A method for treating landfill leachate and application thereof

Abstract

The present application belongs to the technical field of landfill leachate treatment, and discloses a landfill leachate treatment method and application thereof. In the landfill leachate treatment method, the evaporation concentration and back spraying treatment are combined, the feed volume ratio alpha of the landfill leachate and the evaporation concentrated liquid in the mixed liquid satisfies the relationship shown in formula (1), C1 is the COD concentration of the landfill leachate, and C2 is the COD concentration of the evaporation concentration; the atomization back spraying amount beta of the mixed liquid is less than or equal to 6.19% M, M is the weight of the garbage in the furnace; the smoke temperature change caused by the atomization back spraying of the mixed liquid into the furnace is in an excellent state without damaging the furnace components, so that the effect of maintaining the stable operation of the furnace components during the back spraying process while achieving the zero emission treatment of the landfill leachate can be achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of landfill leachate treatment, and particularly relates to a landfill leachate treatment method and application thereof. BACKGROUND

[0002] Landfill leachate refers to high-concentration organic wastewater with extremely complex components generated in the process of storage, transfer, transportation and stacking of garbage; common treatment methods for landfill leachate include solidification, evaporation and back spraying, among which, back spraying has the advantages of complete pollutant removal, good reduction effect and fast treatment speed, and has attracted widespread attention.

[0003] At present, the main treatment steps of back spraying are: filtering the concentrated liquid, and then atomizing the filtered concentrated liquid back to the furnace by a jet pump for incineration. However, the control during incineration is complex and requires high operation level; when the introduction amount of the concentrated liquid, the atomization degree and other conditions are not well controlled, the temperature change of the flue gas brought by the introduction of the concentrated liquid will adversely affect the garbage incineration process and the furnace components, and in severe cases, it will even cause damage to the furnace components, greatly limiting the popularization and application of back spraying. SUMMARY

[0004] In order to realize zero-emission treatment of landfill leachate while maintaining stable operation of the furnace components during back spraying, the present application provides a landfill leachate treatment method and application thereof.

[0005] In the first aspect, the landfill leachate treatment method provided by the present application adopts the following technical solution:

[0006] A landfill leachate treatment method, the treatment method comprising:

[0007] S1, pretreatment: evaporative concentration treatment of landfill leachate to obtain evaporative concentrated liquid;

[0008] S2, back spraying treatment: mixing landfill leachate and evaporative concentrated liquid to obtain mixed liquid, and atomizing the mixed liquid back to the furnace for incineration;

[0009] In step S2, the feed volume ratio a of landfill leachate to evaporative concentrated liquid satisfies the relationship shown in formula (1):

[0010]

[0011] C1 is the COD concentration of landfill leachate, and C2 is the COD concentration of evaporative concentration;

[0012] The atomization back spraying amount b of the mixed liquid satisfies the relationship shown in formula (2):

[0013] β≤6.19% M, wherein M is the weight of the waste in the furnace, and β is in t / h.

[0014] In some embodiments, the evaporation and concentration process in step S1 is performed at a temperature of 65-75°C and a pressure of 30-32 kPa.

[0015] In some embodiments, the evaporation and concentration process in step S1 further comprises reverse osmosis treatment of the leachate using a membrane to obtain concentrated water.

[0016] In some embodiments, the evaporation and concentration process in step S1 further comprises pH adjustment of the leachate using a pH adjusting agent to obtain leachate with a pH of 5.2-5.8.

[0017] In some embodiments, the pH adjusting agent is an acid reagent and / or a base reagent; the acid reagent is selected from one or more of hydrochloric acid, sulfuric acid, ammonium chloride, acetic acid, and phosphoric acid; and the base reagent is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia.

[0018] In some embodiments, the evaporation and concentration process in step S2 is performed at a gas pressure of 0.5-0.6 MPa and a gas-liquid ratio of 0.2-0.4.

[0019] In some embodiments, the incineration in step S2 is performed at a temperature of 900-1200°C and a pressure of 10-20 kPa.

[0020] In some embodiments, the evaporation and concentration process in step S2 further comprises filtration treatment of the mixed solution using a filtration device to obtain filtrate.

[0021] In some embodiments, the filtration device is a microfiltration membrane and / or an ultrafiltration membrane.

