KR102073881B1 - Treatment method of leachates from landfill and device thereof - Google Patents

Abstract

The present invention relates to a landfill leachate treatment method and apparatus therefor. More specifically, the present invention relates to a landfill leachate treatment method capable of effectively reducing contaminants contained in a landfill leachate having a high salt concentration. The present invention also relates to an apparatus therefor. The landfill leachate treatment method comprises: a first step of preparing the landfill leachate; a second step of conducting a softening process; a third step of removing precipitates produced; a fourth step of conducting liquefaction; and a fifth step of removing the precipitate.

Description

Landfill leachate treatment method and apparatus {Treatment method of leachates from landfill and device

The present invention relates to a landfill leachate treatment method and apparatus, and more particularly, to a landfill leachate treatment method and apparatus for effectively reducing the contaminants contained in the dome-type landfill leachate having a high salt concentration. will be.

In general, leachate from waste landfills varies in water quality and amount depending on many environmental variables such as type of waste, landfill waste, landfill period, landfill type, landfill method, rainfall, climatic conditions and waste compaction. Recently, due to the development of living standards and industrial technology, the quality of leachate has become more diverse and complex due to the landfill of new synthetic materials.

Most of organic materials such as BOD and COD in the early landfill leachate are present in VFA (Volatile Fatty Acids) type, and the VFA component decreases over time and Fulvic-Like Material, ie Carboxyl Group, Aromatic Hydroxyl Group, etc. will increase. Nitrogen is a contaminant that causes difficulties in leachate treatment with hardly degradable organic substances such as vulvic-like materials. Nitrogen contained in leachate is about 5 times when the landfill time has elapsed for about 5-6 years. It shows a tendency to increase over, and the concentration range is usually varied from 300 to 4,000 mgN / l.

In the conventional method of treating the sanitary landfill leachate, the process consisting of “anaerobic digestion → activated sludge → chemical flocculation → filtration → advanced treatment” is a form in which each unit process is slightly changed and combined according to the situation. One of these processes consists of “Aerobic Digestion → Aeration Type → Sedimentation Tank → Rotary Disc Process → Sedimentation Tank → Mixed Aggregation → Sand Filtration → Ozone Treatment (or Activated Carbon Filtration)” (Korean Patent Publication No. 97-015493) ). Another treatment process consists of "anaerobic digestion → activated sludge → fenton oxidation → granular activated carbon treatment" (Korean Patent Publication No. 97-042328). On the other hand, there is also a method of treatment with a reverse osmosis membrane as a physicochemical treatment (Korean Patent Publication No. 97-010662).

Meanwhile, in order to bury and dispose of wastes economically and efficiently, an air dome type waste landfill is installed and used. The leachate generated in the air dome type landfill is generally high in concentrations of pollutants such as COD and nitrogen due to the air dome that blocks the inflow of rainwater, and especially calcium salts containing calcium ions in excess. In addition to the high concentration of salt, there is a problem that the treatment of leachate is not possible in the general biological wastewater treatment process treatment.

The present invention has been made in view of the above, and relates to a landfill leachate treatment method and apparatus for effectively purifying a landfill leachate containing a large amount of contaminants and salts containing hardly decomposable organic substances and nitrogen. will be.

In order to solve the above problems, the landfill leachate treatment method of the present invention is a first step of preparing a landfill leachate containing calcium salt and contaminants containing more than 10,000 mg / L COD _Cr and 2,000 mg / L nitrogen, A second step of softening by adding a carbonate (CO ₃ ^2- ) precursor to the prepared landfill leachate, a _third step of generating a precipitate by adding a flocculant to the softened landfill leachate and removing the precipitate In the fourth step of vaporizing the landfill leachate from which the sediment was removed under vacuum conditions and liquefactioning the vaporized landfill leachate again, and adding an adsorbent and a flocculant to the liquefied landfill leachate, a precipitate was formed. It may include a fifth step of removing.

According to a preferred embodiment of the present invention, the calcium salt may comprise calcium ions 300 ~ 900 mg / L.

According to a preferred embodiment of the present invention, in the second step, a base may be added to the prepared landfill leachate to be softened after adjusting the pH to 9 to 13.

According to a preferred embodiment of the present invention, in the second step, 0.08 to 0.24 parts by weight of a carbonate (CO ₃ ^2- ) precursor may be added to 100 parts by weight of the prepared landfill leachate.

According to a preferred embodiment of the present invention, the carbonate (CO ₃ ^2- ) precursor is sodium carbonate (Na ₂ CO ₃ ), sodium bicarbonate (NaHCO ₃ ), potassium carbonate (K ₂ CO ₃ ) and potassium bicarbonate (KHCO ₃ ) It may include one or more selected from.

According to a preferred embodiment of the present invention, in the third step, an acid is added to the softened landfill leachate, and after adjusting the pH to 3 to 7, a coagulant may be added to generate a precipitate.

According to a preferred embodiment of the present invention, in the third step, 0.05 to 0.5 parts by weight of the inorganic flocculant and 0.05 to 0.3 parts by weight of the polymer flocculant may be added to 100 parts by weight of the softened landfill leachate.

According to a preferred embodiment of the present invention, the fourth step of vaporization may be carried out for 1 to 5 hours at a temperature of 70 ~ 100 ℃, pressure of -760 ~ -580 mmHg.

According to a preferred embodiment of the present invention, the liquefaction of the fourth step may be carried out for 0.3 to 1 hour at a temperature of 35 ~ 65 ℃, pressure of 740 ~ 780 mmHg.

According to a preferred embodiment of the present invention, in the fifth step, caustic soda (NaOH) is added to the liquefied landfill leachate, and after adjusting the pH to 5-9, an adsorbent and a flocculant may be added to generate a precipitate.

According to a preferred embodiment of the present invention, in the fifth step, 0.05 to 0.5 parts by weight of the adsorbent, 0.05 to 0.5 parts by weight of the inorganic flocculant and 0.05 to 0.3 parts by weight of the polymer flocculant may be added to 100 parts by weight of the liquefied landfill leachate. .

According to a preferred embodiment of the present invention, the coagulant of the third and fifth steps may each independently include an inorganic coagulant and a polymer coagulant.

