CN111704314A - A kind of high ammonia nitrogen type landfill leachate treatment process - Google Patents

Abstract

The present invention is a high-ammonia-nitrogen type landfill leachate treatment process. The leachate is lifted from a garbage dump collection tank into a regulating tank for reaction, and the reacted mixed solution is pumped into a deamination tower, and the effluent from the deamination tower passes through an RTOS system. After judging that the index is qualified, it enters the denitrifier; in the denitrifier, the organic matter in the influent and the nitrate returned by the MBR undergo a denitrification process to simultaneously realize the removal of the organic matter COD and TN, and separate the muddy water through the separation membrane of the MBR unit; The effluent further enters the NF system to complete a part of the separation of salt and organic matters, and the NF product water is pumped into the RO unit to complete the final purification process. The impact on the change of the water inflow index is eliminated, especially when the ammonia nitrogen index fluctuates greatly and the adjustment tank cannot be buffered, the process of the present invention can effectively solve the impact of the water inflow index on the system, and greatly improve the impact on landfill leachate. The treatment efficiency of the liquid is improved, and the stable operation of the system is achieved, and it is based on the characteristics of such wastewater.

Description

A kind of high ammonia nitrogen type landfill leachate treatment process

technical field

The invention belongs to the technical field of high-ammonia-nitrogen type landfill leachate treatment, and in particular relates to a high-ammonia-nitrogen type landfill leachate treatment process.

Background technique

At present, China's landfill leachate treatment is mainly based on biological treatment technology, while foreign landfill leachate treatment is mainly based on the research and application of physical and chemical treatment technology. However, for the high-concentration and complex wastewater such as landfill leachate, it cannot be treated and discharged up to the standard only by biotechnology. Especially for "aged" landfill leachate, biological treatment basically has no effect.

In fact, most of the leachate from sanitary landfills in China is discharged without reaching the standards set by China, which has caused serious groundwater pollution. As far as the physicochemical treatment technology of leachate is concerned, coagulation and sedimentation can remove most of the suspended solids and macromolecular organic matter in the leachate, but the chemical sludge produced is difficult to treat. Activated carbon adsorption only has the ability to adsorb and remove substances with a molecular weight of less than 1000 in the leachate, and the cost of adsorption treatment is very high. The one-time investment and operating costs of membrane treatment technology are extremely high. Except for a few small-scale leachate treatment with high effluent quality requirements in China, it is not suitable for leachate treatment in most landfills in China.

Electrochemical oxidation and photocatalytic oxidation technology not only have high processing costs and cannot meet the requirements of large-scale processing, but also the reaction device is extremely difficult to realize in practical engineering applications. In contrast, although the chemical catalytic oxidation technology of leachate has the problem of high price of common oxidants (ozone and hydrogen peroxide), it can reduce the amount of oxidants used and improve the utilization rate of oxidants by synthesizing new catalysts, thereby reducing the cost of oxidants. Leachate disposal costs.

Through the development of the domestic industry and technology in recent years, the mainstream process has basically been determined as: conditioning - coagulation and sedimentation pretreatment - activated sludge treatment - advanced membrane treatment - discharge; , The influence of geographical and climatic conditions is very obvious, the water quality of the leachate produced is very large, and the water quality changes greatly during the operation process, resulting in extremely unstable operation of the wastewater treatment system, exceeding the standard is almost normal, especially for high ammonia nitrogen type landfill seepage The treatment technology of leachate is not perfect. When there is a large deviation in the ammonia nitrogen index, the back-end biochemical system will be significantly inhibited, which will affect the overall operation state, resulting in exceeding the standard accident, and even a long time caused by the collapse of the biochemical system. In order to deal with the problem of stable operation of the system, the conventionally used DCS central control system requires more manual intervention and management, and at least 10 operators are deployed.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a process for treating landfill leachate of high ammonia nitrogen type.

Realize the purpose of the present invention to provide technical solutions as follows:

A process for treating landfill leachate with high ammonia nitrogen, comprising the following steps

The leachate is lifted from the garbage collection tank into the adjustment tank. The adjustment tank temporarily stores the incoming garbage leachate, and performs mechanical stirring to prevent material deposition. The adjustment tank is heated by steam, and organic sulfur and PAC are added. PAM three medicines;

The reacted mixed solution is pumped into the deammonia tower, which is a carbon steel anti-corrosion structure as a whole. The ammonia gas blown off by the deammonia tower enters the ammonia absorption tower for absorption, and part of the absorbed ammonia water is returned to the deammonia tower inlet water to lift. The ammonia nitrogen concentration entering the deamination tower promotes the separation of ammonia gas, and part of it is crystallized and transported to the outside.

