KR20020091477A - Leachate treatment system and method using sulfation bacillius in wastes landfill - Google Patents

Abstract

PURPOSE: A treatment system of landfill leachate using sulfur oxidizing bacteria is provided, which is characterized in that leachate is recirculated into landfill. And sulfate is injected into the recirculated leachate for improving denitrification by sulfur oxidizing bacteria and waste decomposition of landfill by sulfate reduction bacteria. CONSTITUTION: The system comprises a device for collecting and storing leachate; a device for aeration of leachate for nitrification; a device for recirculating a portion of treated leachate by the aeration device to the lower part of top cover soil layer of landfill; and a device for injecting sulfate into recirculated leachate for sulfur denitrification process by sulfur oxidation bacteria and waste decomposition by sulfate reduction bacteria.

Description

Leachate Treatment System and Method of Waste Landfill Using Sulfated Bacteria {LEACHATE TREATMENT SYSTEM AND METHOD USING SULFATION BACILLIUS IN WASTES LANDFILL}

The present invention relates to a system and method for treating leachate from waste landfill, and more particularly, to circulate the leachate into landfill, by introducing sulphate to the circulated leachate in the waste landfill by sulfate reducing bacteria Sulfuric acid which promotes waste decomposition and maximizes the efficiency of waste decomposition and leachate by activating the denitrification reaction by sulfated bacteria with sulfide generated as electron donor to remove the non-decomposable substances and nitrogen contained in the leachate. The present invention relates to a leachate treatment system and method for waste landfill using oxidized bacteria.

Currently applied landfills are simply landfilled for anaerobic treatment to simply treat pollutants. The leachate generated is collected and discharged into rivers after various treatment processes.

However, leachate from waste landfill contains a large amount of organic matter, inorganic and ammonia nitrogen, and substances that interfere with flocculant, so it is not easy to treat, and has emerged as a serious cause of water and soil pollution.

Accordingly, in recent years, studies on early stabilization of landfills have been actively conducted to reduce adverse effects on sanitation and living environment due to the discharge and movement of landfill gas and leachate from landfills, and to effectively reuse land by improving landfills.

In other words, in the construction of landfills, various methods are applied to meet the purpose of early stabilization of landfills, various changes are made to create conditions for activating microorganisms in landfills, and leachate is circulated into landfills. have.

Among these, the method of recycling the leachate generated in the landfill is optimized for promoting biodegradation by microorganisms, and evenly disperses landfill waste by uniformly distributing organic materials into the landfill, thereby premature stabilization of waste landfill. In addition to achieving this, it is possible to increase the amount of methane gas available as a leachate treatment and energy source.

However, although the leachate recycling system of the conventional landfill shows the excellent effect as a method of promoting the waste decomposition at the early stage of landfill, the leachate is not effectively processed by microorganisms in the landfill as the landfill period elapses. The efficiency of treatment and waste decomposition is low, and the structure of the leachate circulation system is complicated, which makes it difficult to install and operate.However, methane gas is used as an energy source due to the disadvantage that the amount of methane generated decreases and the concentration of methane decreases as the landfill period elapses. The problem was that it was uneconomic.

Therefore, the present invention was devised to solve the above problems, the leachate generated in the landfill is treated with an aerobic treatment in a leachate abandonment facilities installed outside the nitrification and then added sodium sulfate intermittently into the landfill by the leachate recycle device By circulating, it promotes the decomposition of the degradable and hardly decomposable organic matters of the landfill waste and leachate by the sulfate reducing bacterium, and the sulfides generated thereby promotes the denitrification reaction by the sulfated bacteria in the landfill. It is an object of the present invention to provide a leachate treatment system and method for waste landfill using sulfated bacteria to maximize the leachate treatment efficiency.

1 is a schematic diagram showing an embodiment configuration of a leachate treatment system of landfills using sulfated bacteria according to the present invention.

Figure 2 is a schematic diagram showing the configuration of the leachate aeration system of the leachate treatment system of landfills using sulfated bacteria according to the present invention.

Figure 3 is a schematic diagram showing the configuration of an experimental apparatus for an indoor experiment of the present invention.