According to a preferred embodiment of the present invention, the inorganic flocculant is ferric sulfate (Fe ₂ (SO ₄ ) ₃ ), ferric chloride (FeCl ₃ ), aluminum sulfate (Al ₂ (SO ₃ ) ₃ ) and poly aluminum chloride (PAC) It may include one or more selected from.

According to a preferred embodiment of the present invention, the polymer flocculant may include at least one selected from a nonionic flocculant, a cationic flocculant, and a neutral flocculant.

According to a preferred embodiment of the present invention, the adsorbent of the fifth step may include at least one selected from activated carbon, zeolite, graphite and carbon nanotubes (CNT).

On the other hand, the landfill leachate treatment apparatus of the present invention is a collection tank for collecting and collecting landfill leachate containing calcium salt and more than 10,000 mg / L COD _Cr and 2,000 mg / L nitrogen, introduced through the collection tank A first reaction tank for softening by adding a carbonate (CO ₃ ^2- ) precursor to the landfill leachate, a second reaction tank for adding a flocculant to the landfill leachate introduced through the first reaction tank to produce a precipitate, the production The adsorbent is added to the third reactor and the landfill leachate introduced through the third reactor to vaporize the landfill leachate introduced through the second reaction tank from which the precipitate is removed and to liquefaction the vaporized landfill leachate again. And a fourth reaction tank in which a flocculant is added to generate a precipitate.

According to a preferred embodiment of the present invention, the landfill leachate collected in the sump tank calcium salt may include a calcium ion 300 ~ 900 mg / L.

According to a preferred embodiment of the present invention, the first reaction tank may be softened by adjusting the pH to 9 to 13 by adding a base to the landfill leachate introduced through the sump.

According to a preferred embodiment of the present invention, the second reaction tank can be added to the landfill leachate introduced through the first reaction tank (acid), after adjusting the pH to 3 to 7 to generate a precipitate by adding a flocculant have.

According to a preferred embodiment of the present invention, the fourth reactor is added caustic soda (NaOH) to the landfill leachate introduced through the third reactor, the pH is adjusted to 5 ~ 9, and then the adsorbent and flocculant are added to the precipitate. Can be generated.

The landfill leachate treatment method and apparatus of the present invention can effectively purify the landfill leachate containing a large amount of pollutants and salts, including hardly decomposable organic substances and nitrogen, in a simple and easy manner.

1 is a flow chart showing a treatment process of landfill leachate according to an embodiment of the present invention.
Figure 2 is a flow chart showing a treatment process of landfill leachate according to another preferred embodiment of the present invention

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.

Landfill leachate treatment method of the present invention comprises a first step to a fifth step.

First, the first step of the landfill leachate treatment method of the present invention may prepare a landfill leachate. In this case, the landfill leachate is a leachate generated in the landfill of the air dome type, and may include contaminants and calcium salts.

The contaminants contained in the landfill leachate may include hardly decomposable organic substances and nitrogen, and preferably, the hardly decomposable organic substances COD _Cr are 10,000 mg / L or more, preferably 10,000-30,000 mg / L, more preferably. May include 15,000 to 25,000 mg / L, and may include nitrogen at 2,000 mg / L or more, preferably 2,000 to 4,000 mg / L, more preferably 2,500 to 3,500 mg / L.

In addition, the calcium salt contained in the landfill leachate may include calcium ions (Ca ²⁺ ) 300 mg / L or more, preferably 300 ~ 900 mg / L, more preferably 400 ~ 700 mg / L.

On the other hand, the landfill leachate prepared in the first step of the landfill leachate treatment method of the present invention through the separate filtration process, the floating matter and sediment contained in the landfill leachate can be removed, the landfill leachate from which the floating matter and sediment is removed Can be used as landfill leachate in the second stage of landfill leachate treatment.

Next, the second step of the landfill leachate treatment method of the present invention is to soften by injecting carbonate (CO ₃ ^2- ) precursor to the landfill leachate prepared in the first step or landfill leachate from which suspended matter and sediment is removed. Can be.

The second stage of water softening refers to a process of removing calcium ions contained in landfill leachate and making hard water into soft water. The carbonate leachate (CO ₃ ^2- ) precursor and calcium ions contained in landfill leachate are chemically reacted. Can be softened. Therefore, more than 85%, preferably 85-99%, more preferably 85-98% of calcium ions contained in the landfill leachate may be removed through the second step.

In addition, the ion carbonate (CO ₃ ^2- ) precursor may include at least one selected from sodium carbonate (Na ₂ CO ₃ ), sodium bicarbonate (NaHCO ₃ ), potassium carbonate (K ₂ CO ₃ ), and potassium bicarbonate (KHCO ₃ ). May preferably comprise sodium carbonate.

Meanwhile, in the second step, a base is added to the landfill leachate prepared in the first step or the landfill leachate from which suspended matter and sediment are removed, and the pH is 9 to 13, preferably 10 to 12, more preferably 10.5 to It may be softened after adjusting to 11.5, and if the pH is less than 9 or more than 13, there may be a problem that the removal amount of calcium ions contained in the landfill leachate is significantly lowered.

In this case, the base may include one or more selected from sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium carbonate (Na ₂ CO ₃ ), and may preferably include sodium hydroxide.

In the second step with respect to landfill leachate or suspended matter or sediment is removed landfill leachate 100 parts by weight prepared in the first step, carbonate ions (CO ₃ ^2-) precursor 0.08 ~ 0.24 parts by weight, preferably from 0.08 ~ 0.20 wt. Part, more preferably 0.10 to 0.15 parts by weight, and if less than 0.08 parts by weight, there may be a problem that the removal amount of calcium ions contained in the landfill leachate is significantly lowered. In the landfill leachate treatment method there may be a problem that deterioration of the treated water quality caused by a large amount of bubbles.

Next, in the third step of the landfill leachate treatment method of the present invention, a flocculant may be added to the landfill leachate softened in the second step to generate a precipitate, and the resulting precipitate may be removed.

The sediment is produced by condensation and sedimentation of contaminants contained in the landfill leachate, which can be removed through a separate filtration process, and is difficult to decompose among contaminants contained in the landfill leachate by removing the sediment produced in the third step. The organic material can be removed 50% or more, preferably 70 to 90%, more preferably 80 to 85%.