In the denitrifier, the organic matter in the influent and the nitrate returned from the MBR undergo a denitrification process to simultaneously remove the COD and TN of the organic matter. The effluent from the denitrifier enters the MBR unit for further biodegradation of COD, and all the remaining ammonia nitrogen is converted into Nitrate, the mud water is separated by the separation membrane of the MBR unit;

The separated effluent further enters the NF system to complete a part of the separation of salt and organic matters. The NF product water is pumped into the RO unit to complete the final purification process, and the NF concentrated water is returned to the denitrification tank for reprocessing. The RO unit water can fully meet the discharge requirements. Standard, RO concentrated water is discharged into the landfill, and after adsorption and filtration through the soil layer of the landfill, it enters the adjustment tank for treatment. (RO concentrated water is salt, heavy metals and residual COD.)

Further, in the adjustment pool:

The residence time is 1-2h, set as two pools, and run alternately.

The steam is heated to 30-40°C to promote the separation of ammonia in water.

The dosage of organic sulfur is 100-120mg/l to adsorb heavy metals.

The dosage of PAC is 150-200mg/l for flocculation of suspended solids.

The dosage of PAM is 1-2mg/l to help coagulate the suspended solids.

Further, in the deamination tower:

The top is fed with water, the bottom is fed with air, and the mud-water separation is completed in the desliming part.

Degassing part: the overflow air speed is 10-12m/s, and the high air speed helps to stir the water splash in the multi-layer board packing and realize the separation of air and water.

Desliming part; hydraulic load 2-3m ³ /㎡*h, sedimentation time 3-4h, longer sedimentation time and sedimentation height can effectively reduce the disturbance of the influent to the sedimentation layer and improve the sedimentation effect.

Multi-layer board packing: 60-70 ℃ layout angle, each board layout area 0.5-0.8㎡.

Inclined plate packing: the plate spacing is 50-80mm, and the height of the packing layer is 1-1.2m.

PH conditions: 9-11.

Air-water ratio: 3500:1.

The reflux ratio of ammonia water in the ammonia absorption tower: 15%.

Further, in the denitrification tank:

Effluent TN≤30mg/l.

Nitrogen removal rate: 0.02-0.03 (kgNO3-N)/(kgMLSS·d).

Reaction temperature: 20-40°C.

Pool depth: 4-6m.

Carbon to nitrogen ratio: 10-11:1.

PH condition: 7-10.

Further, in the MBR unit

Effluent COD≤100mg/l, NH3-N≤5mg/l.

COD load rate: 0.05-0.07kgBOD5/(kgMLSS·d).

MLSS concentration: 12000-15000 mg/l.

Cleaning cycle: 1 time/6 months.

Reaction temperature: 20-40°C.

Membrane flux: 150-200L/㎡*d.

Membrane module requirements: CSMBR biofilm.

Further, in the NF system

Effluent COD≤50mg/l, NH3-N≤0.1mg/l, TDS≤2000mg/l.

Water production rate: 95%.

The layout in the NF system is as follows: the first-level NF directly effluent, the first-level NF concentrated water enters the second-level NF for processing, and the second-level NF simultaneously treats the same amount of influent as the first-level NF.

Filtration pressure: 5-6kpa

Further, RO unit settings:

Effluent COD≤10mg/l, NH3-N≤0.1mg/l, TDS≤0.1mg/l

Water production rate: 85%

Arrangement: Two-stage filtration

Filtration pressure: 10-14kpa

RTOS system:

In the aspect of the supervision system in each stage of the present invention, intelligence and automation are required, and the RTOS system is introduced, and corresponding detection equipment and PLC sensors are set in each processing link, and then the corresponding information is transmitted to the overall control center, and the corresponding alarm system is set up. , If the processing requirements are not met, or there is an abnormal working state, an alarm will be automatically issued to stop and check the processing system.

Each stage is set up with online monitoring, and through the particle swarm algorithm, the subsequent index prediction is completed, the key index limits are preset in advance, and the emergency procedures of the system are exceeded.

