be passed through the pretreatment tank to denitrify in the upper denitrification zone; c) a nitrification reaction tank for nitrifying the treated water passing through the anaerobic reactor; d) a post-treatment reaction tank for inducing a denitrification reaction for removing the oxidized nitrogen remaining through the anaerobic reactor and the nitrification reactor with nitrogen gas; And e) Fenton oxidation tank which removes phosphorus, organic matter and chromaticity from the treated water passed through the after-treatment reaction tank and performs the phenton oxidation which produces disinfection effect. Livestock wastewater advanced treatment system comprising a. The method according to claim 1, wherein the pretreatment tank is composed of a mixing tank and a precipitation tank mixed with magnesium salts and inorganic phosphorus components, and the organic matter / nitrogen ratio is maintained at 6: 1 or more using MAP (Magnesium Ammonium Phosphate) precipitation method. By improving the denitrification efficiency livestock wastewater advanced treatment system. The method of claim 1, wherein the anaerobic reactor has a nitrogen removal rate of 75% or more, while reducing the amount of organic matter by 50% or more at the bottom of the acid formation zone at which the hydrolysis reaction and the acid fermentation reaction are induced at an operating temperature of 10 to 40 ° C. Livestock wastewater advanced treatment system consisting of a denitrification zone at the top.