KR20000074335A - Method for highly biologically the tannery waste-water - Google Patents

Abstract

PURPOSE: An advanced biological treatment system is provided, which is characterized in that the system can treat leather wastewater containing the high-concentrations of nitrogen and heavy metals without physical and chemical pre-treatments. The system has the advantages such as the shortening of removal times for COD, BOD, TSS and TN, 50% of chemicals cost and 40% or more of sludge generation rate. CONSTITUTION: An advanced biological treatment system for leather wastewater consists of the following steps: a screening step to remove solid wastes with a fixed size; a first anaerobic/anoxic step to react with anaerobic digestion and denitrification; a first and a second aerobic steps to cultivate aerobes with air and organic matter; a first settling step to clarify treated water from the former steps; a returning step for the clarified water from the settling step to the first anaerobic/anoxic step; a returning step for activated sludge from the settling step to the first anaerobic/anoxic step and the first aerobic step; a second anaerobic/anoxic step to react with the clarified water from the settling step; and a second settling step to clarify treated water from the former step.

Description

METHOOD FOR HIGHLY BIOLOGICALLY THE TANNERY WASTE-WATER}

The present invention relates to a biological treatment method of leather wastewater, and in particular, in the wastewater treatment method using the A / O method and the MLE method, the high-concentration leather wastewater containing a large amount of chromium, sulfur, etc. is changed by appropriately changing sludge return. The present invention relates to a method for biologically advanced treatment of leather wastewater that enables biological treatment without pretreatment and also reduces sludge generated.

In general, the leather manufacturing industry emits malignant wastewater and causes pollution of water quality such as rivers, lakes, coasts and bays. In particular, leather manufacturers are mostly small companies and are concentrated in the water supply area of the Seoul metropolitan area. In addition, leather manufacturers generate a large amount of sludge (that is, impurities mixed in water, oil, etc., deposited on the bottom) during wastewater treatment, and environmental burdens for treating the wastewater account for about 10% of the production cost.

For the reasons described above, the pollution state of public waters such as appeals, inner bays and inland seas, and small and medium urban streams is very prominent. As a result, the achievement rate of Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD), which are water quality standards related to total nitrogen (N) and total phosphorus (P) such as appeal, internal bay and inland sea, are very high. Low condition. In addition, rivers, lakes and dams are often sources of drinking water, so mold odors, filter disturbances and abnormal growth of toxic algae have become a major environmental problem.

As described above, in the case of leather wastewater generated by a leather manufacturer, the wastewater generated in washing, lime dipping, tanning and dyeing processes among the various manufacturing processes is not only large, but also has high concentrations of organic and suspended solids. Since it contains chromium and sulfide, it is not suitable for biological treatment.Therefore, a large amount of sludge is generated due to biological treatment after pretreatment such as flow control, neutralization and flocculation precipitation. Mostly. In addition, due to severe odor problems and difficulties in the treatment of leather wastewater, it is urgently required to develop a countermeasure and an effective treatment method.

On the other hand, as a study on the biological treatment of leather wastewater described above, David was able to process BOD (Biochemical Oxygen Demand) using Carrousel method up to 5 ~ 6mg / L, and Maeda anaerobic digestion of leather sludge. L. Szpyrkowicz studied the inhibitory effects of chromium and sulfides in nitrification and denitrification systems, and reported that up to 43 mg / L and 91 mg / L had no effect on the process. Jackson-Moss studied the effects of chloride and found that microorganisms could be well adapted and treated to high concentrations of chloride-containing leather wastewater. In addition, Panzer conducted a study on nitrogen removal by nitrification / denitrification, and combined nitrification / denitrification system with 93% chemical oxygen demand (COD) removal efficiency and 97% nitrogen removal efficiency. Could.

A / O method and Modified Ludzack-Ettinger (MLE) method are the methods to remove surplus sludge from sedimentation tank while circulating the sludge of anoxic reactor and aerobic reactor, and leather in A / O method and MLE. Wastewater contains a large amount of chromium and sulfides, and if the sludge is circulated, Cr ³⁺ is oxidized to Cr ⁶⁺ due to the pH decrease during nitrification in the aerobic reactor, which has a fatal effect on activated sludge. Likewise, when the pH is lowered, oxidization is performed with sulfate, which accelerates the pH decrease in the aerobic reactor, thereby affecting activated sludge.

