Treatment method and treatment system for high-salinity wastewater

Abstract

The invention provides a treatment method and a treatment system for high-salinity wastewater, and aims to solve the problems of high treatment difficulty and high operation cost in the existing high-salinity wastewater treatment process. The treatment method comprises the following steps: 1) extracting hazardous waste samples containing high-salinity wastewater in batches, and carrying out a curing test and a leaching test in a laboratory; (2) according to a test result, the adding proportion of all components of the hazardous waste is determined, and the components are input into a blender to be subjected to curing treatment; 3) fully stirring and mixing the hazardous wastes by a mixer; 4) conveying the mixture to a curing area for curing; (5) detecting the leaching result of the solidified body after curing, transferring the qualified solidified body to a rigid landfill area for landfill, crushing the unqualified solidified body by a crusher, and continuously conveying the crushed solidified body to a blender for solidification treatment; the treatment system comprises a high-salinity wastewater metering device, a solid salt metering device, a fly ash metering device, a blender, a maintenance station and a rigid landfill. The invention solves the problems of high treatment difficulty and high operation cost of high-salinity wastewater, and achieves the purpose of treating waste with waste.

Description

Technical Field

[0001] The invention relates to the technical field, and in particular to a method and system for treating high-salt wastewater. Background Art

[0002] High-salinity wastewater refers to wastewater with a total salt content of at least 3.5wt% from domestic sewage and industrial wastewater. It has the characteristics of high salt content, high chemical oxygen demand (COD), tar, strong wall adhesion, and a large amount of organic matter, which is manifested as a high concentration of Cl - , SO4 2- , Na + , Ca 2+ It also contains inorganic ions such as chlorinated bicarbonate and chlorinated bicarbonate, and also contains relatively high concentrations of organic matter. Due to its complex and diverse composition, high salt content, and strong inhibitory effect on microbial growth, the technical difficulty of treating this wastewater is much greater than that of ordinary sewage treatment. At present, the treatment method for high-salt wastewater mostly adopts a combination of biochemical + membrane filtration process, and the effluent can meet the discharge standards. However, this type of process will produce membrane concentrates that are enriched with a large amount of difficult-to-degrade organic matter and inorganic salts. The disposal method of membrane concentrates has problems such as severe membrane scaling, decreased membrane recovery rate, and high difficulty in subsequent disposal.

[0003] With the increasing requirements for zero wastewater discharge, full-scale disposal has become the only way to deal with high-salt wastewater. Stabilization landfill treatment provides a new idea for the treatment of high-salt wastewater. Although the current stabilization technology is mature and the construction is simple, there are still problems such as high cost and unclear solidification effect. Summary of the invention

[0004] The purpose of the present invention is to solve the problems existing in the prior art and to provide a method and system for treating high-salt wastewater.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for treating high-salinity wastewater comprises the following steps:

[0007] Step 1: Extract hazardous waste samples containing high-salinity wastewater in batches and conduct laboratory solidification tests and leaching tests;

[0008] Step 2: According to the test results, determine the addition ratio of each component of the hazardous waste and input it into the mixer for solidification treatment;

[0009] Step 3: The hazardous waste is fully stirred and mixed by a mixer;

[0010] Step 4: The mixed mixture is transported to the curing area for curing. After curing in the curing area for about 5 days, the compressive strength of the mixed mixture can reach 5~7kg / cm 2After about 10 days of curing, its compressive strength can reach 10~12.5kg / cm 2 ;

[0011] Step 5: After curing, the leaching results of the solidified body are tested, and qualified ones are transferred to the rigid landfill area for landfill, while unqualified ones are crushed by a crusher and then sent to the mixer for solidification treatment.

[0012] Waste solidification / stabilization treatment is one of the important engineering measures to isolate hazardous wastes disposed of in landfills from the environment as much as possible. In the prior art, lime is often used as a solidifying agent to solidify waste residues containing sulfates or sulfites. The cost of lime raw materials is high, and it cannot achieve the purpose of treating waste with waste.