Figure 4 is a graph showing the experimental results by the experimental apparatus of Figure 3 for the change of nitrogen according to the unit process of the leachate circulated.

Figure 5 is a graph showing the experimental results by the experimental apparatus of Figure 3 for the nitrate nitrogen concentration change.

Figure 6 is a graph showing the experimental results by the experimental apparatus of Figure 3 for the concentration changes of sulfate and sulfide according to the unit process.

7 shows autotrophic denitrification using sulfides as electron donors. To Schematic diagram showing the energy flow when converted to.

* Explanation of symbols for the main parts of the drawings

10 waste landfill 20 leachate collection tank

30: Leachate aeration facility 31: Sulfide oxidation tank

32: nitrification aeration tank 40: leachate circulating device

50: final cover layer 60: leachate collection and drainage

70: surface order film 80: sulfate input device

R1: sulfur cyclic leachate treatment reactor R2: general cyclic leachate treatment reactor

In order to achieve the above object, the present invention, the leachate collection means for collecting and storing the leachate generated in the waste landfill; Leachate aeration means for nitrifying the leachate collected in the leachate collection means; Leachate circulation means for recycling a part of the leachate treated by the leachate aeration means to the bottom of the final cover layer of the landfill; And sulfuric acid input means which is installed at a predetermined position of the leachate circulation means and injects sulfate into recycled leachate to promote the denitrification reaction by sulfated bacteria in the landfill and waste decomposition by sulfate reducing bacteria. Provides a leachate treatment system for waste landfills using pyrobacteria.

In addition, the method of the present invention, the first step of temporarily storing the leachate generated from the waste landfill in the leachate collection tank; A second step of abandoning the leachate discharged from the leachate storage tank to nitrate inorganic and ammonia nitrogen contained in the leachate and to oxidize sulfides to recover as sulfates; A third step of transferring the leachate treated in the second step to the bottom of the final cover layer of the landfill; And sulphate production by sulphate reducing bacteria and sulfate denitrification by sulphate reducing bacteria in a leachate circulation line for circulating the leachate treated in the second step to the bottom of the cover layer of the waste landfill. Provided is a method for treating leachate in a landfill using a sulfated bacterium comprising a fourth step of promoting a reaction.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 is a schematic diagram showing an embodiment configuration of a leachate treatment system of landfills using sulfated bacteria according to the present invention.

The present invention is to increase the leachate treatment and waste decomposition efficiency of the waste landfill by inducing the denitrification reaction by the sulfated bacteria in the landfill in connection with nitrification by the leachate abandoned facility, as shown in Figure 1, waste landfill In the leachate collection tank 20 for collecting and storing the leachate generated in the (10), the leachate aeration system 30 for nitrifying the leachate collected in the leachate collection tank 20, and the aeration system 30 A leachate circulating device 40 for circulating the leachate treated by the bottom of the final cover layer 50 of the landfill 10, and a sulphate input device for introducing sulphate such as sodium sulfate into the leachate recycled by the circulator 40 ( 80).

Here, in the landfill 10, sulfated bacteria that cause a denitrification reaction while oxidizing sulfides generated by reduction of sulfates contained in the leachate introduced into the cover layer 50 by sulfate reducing bacteria into sulfates are dominant paper. Sulfate reducing bacteria (11) and sulfates generated in the sulfide oxidation zones (11) are sulfide reducing bacteria with waste electrons as dominant species. A sulfide producing zone 12 in which the reaction takes place is formed.

In the lower part of the sulfide generating region 12, a plurality of leachate collections for collecting the leachate passing through the water repellent film 70 and the sulfide generating region 12 to prevent the leachate from seeping into the ground and drained to the leachate collection tank 20 Drainage hole 60 is provided.

In addition, the leachate aeration system 30, as shown in Figure 2, the sulfide oxidation tank 31 for oxidizing the sulfide contained in the leachate passing through the sulfide generating zone 12 to recover as a sulfate; It is divided into a plurality of nitrification aeration tanks (32a to 32d) for nitrifying the leachate that has passed through the sulfide oxidation tank (31).

In addition, in this Example, what used sodium sulfate as said sulfate is demonstrated as an example.