The flocculant added in the third step may include an inorganic flocculant and a polymer flocculant. Inorganic flocculents promote the condensation of contaminants in landfill leachate. Specifically, positive charge cations in the inorganic flocculant adhere to the surface of colloidal contaminants with negative charges. By neutralizing the surface potential of the contaminants, condensation can be promoted. In addition, the contaminants whose particle size is increased by the inorganic coagulant may be increased into larger agglomerates by the crosslinking phenomenon of the polymer coagulant, and the heavy contaminants may not settle in water and may precipitate to generate a precipitate.

In addition, the inorganic flocculant may include at least one selected from ferric sulfate (Fe ₂ (SO ₄ ) ₃ ), ferric chloride (FeCl ₃ ), aluminum sulfate (Al ₂ (SO 3) _3, and polyaluminum chloride (PAC). , Preferably ferric sulfate (Fe ₂ (SO ₄ ) ₃ ).

In addition, the polymer flocculant may include at least one selected from a nonionic flocculant, a cationic flocculant, and a neutral flocculant, and may preferably include a nonionic flocculant.

Meanwhile, in the third step, an acid is added to the landfill leachate softened in the second step, and the coagulant is adjusted after adjusting the pH to 3 to 7, preferably 4 to 6, more preferably 4.5 to 5.5. It may be added to produce a precipitate, if the pH is less than 3 may be a problem of poor aggregation, if it exceeds 7 there may be a problem that the nitrogen removal rate is lowered in the evaporation concentration treatment.

In this case, the acid may include one or more selected from sulfuric acid (H ₂ SO ₄ ), hydrochloric acid (HCl), nitric acid (HNO ₃ ), and phosphoric acid (H ₃ PO ₄ ), preferably sulfuric acid. It may include.

In the third step, 0.05 to 0.5 parts by weight of inorganic flocculant, preferably 0.1 to 0.4 parts by weight, more preferably 0.2 to 0.35 parts by weight, may be added to 100 parts by weight of the softened landfill leachate. If the amount is less than 5 parts by weight, there may be a problem in that the condensation action is lowered.

In addition, the third step may be added to 0.05 to 0.3 parts by weight, preferably 0.05 to 0.2 parts by weight, more preferably 0.05 to 0.15 parts by weight based on 100 parts by weight of softened landfill leachate, if 0.05 parts by weight If less than the amount may be a problem of poor coagulation, if more than 0.3 parts by weight may be a problem of foaming.

Next, in the fourth step of the landfill leachate treatment method of the present invention, the landfill leachate from which the deposit is removed in the third step may be vaporized under vacuum conditions, and the vaporized landfill leachate may be liquefaction again. In this way, more than 95% of the contaminants contained in the landfill leachate can be removed, such as non-degradable organic substances including ammonia nitrogen.

Specifically, the vaporization of the fourth stage is carried out for 1 to 5 hours at a temperature of 70 to 100 ℃, preferably a temperature of 80 to 90 ℃, a pressure of -760 to -580mmHg, preferably a pressure of -760 to -650mmHg , Preferably it can be carried out for 2 to 4 hours, if the vaporization temperature is less than 70 ℃ may be a problem that the time of evaporation is excessive, if it exceeds 100 ℃ the vaporization of low-boiling refractory contaminants occur together There may be a problem.

Further, the liquefaction of the fourth stage is 0.3 at a temperature of 35 to 65 ° C, preferably a temperature of 35 to 55 ° C, a pressure of 740 to 780 mmHg, preferably a pressure of 750 to 770 mmHg, more preferably at atmospheric pressure. It can be carried out for 1 hour, preferably 0.3 to 0.6 hours, if the liquefaction temperature is less than 35 ℃ there may be a problem of operating cost rise, if it exceeds 65 ℃ the time required for liquefaction is very long There can be.

Lastly, in the fifth step of the landfill leachate treatment method of the present invention, an adsorbent and a flocculant are added to the landfill leachate liquefied in the fourth step, thereby generating a precipitate and removing the precipitate.

Sediment is produced by the adsorption, flocculation and sedimentation of the contaminants contained in the landfill leachate, can be removed through a separate filtration process, by removing the sediment generated in step 5, among the contaminants contained in the landfill leachate 50% or more of the hardly decomposable organic material, preferably 70 to 90%, more preferably 80 to 85% can be removed.

In the fifth step, the adsorbent is a substance adsorbing hardly decomposable organic substances among contaminants contained in the landfill leachate, and may include one or more selected from activated carbon, zeolite, graphite, and carbon nanotubes (CNT), and preferably Activated carbon.

The flocculant added in the fifth step may include an inorganic flocculant and a polymer flocculant. Inorganic flocculents promote the condensation of contaminants in landfill leachate. Specifically, positive charge cations in the inorganic flocculant adhere to the surface of colloidal contaminants with negative charges. By neutralizing the surface potential of the contaminants, condensation can be promoted. In addition, the contaminants whose particle size is increased by the inorganic coagulant may be increased into larger agglomerates by the crosslinking phenomenon of the polymer coagulant, and the heavy contaminants may not settle in water and may precipitate to generate a precipitate.

In addition, the inorganic flocculant may include at least one selected from ferric sulfate (Fe ₂ (SO ₄ ) ₃ ), ferric chloride (FeCl ₃ ), aluminum sulfate (Al ₂ (SO 3) _3, and polyaluminum chloride (PAC). , Preferably ferric sulfate (Fe ₂ (SO ₄ ) ₃ ).

In addition, the polymer flocculant may include at least one selected from a nonionic flocculant, a cationic flocculant, and a neutral flocculant, and may preferably include a nonionic flocculant.

Meanwhile, in the fifth step, caustic soda (NaOH) is added to the landfill leachate liquefied in the fourth step, and the pH is adjusted to 5-9, preferably 6-8, more preferably 6.5-7.5, and then the adsorbent and A flocculant may be added to produce a precipitate, and if the pH is less than 5 or more than 9, there may be a problem that the microorganisms contained in the landfill leachate are killed.

