Method for treating chlorinated wastewater by alkali-modified calcined clay mineral in cooperation with advanced oxidation

Abstract

This application relates to a method for treating chlorinated wastewater using alkali-modified calcined clay minerals in conjunction with advanced oxidation (PS) technology. The method includes the following steps: S1, adding alkali-modified calcined clay minerals, persulfate, and ferrous salt to chlorinated wastewater for reaction to obtain the reacted wastewater; S2, adjusting the pH of the reacted wastewater to alkaline, then adding a flocculant to assist sedimentation, thereby removing organic matter and chloride ions from the wastewater, and obtaining the supernatant as the treated wastewater effluent. This application uses alkali-modified calcination to treat clay minerals, significantly optimizing the adsorption performance of the resulting alkali-modified calcined clay minerals, enabling them to adsorb not only suspended matter but also chloride ions from the wastewater. By combining alkali-modified calcined clay minerals with PS advanced oxidation technology, the synergistic effect of the two effectively improves the biodegradability of the treated wastewater.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, in particular to a method for treating chlorinated wastewater by alkali-modified calcined clay mineral in cooperation with advanced oxidation. BACKGROUND

[0002] The treatment of industrial wastewater with high chlorine, high salt, high COD concentration and poor biodegradability is one of the focuses and difficulties in wastewater treatment. Advanced oxidation technology is a commonly used method for treating industrial wastewater. It can generate strong oxidizing free radicals through activation and carry out a series of free radical chain reactions with organic pollutants, thereby destroying their structure and gradually degrading them into harmless low molecular weight organic matter, and finally into CO2, H2O and other mineral salts. The main advanced oxidation technologies currently applied are Fenton advanced oxidation technology and persulfate advanced oxidation technology (PS advanced oxidation technology).

[0003] Although advanced oxidation technology can effectively treat refractory compounds in wastewater and improve the biodegradability of wastewater, it cannot effectively remove chloride ions in wastewater. Chloride ions are the most stable form of chlorine. Since microorganisms cannot utilize chloride ions, they cannot be effectively removed by biological methods. In addition, the content of chloride ions in wastewater inhibits the growth of microorganisms and hinders the efficiency of biological wastewater treatment. Common methods for removing chloride ions from wastewater include precipitation, membrane separation, solvent extraction, and ultra-high lime aluminum method. However, these methods are very expensive and are generally only used for small-volume wastewater treatment.

[0004] Therefore, there is a need to provide a method for treating industrial wastewater with high chlorine, high salt, high COD concentration, and poor biodegradability, which can not only remove chloride ions from wastewater but also degrade organic pollutants in wastewater, and is of great significance for improving the biodegradability of wastewater. SUMMARY

[0005] To solve the problems of the prior art, the present application provides a method for treating chlorinated wastewater by alkali-modified calcined clay mineral in cooperation with advanced oxidation. Through the synergistic effect of alkali-modified calcined clay mineral and PS advanced oxidation technology, this method can not only remove part of the chloride ions in wastewater by adsorption of alkali-modified calcined clay mineral, but also efficiently degrade organic pollutants in wastewater by PS advanced oxidation, thereby effectively improving the biodegradability of the treated wastewater effluent.

[0006] Therefore, the first aspect of the present application provides a method for treating chlorinated wastewater by alkali-modified calcined clay mineral in cooperation with advanced oxidation, which comprises the following steps:

[0007] S1. Adding alkali-modified calcined clay mineral, persulfate, and ferrous salt to the chlorinated wastewater for reaction to obtain the reacted wastewater;

[0008] S2, adjusting the pH of the reacted wastewater to alkaline, then adding a flocculant to assist precipitation, and then removing organic matter and chloride ions in the wastewater, to obtain supernatant as treated wastewater effluent.

