CN212504364U - Leachate treatment system for fly ash landfill - Google Patents

Abstract

The utility model belongs to the technical field of sewage treatment, and relates to a fly ash landfill leachate treatment system, wherein a pretreatment system sequentially comprises a regulating tank and a basket filter which are connected by a pipeline; the nanofiltration system sequentially comprises an intermediate water tank communicated with a basket filter pipeline, and a scale inhibitor adding unit and a membrane treatment unit communicated with the intermediate water tank pipeline, wherein the intermediate water tank is provided with a water outlet pipeline communicated with the membrane treatment unit and a circulating stirring pipeline which is provided with an adjusting valve and is communicated with the water outlet pipeline, the water outlet pipeline is provided with a centrifugal pump shared by the circulating stirring and water outlet processes of the intermediate water tank, the membrane treatment unit sequentially comprises a core filtering unit for secondarily filtering percolate, a buffer tank unit for temporarily storing the secondarily filtered percolate, a high-pressure pump and a plurality of membrane columns, and a mesh tube type nanofiltration membrane is arranged in each membrane column.

Description

Leachate treatment system for fly ash landfill

Technical Field

The utility model belongs to the technical field of sewage treatment, a flying dust landfill leachate treatment system is related to, especially relate to a flying dust landfill leachate treatment system efficient, with low costs, the operation is stable.

Background

Waste incineration power generation is the best solution to the current waste surrounding problem. The fly ash is used as a byproduct of waste incineration and has great environmental hazard characteristics. Solidification landfill is one of the most commonly used disposal methods for fly ash. However, leachate from fly ash landfills can also pose significant environmental pollution problems and require proper disposal.

The fly ash landfill leachate is different from the common domestic garbage landfill leachate, and has low organic content and high concentration of heavy metal and TDS. In addition, fly ash landfill leachate typically contains a significant amount of chloride ions. (problems and countermeasures for disposal of fly ash landfill for incineration, solidification and stabilization of refuse [ J ] environmental engineering report 2018,12(10):2717-2724.)

At present, the treatment technology for the leachate of the fly ash landfill is generally carried out by using a reverse osmosis membrane after electrodialysis or ion exchange resin desalination. For example, a treatment technology disclosed in a treatment device (CN207210144U) for incinerating the leachate of the fly ash solidified landfill after power generation. However, the characteristics of high salt and high hardness of the leachate in the fly ash landfill cause the problems of high operation cost of desalination treatment, high reverse osmosis operation pressure and the like in practical application. The water quality standard of the leachate of the fly ash landfill is inversely observed, although the contents of heavy metals and organic matters are strictly limited, no detailed requirements are made on salinity. Thus, the treatment technology of fly ash landfill leachate may reduce operational difficulties and operational costs by reducing desalination requirements.

SUMMERY OF THE UTILITY MODEL

In view of this, the utility model discloses a solve flying dust landfill leachate high salt, high hardness characteristic and lead to flying dust landfill leachate to have the problem that desalination treatment running cost is high, reverse osmosis operating pressure is high, provide a flying dust landfill leachate treatment system.

In order to achieve the purpose, the utility model provides a flying ash landfill leachate treatment system, which comprises a pretreatment system and a nanofiltration system which are matched for use; the pretreatment system sequentially comprises a regulating tank and a basket filter, wherein the regulating tank is connected with a pipeline; the nanofiltration system sequentially comprises an intermediate water tank communicated with a basket filter pipeline, and a scale inhibitor adding unit and a membrane treatment unit which are communicated with the intermediate water tank pipeline, wherein the intermediate water tank is provided with a water outlet pipeline communicated with the membrane treatment unit and a circulating stirring pipeline which is provided with an adjusting valve and is communicated with the water outlet pipeline, the water outlet pipeline is provided with a centrifugal pump shared by the two processes of circulating stirring and water outlet of the intermediate water tank, the membrane treatment unit sequentially comprises a core filtering unit for secondary filtering of the leachate, a buffer tank unit for temporarily storing the leachate after the secondary filtering, a high-pressure pump and a plurality of membrane columns, and the membrane columns are internally provided with mesh-tube nanofiltration membranes.