In the fifth step, 0.05 to 0.5 parts by weight of activated carbon, preferably 0.05 to 0.3 parts by weight, more preferably 0.1 to 0.25 parts by weight, may be added to 100 parts by weight of liquefied landfill leachate, and if less than 0.05 parts by weight, When added to the contaminant removal rate may be a problem, if exceeding 0.5 parts by weight may be a problem of leachate contamination.

In the fifth step, 0.05 to 0.5 parts by weight of inorganic flocculant, preferably 0.1 to 0.4 parts by weight, and more preferably 0.2 to 0.35 parts by weight, may be added to 100 parts by weight of the liquefied landfill leachate. If less than 2 parts by weight, there may be a problem that the condensation action is reduced, when more than 0.5 parts by weight there may be a problem that the sludge is excessively generated.

In the fifth step, 0.05 to 0.3 parts by weight, preferably 0.05 to 0.2 parts by weight, more preferably 0.05 to 0.15 parts by weight, may be added to 100 parts by weight of the liquefied landfill leachate. When added in, there may be a problem of poor coagulation, if more than 0.3 parts by weight may have a problem of foaming.

Furthermore, the landfill leachate from which the sediment is removed in the fifth step may further perform a biological treatment step using microorganisms contained in the landfill leachate.

Specifically, in the sixth step of the landfill leachate treatment method of the present invention, the dissolved oxygen content (dissolved oxyen (DO)) of the landfill leachate from which the sediment is removed in the fifth step is 0.2 mg / L or less, preferably 0.05 to 0.2 mg. / L and perform the first biological treatment for 4-12 hours, preferably 6-10 hours, in an environment of mixed microbial concentration (MLSS) of 3,000 to 5,000 mg / L, preferably 3,500 to 4,500 mg / L. can do. In other words, through the sixth step of the landfill leachate treatment method of the present invention, organic matter decomposition by the microorganisms contained in the landfill leachate and denitrification of nitrogen present as nitrate nitrogen may occur to remove contaminants contained in the landfill leachate. It is.

In addition, in the seventh step of the landfill leachate treatment method of the present invention, the dissolved oxygen content (dissolved oxyen (DO)) of landfill leachate subjected to the first biological treatment in the sixth step is 2.0 mg / L or more, preferably 2.0 To 2,500 to 4,500 mg / L of mixed microbial concentration (MLSS), preferably 3,000 to 4,000 mg / L, for a period of 18-30 hours, preferably 20-28 hours. Processing can be performed. In other words, through the seventh step of the landfill leachate treatment method of the present invention, the contaminants contained in the landfill leachate may be removed through the decomposition of organic matter by the microorganisms contained in the landfill leachate and nitrification of nitrogen.

In addition, the eighth step of the landfill leachate treatment method of the present invention can remove the activated sludge generated in the landfill leachate subjected to the second biological treatment in the seventh step by precipitation method, contaminants contained in the landfill leachate An aqueous solution largely removed of this can be obtained.

Meanwhile, referring to FIG. 1, the landfill leachate treatment apparatus of the present invention includes a collecting tank 10, a first reaction vessel 20, a second reaction vessel 30, a third reaction vessel 40, and a fourth reaction vessel 50. do.

First, the water collecting tank 10 may collect and collect landfill leachate. Landfill leachate flowing into the sump (10) is a leachate generated in the landfill of the air dome type, may include contaminants and calcium salt.

The contaminants contained in the landfill leachate may include hardly decomposable organic substances and nitrogen, and preferably, the hardly decomposable organic substances COD _Cr are 10,000 mg / L or more, preferably 10,000-30,000 mg / L, more preferably. May include 15,000 to 25,000 mg / L, and may include nitrogen at 2,000 mg / L or more, preferably 2,000 to 4,000 mg / L, more preferably 2,500 to 3,500 mg / L.

In addition, the calcium salt contained in the landfill leachate may include calcium ions (Ca ²⁺ ) 300 mg / L or more, preferably 300 ~ 900 mg / L, more preferably 400 ~ 700 mg / L.

In addition, the landfill leachate treatment apparatus of the present invention further includes a filtration tank 11 for removing floating matter and sediment contained in the landfill leachate when the landfill leachate collected in the sump tank 10 is introduced into the first reaction tank 20. Can be.

Next, the first reaction tank 20 may be softened by injecting a carbonate (CO ₃ ^2- ) precursor to the landfill leachate introduced through the sump tank 10 or the filtration tank 11.

Softening refers to a process of removing calcium ions contained in the landfill leachate and making hard water soft water, and the carbonate (CO ₃ ^2- ) precursor and the calcium ions contained in the leachate are chemically injected into the first reactor 20. It can react to soften the leachate. Through such a softening process, more than 85% of calcium ions contained in the landfill leachate, preferably 85 to 99%, more preferably 85 to 98% can be removed.

In addition, the carbonate ion (CO ₃ ^2- ) precursor introduced into the first reactor 10 may include sodium carbonate (Na ₂ CO ₃ ), sodium bicarbonate (NaHCO ₃ ), potassium carbonate (K ₂ CO ₃ ), and potassium bicarbonate (KHCO _3). It may include one or more selected from), preferably may include sodium carbonate.

In addition, the carbonate ion (CO ₃ ^2- ) precursor introduced into the first reaction tank 10 is 0.08 to 0.24 parts by weight, preferably 100 parts by weight of the landfill leachate introduced through the collection tank 10 or the filtration tank 11. 0.08 to 0.20 parts by weight, more preferably 0.10 to 0.15 parts by weight can be added, if less than 0.08 parts by weight may be a problem that the removal amount of calcium ions contained in the landfill leachate is significantly reduced, 0.24 parts by weight If exceeded, there may be a problem in that a large amount of bubbles are generated in the subsequent landfill leachate treatment process, thereby deteriorating the treated water quality.

On the other hand, the first reaction tank 20 is a base (in base) to the landfill leachate introduced through the sump (10) or filtration tank 11, the pH of the landfill leachate introduced into the first reaction tank 20 9 ~ 13 , Preferably 10 to 12, more preferably 10.5 to 11.5 may be softened, and if the pH is less than 9 or more than 13, there is a problem that the removal amount of calcium ions contained in the landfill leachate is significantly lowered. There may be.