Referring to the leachate treatment method by the leachate treatment system of the landfill using the sulfated bacteria according to the present invention configured as described above are as follows.

Leachate generated from the waste landfill 10 is collected in the leachate collection tank 20, the flow rate is adjusted and then flows into the leachate aeration facility 30. The sulfides contained in the leachate are oxidized and recovered as sulfates in the sulfide oxidizing tank 31 of the leachate aeration system 30, and the inorganic and ammonia nitrogen contained in the leachate is nitrified in the nitrification aeration tanks 32a to 32d. If the aeration strength is large during the reaction, ) Sulphate ( Rather than being oxidized to And the like, so that the sulfide oxidation tank 31 is installed and operated separately from the nitrification aeration tanks 32a to 32d.

The leachate treated in the leachate abandonment facility 30 is transferred to the leachate circulation device 40 and supplied to the bottom of the cover layer 50 of the landfill 10 again. In this process, the leachate is discharged through the sulfate input device 80. The re-injection of sodium sulfate is carried out during the transfer of sodium sulfate, and the re-injection time and the amount of sodium sulfate are measured by measuring the concentration of sulfate and sulfide in the leachate after passing through the sulfide oxidation tank 31 for sulfate recovery and decomposing in the waste landfill 10. It is determined by calculating the amount of sulfates and sulfides needed in the process.

In the sulfide oxidation zone 11 of the waste landfill 10, a sulfidation reaction occurs mainly in which sulfides are oxidized by sulfated bacteria and oxidized to sulfates. In the sulfide generating zone 12, sulfides are formed by sulfate reducing bacteria and sulfuric acid. General denitrification reactions occur with denitrification by the bacterium, which leads to decomposition of landfill waste and removal of nitrogen. The leachate passing through the sulfide generating region 12 is collected in the leachate collection tank 20 through the leachate drainage hole 60 installed at the upper part of the membrane 70, some of which are the leachate aeration facility 30 The above process is repeated and the other part is transferred to the outside for subsequent leachate treatment.

On the other hand, a phosphorus input device (not shown) is provided on the leachate circulation pipe connected to the lower cover layer from the abandoned facility 30 to intermittently input phosphorus (P) to the leachate flowing into the landfill 10 described above. It is well known that by promoting the activity of the microorganisms causing the biodegradation reaction to further increase the efficiency of decomposition and leachate treatment of landfill waste.

In the leachate treatment method of a waste landfill using the sulfated bacteria according to the present invention as described above, the denitrification reaction by the sulfated bacteria is carried out using a sulfide as an electron donor and a nitrate nitrogen as an electron acceptor. In other words, the denitrification reaction is caused by the process of anoxic respiration by the sulfated bacteria to obtain energy. Instead of bound oxygen (such as nitrate nitrogen) ) Is used as an electron acceptor and energy metabolism using sulfides as substrates.

Autotrophic denitrification uses sulfides as electron donors To The energy flow at the time of conversion to is shown in Figure 7, the denitrification reaction by the sulfated bacteria using sulfides summarized as follows.

When using sulfide as denitrification electron donor

When elemental sulfur is used as the denitrification electron donor

Thiosulfate as a denitrification electron donor

In particular, in the present embodiment, as a result of identifying the sulfated bacteria using an electron microscope in a leachate recycling treatment experiment using a pilot among various sulfated bacteria naturally present in the landfill, thiobacillus naturally present in the soil The genus Sulfate bacteria appeared as dominant species and was adopted as one of the main components of this example.

On the other hand, in the leachate treatment system and method of the waste landfill using the sulfated bacteria according to the present invention as described above, the leachate by the desulfurization decomposition characteristics by the sulfated bacteria in the waste landfill and the leachate by the associated treatment with the leachate aeration tank installed outside An experimental example for identifying the nitrogen removal treatment characteristics of will be described with reference to FIG.