[0013] The present invention uses fly ash as a solidifying agent. Fly ash is a general term for the captured material produced by the incineration disposal system during the tail gas purification process (such as quenching, bag filter, etc.) and the bottom ash settled at the bottom of the flue. The incineration fly ash of the rotary kiln incineration process generally accounts for about 10% of the entire incineration waste. The waste incineration fly ash belongs to hazardous waste. The incineration fly ash has a very low moisture content and is in the form of light gray powder. The fly ash particles are uneven in size, complex in structure, and variable in properties. They mostly exist in the form of amorphous and polycrystalline polymer structures. Usually, the fly ash particle size is less than 100μm, with a large specific surface area and high porosity. The chemical composition of incineration fly ash includes elements such as Cl, Ca, K, Na, Si, Al, O, etc. The main chemical components are CaO, SiO2, Al2O3, Fe2O3, which have the same properties as lime. A large amount of sulfate and carbonate components in high brine can react with calcium in fly ash. The solid saline alkaline properties adjust the acidity and alkalinity of the system. The reaction process condenses and hardens, and the particles are tightly connected with the unreacted particles into a whole to obtain a solidified body with a certain density, which can be landfilled in a landfill.

[0014] In addition, incineration fly ash often contains high concentrations of heavy metals, such as Hg, Pb, Cd, Cu, Cr and Zn. These heavy metals mainly exist in the form of small aerosol particles and are enriched on the surface of fly ash particles. At the same time, incineration fly ash also contains a small amount of dioxins and furans. In summary, its hazards mainly come from three aspects: (1) water-soluble salts, (2) heavy metals, and (3) dioxins. Fly ash contains a large amount of water-soluble sodium salts, potassium salts, and calcium salts. Although they are not toxic in themselves, the presence of water-soluble salts will cause great harm to the harmless and resource-based treatment of fly ash. Solidification and landfilling are currently the only way out for hazardous waste incineration fly ash.

[0015] In addition, the incineration solid salt produced after the disposal of acrylonitrile and other chemical plants has Na2CO3 as its main component, accounting for more than 81.7%. It is very soluble in water. The solubility of saturated aqueous solution at room temperature is 20g / 100g H2O. The aqueous solution is alkaline, with a pH of 11.5. The volume of this substance does not increase significantly after dissolving in water. Its properties are mainly as follows:

[0016] (1) It is highly soluble in water and releases heat when in contact with water, which results in the risk of heat release during the landfill process, dissolution and collapse of the landfilled materials when in contact with water, and damage to the landfill facilities;

[0017] (2) It has a relatively light specific gravity, with an average specific volume of 4 m3 / t, which occupies landfill capacity and reduces landfill benefits.

[0018] The conventional treatment and disposal solution is rigid landfill treatment, but due to the high risk of direct landfill, its light texture and great difficulty in resource utilization, it can be used as an admixture for stabilization treatment.

[0019] The present invention treats high-salt wastewater, incineration fly ash and solid salt in a coordinated manner, which can effectively solve the difficult problems of high-salt wastewater treatment and high operating costs. At the same time, the incineration fly ash and solid salt are coordinated for solidification-landfill treatment to form a dense solidified body, thereby achieving the purpose of treating waste with waste.

[0020] As the preferred technical solution:

[0021] A method for treating high-salt wastewater as described above, wherein the hazardous waste includes high-salt wastewater, incineration fly ash and solid salt.

[0022] In the above-mentioned method for treating high-salinity wastewater, in step 1, the solidification test and the leaching test specifically include the following steps:

[0023] (1) Weigh 500 g of high-salt wastewater into a beaker and measure the pH;

[0024] (2) adding solid salt to the beaker, mixing and stirring, adjusting the pH of the mixed solution to 7, and recording the cumulative weight of the solid salt added and the total weight of the mixed solution;

[0025] (3) adding incineration fly ash to the mixed liquid in a mass ratio of (1-3): (1-2), stirring until it becomes gelled and no water is separated out, obtaining a mixed material and recording the weight of the added fly ash;

[0026] (4) curing the mixture at room temperature for 8 to 10 days, performing a leaching test on the mixture to obtain a leaching solution, and measuring the concentration of the leaching solution;

[0027] (5) Based on the leaching results and the landfill admission requirements, determine the mass ratio of high-salt wastewater, solid salt and incineration fly ash.

[0028] In the method for treating high-salt wastewater as described above, in step (4), the curing process is natural curing; the leaching test is carried out according to the solid waste toxicity leaching method-horizontal oscillation method, that is, the leaching experiment is carried out according to the standard HJ 557-2010 "Solid Waste Toxicity Leaching Method-Horizontal Oscillation Method" to obtain the leachate; the mass ratio of the high-salt wastewater, solid salt and incineration fly ash is 1: (0.8~1): (1~1.2).