In addition, the base introduced into the first reaction tank 20 may include at least one selected from sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium carbonate (Na ₂ CO ₃ ), and preferably hydroxide. May comprise sodium.

Next, the second reaction tank 30 may generate a precipitate by injecting a flocculant into the landfill leachate introduced through the first reaction tank 20.

The flocculant added to the second reaction tank 30 may include an inorganic flocculant and a polymer flocculant. Inorganic flocculents promote the condensation of contaminants in landfill leachate. Specifically, positive charge cations in the inorganic flocculant adhere to the surface of colloidal contaminants with negative charges. By neutralizing the surface potential of the contaminants, condensation can be promoted. In addition, the contaminants whose particle size is increased by the inorganic coagulant may be increased into larger agglomerates by the crosslinking phenomenon of the polymer coagulant, and the heavy contaminants may not settle in water and may precipitate to generate a precipitate.

Inorganic flocculant added to the second reactor 30 is selected from ferric sulfate (Fe ₂ (SO ₄ ) ₃ ), ferric chloride (FeCl ₃ ), aluminum sulfate (Al ₂ (SO 3) ₃ and polyaluminum chloride (PAC)). It may include more than one species, preferably ferric sulfate (Fe ₂ (SO ₄ ) ₃ ).

In addition, the inorganic flocculant added to the second reaction tank 30 is 0.05 to 0.5 parts by weight, preferably 0.1 to 0.4 parts by weight, more preferably 0.2 to 100 parts by weight of the leachate introduced through the first reaction tank 20. ~ 0.35 parts by weight may be added, if less than 0.05 parts by weight may have a problem that the condensation action is lowered, if more than 0.5 parts by weight there may be a problem that the sludge is excessively generated.

The polymer flocculant to be added to the second reaction tank 30 may include at least one selected from a nonionic flocculant, a cationic flocculant, and a neutral flocculant, and may preferably include a nonionic flocculant.

In addition, the polymer flocculant introduced into the second reaction tank 30 is 0.05 to 0.3 parts by weight, preferably 0.05 to 0.2 parts by weight, more preferably 0.05 to 100 parts by weight of the leachate introduced through the first reaction tank 20. ~ 0.15 parts by weight may be added, if less than 0.05 parts by weight may be a problem of poor coagulation, if more than 0.3 parts by weight may be a problem of foaming.

On the other hand, the second reaction tank 30 is an acid (acid) to the landfill leachate introduced through the first reaction tank 20, the pH of the landfill leachate introduced into the second reaction tank 30 3 to 7, preferably Is 4 to 6, more preferably 4.5 to 5.5 after the coagulant is added to produce a precipitate, if the pH is less than 3 may be a problem of poor coagulation, if it exceeds 7 in the evaporation concentration process There may be a problem that the nitrogen removal rate is lowered.

In addition, the acid introduced into the second reaction tank 30 may include at least one selected from sulfuric acid (H ₂ SO ₄ ), hydrochloric acid (HCl), nitric acid (HNO ₃ ), and phosphoric acid (H ₃ PO ₄ ). And preferably sulfuric acid.

Further, the precipitate generated by the aggregation and precipitation of the contaminants contained in the landfill leachate in the second reaction tank 30 may be removed through a separate filtration process, and by removing the precipitate generated in the second reaction tank 30, 50% or more, preferably 70 to 90%, and more preferably 80 to 85% of the hardly decomposable organic substances in the contaminants contained in the landfill leachate introduced into the second reaction tank 30 may be removed.

Next, the third reactor 40 may vaporize the landfill leachate introduced through the second reactor 30 from which the precipitate is removed, under vacuum conditions, and liquefaction the vaporized landfill leachate again. Through this, more than 95% of contaminants, such as non-degradable organic substances including ammonia nitrogen, can be removed from the contaminants contained in landfill leachate.

On the other hand, the vaporization is 1 to 5 hours, preferably 2 at a temperature of 70 to 100 ° C., preferably a temperature of 80 to 90 ° C., a pressure of -760 to -580 mmHg, preferably a pressure of -760 to -650 mmHg. It may be performed for 4 hours, and if the vaporization temperature is less than 70 ℃ may be a problem that the evaporation time is excessive, if it exceeds 100 ℃ may be a problem that the vaporization of low-boiling refractory pollutants of low boiling point together .

Further, the liquefaction is at a temperature of 35 to 65 ° C., preferably at a temperature of 35 to 55 ° C., at a pressure of 740 to 780 mmHg, preferably at a pressure of 750 to 770 mmHg, more preferably at normal pressure, for 0.3 to 1 hour, Preferably it can be carried out for 0.3 ~ 0.6 hours, if the liquefaction temperature is less than 35 ℃ there may be a problem of operating cost rise, if it exceeds 65 ℃ may be a problem that the time required for liquefaction is very long. .

Next, the fourth reaction tank 50 may generate a precipitate by inputting the adsorbent and the flocculant to the landfill leachate introduced through the third reaction tank (40).

The adsorbent added to the fourth reaction tank 50 is a substance adsorbing hardly decomposable organic substances among contaminants contained in the landfill leachate, and may include one or more selected from activated carbon, zeolite, graphite, and carbon nanotubes (CNT). And preferably, activated carbon.

In addition, the adsorbent introduced into the fourth reaction tank 50 is 0.05 to 0.5 parts by weight, preferably 0.05 to 0.3 parts by weight, more preferably 0.1 to 1 part by weight based on 100 parts by weight of the leachate introduced through the third reaction tank 40. 0.25 parts by weight can be added, if less than 0.05 parts by weight may be a problem of reducing the pollutant removal rate, if more than 0.5 parts by weight may be a problem of leachate contamination.

In addition, the flocculant added to the fourth reaction tank 50 may include an inorganic flocculant and a polymer flocculant.

In this case, the inorganic flocculant may include at least one selected from ferric sulfate (Fe ₂ (SO ₄ ) ₃ ), ferric chloride (FeCl ₃ ), aluminum sulfate (Al ₂ (SO 3) ₃ and polyaluminum chloride (PAC). And, preferably, ferric sulfate (Fe ₂ (SO ₄ ) ₃ ).