(Example)

Experimental apparatus of the leachate treatment system using a sulfated bacterium according to the present invention, as shown in Figure 3, the waste is accommodated inside the reaction tank 110, the waste decomposition and denitrification reaction and the experimental leachate passed through the waste Is connected to the lower portion of the reaction tank 110, the leachate aeration tank 120 and the leachate storage tank 130 connected to the leachate aeration tank 120 for the sulfide oxidation and nitrification of the introduced leachate so that the inflow, It is composed of a circulating pump 140 is mounted on the leachate circulation pipe line 150 connecting the leachate reservoir 130 and the reaction tank 110 to circulate the leachate.

Here, the reaction tank 110 is provided with a gas collecting bag 102 for measuring the gas generated in the waste decomposition and denitrification reaction, and a thermometer 101 for measuring the temperature in the reaction tank 110. In addition, the leachate aeration tank 120 is composed of a plurality of compartments, one side is provided with a blower (blower) (121) for supplying air to the leachate contained in the aeration tank.

In addition, for the comparison, the experimental apparatus is composed of two modifications, and in one tank (hereinafter, referred to as "sulphur cycle reactor R1"), one of each compartment of the leachate aeration tank 120 is a sulfide oxidation tank. The other compartment is used as a nitrification aeration tank to recover sulphate contained in the collected leachate, and then oxidize and circulate. The leachate cycle is operated by adding sodium sulfate intermittently depending on the sulfate concentration in the leachate. In the circulating reactor (R2) "), only leachate was aerated in the leachate aeration tank 120 without nitrifying and nitrified and circulated.

The reactor 110 was made of a transparent acrylic cylinder with a volume of 77 liters (hereinafter referred to as liters), the outer wall was wrapped with aluminum foil to block visible light, and experimented to prevent inhibition of microbial activity by temperature drop. The external temperature of the device was maintained at 30 to 35 ° C. The reactor was filled with garbage from household waste landfills of more than 10 years, and the packing density was uncompressed to have a specific gravity of 0.67. In addition, the circulation amount of the leachate collected after passing through the reaction tank 110 and circulated back to the reaction tank 110 by the circulation pump 140 through the aeration tank 120 was 6 liters per day.

Table 1 shows a comparison of the experimental conditions of the R1 and R2.

Operating Conditions of Leachate Treatment Reactor Operating conditions Reactor R1 R2 Denitrification stage (reactor) Reactor size (mm) Ø240 × 1,700 H Reactor temperature (℃) 30 to 35 Denitrification Retention Time (day) 6 to 7 Circulation condition (liter / day) 6 Sodium sulfate input (g / liter) 3.5 to 4.0 0 Nitrification step (aeration tank) Aeration tank size (mm) 750 W × 200 L × 450 H Aeration tank temperature (℃) 18 to 22 Dissolved oxygen (mg / liter) 2.5 to 3.0 Sludge Return Rate (Q) 0.25 F / M ratio 0.1 to 0.4 MLSS (mg / liter) 5,000-6,000 Solid residence time (day) 80-100 Nitrification Retention Time (day) 6.5 Circulation conditions 50% return after nitrification Sulfate Concentration (g / liter) 2.5 to 3.0 Less than 0.4

After approximately 150 days of experiments, the nitrogen circulating leachate treatment system (R1), which circulates sulphates and sulfides to induce a denitrification reaction, has more efficient nitrogen removal in the waste than the general cyclic leachate treatment system (R2) where only leachate is circulated. Found to be excellent.

That is, Figure 4 shows the change of the total nitrogen content in the leachate in the unit process, the change in total nitrogen concentration before and after the denitrification process in the case of R1 was reduced from 1,560mg / liter to 1,340mg / liter, in the case of R2 1,496 It was reduced from mg / liter to 1,388 mg / liter.

In addition, Figure 5 shows the change in the concentration of nitrate nitrogen in the landfill waste tank, the nitrate nitrogen before the denitrification process was an average of 380mg / liter, after the denitrification process was reduced to 149mg / liter to have a nitrogen removal rate of about 61% In the case of R2, it was introduced at a concentration of 384 mg / liter and flowed out at 195 mg / liter, resulting in a treatment rate of 49%, indicating that the nitrogen removal efficiency of the sulfuric cycle leachate treatment system (R1) was superior to that of the general leachate treatment system (R2). appear.

