Waste incineration fly ash washing wastewater treatment system

Abstract

The utility model relates to a waste incineration fly ash washing wastewater treatment system, which comprises a raw water tank for collecting fly ash washing wastewater; the heavy metal removal reaction tank is used for removing heavy metals from the wastewater to obtain a mud-water mixture, and carrying out solid-liquid separation on the mud-water mixture to generate heavy-removed water; the hardness removal reaction tank is used for removing calcium and magnesium ions from the heavy water to obtain a mud-water mixture II and carrying out solid-liquid separation to generate softened water and calcium carbonate sludge; the pH adjusting barrel is used for adjusting the pH of the softened water to generate reclaimed water; the COD removal system is used for removing COD in the reclaimed water; the multi-medium filter is used for filtering the COD-removed water to obtain filtered water; the ultrafiltration equipment is used for filtering the filtered water to obtain ultrafiltration permeate liquid; the nanofiltration equipment is used for carrying out nanofiltration on the ultrafiltration permeate liquid, and chlorine salt enters separation membrane permeate liquid; and the evaporative crystallization equipment is used for evaporating and concentrating the separation membrane permeate to generate sodium chloride and potassium chloride. The device disclosed by the utility model can efficiently remove COD (Chemical Oxygen Demand) and heavy metals, reduce calcium ions in washing wastewater and ensure the quality of subsequent evaporative crystallization products.

Description

Technical Field

[0001] The utility model belongs to the technical field of high-salt wastewater treatment, and specifically relates to a garbage incineration fly ash washing wastewater treatment system. Background Art

[0002] Domestic waste incineration fly ash (referred to as "fly ash") comes from the fly ash obtained from the flue gas collection system of the waste incineration power plant, including fluidized bed fly ash and grate furnace fly ash. The main components of fly ash are CaO, SiO 2 、Na 2 O.K 2 O, Fe 2 O 3 、Al 2 O 3 , MgO, among which CaO has the highest mass fraction of 20.4-37.9%; the main hazardous substances are heavy metals (Zn, Pb, Cu, Cr, Cd, Ni and Hg, etc.) and dioxin-like organic compounds. The mass fraction of chlorine in incineration fly ash is the highest, which can exceed 25%, among which soluble chlorine accounts for 40.6-83.9% of the total chlorine.

[0003] The fly ash washing wastewater comes from the fly ash washing process in the fly ash resource utilization process. It is a high-salt wastewater with the main components of Cl - 、Na + , K + , Ca 2+ 、SO 4 2- and Pb 2+ 、Zn 2+ , Cu 2+ 、Cd 2+ Cr 6+ Heavy metals such as Cl - 、Na + , K + Sodium chloride and potassium chloride products can be made through evaporation and crystallization salt separation technology. In order to ensure the quality of sodium chloride and potassium chloride products and the stability of evaporation and crystallization equipment, it is necessary to remove COD, SS, Ca in the fly ash washing wastewater. 2+ 、SO 4 2- and Pb 2+ 、Zn 2 + , Cu 2+ 、Cd 2+ Cr 6+ And other heavy metal elements.

[0004] The current method for removing heavy metals from high-salt wastewater is mainly to add sodium sulfide or heavy metal chelating agents, which can effectively remove heavy metals such as lead.

[0005] At present, the main methods for removing calcium ions from high-salt wastewater are sodium carbonate decalcification, carbon dioxide decalcification, and sodium sulfate decalcification. Sodium carbonate decalcification has the best effect, with a calcium ion removal rate of more than 99%; carbon dioxide decalcification has a low removal efficiency and needs to be used in combination with sodium carbonate decalcification, which has a high treatment cost. Sodium sulfate decalcification is difficult to remove calcium ions from high-salt wastewater. At the same time, a large amount of sulfate is introduced into the wastewater, which seriously affects the quality of sodium chloride and potassium chloride products in the evaporation crystallization equipment. In the absence of a removal process, sulfate in fly ash washing wastewater will continue to accumulate in the evaporation crystallization equipment, which will also affect the quality of sodium chloride and potassium chloride products.

[0006] Fly ash washing wastewater contains a certain concentration of COD. At present, physical, chemical and biochemical methods are generally used to remove COD. However, fly ash washing wastewater contains a large amount of chloride ions and heavy metals, which is not suitable for biochemical removal. At the same time, the biochemical method has too high a production cost and occupies a large space. Physical methods can only remove particulate organic matter, and the removal effect is not good for small particles or water-soluble organic matter. Therefore, the chemical method is currently commonly used to remove COD from fly ash washing wastewater.