The present invention was devised to solve the problems as described above, and to present a biological treatment possibility of high concentration malignant wastewater, such as leather wastewater, and a method for biologically advanced treatment of leather wastewater to reduce sludge in the wastewater treatment process. The purpose is to provide. That is, leather wastewater containing high nitrogen, heavy load fluctuations and heavy metals such as heavy metals can be treated without physical and chemical pretreatment.

A second object of the present invention is to determine the influence on the substances and the like that inhibit the biological treatment process of leather wastewater.

The third object of the present invention is to be able to treat a large amount of industrial wastewater by treating a large amount of wastewater in a short time.

A fourth object of the present invention is to improve anaerobic digestion and denitrification in one reactor to improve the treatment efficiency of organic high concentration malignant wastewater.

The fifth object of the present invention is not to remove the activated sludge in the sedimentation tank, but to return the activated sludge to the first anaerobic and anoxic reactor to be decomposed by anaerobic digestion to be used as a carbon source that is likely to be insufficient in denitrification. There is no need for supply.

The sixth object of the present invention is to return the supernatant of the settling tank to the first anaerobic and anoxic reaction tank to be diluted with the incoming wastewater, and to remove nitrate that is not completely removed from the second anoxic reactor by denitrification. .

Features of the present invention configured to achieve the above object are as follows. That is, the process of storing the raw waste water filtered out the suspended matter with a filter of 2mm; A first anaerobic and anaerobic reaction process for continuous anaerobic digestion and denitrification of the wastewater introduced from the raw wastewater storage process; A first and second aerobic reaction step of continuously culturing a mixed group of microorganisms in the presence of dissolved oxygen using various organic matters of wastewater introduced from the first anaerobic and anoxic reaction step as incubators; An air injection step of injecting air into each of the first and second aerobic reaction steps; A first sludge settling step of precipitation of sludge from the wastewater that passed through the second aerobic reaction step; Returning a portion of the supernatant of the first sludge settling step to the first anaerobic and anoxic reaction step; A step of returning the activated sludge precipitated in the first sludge precipitation process to the first anaerobic and anoxic reaction step and the first aerobic reaction step; A secondary anaerobic and anoxic reaction step of continuously culturing a mixed group of microorganisms under anoxic conditions by using various organic matters of wastewater that have undergone the first sludge settling process as an incubator; And a second sludge settling step of precipitating sludge from the wastewater introduced through the second anaerobic and anoxic reaction step and discharging the supernatant to the outside.

The first anaerobic and anaerobic reaction process of the above-described configuration may be further provided with a step of discharging the sludge to the outside.

The above-described first anaerobic and anaerobic reaction process may further include a step of maintaining the introduced wastewater at an appropriate temperature for the growth of microorganisms.

Meanwhile, each of the first anaerobic and anoxic reaction process, the first sludge settling process, the second anaerobic and anoxic reaction process, and the second sludge settling process may further include a step of stirring the introduced wastewater.

In addition, each of the first aerobic reaction process and the second anaerobic and anaerobic reaction process may be further provided with a process for adjusting the pH of the introduced wastewater.

In the above configuration, the first anaerobic and anaerobic reaction process, the first aerobic reaction process, the first aerobic reaction process, the second aerobic reaction process, the second aerobic reaction process, the first sludge precipitation process, the first sludge precipitation process Wastewater flowing into the secondary anaerobic and anoxic reaction process from the secondary anaerobic and anoxic reaction process to the secondary sludge settling process is preferred to be introduced by the head of the water.

1 is a block diagram showing a wastewater treatment apparatus according to the present invention.

** Description of symbols for the main parts of the drawing **

10. Primary anaerobic and anoxic reactor 12, stirrer

14. Heater 16. Sludge Outlet

20. First Unit Reactor 22. Blower

24, 32. Aeration pipe 30. Second aerobic reactor

40. Primary sludge settling tank 42. Stirrer

44, 46. Sludge conveying pipes 44 ', 46'. Sludge Return Pump

48. Supernatant return pipe 48 '. Supernatant return pump

50. Second anaerobic and anoxic reactor 52. Agitator

60. Secondary sludge settling tank 62. Stirrer

The biological treatment method for reducing leather wastewater and sludge according to the present invention enables the anaerobic digestion and denitrification to occur directly in the first and second anaerobic and anaerobic reaction processes without undergoing physical and chemical pretreatment of high concentration leather wastewater. Only the supernatant of the secondary anaerobic and anaerobic reaction process is allowed to flow into the next stage of the first aerobic reaction process by water head tea, and the accumulated sludge can be regularly removed within the first anaerobic and anaerobic reaction process. to be.