Compared with the prior art, the present invention has significant advantages compared with the prior art:

1. It can effectively resist the impact of influent water quality, especially the impact of ammonia nitrogen indicators. Before entering the biochemical section, the main indicators do not change with the change of raw water, and are basically constant, which avoids the restriction of indicators on the system influent during operation;

2. The deamination system completes the separation of suspended solids, dissolved ammonia and water in one step, shortens the process unit, and reduces the cost of input, operation and management. ) removal rate is increased by more than 50%, and the operating pH range and temperature range are reduced at the same time, thereby reducing energy consumption;

3. Compared with the current technology, the MBR maintenance cycle adopted is doubled, and the amount of biochemical sludge is almost reduced to 15% of the 0NF water production, which reduces the investment and maintenance cost of the NF system;

4. The system is equipped with an RTOS control system, which predicts the next-step indicators while monitoring the online indicators of the system, which effectively prevents the system from exceeding the standard, improves the system's automatic control operation ability, and reduces the number of operators.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

Fig. 2 is the working schematic diagram of the deamination tower unit.

Fig. 3 is the working schematic diagram of RTOS system.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings

The present invention is a processing technology for landfill leachate of high ammonia nitrogen type, which realizes the elimination of the influence on the change of the water inflow index, especially when the ammonia nitrogen index fluctuates greatly and the adjustment tank cannot perform buffering, the technology can effectively It solves the impact of water inflow indicators on the system, greatly improves the treatment efficiency of landfill leachate, and realizes the stable and up-to-standard operation of the system, and is based on the characteristics of such wastewater.

The process technology of the invention can reduce the operating cost by more than 20%, and reduce the operating personnel to 4 through the RTOS (real-time operating system) control system, so as to realize the automatic control operation ability of the system

A process for treating landfill leachate with high ammonia nitrogen, as shown in Figure 1, includes the following steps

The leachate is lifted from the garbage collection tank into the adjustment tank. The adjustment tank temporarily stores the incoming garbage leachate, and performs mechanical stirring to prevent material deposition. The adjustment tank is heated by steam, and organic sulfur and PAC are added. PAM three medicines;

The reacted mixed solution is pumped into the deammonia tower, which is a carbon steel anti-corrosion structure as a whole. The ammonia gas blown off by the deammonia tower enters the ammonia absorption tower for absorption, and part of the absorbed ammonia water is returned to the deammonia tower inlet water to lift. The ammonia nitrogen concentration entering the deamination tower promotes the separation of ammonia gas, and part of it is crystallized and transported to the outside.

In the denitrifier, the organic matter in the influent and the nitrate returned from the MBR undergo a denitrification process to simultaneously remove the COD and TN of the organic matter. The effluent from the denitrifier enters the MBR unit for further biodegradation of COD, and all the remaining ammonia nitrogen is converted into Nitrate, the mud water is separated by the separation membrane of the MBR unit;

The separated effluent further enters the NF system to complete a part of the separation of salt and organic matters. The NF product water is pumped into the RO unit to complete the final purification process, and the NF concentrated water is returned to the denitrification tank for reprocessing. The RO unit water can fully meet the discharge requirements. Standard, RO concentrated water is discharged into the landfill, and after adsorption and filtration through the soil layer of the landfill, it enters the adjustment tank for treatment. (RO concentrated water is salt, heavy metals and residual COD.)

In the conditioning pool:

The residence time is 1-2h, set as two pools, and run alternately.

The steam is heated to 30-40°C to promote the separation of ammonia in water.

The dosage of organic sulfur is 100-120mg/l to adsorb heavy metals.

The dosage of PAC is 150-200mg/l for flocculation of suspended solids.

The dosage of PAM is 1-2mg/l to help coagulate the suspended solids.

In the deamination tower:

The top is fed with water, the bottom is fed with air, and the mud-water separation is completed in the desliming part.

Degassing part: the overflow air speed is 10-12m/s, and the high air speed helps to stir the water splash in the multi-layer board packing and realize the separation of air and water.

Desliming part; hydraulic load 2-3m ³ /㎡*h, sedimentation time 3-4h, longer sedimentation time and sedimentation height can effectively reduce the disturbance of the influent to the sedimentation layer and improve the sedimentation effect.

Multi-layer board packing: 60-70 ℃ layout angle, each board layout area 0.5-0.8㎡.

Inclined plate packing: the plate spacing is 50-80mm, and the height of the packing layer is 1-1.2m.