The beneficial effect of this basic scheme lies in: basket filters in the pretreatment system are used to remove the suspended matter from the leachate. The main component of the scale inhibitor adding unit in the nanofiltration system is hydrochloric acid, so that the scale formation of the intermediate water tank can be effectively prevented, and the softening operation of the percolate is reduced. The core filter unit among the membrane processing unit is used for carrying out the secondary filtration with filtration liquid, and the buffer tank unit is used for keeping in filtration liquid temporarily, and high-pressure pump is used for the secondary filtration liquid pressurized pump in the buffer tank unit to go into the membrane post. The mesh-tube nanofiltration membrane in the membrane column has selective interception property, allows monovalent salt to permeate through and has medium salt permeation rate. And because the monovalent ions can permeate the membrane, compared with a reverse osmosis treatment method, the osmotic pressure is greatly reduced, and the desalting requirement and the operating pressure of the leachate treatment are reduced by utilizing the characteristic that the nanofiltration membrane runs the monovalent salts to permeate the membrane.

Furthermore, the membrane processing unit also comprises an online pump unit for driving the percolate to circulate in the membrane column and a control cabinet unit for controlling the high-pressure pump and the online pump unit to be opened, and control valves on pipelines in the membrane processing unit are also controlled by the control cabinet unit. Has the advantages that: control valves on all pipelines in the whole membrane processing unit are controlled through the control cabinet unit, so that the membrane processing unit is more convenient and faster.

And further, the membrane treatment unit also comprises a compressed air system, and compressed air required by opening and closing of each pneumatic valve in the membrane treatment unit is provided by the compressed air system.

Further, a metering pump is arranged on a connecting pipeline between the scale inhibitor adding unit and the intermediate water tank. Has the advantages that: the scale inhibitor adding unit utilizes a metering pump to quantitatively add the scale inhibitor into the intermediate water tank.

Furthermore, a submersible sewage pump is arranged in the regulating tank, and a manual ball valve, a check valve and a flowmeter are sequentially installed on a water outlet pipeline of the submersible sewage pump. Has the advantages that: and the flow meter on the water outlet pipeline of the submersible sewage pump is used for controlling the liquid flow of the percolate in the regulating tank entering the basket filter.

Furthermore, a water pipe liquid level display is also installed on one side of the middle water tank, and an overflow port is arranged on the upper part of the middle water tank. Has the advantages that: the volume of filtration liquid in the water pitcher in the middle of water pipe liquid level display can real-time supervision, and the overflow mouth on the middle water pitcher can overflow unnecessary sewage in the middle water pitcher to the trench.

A process for treating leachate in a fly ash landfill comprises the following steps:

A. guiding the leachate of the fly ash landfill in the regulating tank into a basket filter through a pipeline by using a submersible sewage pump to filter and remove suspended matters, guiding the leachate after removing the suspended matters into an intermediate water tank, adding a scale inhibitor into the intermediate water tank through a scale inhibitor adding unit, overflowing clear liquid above the intermediate water tank to a trench, connecting a water outlet below the intermediate water tank with a centrifugal pump, pumping out two paths of water by the centrifugal pump, returning one path to the intermediate water tank to be used for circular stirring, and connecting the other path to a water inlet of a membrane treatment unit;

B. the leachate enters a membrane treatment unit and then is subjected to secondary filtration through a core filtration unit, effluent of the core filtration unit enters a buffer tank for temporary storage, and then enters a membrane column through pressurization of a high-pressure pump to be filtered through a nanofiltration membrane in the membrane column, the membrane separation unit adopts a cross flow type, and the membrane material uses a mesh tube type nanofiltration membrane.

Furthermore, the molecular weight cut-off of the mesh-tube nanofiltration membrane in the step B is usually 150-1000.