The composition for the advanced biological treatment of leather wastewater according to the present invention is to inject air into the raw wastewater storage process, the first anaerobic and anaerobic reaction process, the first and second aerobic reaction process, the first and second aerobic reaction process, respectively Process, the first sludge settling process to precipitate sludge, the process of returning part of the supernatant to the first anaerobic and anoxic reaction process, the sludge is returned to the first anaerobic and anoxic reaction process and the first aerobic reaction process, the second It consists of anaerobic and anaerobic reaction process and secondary sludge settling process.

The raw waste water storage process is a process for storing industrial wastewater (leather wastewater) leaked from a factory, etc. In this process, the wastewater is stored after filtering a floating material having a predetermined size or more using a 2mm filter. On the other hand, the stored wastewater is transferred to the first anaerobic and anaerobic reaction process.

The first anaerobic and anaerobic reaction process is for the continuous anaerobic digestion and denitrification of the wastewater from the raw wastewater storage process. The anaerobic digestion and denitrification is carried out under anoxic conditions.

On the other hand, in the first anaerobic and anoxic reaction process, excess sludge is discharged to the outside by the sludge discharge process, and the wastewater of the first anaerobic and anoxic reaction process is slow even during anaerobic digestion and denitrification under anoxic conditions. 25-25 rpm) Stirring is performed continuously by the stirring process. Wastewater, which has undergone anaerobic digestion and denitrification, is sent to the first aerobic process by chicken pox.

The 1st and 2nd aerobic reaction process is to supply sufficient oxygen to the wastewater which passed the first anaerobic and anoxic reaction process to remove nitrogen in the wastewater through nitrification. An air injection process is provided to supply oxygen to the wastewater. Nitrogen present in the wastewater is nitrified by injecting oxygen into the first and second aerobic reaction processes. Wastewater from the first and second aerobic reaction processes is transferred to the first sludge sedimentation process by the head difference.

The first sludge settling process is to precipitate activated sludge from the wastewater which has undergone the second aerobic reaction process and separate it from the treated water.In the first sludge settling process, the precipitated activated sludge is the first anaerobic and anaerobic reaction process and the first. A step for returning to the first aerobic reaction step and a step for returning part of the supernatant of the first sludge settling step to the first anaerobic and anoxic reaction step are provided. Further, there is further provided a stirring step of stirring the wastewater at a slow speed (rotational speed of 1 rpm) while the wastewater is precipitated in the primary sludge precipitation process.

As described above, the purpose of returning the activated sludge precipitated in the primary sludge settling process to the first anaerobic and anoxic reaction step and the first aerobic reaction step is to dispose of excess sludge in the first anaerobic and anoxic reaction step. In the aerobic reaction process, the purpose is to maintain the amount of microorganisms.

On the other hand, in order to completely remove excess nitrate and organic compounds, the purpose of the supernatant conveyance step for returning a part of the supernatant (treated water) in the primary sludge settling step to the first anaerobic and anoxic reaction step is to remove the activated sludge. This is to return to the first anaerobic and anoxic reaction process instead of the secondary sludge settling process to be decomposed by anaerobic digestion and to be used as a carbon source that is likely to be insufficient in denitrification so that an external carbon source is not required. Meanwhile, the wastewater that has undergone the first sludge sedimentation process is transferred to the second anaerobic and anoxic reaction process by the head of water.

The second anaerobic and anaerobic reaction process is to remove the nitrates generated in the first and second aerobic reaction processes. The mixed population will be cultured continuously. Secondary anaerobic and anaerobic reaction processes also undergo anaerobic digestion and denitrification as in the first anaerobic and anaerobic reaction processes. In addition, the wastewater of the second anaerobic and anaerobic reaction process is continuously stirred by a slow (rotating speed of 25 to 30 rpm) stirring process during anaerobic digestion and denitrification under anoxic conditions. After anaerobic digestion and denitrification, the wastewater is sent to the secondary sludge sedimentation process by water head tea.

Secondary sludge sedimentation is a process for sedimenting sludge from wastewater that has undergone a secondary anaerobic and anoxic reaction process, and is a process for discharging only the treated water (supernatant) to the outside in a state in which activated sludge is precipitated. On the other hand, the secondary sludge settling step is further provided with a stirring step for stirring the wastewater at a slow (rotational speed 1rpm) during the sedimentation of the wastewater. The treated water discharged from the secondary sludge sedimentation process is discharged to rivers, lakes, bays and inland seas.