[0029] In the method for treating high-salt wastewater as described above, in step 2, the order in which the hazardous waste is input into the mixer is to first add fly ash and solid salt and then add high-salt wastewater.

[0030] In the method for treating high-salt wastewater as described above, in step three, the sufficient stirring and mixing means that the obtained mixture has a high density, and the leachate and water-soluble salts are not obviously precipitated, that is, the mixture is fully mixed; the stirring and mixing device is a mixer with a double-axis spiral structure. The principle is: using a double-axis spiral structure, the arrangement of the stirring blades on each stirring shaft is in an intermittent spiral form, and through the reasonable arrangement of the blades, when the two stirring shafts rotate in opposite directions, an overlapping area is formed at the radial center of the mixer. This area is the vortex junction area of ​​the two stirring cycles, and the materials produce a strong mutual flow effect here. The materials produce a cyclic three-dimensional motion during stirring, thereby achieving a three-dimensional stirring effect, so that the equipment can make the mixed materials have a strong relative motion at a relatively low speed to achieve the best stirring effect. At the same time, at any time during the stirring process, all spatial materials are stirred, which can fully meet the requirements of environmental protection emissions.

[0031] The present invention also provides a high-salt wastewater treatment system, which is characterized by comprising a high-salt wastewater metering device, a solid salt metering device, a fly ash metering device, a mixer, a maintenance station and a rigid landfill;

[0032] The high-salt wastewater metering device comprises a wastewater tank, a metering pump and a weighing device connected in sequence, and the outlet of the weighing device is connected to the inlet of the mixer;

[0033] The solid salt metering device comprises a metering bin I and a screw feeder I which are connected in sequence, and the outlet of the screw feeder I is connected to the inlet of the mixer;

[0034] The fly ash metering device comprises a metering bin II and a screw feeder II which are connected in sequence, and the outlet of the screw feeder II is connected to the inlet of the mixer;

[0035] The high-salt wastewater metering device, the solid salt metering device and the fly ash metering device transport the well-proportioned high-salt wastewater, solid salt and fly ash to the mixer for solidification treatment in accordance with the method described above, and then transport them to the maintenance station for maintenance treatment, and finally send them to the rigid landfill for landfill treatment.

[0036] Invention mechanism:

[0037] The fly ash rich in calcium oxide and high-salt wastewater are used for synergistic treatment with the aid of solid salt additives. The fly ash contains metal oxides (such as CaO) and sulfates and solid salts as admixtures in a certain proportion. With high-salt wastewater as the medium, through acid-base reaction, a solidified body with sulfate bonding phase is generated. The reaction mechanism diagram is shown in the figure below. Figure 1 As shown, during the solidification reaction, the calcium ions in the fly ash react with the sulfate in the high-salt wastewater to form calcium sulfate and other precipitates, and react with the carbonate in the solid salt to form carbonate precipitates. The solid salt provides alkaline conditions for the reaction system and accelerates the precipitation reaction. After curing, the various phases of the precipitate bond with each other to form a dense whole, which improves the density of the solidified body; and the harmful substances (soluble metal ions, salts, etc.) are physically sealed through the physical encapsulation of the precipitate cementing phase; at the same time, the fly ash can play an adsorption role. The entire stabilization process achieves harmless treatment of waste through the triple effects of chemical precipitation, physical encapsulation and physical adsorption.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. By adopting the solidification-landfill method to coordinately treat high-salt wastewater with incineration fly ash and incineration solid salt, the effect of treating waste with waste is achieved, the problem of high-salt wastewater being difficult to discharge zero is solved, and ideas are provided for the treatment of high-salt wastewater; at the same time, the problem that solid salt is difficult to landfill directly is solved, thus reducing the risk.

[0040] 2. The present invention reduces the leaching concentration of the obtained mixture through the landfill solidification process, reduces the leaching rate of the mixture, and after the mixture is cured, the strength of the solidified body is enhanced, which is beneficial to the landfill of the solidified body;

[0041] 3. The present invention continuously adjusts the reaction ratio through the solidification test and leaching test before solidification landfill, thereby maintaining the stability of the solidified mixture characteristics, reducing fluctuations, and reducing the impact on subsequent landfill treatment.