PH conditions: 9-11.

Air-water ratio: 3500:1.

The reflux ratio of ammonia water in the ammonia absorption tower: 15%.

In the denitrification tank:

Effluent TN≤30mg/l.

Nitrogen removal rate: 0.02-0.03 (kgNO3-N)/(kgMLSS·d).

Reaction temperature: 20-40°C.

Pool depth: 4-6m.

Carbon to nitrogen ratio: 10-11:1.

PH condition: 7-10.

in MBR unit

Effluent COD≤100mg/l, NH3-N≤5mg/l.

COD load rate: 0.05-0.07kgBOD5/(kgMLSS·d).

MLSS concentration: 12000-15000 mg/l.

Cleaning cycle: 1 time/6 months.

Reaction temperature: 20-40°C.

Membrane flux: 150-200L/㎡*d.

Membrane module requirements: CSMBR biofilm.

In NF system

Effluent COD≤50mg/l, NH3-N≤0.1mg/l, TDS≤2000mg/l.

Water production rate: 95%.

The layout in the NF system is as follows: the first-level NF directly effluent, the first-level NF concentrated water enters the second-level NF for processing, and the second-level NF simultaneously treats the same amount of influent as the first-level NF.

Filtration pressure: 5-6kpa

RO system:

Effluent COD≤10mg/l, NH3-N≤0.1mg/l, TDS≤0.1mg/l

Water production rate: 85%

Arrangement: Two-stage filtration

Filtration pressure: 10-14kpa

RTOS system:

In each stage of the present invention, in terms of the supervision system, intelligence and automation are required, the RTOS system is introduced, and corresponding detection equipment and PLC sensors are installed in each processing link, and then the corresponding information is transmitted to the overall control center, and the corresponding alarm system is set up. , If the processing requirements are not met, or there is an abnormal working state, an alarm will be automatically issued to stop and check the processing system. Specifically as shown in Figure 3.

Each stage is equipped with online monitoring, and through the particle swarm algorithm, the subsequent index prediction is completed, the key index limits are preset in advance, and the emergency procedures of the system are exceeded.

The present invention adopts the particle swarm algorithm to predict the results as shown in Table 1

Table 1 Particle swarm algorithm prediction result table

In the present invention, the traditional process of a certain project is transformed into a deamination device, the material of the membrane is changed, the nanofiltration system is used, and the supervision system is optimized. As shown in Tables 2, 3, 4, 5, 6, and 7.

Table 2 The effluent indicators before and after the system transformation

Table 3 Pollutant removal rate before and after system renovation

Table 4 Energy saving of fan operation before and after renovation

Table 5 Mud discharge before and after reconstruction

Table 6 PAM usage

Table 7 Data table of main indicators of effluent in the first half of August before and after transformation (mg/l)

Claims (10)

1. A treatment process of high ammonia nitrogen type waste leachate is characterized by comprising the following steps:

the leachate is lifted from a garbage field collecting tank and enters an adjusting tank, the adjusting tank temporarily stores the entering garbage leachate, the garbage leachate is mechanically stirred to prevent substance deposition, the adjusting tank is subjected to steam temperature rise, and three medicaments of organic sulfur, PAC and PAM are added;

pumping the reacted mixed liquid into a deamination tower, wherein the whole deamination tower is of a carbon steel corrosion-resistant structure, ammonia blown off by the deamination tower enters an ammonia absorption tower for absorption, part of the absorbed ammonia water flows back to the deamination tower for water inlet, the ammonia nitrogen concentration entering the deamination tower is improved, ammonia separation is promoted, part of the ammonia water is crystallized and transported out, and the effluent of the deamination tower enters a denitrification device after the index of the effluent of the deamination tower is judged to be qualified by an RTOS system;

in the denitrification device, the influent organic matter and the nitrate radical refluxed by the MBR are subjected to denitrification process, the removal of COD and TN of the organic matter is synchronously realized, the effluent of the denitrification device enters the MBR unit for further biodegradation of COD, the residual ammonia nitrogen is completely converted into the nitrate radical, and the mud and water are separated by a separation membrane of the MBR unit;

the separated water further enters an NF system to complete the separation of partial salt and organic matters, the NF produces water and is pumped into an RO unit to complete the final purification process, the NF concentrated water flows back to a denitrification tank to be reprocessed, the RO unit produces water meeting the discharge standard, and the RO concentrated water is discharged into a refuse landfill and is subjected to adsorption filtration through a soil layer of the landfill and then enters an adjusting tank to be processed.