The summary of the leather wastewater treatment method of the present invention configured as described above is as follows. In other words, the first anaerobic and anaerobic reaction process for the continuous anaerobic digestion and denitrification of the wastewater from the original wastewater storage process, the wastewater storage process, and the first anaerobic and anoxic reaction process Air injection process for injecting air into each of the first and second aerobic reaction processes, the first and second aerobic reaction processes, which continuously incubate a mixed group of microorganisms in the presence of dissolved oxygen, using various organic matters of the wastewater, The first sludge settling process that precipitates the wastewater introduced from the first aerobic reaction process, the part of the supernatant of the first sludge settling process is returned to the first anaerobic and anoxic reaction process, and the activated sludge precipitated in the first sludge settling process is Various organic matters from wastewater that passed through the anaerobic and anaerobic reaction process and the first aerobic reaction process and the first sludge settling process As a secondary sludge settling process to precipitate active sludge from the wastewater introduced in the second anaerobic and anoxic reaction process to continuously cultivate a mixed group of microorganisms under anoxic conditions, and to discharge the supernatant to the outside. Is done.

On the other hand, in addition to the above-described process, the first anaerobic and anoxic reaction process further includes a step of discharging the sludge to the outside and a step of maintaining the introduced wastewater at an appropriate temperature for the growth of microorganisms.

In addition, each of the above-described first anaerobic and anaerobic reaction process, the first sludge settling process, the second anaerobic and anoxic reaction process and the second sludge sedimentation process is further provided with a step of stirring the introduced wastewater, while the first aerobic reaction Each of the process and the second anaerobic and anaerobic reaction process is further provided with a process for adjusting the pH of the wastewater introduced.

In the above configuration, the first anaerobic and anaerobic reaction process, the first aerobic reaction process, the first aerobic reaction process, the second aerobic reaction process, the second aerobic reaction process, the first sludge precipitation process, the first sludge precipitation process Wastewater flowing into the secondary anaerobic and anoxic reaction process from the secondary anaerobic and anoxic reaction process to the secondary sludge sedimentation process is introduced by water head tea.

As described above, in the present invention for purifying and treating leather wastewater, each process is continuously performed. In other words, the first and second anaerobic and anaerobic reaction processes, the first and second aerobic reaction processes, the first and second sludge settling processes, the sludge conveyance process, and the supernatant return, while the leather wastewater flows into the raw wastewater storage process. The process, the sludge discharge process, the temperature maintenance process, the stirring process and the pH adjusting process are continuously performed.

As described above, in the treatment of leather wastewater using the biological treatment method for reducing the leather wastewater and sludge of the present invention, COD, BOD, TSS ( Solid suspended solids) and TN (total nitrogen) removal efficiency is almost the same, but the removal time is about twice as fast as the conventional method, the drug cost is reduced by about 50%, the sludge reduction rate was about 40% or more.

Hereinafter, with reference to the accompanying drawings will be described in detail a biological advanced treatment method of leather wastewater in accordance with a preferred embodiment of the present invention.

1 is a block diagram showing a wastewater treatment apparatus according to the present invention.

Before explaining the present invention as illustrated in the drawings, look at the experimental apparatus and method for examining the properties of the leather wastewater as follows.

First, as a material for investigating the characteristics of the leather wastewater, the leather wastewater generated from the I company in the city of D and the K company of the city of Y was used. The leather wastewater was used for the analysis after filtering the suspended matter with a 2 mm filter.

Modified A / O and MLE process systems used in the experiments according to the invention are as shown in FIG. 1. The experimental apparatus according to the present invention as described above for the precipitation of sludge of the first and second anaerobic and anoxic reactors (10, 50) and the first and second aerobic reactors (20, 30) and wastewater made of 10L volume of acrylic material It consists of the first and second sludge settling tank (40, 60).

In the above-described configuration, the first and second anaerobic and anoxic reaction tanks 10 and 50 are provided with agitators 12 and 52 for mixing sludge by stirring at a rotational speed of 25 to 30 rpm, and the first and second aerobic reaction tanks ( 20, 30) is provided with a blower (40L / min; 22) and the width pipes (24, 32), which is an air injection device for maintaining the DO concentration of waste water at 5 ~ 6mg / L, the first and second sludge sedimentation tank ( 40 and 60 are provided with agitators 42 and 62 having a rotational speed of 1 rpm to agitate the sludge.

Meanwhile, in the primary sludge settling tank 40, sludge conveying pipes 44 and 46 and sludge conveying pumps 44 'and 46 for conveying sludge to the first anaerobic and anaerobic reaction tank 10 and the first aerobic reaction tank 20 are provided. ′) Is provided. In addition, the primary sludge settling tank 40 is provided with a supernatant liquid conveying pipe 48 and a supernatant liquid conveying pump 48 'for conveying the supernatant to the primary anaerobic and anaerobic reaction tank 10.