[0022] In some embodiments, the leachate is obtained from a landfill and / or a waste incineration plant.

[0023] Advantages:

[0024] 1. The organic combination scheme of evaporation concentration and back spraying treatment in the present application is as follows: firstly, the landfill leachate is subjected to evaporation concentration to obtain evaporation concentrated liquid, the landfill leachate and the evaporation concentrated liquid are mixed according to a certain proportion, and then the mixture is atomized and sprayed back into the furnace for incineration; it needs to be particularly pointed out that in the process of mixing the landfill leachate and the evaporation concentrated liquid, the feeding ratio a of the landfill leachate and the evaporation concentrated liquid needs to be adjusted according to the specific COD concentrations of the two to satisfy the specific relationship formula of formula (1), so that the heat value and the pollutant concentration of the mixture are in a stable and reasonable interval, and at the same time, the spraying amount b of the mixture is controlled in a specific range, so that the change of the flue gas temperature caused by the atomized and sprayed mixture into the furnace for incineration is in an excellent state of not damaging the furnace components, thereby achieving the effect of maintaining the stable operation of the furnace components during the zero discharge treatment of the landfill leachate.

[0025] 2. In the present application, through the atomized back spraying of the evaporation concentrated liquid and the landfill leachate, the purification treatment of the landfill leachate is realized, and at the same time, the NOx x reaction in the incinerator is also realized, which plays a role in denitration in the furnace and achieves a better effect of landfill incineration treatment.

[0026] 3. The construction and operation cost of the treatment method provided by the present application is low, which can well solve the problems of high landfill leachate treatment cost and poor treatment effect, and has a good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The present application provides a landfill leachate treatment flow chart. DETAILED DESCRIPTION

[0028] The landfill leachate treatment method provided by the present application specifically includes the following steps:

[0029] S1, pretreatment: the landfill leachate is subjected to evaporation concentration treatment to obtain evaporation concentrated liquid;

[0030] S2, back spraying treatment: the landfill leachate is mixed with the evaporation concentrated liquid to obtain a mixture, and the mixture is atomized and sprayed back into the furnace for incineration;

[0031] In step S2, the feeding volume ratio a of the landfill leachate and the evaporation concentrated liquid satisfies the relationship formula shown in formula (1),

[0032]

[0033] C1 is the COD concentration of the landfill leachate, C2 is the COD concentration of the evaporation concentration, and the units of C1 and C2 are mg / L;

[0034] The atomized spraying amount b of the mixture satisfies the relationship formula shown in formula (2):

[0035] β≤6.19% M, where M is the weight of the waste in the furnace, and the units of β and M are t / h.

[0036] In step S1 of the present application, the organic impurities and water in the landfill leachate are concentrated by evaporation, and the residue in the leachate is further concentrated, so as to obtain an evaporation concentrate with small volume and high concentration. In some specific embodiments, the temperature of the evaporation concentration process is preferably 65-75℃, and can be 65℃, 67℃, 68℃, 70℃, 72℃, 74℃, 75℃ or any value therebetween; the pressure of the evaporation concentration is preferably 30-32kPa, and can be 30kPa, 30.5kPa, 31kPa, 31.5kPa, 32kPa or any value therebetween.

[0037] In step S1 of the present application, the evaporation concentration time is adjusted according to the specific conditions of the landfill leachate, and is exemplarily 30-60min, such as 30min, 32min, 35min, 40min, 45min, 50min, 55min, 60min or any value therebetween.

[0038] In step S1 of the present application, in order to achieve better evaporation concentration effect, the reverse osmosis membrane is preferably used for reverse osmosis treatment of the landfill leachate, and the concentrated water is obtained for evaporation concentration treatment.

[0039] In some specific embodiments, the pore size of the reverse osmosis membrane is preferably 0.5-10nm, and can be 0.5nm, 1.0nm, 3.0nm, 5.0nm, 7.5nm, 10.0nm or any value therebetween.

[0040] In step S1 of the present application, in order to make the landfill leachate have better treatment effect in subsequent incineration, the pH adjusting agent is preferably used for pH adjustment treatment of the landfill leachate, and the landfill leachate with pH of 5.2-5.8 is obtained for evaporation concentration treatment. The pH adjusting agent can be an acid reagent and / or a base reagent, and the type of the pH adjusting agent is selected according to the pH of the evaporation concentrate in the specific operation.