[0007] Therefore, there is an urgent need in the art to propose a waste incineration fly ash washing wastewater treatment system to efficiently remove COD and heavy metals, reduce calcium ions in the wastewater washing liquid, ensure the quality of subsequent evaporation and crystallization products, and control treatment costs. Utility Model Content

[0008] Based on the above-mentioned shortcomings and deficiencies in the prior art, one of the purposes of the present invention is to at least solve one or more of the above-mentioned problems in the prior art. In other words, one of the purposes of the present invention is to provide a waste incineration fly ash washing wastewater treatment system that meets one or more of the above-mentioned needs.

[0009] In order to achieve the above utility model purpose, the utility model adopts the following technical solutions:

[0010] A waste incineration fly ash washing wastewater treatment system, comprising:

[0011] Raw water tank, used to collect fly ash washing wastewater;

[0012] The heavy metal removal reaction tank is used to remove heavy metals from the fly ash washing wastewater output from the original water tank to obtain a mud-water mixture;

[0013] A first solid-liquid separation device is used to perform solid-liquid separation on the mud-water mixture output from the de-heavy reaction tank to produce de-heavy water and heavy metal sludge;

[0014] a hardness removal reaction tank, used for removing calcium and magnesium ions from the de-heavy water outputted from the first solid-liquid separation device, to obtain a second mud-water mixture;

[0015] The second solid-liquid separation device is used to perform solid-liquid separation on the mud-water mixture 2 output from the hardness removal reaction tank to produce softened water and calcium carbonate sludge;

[0016] A pH adjustment tank, used for adjusting the pH of the softened water outputted from the second solid-liquid separation device to produce reclaimed water;

[0017] The COD removal system is used to remove COD from the reclaimed water output from the pH adjustment tank to obtain COD-removed water;

[0018] Multi-media filter, used to separate large particle impurities from COD removal water output by COD removal system to obtain filtered water;

[0019] Ultrafiltration equipment is used to perform deep filtration on the filtered water output from the multi-media filter to obtain ultrafiltration permeate;

[0020] Nanofiltration equipment is used to separate impurity ions and chloride salts from the ultrafiltration permeate output by the ultrafiltration equipment, the impurity ions are concentrated and enter the separation membrane concentrate, and the chloride salts enter the separation membrane permeate;

[0021] The evaporation crystallization equipment is used to evaporate and concentrate the separation membrane permeate output by the nanofiltration equipment to produce sodium chloride and potassium chloride.

[0022] As a preferred embodiment, the COD removal system includes an iron-carbon micro-electrolysis device and a Fenton reaction device. The reclaimed water output by the pH adjustment tank enters the iron-carbon micro-electrolysis device, the electrolyzed water output by the iron-carbon micro-electrolysis device enters the Fenton reaction device, and the COD removal water output by the Fenton reaction device enters the multi-media filter.

[0023] As a preferred solution, the filler in the iron-carbon micro-electrolysis device is an iron-carbon column, and the reclaimed water output from the pH adjustment barrel enters the iron-carbon micro-electrolysis device through a booster pump.

[0024] As a preferred solution, the Fenton reaction equipment is provided with a pulse dosing pump for pulse adding hydrogen peroxide.

[0025] As a preferred solution, the pumping pipeline between the weight removal reaction tank and the first solid-liquid separation device adopts a screw sludge pump or a sludge diaphragm pump;

[0026] The pumping pipeline between the hardness removal reaction tank and the second solid-liquid separation device adopts a screw sludge pump or a sludge diaphragm pump.

[0027] As a preferred solution, the pumping pipeline between the raw water tank and the weight removal reaction tank adopts a self-priming pump;

[0028] The pumping pipeline between the first solid-liquid separation device and the hardness removal reaction tank adopts a self-priming pump;

[0029] The pumping pipeline between the second solid-liquid separation device and the pH adjustment barrel adopts a self-priming pump;

[0030] The pumping pipeline between the pH adjustment tank and the COD removal system uses a self-priming pump;

[0031] The pumping pipeline between the COD removal system and the multi-media filter uses a self-priming pump;

[0032] The pumping pipeline between the multi-media filter and the ultrafiltration equipment adopts a self-priming pump;

[0033] The pumping pipeline between the ultrafiltration equipment and the nanofiltration equipment adopts a self-priming pump;

[0034] A self-priming pump is used in the pumping pipeline between the nanofiltration equipment and the evaporation crystallization equipment.