The temperature of the primary anaerobic and anoxic reactor 10 is maintained at 25 ° C. using a 100 W heater 14, and the external temperature of the primary anaerobic and anoxic reactor 10 is a cold / hot air fan (not shown). Keep at 25 ± 5 ℃.

Referring to the operation of the experimental apparatus according to the present invention configured as described above, first, the leather wastewater generated in the leather processing plant is filtered through a 2mm filter and then introduced into the first anaerobic and anoxic reactor 10. Leather wastewater introduced into the first anaerobic and anaerobic reactor 10 undergoes anaerobic digestion for a certain period of time to decompose and extinguish organic matter and undergo a denitrification process for a certain period of time. During this denitrification, the nitrate nitrogen present in the leather wastewater is removed.

On the other hand, the heater 14 is controlled by a control circuit (not shown) during the denitrification process of the leather wastewater introduced into the first anaerobic and anoxic reactor 10 so that the first anaerobic and anoxic reactor 10 The wastewater temperature is maintained at the optimum growth temperature of the microorganisms.

In the first anaerobic and anaerobic reaction tank 10, the leather wastewater from which nitric acid is removed to some extent by the denitrification is introduced into the first aerobic reactor 20 by hydrocephalus. At this time, the oxygen is injected into the leather wastewater through the driving pipe 24 and the width pipe 24 installed in the inner lower portion of the first exhalation reaction tank 20 so that the nitrification microorganisms can be continuously expanded, thereby ammonia-containing in the leather wastewater. Remove nitrogen.

In addition, the primary exhalation reactor 20 through a pH control circuit (not shown) in order to facilitate the nitrification of the leather wastewater in the primary exhalation reactor (2) conditions that microorganisms can be satisfactorily propagated. The pH of the leather wastewater is maintained at an appropriate level.

Activated sludge and leather wastewater stayed in the primary exhalation reactor 20 for a predetermined time is introduced into the secondary exhalation reactor 30 by water head difference. The reaction in the secondary exhalation reactor 30 is operated in the same manner as the primary exhalation reactor 30. However, the pH control is made only in the first breathing tank 20.

Activated sludge and leather wastewater stayed in the second aerobic reaction tank 30 for a predetermined time is introduced into the primary sludge settling tank 40 by the water head tea to precipitate the activated sludge. At this time, the sludge precipitated in the primary sludge settling tank 40 through the sludge conveying pipes 44 and 46 and the sludge conveying pumps 44 'and 46' is the first anaerobic and anoxic reactor 10 and the first exhalation reactor ( 20).

Activated sludge returned to the first anaerobic and anoxic reactor 10 is decomposed by anaerobic digestion and used as an organic source during denitrification. The surplus sludge returned to the primary exhalation reactor 20 is used to hold microorganisms in the primary exhalation reactor 20.

In the first anaerobic and anaerobic reactor (10), solid substances that are not decomposed even through anaerobic digestion and harmful substances such as chromium and sulfur accumulate, so that the first anaerobic and anaerobic reactor (10) is periodically stored through the sludge outlet (16). Removes accumulated sludge

Meanwhile, a part of the supernatant of the primary sludge settling tank 40 is returned to the primary anaerobic and anoxic reaction tank 10 through the supernatant conveying pipe 48 and the supernatant conveying pump 48 ', and the primary anaerobic and anoxic reaction tank 10 The supernatant returned to) is diluted with the raw wastewater flowing into the primary anaerobic and anoxic reactor 10 and used to remove excess nitrate and organic compounds.

Activated sludge and leather wastewater stayed in the primary sludge settling tank 40 for a predetermined time is introduced into the secondary anaerobic and anoxic reaction tank 50 by the head water. The activated sludge and the leather wastewater introduced into the secondary anaerobic and anoxic reactor (50) were stirred to mix well through the stirrer (52), so that the nitrate nitrogen and residual organic matter produced in the secondary aerobic reactor (30) were brought to the legal discharge level. Remove

The treated water and activated sludge purified in the secondary anaerobic and anoxic reactor 50 are introduced into the secondary sludge settling tank 60 by the head difference. The supernatant is discharged through an outlet (not shown) by separating the mixture of the treated water and the activated sludge introduced from the secondary anaerobic and anoxic reactor 50 by physical precipitation.