In addition, Figure 6 shows the concentration changes of sulfate and sulfide in the sulfur cyclic leachate treatment system (R1) according to the denitrification process.

On the other hand, while the sulfur cyclic leachate treatment system (R1) as shown in Figure 4 has a high sulfur denitrification efficiency as shown in Figure 5 compared to the general cyclic leachate treatment system (R2) increase value of the total nitrogen removal rate The lower is that the nitrogen contained in the leachate is dissipated into nitrogen gas by the denitrification reaction in the waste of the reaction tank 110, but ammonia nitrogen and inorganic nitrogen is eluted out of the leachate during the decomposition of the waste in the reaction tank (110) It is because of this.

As described above, since the degradable organic matter is easily eluted from the landfill waste into the leachate, the denitrification is easily performed by general denitrification microorganisms in the landfill during the leachate circulation. The eluted organic matter contains more hardly decomposable substances than the decomposable substances, and thus, denitrification efficiency is low because general denitrification microorganisms cannot fully function as electron donors.

On the other hand, in the case of sulfated bacteria, since sulfides are used instead of organic substances as electron donors to cause denitrification in landfills, the nitrogen removal effect of landfills with long years of reclamation is superior to that of general denitrification microorganisms. This can reduce the capacity of subsequent leachate treatment facilities and reduce leachate treatment costs.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be apparent to those of ordinary knowledge.

According to the present invention as described above, it is possible to easily decompose the hardly decomposable organic matter contained in the leachate, which increases as the number of years of landfill increases, can reduce the leachate treatment cost and increase the landfill stabilization rate, sulfated bacteria It is possible to reduce the required cost and capacity of the subsequent leachate treatment process by increasing the removal efficiency of nitrogen contained in the leachate through the nitrification by the denitrification and leachate aeration facilities.

Claims (6)

Leachate collecting means for collecting and storing the leachate generated in the waste landfill; Leachate aeration means for nitrifying the leachate collected in the leachate collection means; Leachate circulation means for recycling a part of the leachate treated by the leachate aeration means to the bottom of the final cover layer of the landfill; And Sulfate input means which is installed at a predetermined position of the leachate circulation means, by introducing sulfate into recycled leachate to promote the denitrification reaction by sulfated bacteria and waste decomposition by sulfate reducing bacteria in the landfill Leachate treatment system of landfills using sulfated bacteria comprising a. The method of claim 1, A lower portion of the waste landfill is formed with a shield for preventing leachate from seeping underground, The leachate collection means A plurality of leachate collection and drainage holes installed on an upper portion of the water-repellent film and for draining leachate passing through a lower cover layer of the landfill to the outside of the landfill; Leachate storage tank is connected to the end of the leachate drainage water collecting and storing the leachate Leachate treatment system of landfill waste using sulfated bacteria comprising a. The method of claim 1, The leachate aeration means is a sulfide oxidation tank for oxidizing the sulfide contained in the leachate passing through the sulfide generating zone of the landfill to recover as a sulfate; At least one nitrification aeration tank for nitrifying the leachate that has passed through the sulfide oxidation tank Leachate treatment system of landfills using sulfated bacteria comprising a. The method of claim 1, A leachate treatment system for waste landfills using sulfated bacteria, characterized in that the sulfate introduced from the sulfate injection means consists of industrial sodium sulfate. A first step of temporarily storing the leachate generated from the waste landfill in the leachate collection tank; A second step of abandoning the leachate discharged from the leachate storage tank to nitrate inorganic and ammonia nitrogen contained in the leachate and to oxidize sulfides to recover as sulfates; A third step of transferring the leachate treated in the second step to the bottom of the final cover layer of the landfill; And Sulfate production was performed on the leachate circulation line for circulating the leachate treated in the second step to the bottom of the cover layer of the waste landfill, and sulfide formation reaction was performed by sulfate reducing bacteria in the landfill and denitrification reaction by the sulfated bacteria. Facilitating Fourth Step Leachate treatment method of landfills using sulfated bacteria comprising a. The method of claim 5, And a fifth step of activating the activity of microorganisms causing biodegradation reaction by intermittently adding phosphorus to leachate transferred to landfill.