[0041] In some specific embodiments, the acid reagent can be but is not limited to one or more of hydrochloric acid, sulfuric acid, ammonium chloride, acetic acid and phosphoric acid; the base reagent can be but is not limited to one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate and ammonia.

[0042] In step S1 of the present application, the reverse osmosis treatment and the pH adjustment treatment described above can be performed in any order, that is, the reverse osmosis treatment is performed first and then the pH adjustment treatment is performed, or the pH adjustment treatment is performed first and then the reverse osmosis treatment is performed. In some preferred embodiments, the step is preferably performed first, and then the pH adjustment treatment is performed to achieve more accurate adjustment of the pH value of the landfill leachate.

[0043] In step S2 of the present application, the feed ratio a of the landfill leachate and the evaporation concentrated liquid is adjusted according to the control of the COD concentration in the two liquids, so that the heat value and the pollutant concentration of the mixed liquid entering the atomization back spraying treatment are in a stable and reasonable range. In some specific embodiments, the COD concentration in the landfill leachate and the evaporation concentrated liquid can be monitored in real time by a COD detector, and the feed ratio of the two liquids is adjusted in real time according to the real-time concentration.

[0044] In step S2 of the present application, when the atomization back spraying amount b of the mixed liquid is ≤6.19% M, the mixed liquid can ensure a certain treatment efficiency while also making the change in flue gas temperature caused by the mixed liquid entering the furnace through atomization back spraying be in an excellent state that does not damage the furnace components, thereby achieving the effect of maintaining the stable operation of the furnace components during the back spraying process while achieving zero discharge treatment of the landfill leachate.

[0045] In step S2 of the present application, the mixed liquid is fully atomized by atomization back spraying to reduce the influence of back spraying on the combustion conditions of the furnace, so that the furnace components can operate stably during the treatment process. In some specific embodiments, compressed air is used as the medium for atomization treatment of the mixed liquid in the atomization back spraying, and the gas pressure of the atomization back spraying is preferably 0.5-0.6 MPa, specifically 0.5 MPa, 0.52 MPa, 0.54 MPa, 0.58 MPa, 0.6 MPa or any value therebetween; the gas-liquid ratio of the atomization back spraying is preferably 0.2-0.4, specifically 0.2, 0.21, 0.24, 0.28, 0.3, 0.35, 0.39, 0.4 or any value therebetween.

[0046] In step S2 of the present application, the mixed liquid enters the furnace after being atomized and back sprayed, achieving rapid and complete removal of pollutants in the mixed liquid. In some specific embodiments, the temperature of the incineration is preferably 900-1000℃, specifically 900℃, 920℃, 950℃, 960℃, 1000℃ or any value therebetween; the pressure of the incineration is preferably 10-20 kPa.

[0047] In step S2 of the present application, in order to achieve better incineration effect, the mixed liquid is preferably filtered by a filtering device before atomization back spraying.

[0048] In some embodiments, the filtration device can be, but is not limited to, one or more of microfiltration membranes and ultrafiltration membranes. More specifically, the pore size of the microfiltration membrane is preferably 0.1-25 um, and can be 0.1 um, 3 um, 8 um, 10 um, 20 um, 25 um or any value therebetween; the pore size of the ultrafiltration membrane is preferably 1-10 nm, and can be 1 nm, 3 nm, 5 nm, 7 nm, 10 nm or any value therebetween.

[0049] The method for treating landfill leachate provided by the application can achieve zero discharge treatment of landfill leachate while maintaining the stable operation of the furnace components during the back spraying process, and can be well applied to the treatment of landfill leachate generated in landfill plants, waste incineration plants and the like, and has good practical application prospects.

[0050] The embodiments of the application are described in detail below, and the examples of the embodiments are intended to explain the application and cannot be understood as limiting the application. If a specific technique or condition is not specified in the embodiments, the technique or condition described in the literature in the art or according to the product manual is used. If the manufacturer of the reagent or instrument is not specified, it is a conventional product that can be obtained by purchase.