In addition, the inorganic flocculant added to the fourth reaction tank 50 is 0.05 to 0.5 parts by weight, preferably 0.1 to 0.4 parts by weight, more preferably 0.2 to 100 parts by weight of leachate introduced through the third reaction tank 40. ~ 0.35 parts by weight may be added, if less than 0.05 parts by weight may have a problem that the condensation action is lowered, if more than 0.5 parts by weight there may be a problem that the sludge is excessively generated.

In addition, the polymer flocculant added to the fourth reaction tank 50 may include at least one selected from a nonionic flocculant, a cationic flocculant, and a neutral flocculant, and may preferably include a nonionic flocculant.

In addition, the polymer flocculant added to the fourth reactor 50 is 0.05 to 0.3 parts by weight, preferably 0.05 to 0.2 parts by weight, more preferably 0.05 to 100 parts by weight of the leachate introduced through the third reactor 40. ~ 0.15 parts by weight may be added, if less than 0.05 parts by weight may be a problem of poor coagulation, if more than 0.3 parts by weight may be a problem of foaming.

Meanwhile, caustic soda (NaOH) is added to the fourth reaction tank 50, and the pH of the landfill leachate introduced into the fourth reaction tank 50 is 5 to 9, preferably 6 to 8, and more preferably 6.5 to 7.5. If the pH is less than 5 or more than 9, there may be a problem that the microorganisms contained in the landfill acupuncture water is killed.

In addition, the precipitate generated by the adsorption, flocculation and precipitation of the contaminants contained in the landfill leachate in the fourth reaction tank 50 may be removed through a separate filtration process, and the precipitate generated in the fourth reaction tank 50 may be removed. By doing so, it is possible to remove more than 50%, preferably 70 to 90%, more preferably 80 to 85% of the hardly decomposable organic substances in the contaminants contained in the landfill leachate introduced into the fourth reaction tank (50).

Meanwhile, the landfill leachate from which the sediment is removed in the fourth reaction tank 50 may remove contaminants contained in the landfill leachate through an additional landfill leachate treatment device.

Specifically, referring to Figure 2, the landfill leachate treatment apparatus of the present invention in addition to the sump tank 10, the first reaction tank 20, the second reaction tank 30, the third reaction tank 40 and the fourth reaction tank 50 It may further include an anaerobic tank 60, aeration tank 70 and the settling tank (80).

First, the anoxic tank 60 is a place for performing biological treatment using microorganisms contained in the landfill leachate, 0.2 mg / L dissolved oxygen of the landfill leachate introduced through the fourth reaction tank (50) (L) Or less, preferably adjusted to 0.05 ~ 0.2 mg / L, biological treatment can be carried out by maintaining an environment of mixed microbial concentration (MLSS) 3,000 ~ 5,000 mg / L, preferably 3,500 ~ 4,500 mg / L.

Next, the aeration tank 70 is a place for performing a biological treatment using microorganisms contained in the landfill leachate, the dissolved oxygen amount (dissolved oxyen (DO)) of landfill leachate introduced through the anaerobic tank 60 (2.0) / L or more , Preferably 2.0 to 5.0 mg / L, and the biological treatment can be carried out by maintaining a mixed microbial concentration (MLSS) of 2,500 ~ 4,500 mg / L, preferably 3,000 ~ 4,000 mg / L environment.

Finally, the sedimentation tank 80 may remove the precipitate by performing the sedimentation method in the landfill leachate introduced through the aeration tank (70). Finally, when the precipitate is removed through the sedimentation tank 80, it is possible to obtain an aqueous solution in which most of the contaminants contained in the landfill leachate is removed.

The present invention has been described above with reference to the embodiments, which are merely exemplary and are not intended to limit the embodiments of the present invention, and those skilled in the art to which the embodiments of the present invention belong may have the essential characteristics of the present invention. It will be appreciated that various modifications and applications not illustrated above are possible without departing from the scope of the invention. For example, each component specifically shown in the embodiment of the present invention may be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

Example 1 landfill leachate treatment method

(1) Preparation

A landfill leachate containing contaminants and calcium salts was prepared. The prepared landfill leachate contained 20,000 mg / L of COD _Cr , which is a hardly decomposable organic substance, 3,000 mg / L of nitrogen, and 550 mg / L of calcium ion (Ca ²⁺ ) (= initial stage).

(2) softening stage

Float and sediment were removed from the prepared landfill leachate, and sodium hydroxide was added thereto to adjust the pH to 11, followed by sodium carbonate to soften the landfill leachate. At this time, sodium carbonate was added in an amount of 0.125 parts by weight based on 100 parts by weight of landfill leachate from which suspended matter and sediment were removed. The contents of COD _Cr , nitrogen and calcium ions (Ca ²⁺ ) contained in the softened landfill leachate were measured by the calcium ion electrode method (= Measurement 1) and are shown in Tables 1 to 2 below.

(3) removing the first precipitate

Sulfuric acid was added to the softened landfill leachate to adjust the pH to 5, and then ferric sulfate and a nonionic flocculant were added to form a precipitate. At this time, the ferric sulfate was added 0.3 parts by weight based on 100 parts by weight of the softened landfill leachate, 0.1 parts by weight based on 100 parts by weight of the softened landfill leachate. The produced precipitates were removed, and the contents of COD _Cr , nitrogen, and calcium ions (Ca ²⁺ ) contained in the landfill leachate from which the precipitates were removed were measured by the calcium ion electrode method (= measurement 2) and are shown in Tables 1 to 2 below.

(4) evaporation concentration step

The landfill leachate from which the precipitate was removed was vaporized for 2 hours at a temperature of 85 ° C. under vacuum conditions and a pressure of −700 mmHg, and the vaporized landfill leachate was liquefaction again at a temperature of 45 ° C. under vacuum conditions for 0.4 hours. The contents of COD _Cr , nitrogen and calcium ions (Ca ²⁺ ) contained in the liquefied landfill leachate were measured by the calcium ion electrode method (= measurement 3) and are shown in Tables 1 to 2 below.