[0035] As a preferred solution, the first solid-liquid separation device and the second solid-liquid separation device are plate and frame filter press, belt filter press or horizontal screw centrifuge.

[0036] As a preferred solution, the operating pressure of the ultrafiltration equipment is less than 2 bar.

[0037] As a preferred solution, the concentrated liquid produced by the nanofiltration device and the ultrafiltration device is transported to the raw water pool through a loop pipeline.

[0038] As a preferred solution, the ultrafiltration membrane of the ultrafiltration equipment is a tubular membrane or a plate membrane.

[0039] Compared with the prior art, the utility model has the following beneficial effects:

[0040] (1) The utility model can efficiently remove COD, heavy metals, reduce calcium ions in water washing wastewater, and ensure the quality of subsequent evaporation and crystallization products;

[0041] (2) The utility model utilizes iron-carbon micro-electrolysis and Fenton reaction equipment to remove a large amount of COD, and can achieve a maximum COD removal rate of 80%, thereby improving the water quality of wastewater, being more conducive to the stable operation of evaporation and crystallization salt separation equipment, and improving the quality of chloride salt;

[0042] (3) The utility model removes most of the heavy metals by adjusting the pH of the wastewater, reduces the addition of sodium sulfide, avoids the wind caused by hazardous chemicals, and reduces the treatment cost by more than 46% compared with the treatment cost of removing heavy metals with sodium sulfide, and has low comprehensive energy consumption;

[0043] (4) The utility model uses ultrafiltration equipment to remove SS, and the generated ultrafiltration concentrate is recycled to the raw water pool. The generated ultrafiltration permeate enters the nanofiltration equipment to achieve effective separation of impurities such as sulfate and chloride salts, so that the concentration of impurities such as sulfate in the effluent is lower, which is more conducive to the stable operation of the evaporation crystallization salt separation equipment. The separation membrane concentrate enters the hardness removal system for recycling, so as to achieve the purpose of removing sulfate from fly ash washing wastewater and reducing the cost of calcium ion treatment;

[0044] (5) The calcium carbonate sludge of the utility model enters the fly ash washing system to obtain washed finished ash. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a structural diagram of the waste incineration fly ash washing wastewater treatment system of Example 1 of the utility model. DETAILED DESCRIPTION

[0046] In order to more clearly illustrate the embodiments of the utility model, the specific implementation methods of the utility model will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0047] Embodiment 1:

[0048] like Figure 1 As shown, the waste incineration fly ash washing wastewater treatment system of this embodiment includes: a raw water tank, a weight removal reaction tank, a first solid-liquid separation device, a hardness removal reaction tank, a second solid-liquid separation device, a pH adjustment tank, an iron-carbon micro-electrolysis device, a Fenton reaction equipment, a multi-media filter, an ultrafiltration device, a nanofiltration device and an evaporation crystallization salt separation device.

[0049] Specifically, the raw water tank of this embodiment is used to collect fly ash washing wastewater. The raw water tank is underground, semi-underground or above-ground. The raw water tank is a concrete structure, one of Q235 or SUS316L. In addition, the volume of the raw water tank meets the liquid storage capacity for continuous operation for 15 hours.

[0050] In addition, the raw water pool is connected to the fly ash washing wastewater source through a pumping pipeline so as to treat the waste incineration fly ash wastewater.

[0051] The de-heavy reaction tank of this embodiment is used to remove heavy metals from the fly ash washing wastewater output from the raw water tank to obtain a mud-water mixture 1; the mud-water mixture 1 is pumped to the first solid-liquid separation device for solid-liquid separation to produce de-heavy water and heavy metal sludge. Specifically, the de-heavy reaction tank is connected to the first solid-liquid separation device, and the first solid-liquid separation device is connected to the hardness removal reaction tank through pumping pipelines.

[0052] The weight removal reaction tank of this embodiment includes a dosing unit, a coagulation reaction unit, a flocculation reaction unit, and a sedimentation unit. The treatment process of the fly ash washing wastewater in the weight removal reaction tank includes dosing, coagulation reaction, flocculation reaction and precipitation in sequence; wherein, the dosing is to add hydrochloric acid and remove heavy metals by adjusting the pH; the flocculant of the flocculation reaction is anionic PAM or non-ionic PAM; the sedimentation tank is semi-underground or above-ground, using concrete structure, Q235 or SUS316L, and the volume must meet the sedimentation time of more than 15 hours.