[0051] Embodiments

[0052] A method for treating landfill leachate is provided in this embodiment, which is used to treat landfill leachate from a waste incineration plant. Referring to Figure 1 , the method specifically comprises the following steps:

[0053] S1, pretreatment:

[0054] (a) reverse osmosis membrane filtration treatment: landfill leachate generated by a waste incineration plant is collected and delivered to a reverse osmosis membrane by a water pump, and the landfill leachate is treated under the conditions of a membrane pore size of 1 nm, a temperature of 25℃ and a pressure of 90 bar, and concentrated water is collected.

[0055] (b) pH adjustment treatment: the concentrated water is transferred to an adjustment tank by a water pump, the pH value of the concentrated water is detected, and ammonium chloride or ammonia water is added accordingly to adjust the pH value of the concentrated water to about 5.5.

[0056] (c) evaporation concentration treatment: the concentrated water is transferred to an evaporator by a water pump, and evaporation is carried out under the conditions of a temperature of 70℃ and a pressure of 31.2 kPa, and an evaporation concentrate is collected.

[0057] The water quality test results of the landfill leachate and the obtained evaporation concentrate are shown in Table 1:

[0058] Table 1. Water quality test results

[0059] Test item Landfill leachate Evaporation concentrate COD (mg / L) 4311.2 28023.0 [NH3-N (mg / L)] 6072.6 39472.2 TN (mg / L) 6366.2 41380.0 pH 8.2 5.5 Conductivity (μs / cm) 73231 476000 Total hardness (mg / L as CaCO3) 1046.4 6801.6 Ca2 + (mg / L)]]> 14.0 90.7 Mg 2+ (mg / L) 242.8 1578.0 TDS (mg / L) 65104.6 423180 Total alkalinity (mg / L as CaCO3) - -

[0060] S2, back spraying treatment:

[0061] The landfill leachate and the evaporation concentrated liquid were mixed in a volume ratio of 1:5 to obtain a mixed liquid; then the mixed liquid was uniformly atomized and sprayed into the furnace by an atomizing spray gun using compressed air as the medium under the conditions of a gas pressure of 0.6 MPa, a gas-liquid ratio of 0.3, and a back spraying amount of 2 t / h; and incineration was performed under the conditions of a temperature of 1000℃ and a pressure of 20 kPa.

[0062] In the furnace, the weight of the landfill was 35 t / h, the heat value of the landfill was 7000 KJ / kg, the flue gas density was 1.2 kg / m 3 , the flue gas flow was 260000 Nm 3 / h, and the original flue gas temperature was 1020℃.

[0063] Comparative Example

[0064] In the comparative example, a method for treating landfill leachate was provided, and landfill leachate from a landfill incineration plant was treated. The method specifically included the following steps:

[0065] S1, pretreatment:

[0066] (a) reverse osmosis membrane filtration treatment: landfill leachate generated by a landfill incineration plant was collected and transported to a reverse osmosis membrane by a water pump, and the landfill leachate was treated under the conditions of a membrane pore size of 1 nm, a temperature of 25℃, and a pressure of 90 bar to collect concentrated water.

[0067] (b) pH adjustment treatment: the concentrated water was transferred to an adjustment tank by a water pump, the pH value of the concentrated water was detected, and ammonium chloride or ammonia water was added accordingly to adjust the pH value of the concentrated water to about 5.5.

[0068] (c) evaporation concentration treatment: the concentrated water was transferred to an evaporator by a water pump and evaporated under the conditions of a temperature of 70℃ and a pressure of 31.2 kPa to collect an evaporation concentrated liquid.

[0069] The water quality test results of the landfill leachate and the obtained evaporation concentrated liquid are shown in Table 2:

[0070] Table 2. Water quality test results

[0071] Test item Landfill leachate Evaporation concentrate COD (mg / L) 5500 32116 [NH3-N (mg / L)] 2120 12263 TN (mg / L) 2511 14682 pH 8.4 5.6 Conductivity (μs / cm) 82419 478198 Total hardness (mg / L as CaCO3) 1198 68304 Ca2 + (mg / L)]]> 102 569 Mg 2+ (mg / L) 264.2 1536 TDS (mg / L) 66759.39 387938 Total alkalinity (mg / L as CaCO3) - -

[0072] S2, back spraying treatment:

[0073] The landfill leachate and the evaporation concentrated liquid are mixed according to a volume ratio of 1:0.5 to obtain a mixed liquid; then the mixed liquid is uniformly atomized and sprayed into the furnace by an atomizing spray gun and using compressed air as a medium under the conditions of a gas pressure of 0.6 MPa, a gas-liquid ratio of 0.3 and a back spraying amount of 2 t / h; and incineration is carried out under the conditions of a temperature of 1000 DEG C and a pressure of 20 kPa.