(5) removing the second precipitate

Caustic soda (NaOH) was added to the liquefied landfill leachate to adjust the pH to 7, and then activated carbon, ferric sulfate, and a nonionic flocculant were added to form a precipitate. At this time, 0.2 parts by weight of activated carbon was added to 100 parts by weight of liquefied landfill leachate, and 0.3 parts by weight of ferric sulfate was added to 100 parts by weight of liquefied landfill leachate, and 100 parts by weight of liquefied landfill leachate was used. 0.1 part by weight of the part was added. The produced precipitate was removed, and the contents of COD _Cr , nitrogen, and calcium ions (Ca ²⁺ ) contained in the landfill leachate from which the precipitate was removed were measured by the calcium ion electrode method (= measurement 4) and are shown in Tables 1 to 2 below.

(6) biological treatment steps

The dissolved oxygen content (DO) of the landfill leachate from which the precipitate was removed was adjusted to 0.1 mg / L, and the first biological treatment was performed for 8 hours under an environment of 4,000 mg / L of mixed microbial concentration (MLSS). The dissolved oxygen content (DO) of the landfill leachate subjected to the first biological treatment was adjusted to 3.1 mg / L, and the second biological treatment was performed for 24 hours under an environment of 3,500 mg / L mixed microbial concentration (MLSS). After removing the activated sludge from the landfill leachate subjected to the second biological treatment by precipitation, the contents of COD _Cr , nitrogen, and calcium ions (Ca ²⁺ ) contained in the supernatant were measured by the calcium ion electrode method (= measurement 5). It is shown in Tables 1-2.

Example 2 Landfill Leachate Treatment Method

Landfill leachate was treated in the same manner as in Example 1. However, unlike Example 1, in the softening step, the landfill leachate was softened after adjusting the pH to 14.

Example 3 Landfill Leachate Treatment Method

Landfill leachate was treated in the same manner as in Example 1. However, unlike Example 1, in the softening step, the landfill leachate was softened after adjusting the pH to 8.

Example 4 Landfill Leachate Treatment Method

Landfill leachate was treated in the same manner as in Example 1. However, unlike Example 1, in the softening step, sodium carbonate was introduced at 0.05 parts by weight based on 100 parts by weight of landfill leachate from which suspended matter and sediment were removed, thereby softening the landfill leachate.

Example 5 Landfill Leachate Treatment Method

Landfill leachate was treated in the same manner as in Example 1. However, unlike Example 1, in the softening step, sodium carbonate was introduced at 0.3 part by weight based on 100 parts by weight of landfill leachate from which suspended matter and sediment were removed, thereby softening the landfill leachate.

Example 6 Landfill Leachate Treatment Method

Landfill leachate was treated in the same manner as in Example 1. However, unlike Example 1, in the first precipitate removal step, the pH was adjusted to 2, and then ferric sulfate and a nonionic flocculant were added to generate a precipitate.

Example 7 Landfill Leachate Treatment Method

Landfill leachate was treated in the same manner as in Example 1. However, unlike Example 1, in the first precipitate removal step, the pH was adjusted to 8 and then ferric sulfate and a non-ionic flocculant were added to generate a precipitate.

Example 8 Landfill Leachate Treatment Method

Landfill leachate was treated in the same manner as in Example 1. However, unlike Example 1, in the first precipitate removal step, ferric sulfate was added 0.03 parts by weight based on 100 parts by weight of softened landfill leachate, and 0.03 part by weight of 100 parts by weight of softened landfill leachate. Part by weight was added to produce a precipitate.

Example 9 Landfill Leachate Treatment Method

Landfill leachate was treated in the same manner as in Example 1. However, unlike Example 1, in the step of removing the first precipitate, ferric sulfate was added 0.6 parts by weight based on 100 parts by weight of the softened landfill leachate, and 0.4 parts by weight of 100 parts by weight of the softened landfill leachate. Part by weight was added to produce a precipitate.

Example 10 Landfill Leachate Treatment Method

Landfill leachate was treated in the same manner as in Example 1. However, unlike Example 1, in the step of removing the second precipitate, after adjusting the pH to 4, activated carbon, ferric sulfate, and nonionic flocculant were added to generate a precipitate.

Example 11 Landfill Leachate Treatment Method

Landfill leachate was treated in the same manner as in Example 1. However, unlike Example 1, in the step of removing the second precipitate, after adjusting the pH to 10, activated carbon, ferric sulfate, and nonionic flocculant were added to generate a precipitate.

Example 12 Landfill Leachate Treatment Method

Landfill leachate was treated in the same manner as in Example 1. However, unlike Example 1, in the second precipitate removal step, activated carbon was added 0.03 parts by weight of activated carbon to 100 parts by weight of liquefied landfill leachate to generate a precipitate.

Example 13 Landfill Leachate Treatment Method

Landfill leachate was treated in the same manner as in Example 1. However, unlike Example 1, in the second precipitate removal step, activated carbon was added to 0.6 parts by weight of activated carbon based on 100 parts by weight of liquefied landfill leachate to generate a precipitate.

Comparative Example 1 Landfill Leachate Treatment Method

(1) Preparation

A landfill leachate containing contaminants and calcium salts was prepared. The prepared landfill leachate contained 20,000 mg / L of COD _Cr , which is a hardly decomposable organic substance, 3,000 mg / L of nitrogen, and 550 mg / L of calcium ion (Ca ²⁺ ) (= initial stage).

(2) removing the first precipitate

Float and precipitate were removed from the prepared landfill leachate, sulfuric acid was added to adjust the pH to 5, and ferric sulfate and nonionic flocculant were added to produce a precipitate. At this time, ferric sulfate was added 0.3 parts by weight based on 100 parts by weight of the prepared landfill leachate, 0.1 parts by weight based on 100 parts by weight of the softened landfill leachate. The produced precipitates were removed, and the contents of COD _Cr , nitrogen, and calcium ions (Ca ²⁺ ) contained in the landfill leachate from which the precipitates were removed were measured by the calcium ion electrode method (= measurement 2) and are shown in Table 2 below.

(3) evaporation concentration step

The landfill leachate from which the precipitate was removed was vaporized for 2 hours at a temperature of 85 ° C. under vacuum conditions and a pressure of −700 mmHg, and the vaporized landfill leachate was liquefaction again at a temperature of 45 ° C. under vacuum conditions for 0.4 hours. The contents of COD _Cr , nitrogen, and calcium ions (Ca ²⁺ ) contained in the liquefied landfill leachate were measured by the calcium ion electrode method (= measurement 3) and are shown in Table 2 below.