2. The process for the treatment of landfill leachate of high ammonia nitrogen type according to claim 1, characterized in that in the conditioning tank:

the retention time is 1-2h, two pools are arranged and alternately run; raising the temperature of the steam to 30-40 ℃ to promote the separation of ammonia in water; the adding amount of organic sulfur is 100-120mg/l for absorbing heavy metal; PAC dosage of 150-; PAM is added in an amount of 1-2mg/l to help coagulate suspended matter.

3. The process for treatment of landfill leachate of high ammonia nitrogen type according to claim 1, characterized in that in the deamination tower:

water is fed from the top, air is fed from the bottom, mud and water are separated from the desliming part, and NH3-N of the deamination effluent is less than or equal to 100 mg/l;

and (3) degassing part: the velocity of the overflowing gas is 10-12m/s, and the high gas velocity is beneficial to stirring water bloom in the multilayer plate filler, so that gas-water separation is realized;

a desliming part: hydraulic load 2-3m³Per square meter, settling time is 3-4 h;

filling a multilayer board: the arrangement angle is 60-70 ℃, and the arrangement area of each plate is 0.5-0.8 square meter; filling with an inclined plate: the plate spacing is 50-80mm, and the height of the filler layer is 1-1.2 m;

and (3) pH condition: 9-11;

gas-water ratio: 3500: 1;

ammonia reflux ratio of ammonia absorption tower: 15 percent.

4. The process for the treatment of landfill leachate of high ammonia nitrogen type according to claim 1, characterized in that in the denitrification tank:

the TN of the effluent is less than or equal to 30 mg/l;

denitrification rate: 0.02-0.03(kgNO 3-N)/(kgMLSS. d);

reaction temperature: 20-40 ℃;

depth of the pool body: 4-6 m;

the carbon-nitrogen ratio is as follows: 10-11: 1;

and (3) pH condition: 7-10.

5. The process for treatment of landfill leachate of high ammonia nitrogen type according to claim 1, characterized in that in the MBR unit:

COD of the effluent is less than or equal to 100mg/l, and NH3-N is less than or equal to 5 mg/l;

COD load factor: 0.05-0.07kgBOD 5/(kgMLSS. d);

MLSS concentration: 12000-15000 mg/l;

cleaning cycle: 1 time/6 months;

reaction temperature: 20-40 ℃;

membrane flux: 150 plus 200L/square meter x d;

membrane module requirements: CSMBR biofilm.

6. The process for treatment of high ammonia nitrogen type landfill leachate according to claim 1, wherein in the NF system:

COD of the effluent is less than or equal to 50mg/l, NH3-N is less than or equal to 0.1mg/l, and TDS is less than or equal to 2000 mg/l;

water yield: 95 percent.

7. The process for treating waste leachate of high ammonia nitrogen type according to claim 6, wherein the arrangement mode in the NF system is as follows: the first-stage NF directly discharges water, the concentrated water of the first-stage NF enters the second-stage NF for treatment, and the second-stage NF simultaneously treats the water inlet with the same quantity as the first-stage NF; and (3) filtering pressure: 5-6 kpa.

8. The waste leachate treatment process of high ammonia nitrogen type according to claim 6, wherein the RO unit is configured to:

COD of the effluent is less than or equal to 10mg/l, NH3-N is less than or equal to 0.1mg/l, and TDS is less than or equal to 0.1 mg/l;

water yield: 85 percent;

the arrangement mode is as follows: two-stage filtration;

and (3) filtering pressure: 10-14 kpa.

9. The technology for treating high ammonia nitrogen type landfill leachate according to claim 1, wherein an RTOS system is provided specifically as follows:

introducing an RTOS system at each stage of the treatment process, arranging corresponding detection equipment and a PLC sensor in each treatment link, then transmitting corresponding information to a general control center, arranging a corresponding alarm system, and automatically alarming to stop and check the treatment system if the treatment requirement is not met or an abnormal working state exists.

10. The high ammonia nitrogen type landfill leachate treatment process according to claim 9, wherein each stage is provided with online monitoring, and the subsequent index prediction is completed through a particle swarm algorithm, and key index limits and emergency procedures of the overproof system are preset in advance.

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