[0074] The weight of the garbage in the furnace is 35 t / h, the heat value of the garbage is 7000 KJ / kg, the flue gas density is 1.2 kg / m 3 , the flue gas flow is 260000 Nm 3 / h, and the original flue gas temperature is 1020 DEG C.

[0075] Test Example

[0076] During the treatment of the landfill leachate in the examples and the comparative examples, the temperature of the flue gas in the furnace before and after the mixed liquid is put into operation is detected, and the specific conditions are shown in Table 3.

[0077] Table 3.

[0078] Group Feed ratio a Atomization back spray amount b (t / h) Flue gas temperature before operation (°C) Flue gas temperature before and after operation (°C) Example 1:5 2 1020 1010 Comparative example 1:0.5 2 1020 836

[0079] As shown in Table 3, compared with the comparative examples, the method provided by the present application can realize zero discharge treatment of the landfill leachate while maintaining stable operation of the furnace, and has a good application prospect.

[0080] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments without departing from the principles and purposes of the present application within the scope of the present application.

Claims

1. A method for treating landfill leachate, characterized by, The processing method comprises: S1, pretreatment: evaporative concentration treatment is performed on the landfill leachate to obtain evaporative concentrated liquid; S2, back spraying treatment: landfill leachate is mixed with the evaporative concentrated liquid to obtain mixed liquid, and the mixed liquid is atomized and back sprayed into the furnace chamber for incineration; In step S2, the feed volume ratio a of the landfill leachate to the evaporative concentrated liquid satisfies the relationship shown in formula (1): C1 is the COD concentration of the landfill leachate, and the unit is mg / L; C2 is the COD concentration of the evaporative concentration, and the unit is mg / L; The atomized back spraying amount β of the mixed liquid satisfies the relationship shown in formula (2): M is the weight mass of the garbage in the furnace chamber, and the unit is t / h; the unit of the atomized back spraying amount β is t / h.

2. The treatment method of landfill leachate according to claim 1, characterized by, The temperature of the evaporative concentration treatment in step S1 is 65-75℃, and the pressure is 30-32kPa.

3. The treatment method of landfill leachate according to claim 1, characterized by, Step S1 further comprises reverse osmosis treatment of the landfill leachate by using a reverse osmosis membrane to obtain concentrated water for evaporative concentration treatment.

4. The treatment method of landfill leachate according to claim 1, characterized by, In step S1, further comprising using a pH adjusting agent to adjust the pH of the landfill leachate to obtain landfill leachate with a pH of 5.2-5.8 for evaporative concentration treatment.

5. The treatment method of landfill leachate according to claim 4, characterized in that, The pH adjusting agent is an acid reagent and / or a base reagent; the acid reagent is selected from one or more of hydrochloric acid, sulfuric acid, ammonium chloride, acetic acid and phosphoric acid; the base reagent is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate and ammonia.

6. The treatment method of landfill leachate according to claim 1, characterized by, In step S2, the gas pressure of the atomized back spraying is 0.5-0.6MPa, and the gas-liquid ratio is 0.2-0.

4.

7. The treatment method of landfill leachate according to claim 1, characterized by, In step S2, the temperature of the incineration is 900-1200℃, and the pressure is 10-20kPa.

8. The treatment method of landfill leachate according to claim 1, characterized by, Step S2 further comprises filtering treatment of the mixed liquid by using a filtering device to obtain filtrate for atomized back spraying.

9. The treatment method of landfill leachate according to claim 8, characterized in that, The filtering device is a microfiltration membrane and / or an ultrafiltration membrane.

10. The method for treating landfill leachate according to any one of claims 1 to 9, characterized by, The landfill leachate is from a landfill and / or a garbage incineration plant.

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