[0053] The hardness removal reaction pool of this embodiment is used to remove calcium from the deionized water output by the first solid-liquid separation device to obtain mud-water mixture 2. Specifically, the hardness removal reaction pool is connected to the deionized water outlet of the first solid-liquid separation device through a pumping pipeline. The specific structure of the hardness removal reaction pool can refer to the prior art and will not be repeated here.

[0054] The second solid-liquid separation device of this embodiment is used to perform solid-liquid separation on the mud-water mixture output from the hardness removal reaction tank to produce softened water and calcium carbonate sludge. The second solid-liquid separation device is connected to the mud-water mixture outlet of the hardness removal reaction tank through a pumping pipeline.

[0055] The pH adjustment barrel of this embodiment is used to adjust the pH of the softened water output by the second solid-liquid separation device to produce neutral water. The pH adjustment barrel is connected to the softened water outlet of the second solid-liquid separation device through a pumping pipeline.

[0056] The iron-carbon micro-electrolysis device of this embodiment is used to perform preliminary COD removal on the softened water output from the pH adjustment barrel to obtain electrolyzed water. Specifically, the filler in the iron-carbon micro-electrolysis device is an iron-carbon column, and the iron-carbon micro-electrolysis device is connected to the water outlet of the pH adjustment barrel through a pumping pipeline. In addition, the water output from the pH adjustment barrel enters the iron-carbon micro-electrolysis device through a booster pump.

[0057] The Fenton reaction device of this embodiment is used to perform secondary COD removal on the electrolyzed water output by the iron-carbon micro-electrolysis device to obtain COD-removed water. Specifically, the Fenton reaction device is connected to the electrolyzed water outlet of the iron-carbon micro-electrolysis device through a pumping pipeline. In addition, the Fenton reaction device is provided with a pulse dosing pump for pulse adding hydrogen peroxide.

[0058] The multi-media filter of this embodiment is used to separate large particle impurities from the COD removal water output by the Fenton reaction device to obtain filtered water. The multi-media filter is connected to the COD removal water outlet of the Fenton reaction device through a pumping pipeline. The specific structure of the multi-media filter can refer to the prior art and will not be repeated here.

[0059] The ultrafiltration device of this embodiment is used to perform deep filtration on the filtered water output by the multi-media filter, remove COD and SS in the filtered water, and produce ultrafiltration concentrate and ultrafiltration permeate. Specifically, the ultrafiltration device is connected to the filtered water outlet of the multi-media filter through a pumping pipeline.

[0060] Among them, the operating pressure of the ultrafiltration equipment is less than 2 bar, the ultrafiltration membrane of the ultrafiltration equipment is a tubular membrane or a plate membrane, and the specific structure of the ultrafiltration membrane subsystem can refer to the existing technology and will not be repeated here.

[0061] The nanofiltration device of this embodiment is used to separate sulfate and other impurities from chloride salts in the ultrafiltration permeate output by the ultrafiltration device, and the sulfate and other impurities are concentrated into the separation membrane concentrate, and the chloride salts enter the separation membrane permeate. Specifically, the nanofiltration device is connected to the ultrafiltration permeate outlet of the ultrafiltration device through a pumping pipeline.

[0062] The operating pressure of the membrane separation subsystem of the nanofiltration device is 5 to 30 bar, and the separation membrane of the nanofiltration device is a rolled organic polyamide membrane. The specific structure of the membrane separation subsystem of the nanofiltration device can refer to the prior art and will not be described here.

[0063] The evaporation crystallization salt separation device of this embodiment is used to perform evaporation crystallization salt separation on the separation membrane permeate output by the nanofiltration device to produce sodium chloride and potassium chloride. Specifically, the evaporation crystallization salt separation device is connected to the separation membrane permeate outlet of the nanofiltration device through a pumping pipeline. The specific structure of the evaporation crystallization salt separation device can refer to the prior art and will not be repeated here.

[0064] In addition, the concentrated liquid produced by the nanofiltration equipment and the ultrafiltration equipment is transported to the raw water pool through the loop pipeline.

[0065] All the pumping pipelines for pumping the above-mentioned mud-water mixture adopt screw sludge pumps or sludge diaphragm pumps, and the remaining pumping pipelines adopt self-priming pumps; gravity can also be used, which can be determined according to the actual installation environment. In addition, the pipeline material is Q235 or SUS316L or 2205 duplex stainless steel to achieve corrosion resistance.