The beneficial effects of the utility model reside in that:

1. the utility model discloses a flying dust landfill filtration liquid processing system, filtration liquid use receive filter membrane separation pollutant after the suspended solid is got rid of in preliminary treatment. The nanofiltration membrane has the characteristics of selective interception and allowing monovalent salt to permeate through the membrane, and has medium salt permeation rate. And because the monovalent ion permeable membrane has greatly reduced osmotic pressure compared with reverse osmosis, the method has lower operating pressure, and reduces the desalting requirement and operating pressure of leachate treatment. The outer membrane processing unit adopts a network pipe open type flow channel design, has good pollution resistance, stable operation and relatively small water quality fluctuation.

2. The utility model discloses a flying dust landfill filtration liquid processing system directly utilizes to receive the filter membrane and handles flying dust landfill filtration liquid, has avoidd the treatment pressure that high salinity brought. The scale inhibitor adding unit solves the problem of pipeline blockage caused by calcium hardness, and ensures the stability of system operation. The nanofiltration membrane allows monovalent ions to permeate while trapping organic matters and divalent and above heavy metal ions, and reduces osmotic pressure, thereby reducing the operating pressure of the nanofiltration system and improving the water yield of the membrane system. Therefore, the nanofiltration system is used for advanced treatment, which is beneficial to reducing the operation cost, saving the desalination treatment process, simplifying the treatment process and improving the operation stability and the treatment efficiency of the system.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and/or combinations particularly pointed out in the appended claims.

Drawings

For the purposes of promoting a better understanding of the objects, features and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic structural view of the leachate treatment system of the fly ash landfill of the present invention;

FIG. 2 is a schematic structural diagram of a membrane treatment unit in the leachate treatment system of the fly ash landfill of the present invention.

Reference numerals: the device comprises a regulating tank 1, a basket filter 2, an intermediate water tank 3, a circulating stirring pipeline 4, a water outlet pipeline 5, a centrifugal pump 6, a regulating valve 7, a scale inhibitor adding unit 8, a metering pump 9, a membrane processing unit 10, a core filtering unit 11, a buffer tank unit 12, a high-pressure pump 13, a membrane column 14, an online pump unit 15, a control cabinet unit 16 and a compressed air system 17.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The present invention can also be implemented or applied through other different specific embodiments, and various details in the present specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the features in the following embodiments and examples may be combined with each other without conflict.

Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in any way limiting the scope of the invention; for a better understanding of the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc., indicating directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for convenience of description and simplification of description, but it is not intended to indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore, the terms describing the positional relationships in the drawings are only used for illustrative purposes and are not to be construed as limiting the present invention, and those skilled in the art can understand the specific meanings of the terms according to specific situations.

As shown in FIGS. 1-2, the construction scale of the leachate treatment station in the fly ash landfill is 100m³And d. The fly ash landfill leachate treatment system comprises a pretreatment system and a nanofiltration system which are matched for use; the pretreatment system comprises a regulating tank 1 and a basket filter 2 which are connected by pipelines and used for removing suspended matters in the leachate in sequence; a submersible sewage pump is arranged in the adjusting tank 1, and a manual ball valve, a check valve and a flowmeter are sequentially arranged on a sewage pump water outlet pipeline 5 and used for controlling the liquid flow of the percolate in the adjusting tank 1 entering the basket filter 2. The pipeline that basket filter 2 and equalizing basin 1 are connected sets gradually flowmeter and manual butterfly valve on, also sets gradually flowmeter and manual butterfly valve on the pipeline that basket filter 2 and middle water pitcher 3 are connected, is used for controlling the flow that flows in and flows out basket filter 2 respectively.

The nanofiltration system sequentially comprises an intermediate water tank 3 communicated with the basket filter 2 through a pipeline, and a scale inhibitor adding unit 8 and a membrane treatment unit 10 communicated with the intermediate water tank 3 through a pipeline, wherein the leachate is lifted from the regulating tank 1 to the basket filter 2 through a lift pump, suspended matters in the leachate are removed, and then the leachate enters the intermediate water tank 3.