In the wastewater treatment apparatus for purifying and treating leather wastewater through the reaction process, each reaction process proceeds continuously. In other words, even during the inflow of raw wastewater, the first and second anaerobic and anaerobic reaction processes, the first and second aerobic reaction processes, the first and second precipitation processes, the stirring process, the excess sludge conveying process, and the supernatant conveying process are performed. It proceeds continuously.

As an experimental method, activated sludge (MLSS; 9,000mg / L) of denitrification and dephosphorization plant in Y city was added to the reaction tank, and the dilution water of leather wastewater was adjusted to pH 10 ± 2. Activation and stabilization for about 3 months.

On the other hand, in this process, to reduce the sludge, the raw wastewater is removed with a 2 mm diameter filter, and then flows directly into the primary anaerobic and anoxic reactor (10) without undergoing pretreatment (primary physical and chemical treatment). The waste water introduced into the anoxic reaction tank 10 was slowly stirred through a stirrer 12 having a rotation speed of 25 to 30 rpm to maintain a completely mixed state so that sludge did not flow into the first aerobic reactor 20. As such, the wastewater introduced into the first anaerobic and anaerobic reaction tank 10 is denitrated and endogenous respiration to remove organic matter and nitrate nitrogen.

Meanwhile, the supernatant of the first anaerobic and anaerobic reactor 10 is introduced into the first and second aerobic reactor 20 to remove some organic matter and ammonia nitrogen while undergoing nitrification, and the supernatant and the sludge are the first sludge settling tank. Inflow to (40). The supernatant and sludge of the first sludge settling tank 40 are returned to the first anaerobic and anoxic reactor 10 at a ratio of 1Q and 0.2Q, respectively, and the sludge of the first sludge settling tank 40 is first aerobic reactor at a ratio of 0.8Q. It returns to (20) and adjusts the MLSS of the primary exhalation reactor 20. At this time, the excess sludge is discharged from the first anaerobic and anaerobic reaction tank (10). HRT is 2.5 to 3 days in this process, SRT is 5 days, and the return cost is operated at 2.

In the above-described experiment _{pH, COD cr, TKN, TSS} , NH 4 + -N, NO 3 - -N, TP, Cr and S2 ^- analysis was analyzed by spectrophotometer (Spectrophotometer) method in accordance with standard methods. BOD ₅ was analyzed by water quality test method (KSM 0111 (93)}, Cl ^- was analyzed by Mercuric Thiocyanate Method, and color was analyzed by Platinum-Cobalt Method.

Next, the properties of the raw water of the leather wastewater and the properties of the treated water of the wastewater subjected to the process according to the present invention are compared through Tables 1 and 2.

Properties of Raw Water in Leather Wastewater (Unit: mg / L, Excluding pH) Item content maximum at least Average pH 12.4 9.9 11.2 COD _cr 5,250 1,250 3,450 BOD ₅ 2,342 2,171 2,286 TSS 13,233 1,300 5,117 TKN 1,006 633 883 NH ₄ ⁺ 513 323 446 NO ₃ ^- 500 30 185 TP 30 ND 3 S ^2- 384 ND 69 CR 98 175 100

* N = 49 average (except max and min)

Properties of treated water of the process according to the invention (unit: mg / L, excluding pH) Item content maximum at least Average pH 8.8 7.0 8.1 COD _cr 850 250 526 COD _Mn 162 149 156 NH ₄ ⁺ 33 13 27 NO ₃ ^- 95 0 16 TP 18 10 10 S ^2- 0.01 0.00 0.01 CR ND ND ND Color 172 150 154

* N = 49 average (except max and min)

* Color unit: Pt Co Color

As shown in Tables 1 and 2, it can be seen that other items such as TN except COD satisfy the effluent discharge limit.

On the other hand, the result of operating the A / O process for about 80 days is the same as the graph showing the results of the characteristics of the leather wastewater in the second aerobic reaction process of Table 3 and the second anaerobic and anaerobic reaction process of Table 4.

As shown in the graphs of Tables 3 and 4, COD _cr , NH ₄ ⁺ -N, NO ₃ ^-- N and TSS showed removal efficiencies of 84.8%, 93.9%, 91.4% and 97.1%, respectively.

On the other hand, the graph of Table 5 shows the change in the appearance of waste water in each reactor over time.

As shown in Table 5, the COD and NO ₃ ⁻ -N removal rates in the first anaerobic and anaerobic reactor 10 are 74% and 70%, respectively, and the COD and NH ₄ ⁺ −N in the primary aerobic reactor 20 are 65%, 77%, secondary aerobic reactor 30 is 17%, 52%, COD, NO ₃ ^-- N removal rate in the secondary anaerobic and anoxic reactor 50 is 26%, 80%.