[0066] The first solid-liquid separation device and the second solid-liquid separation device of this embodiment are selected from plate and frame filter press, belt filter press or horizontal screw centrifuge, which can be determined according to the actual application scenario.

[0067] The treatment process of the waste incineration fly ash washing wastewater treatment system of this embodiment includes:

[0068] (1) Fly ash washing wastewater enters the raw water tank, and the raw water regulating tank is used to store and homogenize the fly ash washing wastewater;

[0069] Specifically, the fly ash washing wastewater (hereinafter referred to as washing filtrate) of this embodiment has a chloride ion content of 8-15%, a sodium ion content of 1-3%, a potassium ion content of 1-3%, and a calcium ion content of 2-4%;

[0070] (2) The fly ash washing wastewater from the raw water pool enters the heavy metal removal reaction pool to remove heavy metals such as lead, zinc, copper, cadmium, and chromium, producing a mud-water mixture;

[0071] (3) The sludge-water mixture is subjected to solid-liquid separation to produce deionized water and heavy metal sludge; the heavy metal sludge enters the hazardous waste temporary storage warehouse, and the heavy metal sludge is packaged in ton bags and transported by forklifts; the removal rate of heavy metals such as lead, zinc, copper, cadmium and chromium in the deionized water is greater than 90%, and the water content of the heavy metal sludge is 50-60%;

[0072] (4) removing calcium and magnesium ions from the deionized water (i.e., removing hardness) to obtain a mud-water mixture II;

[0073] Among them, the softener used for hardness removal is industrial sodium carbonate;

[0074] (5) solid-liquid separation of the mud-water mixture 2 to produce softened water and calcium carbonate sludge; the calcium carbonate sludge enters the fly ash washing system and eventually enters the washed finished ash to be used as a raw material for building materials;

[0075] Among them, the calcium ion removal rate in softened water is greater than 99%, and the water content of calcium carbonate sludge is 30-35%;

[0076] (6) The softened water enters the iron-carbon micro-electrolysis device to remove the COD therein at the primary level; wherein the solution entering the iron-carbon micro-electrolysis device needs to adjust the pH to between 3 and 4;

[0077] (7) The water after iron-carbon micro-electrolysis enters the Fenton reaction equipment to further remove the COD;

[0078] (8) The filtrate after COD removal enters a multi-media filter to obtain filtered water;

[0079] (9) Deeply filter the filtered water to remove the remaining COD and SS, and produce ultrafiltration concentrate and ultrafiltration permeate; the ultrafiltration concentrate is recycled to the raw water regulating tank;

[0080] Among them, the operating pressure of the ultrafiltration membrane subsystem is less than 2 bar, the ultrafiltration membrane is a tubular membrane or a plate membrane, the ultrafiltration concentrate has a concentration rate of more than 10 times that of the influent, the COD interception efficiency of the ultrafiltration permeate is 30-50%, and the SS interception efficiency is more than 99%;

[0081] (10) The ultrafiltration permeate enters the nanofiltration equipment to separate impurities such as sulfate from chloride salts. The impurities such as sulfate are concentrated and enter the separation membrane concentrate, and the chloride salt enters the separation membrane permeate. The separation membrane concentrate is recycled to the raw water regulating tank;

[0082] The operating pressure of the nanofiltration equipment is 20-30 bar, the separation membrane is a rolled organic polyamide membrane, the concentration rate of the separation membrane concentrate is not less than 10 times that of the influent, the interception efficiency of the separation membrane permeate for impurities such as sulfate is 95-98%, and the interception efficiency for chloride salt is 20-30%;

[0083] (11) The permeate of the separation membrane is evaporated and crystallized to separate the salts of sodium and potassium, and is used for the preparation of sodium chloride and potassium chloride products.

[0084] The waste incineration fly ash washing wastewater treatment system of this embodiment can save more than 46% of the heavy metal removal cost. The water treatment effluent (i.e., the effluent from the nanofiltration device) has a lower sulfate content than the fly ash washing wastewater, which is more conducive to the stable operation of the evaporation crystallization equipment.

[0085] The above description is only a detailed description of the preferred embodiments and principles of the present invention. For ordinary technicians in this field, according to the ideas provided by the present invention, there will be changes in the specific implementation methods, and these changes should also be regarded as the protection scope of the present invention.