[0042] 4. The present invention adopts automated operation and mechanized feeding, which reduces the cost of manual feeding in production, improves production efficiency, and enhances the safety and sustainable practicality of the production line to a greater extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0044] Figure 1 It is the principle diagram of the method of the present invention;

[0045] Figure 2 It is a flow chart of the high-salinity wastewater treatment system of the present invention; DETAILED DESCRIPTION

[0046] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0047] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0048] Example 1

[0049] A method for treating high-salinity wastewater comprises the following steps:

[0050] Step 1: Take samples of high-salt wastewater, incineration fly ash and solid salt in batches and conduct solidification tests and leaching tests in the laboratory. The specific steps of the solidification test and leaching test are as follows:

[0051] (1) Weigh 500 g of high-salt wastewater into a beaker and measure the pH;

[0052] (2) adding solid salt to the beaker, mixing and stirring, adjusting the pH of the mixed solution to 7, and recording the cumulative weight of the solid salt added and the total weight of the mixed solution;

[0053] (3) Add incineration fly ash to the mixed liquid in a mass ratio of 1:1, stir until it becomes gelled and no water is separated out, obtain a mixed material and record the weight of the added fly ash;

[0054] (4) curing the mixture at room temperature for 8 to 10 days, performing a leaching test on the mixture to obtain a leachate, and measuring the concentration of the leachate, wherein the curing process is natural curing; the leaching test process is performed in accordance with HJ 557-2010 "Toxic Leaching Methods for Solid Waste - Horizontal Oscillation Method" to obtain a leachate;

[0055] (5) Based on the leaching results and the landfill admission requirements, the mass ratio of high-salinity wastewater, solid salt and incineration fly ash is determined to be 1:0.8:1;

[0056] Step 2: After determining the addition ratio of each component of high-salt wastewater, incineration fly ash and solid salt according to the test results, first input the fly ash and solid salt into the mixer, stir and mix for a period of time, and then input the high-salt wastewater into the mixer for solidification treatment;

[0057] Step 3: The mixer fully mixes the high-salt wastewater, incineration fly ash and solid salt, wherein the obtained mixture has a high density and no obvious precipitation of leachate and water-soluble salt is sufficient;

[0058] Step 4: The mixed mixture is transported to the curing area for curing. After curing in the curing area for about 5 days, the compressive strength of the mixture can reach 6.8kg / cm 2 After about 10 days of curing, its compressive strength can reach 12.5kg / cm 2 ;

[0059] Step 5: After curing, the leaching results of the solidified body are tested, and qualified ones are transferred to the rigid landfill area for landfill, while unqualified ones are crushed by a crusher and then sent to the mixer for solidification treatment.

[0060] The qualified solidification body test results are shown in Table 1 below:

[0061] Table 1

[0062] Calorific value Moisture content Cyanide Cu Pb Zn Ni Sn Na Salt Nitrate Sulfate cal / g % mg / Kg % % % % % % % % % ＜200 14.83 0.04 0.82 0.05 0.28 0.11 0.04 1.21 28.6 1.46 8.13

[0063] Example 2

[0064] A method for treating high-salt wastewater is basically the same as in Example 1, except that in step 1, in the specific step (3) of the solidification test and the leaching test, the mass ratio of the mixed liquid to the incineration fly ash is 2:1, and in step (5), the mass ratio of the high-salt wastewater, the solid salt and the incineration fly ash is 1:1:1.2; in step 4, the compressive strength after curing for 5 days is 7kg / cm 2 The compressive strength after 10 days of curing is 11.6kg / cm 2 .

[0065] Example 3

[0066] A method for treating high-salt wastewater is basically the same as in Example 1, except that in step 1, the mass ratio of the mixed liquid to the incineration fly ash in the specific step (3) of the solidification test and the leaching test is 3:2, and the mass ratio of the high-salt wastewater, solid salt and incineration fly ash in step (5) is 1:1:1; in step 4, the compressive strength after curing for 5 days is 5kg / cm 2 The compressive strength after 10 days of curing is 10kg / cm 2.

[0067] The present invention also provides a high-salt wastewater treatment system, comprising a high-salt wastewater metering device, a solid salt metering device, a fly ash metering device, a mixer, a maintenance station and a rigid landfill; wherein:

[0068] The high-salinity wastewater metering device comprises a wastewater tank, a metering pump and a weighing device connected in sequence, wherein the outlet of the weighing device is connected to the inlet of the mixer;

[0069] The solid salt metering device comprises a metering bin I and a screw feeder I which are connected in sequence, and the outlet of the screw feeder I is connected to the inlet of the mixer;

[0070] The fly ash metering device comprises a metering bin II and a screw feeder II which are connected in sequence, and the outlet of the screw feeder II is connected to the inlet of the mixer;

[0071] The high-salt wastewater metering device, the solid salt metering device and the fly ash metering device transport the well-proportioned high-salt wastewater, solid salt and fly ash to the mixer for solidification treatment according to the above method, and then transport them to the maintenance station for maintenance treatment, and finally send them to the rigid landfill for landfill treatment.