Generally, in the A / O process, excess sludge is removed from the sludge settling tank while circulating the sludge of each reactor. However, since the leather wastewater contains a large amount of chromium and sulfides, when the sludge is circulated, Cr ³⁺ is oxidized to Cr ⁶⁺ due to the pH decrease during nitrification in the aerobic reactor, which has a fatal effect on the activated sludge. Generally, the total Cr concentration that can be inhibited by microorganisms is known to be about 50 mg / L. Like chromium, sulfides are oxidized to sulphate when the pH is lowered, accelerating the pH lowering in the first aerobic reaction tank, and affects activated sludge like chromium when present at a certain amount (91 mg / L).

On the contrary, in the process according to the present invention, chromium and sulfides did not show an inhibitory effect even in the presence of about 100 mg / L and 150 mg / L, respectively. The primary anaerobic and anoxic reactor (10) prevents sludge outflow into the aerobic reactors (20, 30) while maintaining the pH above 8.0, and precipitates chromium and sulfides in the raw waste water in salt state. In 10) with sludge. Chromium was not detected in the effluent and sulfides were detected in small amounts (0.01 mg / L). In addition, no inhibitory effect on chloride was observed.

On the other hand, the characteristics of the leather wastewater, the ratio of total phosphorus is very low compared to the total nitrogen (N: P = 200: 1) to supplement the minimum phosphorus required for the nitrification process in the first aerobic reactor (20). After investigating the change in phosphorus over time, 2.5 ± 0.5ml of 1.4N KH ₂ PO ₄ was added to the primary exhalation reactor 20 at intervals of 24 hours in order to facilitate the nitrification of the primary exhalation reactor 20 in this process. Replenished. Since the second aerobic reactor 30 requires about 0.037 mg PO43--P / mg MLSS · day, a minimum amount of phosphorus should be replenished. The consumption of phosphorus by the MLSS in the primary exhalation reactor 20 and the consumption of phosphorus over time in the primary exhalation reactor 20 are shown as in the graphs of Tables 6 and 7.

As a result of analyzing the sludge produced by K and I companies, sludge produced by K company with daily treatment capacity of 1,620m ³ / day totaled 21,600kg / day. Sludge of about m ³ occurs. In addition, the small entrepreneurs I used this is 14.4~18.0kg / m ³ caused so 80~100m ³ / day capacity. In the process system according to the present invention, about 8.8 kg / m ³ of sludge is generated, and about 40% of the sludge generated is reduced compared to the conventional treatment method.

The experimental results for the modified A / O and MLE process system for the treatment of high concentration malignant wastewater such as leather wastewater are as follows.

First, the characteristics of the process according to the present invention is the raw wastewater input and sludge circulation. That is, to reduce the sludge generation, the raw wastewater of pH 10 ± 2 was directly added to the first anaerobic and anoxic reaction process without physical and chemical treatment and pH control of the raw wastewater. The sludge of the first anaerobic and anoxic reaction process was prevented from sludge inflow into the first aerobic reaction process by slow stirring (25 to 30 rpm), and all sludge produced in each process was removed from the first anaerobic and anoxic reaction process. This reduced the sludge by more than 40% and was able to efficiently remove harmful substances such as chromium and sulfides.

Second, L. Szpyrkowicz et al reported that in the nitrification and denitrification system, Cr is 43 mg / L, S ^2- is 91 mg / L does not inhibit, but in the experiment according to the invention Cr 100 in the raw waste water / L, S ^2- did not show an inhibitory effect on the biological treatment even in the presence of about 150 mg / L.

Third, the treated water of the A / O process is pH 8.2 ± 0.5, COD _cr 450 ± 50 mg / L, NH ₄ ⁺ -N 23 ± 10 mg / L, NO ₃ ^-- N 13 ± 5 mg / L, TP 6 ± mg / L, TSS 100 ± 30 mg / L, ghkdghkanfdms 0.01 mg / L, and chromium was not detected, satisfying the legal discharge limit.

Fourth, the A / O process was operated with hydraulic retention time (HRT) of 2.5 to 3 days, sludge receipt (SRT) for 5 days, and the return cost was 2 long, resulting in COD, NH ₄ ⁺ -N, NO ₃ ^-- N And TSS obtained removal efficiencies of 84.8%, 93.9%, 91.4% and 97.1%, respectively.