[0009] In the present application, the alkali-modified calcined clay mineral added in the method is treated by alkali modification and calcination, so that its adsorption performance is greatly optimized. It can not only adsorb suspended substances in wastewater, but also effectively adsorb chloride ions in wastewater, thereby removing part of the chloride ions in the wastewater. The added persulfate (such as sodium persulfate) is activated and decomposed in water to generate persulfate ions, which have strong oxidizing ability and good stability, thereby decomposing the refractory organic pollutants in the water into small molecular substances and completely removing the pollutants. The added ferrous salt ionizes in water to generate Fe 2+ , which can activate persulfate to generate persulfate ions (SO4 - ) at room temperature, so that the persulfate effectively exerts its oxidizing effect. At the same time, the large amount of chloride ions present in the wastewater will consume the persulfate ions generated by the activation of persulfate, reducing the decomposition ability of PS advanced oxidation technology on refractory organic matter. The alkali-modified calcined clay mineral can adsorb chloride ions in wastewater, thereby improving the ability of PS advanced oxidation technology to degrade organic pollutants in wastewater. That is, through the synergistic effect of alkali-modified calcined clay mineral and PS advanced oxidation technology, part of the chloride ions can be removed by the adsorption of alkali-modified calcined clay mineral, and the PS advanced oxidation technology can be fully utilized to efficiently degrade organic pollutants and improve the biodegradability.

[0010] In some embodiments, the method for preparing the alkali-modified calcined clay mineral comprises the following steps:

[0011] T1, soaking the clay mineral in a sodium hydroxide solution to obtain an alkali-modified clay mineral;

[0012] T2, vacuum drying the alkali-modified clay mineral, calcining it in an inert atmosphere, and then crushing it to obtain an alkali-modified calcined clay mineral.

[0013] In the present application, the alkali-modified calcined clay mineral is prepared by soaking the clay mineral in alkali and then calcining it in an inert atmosphere. The inventors have creatively found that the adsorption performance of the alkali-modified calcined clay mineral obtained by the above treatment is greatly improved. It not only improves the adsorption effect of suspended substances in wastewater, but also has the ability to adsorb chloride ions. In this way, by adding the alkali-modified calcined clay mineral to wastewater containing chloride, part of the chloride ions in the wastewater can be removed through simple adsorption.

[0014] In some embodiments, the clay mineral is a mixture of bentonite and kaolin; the mass ratio of bentonite to kaolin in the mixture is (5-10):(2-4).

[0015] In some specific embodiments, the mass ratio of bentonite to kaolin in the mixture can be 5:3, 6:3, 7:3, 8:3, 9:3 or 10:3, etc. In some preferred embodiments, the mass ratio of bentonite to kaolin is 7:3.

[0016] In the present application, bentonite has good swelling and adsorption properties, and kaolin has good cohesiveness and is easy to disperse and suspend in water. By using bentonite and kaolin as clay minerals, and controlling the mass ratio of the two within the above range, the adsorption performance of the prepared alkali-modified calcined clay mineral in wastewater is better.

[0017] In some embodiments, the concentration of sodium hydroxide in the sodium hydroxide solution is 1-3 mol / L. In some specific embodiments, the concentration of sodium hydroxide in the sodium hydroxide solution can be 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L or 3 mol / L, etc. In some preferred embodiments, the concentration of sodium hydroxide in the sodium hydroxide solution is 1.5-2.5 mol / L.

[0018] In some embodiments, the soaking time is 18-24 h. In some specific embodiments, the soaking time can be 18 h, 20 h, 22 h or 24 h, etc. In some preferred embodiments, the soaking time is 22-24 h.

[0019] In the present application, during the soaking process of the clay mineral with the sodium hydroxide solution, the concentration of the sodium hydroxide solution and the soaking time have a great influence on the alkali modification effect of the clay mineral, which in turn affects the adsorption effect of the prepared alkali-modified calcined clay mineral. By controlling the concentration of the sodium hydroxide solution and the soaking time within the above range, the prepared alkali-modified calcined clay mineral has better adsorption effect.

[0020] In the present application, the soaking is carried out under sealed conditions to avoid the influence of external factors on the soaking effect during the soaking process.