The middle water tank 3 is provided with a water outlet pipeline 5 communicated with the membrane processing unit 10 and a circulating stirring pipeline 4 which is provided with an adjusting valve 7 and communicated with the water outlet pipeline 5, the water outlet pipeline 5 is provided with a centrifugal pump 6, the circulating stirring and the water outlet of the middle water tank 3 share one centrifugal pump 6, and the adjusting valve 7 on the circulating stirring pipeline 4 can adjust the circulating water flow of the middle water tank 3. The upper circulating stirring pipeline 4 of the intermediate water tank 3 is used for uniformly stirring the percolate and the scale inhibitor; a water pipe liquid level display is also arranged on one side of the middle water tank 3, and an overflow port is arranged on the upper part. Still set gradually manual butterfly valve, circulating pump, manual ball valve, pH meter, flowmeter, flow switch on the circulation stirring pipeline 4, wherein the circulating pump is regarded as membrane processing unit 10 intake pump simultaneously, links to each other with membrane processing unit 10 inlet tube.

The metering pump 9 is installed on a connecting pipeline between the scale inhibitor adding unit 8 and the intermediate water tank 3, the scale inhibitor adding unit 8 utilizes the metering pump 9 to quantitatively add the scale inhibitor into the intermediate water tank 3, the main component of the scale inhibitor is hydrochloric acid, calcium ions in water are removed in a main functional mode, the hardness of the leachate in the fly ash landfill is reduced, the intermediate water tank 3 and the pipeline can be effectively prevented from scaling, the leachate softening operation is reduced, the operation flow is simplified, and the treatment cost is saved.

The membrane processing unit 10 comprises a core filtering unit 11 for secondary filtering of the percolate, a buffer tank unit 12 for temporary storage of the percolate after the secondary filtering, a high- pressure pump 13 and 15 membrane columns 14 which are arranged in parallel in sequence, the core filtering unit 11, the buffer tank unit 12, the high-pressure pump 13 and the membrane columns 14 are connected through pipelines, and instrument valves are installed at each position of the pipeline according to requirements. The cartridge filter unit 11 carries out secondary filtration to filtration liquid, prevents that the membrane pore of follow-up interior nanofiltration membrane of membrane column 14 from blockking up, and high-pressure pump 13 is used for secondary filtration liquid pressure pump in with buffer tank unit 12 into membrane column 14. The inside of the membrane column 14 is provided with a mesh pipe type nanofiltration membrane which has selective interception and allows monovalent salt to permeate through the membrane, and has medium salt permeation rate. And because the monovalent ions can permeate the membrane, compared with a reverse osmosis treatment method, the osmotic pressure is greatly reduced, and the desalting requirement and the operating pressure of the leachate treatment are reduced by utilizing the characteristic that the nanofiltration membrane runs the monovalent salts to permeate the membrane. The nanofiltration membrane component has the molecular weight cutoff of 150-300 daltons, and has good removal effect on organic matters, heavy metals, high-valence salts and chromaticity in the leachate. The nanofiltration recovery rate can reach more than 90 percent, and the recovery rate can be higher than that of reverse osmosis. The membrane treatment unit 10 further comprises an on-line pump unit 15 for driving the percolate to circulate in the membrane column 14 and a control cabinet unit 16 for controlling the high-pressure pump 13 and the on-line pump unit 15 to be opened, the control valves on the various lines in the membrane treatment unit 10 also being controlled by the control cabinet unit 16.

And a compressed air system 17 is further included, and compressed air required by opening and closing of each pneumatic valve in the membrane processing unit 10 is provided by the compressed air system 17. The clear liquid of the water produced by the membrane processing unit 10 is discharged after reaching the standard, the concentrated liquid is re-filled to a landfill site, the flushing liquid and the sewage are discharged to a trench, and the cleaning water is industrial water.

The whole percolate treatment system adopts a network management open type flow channel design, and has the advantages of good pollution resistance, stable operation and relatively small water quality fluctuation. Through operation, the water yield of the STNF reaches 90%, the system operates stably, and the effluent quality meets the relevant standard regulations.