Claims

1. A waste incineration fly ash washing wastewater treatment system, characterized in that: include: Raw water tank, used to collect fly ash washing wastewater; The heavy metal removal reaction tank is used to remove heavy metals from the fly ash washing wastewater output from the original water tank to obtain a mud-water mixture; A first solid-liquid separation device is used to perform solid-liquid separation on the mud-water mixture output from the de-heavy reaction tank to produce de-heavy water and heavy metal sludge; a hardness removal reaction tank, used for removing calcium and magnesium ions from the de-heavy water outputted from the first solid-liquid separation device, to obtain a second mud-water mixture; The second solid-liquid separation device is used to perform solid-liquid separation on the mud-water mixture 2 output from the hardness removal reaction tank to produce softened water and calcium carbonate sludge; A pH adjustment tank, used for adjusting the pH of the softened water outputted from the second solid-liquid separation device to produce reclaimed water; COD removal equipment, used to remove COD from the reclaimed water output from the pH adjustment tank to obtain COD-removed water; Multi-media filter, used to separate large particle impurities from COD removal water output by COD removal system to obtain filtered water; Ultrafiltration equipment is used to perform deep filtration on the filtered water output from the multi-media filter to obtain ultrafiltration permeate; Nanofiltration equipment is used to separate impurity ions and chloride salts from the ultrafiltration permeate output by the ultrafiltration equipment, the impurity ions are concentrated and enter the separation membrane concentrate, and the chloride salts enter the separation membrane permeate; The evaporation crystallization equipment is used to evaporate and concentrate the separation membrane permeate output by the nanofiltration equipment to produce sodium chloride and potassium chloride.

2. The waste incineration fly ash washing wastewater treatment system according to claim 1 is characterized in that: The COD removal system comprises an iron-carbon micro-electrolysis device and a Fenton reaction device. The reclaimed water outputted from the pH adjustment tank enters the iron-carbon micro-electrolysis device, the electrolyzed water outputted from the iron-carbon micro-electrolysis device enters the Fenton reaction device, and the COD-removed water outputted from the Fenton reaction device enters the multi-media filter.

3. The waste incineration fly ash washing wastewater treatment system according to claim 2 is characterized in that: The filler in the iron-carbon micro-electrolysis device is an iron-carbon column, and the reclaimed water output from the pH adjustment barrel enters the iron-carbon micro-electrolysis device through a booster pump.

4. The waste incineration fly ash washing wastewater treatment system according to claim 2, characterized in that: The Fenton reaction equipment is provided with a pulse dosing pump for pulse adding hydrogen peroxide.

5. The waste incineration fly ash washing wastewater treatment system according to claim 1, characterized in that: The pumping pipeline between the weight removal reaction tank and the first solid-liquid separation device adopts a screw sludge pump or a sludge diaphragm pump; The pumping pipeline between the hardness removal reaction tank and the second solid-liquid separation device adopts a screw sludge pump or a sludge diaphragm pump.

6. The waste incineration fly ash washing wastewater treatment system according to claim 1, characterized in that: The pumping pipeline between the raw water tank and the weight removal reaction tank adopts a self-priming pump; The pumping pipeline between the first solid-liquid separation device and the hardness removal reaction tank adopts a self-priming pump; The pumping pipeline between the second solid-liquid separation device and the pH adjustment barrel adopts a self-priming pump; The pumping pipeline between the pH adjustment tank and the COD removal system uses a self-priming pump; The pumping pipeline between the COD removal system and the multi-media filter uses a self-priming pump; The pumping pipeline between the multi-media filter and the ultrafiltration equipment adopts a self-priming pump; The pumping pipeline between the ultrafiltration equipment and the nanofiltration equipment adopts a self-priming pump; A self-priming pump is used in the pumping pipeline between the nanofiltration equipment and the evaporation crystallization equipment.

7. The waste incineration fly ash washing wastewater treatment system according to claim 1, characterized in that: The first solid-liquid separation device and the second solid-liquid separation device are plate-and-frame filter press, belt filter press or horizontal screw centrifuge.

8. The waste incineration fly ash washing wastewater treatment system according to claim 1, characterized in that: The operating pressure of the ultrafiltration device is less than 2 bar.

9. The waste incineration fly ash washing wastewater treatment system according to claim 1, characterized in that: The concentrated liquid produced by the nanofiltration device and the ultrafiltration device is transported to the raw water pool through a loop pipeline.

10. The waste incineration fly ash washing wastewater treatment system according to claim 1, characterized in that: The ultrafiltration membrane of the ultrafiltration equipment is a tubular membrane or a plate membrane.

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