(4) removing the second precipitate

Caustic soda (NaOH) was added to the liquefied landfill leachate to adjust the pH to 7, and then activated carbon, ferric sulfate, and a nonionic flocculant were added to form a precipitate. At this time, 0.2 parts by weight of activated carbon was added to 100 parts by weight of liquefied landfill leachate, and 0.3 parts by weight of ferric sulfate was added to 100 parts by weight of liquefied landfill leachate, and 100 parts by weight of liquefied landfill leachate was used. 0.1 part by weight of the part was added. The produced precipitate was removed, and the contents of COD _Cr , nitrogen, and calcium ions (Ca ²⁺ ) contained in the landfill leachate from which the precipitates were removed were measured by the calcium ion electrode method (= measurement 4) and are shown in Table 2 below.

(5) biological treatment steps

The dissolved oxygen content (DO) of the landfill leachate from which the precipitate was removed was adjusted to 0.1 mg / L, and the first biological treatment was performed for 8 hours under an environment of 4,000 mg / L of mixed microbial concentration (MLSS). The dissolved oxygen content (DO) of the landfill leachate subjected to the first biological treatment was adjusted to 3.1 mg / L, and the second biological treatment was performed for 24 hours under an environment of 3,500 mg / L mixed microbial concentration (MLSS). After removing the activated sludge from the landfill leachate subjected to the second biological treatment by precipitation, the contents of COD _Cr , nitrogen, and calcium ions (Ca ²⁺ ) contained in the supernatant were measured by the calcium ion electrode method (= measurement 5). It is shown in Table 2 below.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (15)

A first step of preparing a landfill leachate containing 10,000 to 30,000 mg / L of COD _Cr and 2,000 to 4,000 mg / L of nitrogen and 300 to 900 mg / L of calcium ions;
Base was added to the prepared landfill leachate to adjust the pH to 10.5 to 11.5, and then softened by adding 0.10 to 0.15 parts by weight of a carbonate (CO ₃ ^2- ) precursor to 100 parts by weight of the prepared landfill leachate. Step 2);
Acid was added to the softened landfill leachate to adjust the pH to 4.5 to 5.5, and then 0.2 to 0.35 parts of inorganic flocculant and 0.05 to 0.15 part by weight of polymer flocculant were added to 100 parts by weight of the softened landfill leachate. A third step of generating a precipitate and removing the generated precipitate;
The landfill leachate from which the sediment was removed was vaporized for 1 to 5 hours at a temperature of 80 to 90 ° C. under vacuum conditions and a pressure of -760 to -580 mmHg, and the vaporized landfill leachate was again heated to a temperature of 35 to 55 ° C., 740. A fourth step of liquefaction for 0.3 to 1 hour at a pressure of ˜780 mmHg; And
Caustic soda (NaOH) was added to the liquefied landfill leachate to adjust the pH to 6.5 to 7.5, and then 0.1 to 0.25 parts by weight of the adsorbent, 0.2 to 0.35 parts by weight of the inorganic flocculant and the polymer with respect to 100 parts by weight of the liquefied landfill leachate. A fifth step of generating a precipitate by adding 0.05 to 0.15 parts by weight of a flocculant, and removing the generated precipitate;
Landfill leachate treatment method comprising a.
delete delete delete The method of claim 1,
The carbonate (CO ₃ ^2- ) precursor includes one or more selected from sodium carbonate (Na ₂ CO ₃ ), sodium bicarbonate (NaHCO ₃ ), potassium carbonate (K ₂ CO ₃ ) and potassium bicarbonate (KHCO ₃ ) Landfill leachate treatment method characterized in that.
delete delete delete delete delete The method of claim 1,
The inorganic coagulants of the third and fifth steps are ferric sulfate (Fe ₂ (SO ₄ ) ₃ ), ferric chloride (FeCl ₃ ), aluminum sulfate (Al ₂ (SO ₃ ) ₃ ) and poly aluminum chloride (PAC) Contains at least one selected,
The landfill leachate treatment method of claim 3 or 5, wherein the polymer coagulant comprises at least one selected from a nonionic coagulant, a cationic coagulant, and a neutral coagulant.
The method of claim 1,
The landfill leachate treatment method of claim 5, wherein the adsorbent of the fifth step comprises at least one selected from activated carbon, zeolite, graphite, and carbon nanotubes (CNT).
A sump collecting and introducing a landfill leachate containing 10,000 to 30,000 mg / L of COD _Cr and 2,000 to 4,000 mg / L of nitrogen and 300 to 900 mg / L of calcium ions;
A base was added to the landfill leachate introduced through the sump, the pH was adjusted to 10.5 to 11.5, and then 0.10 to 0.15 parts by weight of a carbonate (CO ₃ ^2- ) precursor was added to 100 parts by weight of the prepared landfill leachate. A first reactor for softening by softening;
Acid was added to the landfill leachate introduced through the first reactor to adjust the pH to 4.5 to 5.5, and then 0.2 to 0.35 parts of an inorganic flocculant and a polymer flocculant 0.05 to 100 parts by weight of the softened landfill leachate. A second reactor for generating a precipitate by adding 0.15 parts by weight;
The landfill leachate introduced through the second reaction tank from which the precipitate was removed is vaporized for 1 to 5 hours at a temperature of 80 to 90 ° C. and a pressure of -760 to -580 mmHg under vacuum conditions, and the vaporized landfill leachate A third reactor for liquefaction again at a temperature of 35 to 55 ° C. and a pressure of 740 to 780 mmHg for 0.3 to 1 hour; And
Caustic soda (NaOH) was added to the landfill leachate introduced through the third reactor, the pH was adjusted to 6.5 to 7.5, and then 0.1 to 0.25 parts by weight of the adsorbent, 0.2 to 0.2 parts by weight of the inorganic flocculant 0.2 A fourth reaction tank generating a precipitate by adding 0.3-5 parts by weight and 0.05 to 0.15 parts by weight of a polymer flocculant;
Landfill leachate treatment apparatus comprising a.
delete delete

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