The process for treating the percolate by using the percolate treatment system comprises the following steps:

A. the method comprises the steps of guiding the fly ash landfill leachate in a regulating tank 1 into a basket filter 2 through a pipeline by using a submersible sewage pump to filter and remove suspended matters, guiding the leachate after removing the suspended matters into an intermediate water tank 3, adding a scale inhibitor into the intermediate water tank 3 through a scale inhibitor adding unit 8, overflowing clear liquid above the intermediate water tank 3 to a trench, connecting a water outlet below the intermediate water tank 3 with a centrifugal pump 6, dividing water out of the centrifugal pump 6 into two paths, returning the two paths to the intermediate water tank 3 as circulating stirring, and connecting the other path to a water inlet of a membrane treatment unit 10.

B. The percolate enters the membrane treatment unit 10 and then is firstly filtered for the second time through the core filtering unit 11 so as to avoid the blockage of membrane pores. The effluent of the core filtering unit 11 enters a buffer tank for temporary storage, and then is pressurized by a high-pressure pump 13 to enter a membrane column 14 to be filtered by a nanofiltration membrane in the membrane column 14. The function of the in-line pump unit 15 is to circulate the permeate through the membrane column 14 in order to reduce the operating pressure. In order to further reduce the operating pressure, the membrane separation unit adopts a cross flow type, and the membrane material adopts a mesh pipe type nanofiltration membrane. The net-tube type nanofiltration membrane is different from a common reverse osmosis membrane in retention capacity, the retention molecular weight of the net-tube type nanofiltration membrane is usually 150-1000, ammonia nitrogen, nitrate, other monovalent salts and part of small molecular organic matters can permeate the net-tube type nanofiltration membrane and enter permeate liquid, and the net-tube type nanofiltration membrane has higher retention rate on the large molecular organic matters and the high-valence salts, so that the net-tube type nanofiltration membrane is less influenced by the osmotic pressure of the monovalent salts, and the operation pressure is lower.

Finally, the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the scope of the claims of the present invention.

Claims (6)

1. A fly ash landfill leachate treatment system is characterized by comprising a pretreatment system and a nanofiltration system which are used in a matched manner; the pretreatment system sequentially comprises a regulating tank and a basket filter, wherein the regulating tank is connected with a pipeline; the nanofiltration system sequentially comprises an intermediate water tank communicated with a basket filter pipeline, and a scale inhibitor adding unit and a membrane treatment unit which are communicated with the intermediate water tank pipeline, wherein the intermediate water tank is provided with a water outlet pipeline communicated with the membrane treatment unit and a circulating stirring pipeline which is provided with an adjusting valve and is communicated with the water outlet pipeline, the water outlet pipeline is provided with a centrifugal pump shared by the two processes of circulating stirring and water outlet of the intermediate water tank, the membrane treatment unit sequentially comprises a core filtering unit for secondary filtering of the leachate, a buffer tank unit for temporarily storing the leachate after the secondary filtering, a high-pressure pump and a plurality of membrane columns, and the membrane columns are internally provided with mesh-tube nanofiltration membranes.

2. The fly ash landfill leachate treatment system of claim 1, wherein the membrane treatment unit further comprises an on-line pump unit for driving the circulation of leachate through the membrane column and a control cabinet unit for controlling the high pressure pump and the on-line pump unit to be opened, and the control valves on the pipes in the membrane treatment unit are also controlled by the control cabinet unit.

3. The fly ash landfill leachate treatment system of claim 2, further comprising a compressed air system, wherein the compressed air required for opening and closing each pneumatic valve in the membrane treatment unit is provided by the compressed air system.

4. The fly ash landfill leachate treatment system of claim 3, wherein a metering pump is installed on the connection pipeline between the scale inhibitor addition unit and the intermediate water tank.

5. The fly ash landfill leachate treatment system of claim 4, wherein a submersible sewage pump is disposed in the conditioning tank, and a manual ball valve, a check valve and a flow meter are sequentially installed on a water outlet pipeline of the submersible sewage pump.

6. The fly ash landfill leachate treatment system of claim 5, wherein one side of the intermediate water tank is further installed with a water pipe level display, and the upper part of the intermediate water tank is provided with an overflow port.

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