Fifth, it was suggested that high concentration malignant wastewater such as leather wastewater can be treated only by biological process without physical and chemical pretreatment.

As described above, in the treatment of leather wastewater using the biological treatment device for reducing the leather wastewater and sludge of the present invention, COD, BOD, TSS ( Solid suspended solids) and TN (total nitrogen) removal efficiency is almost the same, but the removal time is about twice as fast as the conventional method.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea of the present invention. In addition, the wastewater treatment apparatus according to the present invention is not only leather wastewater, but also livestock industry, animal husbandry food manufacturing industry, dairy product manufacturing industry, canned fishery manufacturing industry, marine fish products manufacturing industry, pickled vegetables manufacturing industry, miso manufacturing industry, soy sauce manufacturing industry, chemical seasoning manufacturing industry, sugar manufacturing industry, machinery It can be applied to waste water treatment in dyeing industry, printing industry, manure processing industry, slaughterhouse, etc.

As described above, by applying the leather wastewater treatment method according to the present invention, the treatment efficiency is similar to that of a high concentration and malignant leather wastewater, which is similar to the biological treatment after the conventional physical and chemical pretreatment with only pure biological treatment. The effect which can shorten processing time more than 2 times is exhibited.

Another effect of the present invention is that the treatment process of the leather wastewater by the pure biological treatment method without the conventional physical and chemical pretreatment is omitted by the conventional chemical input process is omitted, reducing the chemical cost by about 50% or more to maintain the operating cost of the wastewater treatment apparatus The saving effect is exerted.

Another effect of the present invention is to reduce the amount of sludge generated by about 40% or more by applying a method of decomposing by conventional anaerobic digestion rather than by removing the excess sludge in the sedimentation tank. Therefore, the environmental burden of the enterprise can be reduced to reduce the production cost of leather products.

On the other hand, another effect of the present invention is that it can treat a large amount of wastewater in a short time with a small plot, there is an effect that can be applied to large-scale high concentration industrial wastewater treatment.

In addition, the present invention can efficiently treat industrial wastewater containing a large amount of harmful substances such as heavy metals, and since heavy metals are concentrated in the excess sludge, the material required for the process can be recovered and reused.

Claims (6)

Raw waste water storage process for storing the raw waste water from which particles of a predetermined size or more; A first anaerobic and anaerobic reaction process for continuously performing anaerobic digestion and denitrification of the wastewater introduced from the raw wastewater storage process; A first and second aerobic reaction step of continuously culturing a mixed group of microorganisms in the presence of dissolved oxygen using various organic matters of wastewater introduced from the first anaerobic and anoxic reaction step as incubators; An air injection step of injecting air into each of the first and second aerobic reaction processes; A first sludge precipitation step of precipitating activated sludge from the wastewater that passed through the second aerobic reaction step; Conveying a part of the supernatant of the primary sludge settling step to the primary anaerobic and anoxic reaction step; Returning the activated sludge precipitated in the primary sludge settling step to the first anaerobic and anoxic reaction step and the first aerobic reaction step; A second anaerobic and anoxic reaction step of continuously culturing a mixed group of microorganisms under anoxic conditions using various organic matters of the wastewater that passed through the first sludge settling step as a cultivator; And a second sludge settling step of precipitating activated sludge from the wastewater introduced in the second anaerobic and anoxic reaction step and discharging the supernatant to the outside. The method of claim 1, wherein the first anaerobic and anoxic reaction step further comprises the step of discharging the sludge to the outside. The method of claim 2, wherein the first anaerobic and anaerobic reaction process further comprises the step of maintaining the introduced waste water at an appropriate temperature for the growth of microorganisms further comprises. The method of claim 3, wherein the first anaerobic and anoxic reaction process, the first sludge settling process, the second anaerobic and anoxic reaction process and the second sludge settling process are further provided with a step of stirring the introduced waste water. Advanced biological treatment of leather wastewater. 5. The method of claim 4, wherein each of the first aerobic reaction process and the second anaerobic and anaerobic reaction process further comprises a step of adjusting pH of the introduced wastewater. The process according to any one of claims 1 to 5, wherein in the first anaerobic and anoxic reaction step, the first aerobic reaction step, in the first aerobic reaction step, in the second aerobic reaction step, and in the second aerobic reaction step, Leather, characterized in that the wastewater flowing into the secondary sludge settling process, the first sludge settling process to the second anaerobic and anoxic reaction process, and the second anaerobic and anoxic reaction to the second sludge settling process Advanced biological treatment of waste water.