[0072] The method of the present invention provides ideas for the coordinated treatment of high-salt wastewater, incineration fly ash and solid salt, which can effectively solve the difficult problems of high-salt wastewater treatment and high operating costs. At the same time, the incineration fly ash and solid salt are coordinated for solidification-landfill treatment to form a dense solidified body, thereby achieving the purpose of treating waste with waste.

Claims

1. A method for treating high-salinity wastewater, characterized in that: The steps include: Step 1: Extract hazardous waste samples containing high-salinity wastewater in batches and conduct laboratory solidification tests and leaching tests; Step 2: According to the test results, determine the addition ratio of each component of the hazardous waste and input it into the mixer for solidification treatment; Step 3: The hazardous waste is fully stirred and mixed by a mixer; Step 4: The mixed mixture is transported to the curing area for curing. After curing in the curing area for about 5 days, the compressive strength of the mixed mixture reaches 5-7 kg / cm 2 After about 10 days of curing, the compressive strength reaches 10~12.5kg / cm 2 ; Step 5: After curing, the leaching results of the solidified body are tested, and qualified ones are transferred to the rigid landfill area for landfill, while unqualified ones are crushed by a crusher and then sent to the mixer for solidification treatment.

2. A method for treating high-salt wastewater according to claim 1, characterized in that: The hazardous wastes include high-salinity wastewater, incineration fly ash and solid salt.

3. A method for treating high-salt wastewater according to claim 2, characterized in that: In step 1, the curing test and the leaching test specifically include the following steps: (1) Weigh 500 g of high-salt wastewater into a beaker and measure the pH; (2) adding solid salt to the beaker, mixing and stirring, adjusting the pH of the mixed solution to 7, and recording the cumulative weight of the solid salt added and the total weight of the mixed solution; (3) adding incineration fly ash to the mixed liquid in a mass ratio of (1-3): (1-2), stirring until it becomes gelled and no water is separated out, obtaining a mixed material and recording the weight of the added fly ash; (4) curing the mixture at room temperature for 8 to 10 days, performing a leaching test on the mixture to obtain a leaching solution, and measuring the concentration of the leaching solution; (5) Based on the leaching results and the landfill admission requirements, determine the mass ratio of high-salt wastewater, solid salt and incineration fly ash.

4. A method for treating high-salt wastewater according to claim 3, characterized in that: In step (4), the curing process is natural curing; the leaching test is carried out according to the solid waste toxicity leaching method-horizontal oscillation method; the mass ratio of the high-salt wastewater, solid salt and incineration fly ash is 1: (0.8~1): (1~1.2).

5. A method for treating high-salt wastewater according to claim 2, characterized in that: In step 2, the order in which the hazardous waste is input into the mixer is to add fly ash and solid salt first and then add high-salt wastewater.

6. A method for treating high-salt wastewater according to claim 2, characterized in that: In step three, the sufficient stirring and mixing means that the obtained mixture has high density and there is no obvious precipitation of leachate and water-soluble salt, which means that the mixing is sufficient; the stirring and mixing device is a mixer with a double-axis spiral structure.

7. A high-salinity wastewater treatment system, characterized in that: Includes high-salinity wastewater metering device, solid salt metering device, fly ash metering device, mixer, curing station and rigid landfill; The high-salt wastewater metering device comprises a wastewater tank, a metering pump and a weighing device connected in sequence, and the outlet of the weighing device is connected to the inlet of the mixer; The solid salt metering device comprises a metering bin I and a screw feeder I which are connected in sequence, and the outlet of the screw feeder I is connected to the inlet of the mixer; The fly ash metering device comprises a metering bin II and a screw feeder II which are connected in sequence, and the outlet of the screw feeder II is connected to the inlet of the mixer; The high-salt wastewater metering device, the solid salt metering device and the fly ash metering device transport the well-proportioned high-salt wastewater, solid salt and fly ash to the mixer for solidification treatment in accordance with the method described in any one of claims 1 to 6, and then transport them to the maintenance station for maintenance treatment, and finally send them to the rigid landfill for landfill treatment.

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