[0021] In the present application, the vacuum drying process of the alkali-modified clay mineral can be in a vacuum drying oven, and the drying temperature can be 50-60℃.

[0022] In some embodiments, the calcination is performed at a temperature rising rate of 3-8℃ / min to 550-650℃ and maintained for 2-3 h.

[0023] In some preferred embodiments, the calcination is performed by increasing the temperature to 600℃ at a rate of 5℃ / min and maintaining the temperature for 2h.

[0024] In the present application, the calcination temperature in the calcination process affects the porosity of the alkali-modified calcined clay mineral prepared, and further affects the porosity of the alkali-modified calcined clay mineral. By controlling the calcination temperature and time within the above range, the alkali-modified calcined clay mineral prepared has better adsorption effect.

[0025] In the present application, the calcination process can be performed in a tube furnace. The present application does not specifically limit the inert atmosphere of the calcination process, and those skilled in the art can make routine selection according to actual needs. In some specific embodiments, the inert atmosphere is selected from one or more of nitrogen, helium and argon.

[0026] In the present application, the particle size of the alkali-modified calcined clay mineral obtained after crushing is about 2μm.

[0027] In some embodiments, in step S1, the amount of the alkali-modified calcined clay mineral added in the chlorinated wastewater is 5-10g / L.

[0028] By controlling the amount of the alkali-modified calcined clay mineral within the above range, the removal effect of the chloride ions in the wastewater is better. If the amount of the alkali-modified calcined clay mineral is too small, the removal effect of the chloride ions is poor. If the amount of the alkali-modified calcined clay mineral is too large, not only the removal effect of the chloride ions will not be increased, but also the excessive alkali-modified calcined clay mineral will cause waste, and the excessive alkali-modified calcined clay mineral is also not conducive to subsequent removal by precipitation.

[0029] In some embodiments, in step S1, the mass ratio of the ferrous salt to the persulfate salt is (2-5):1, and the mass ratio of the persulfate salt to the COD in the chlorinated wastewater is (0.5-1.5):1.

[0030] In some preferred embodiments, in step S1, the mass ratio of the ferrous salt to the persulfate salt is (3-4):1, and the mass ratio of the persulfate salt to the COD in the chlorinated wastewater is 1:1.

[0031] In the present application, the ferrous salt ionizes in water to generate Fe 2+ to activate the persulfate to generate persulfate ions (SO4 - The mass relationship between the ferrous salt and the persulfate salt has a very obvious influence on the presence and amount of SO4 – When the mass ratio of the ferrous salt to the persulfate salt is low, the content of Fe 2+ is low, which affects the content of SO4 –The generation rate of the free radicals further affects the decomposition effect of the refractory organic matter; when the mass ratio of the ferrous salt to the persulfate is high, the content of Fe 2+ is high, which is easy to cause new pollution. In the application, the adding amount of the ferrous salt and the persulfate is controlled in the above range, so that a better wastewater treatment effect can be obtained.

[0032] In the application, the added persulfate can be sodium persulfate, and the added ferrous salt can be ferrous sulfate.

[0033] In some embodiments, in step S1, the reaction is carried out under stirring, and the reaction time is 2-3h.

[0034] In the application, by carrying out the reaction under stirring, the alkali-modified calcined clay mineral, the persulfate and the ferrous salt can be uniformly dispersed in the chlorinated wastewater to be treated, so that the treatment effect is improved. By controlling the reaction time to be 2-3h, the adsorption effect of the alkali-modified calcined clay mineral on the chloride ions and the decomposition effect of the PS advanced oxidation technology on the refractory organic matter can be fully exerted.

[0035] In some embodiments, in step S2, the pH value of the adjusted wastewater is 8.0-9.0. In some preferred embodiments, the pH value of the adjusted wastewater is 8.5.

[0036] In the application, the pH value of the wastewater can be adjusted by using a sodium hydroxide solution, and by adjusting the pH value of the wastewater to be in the above range, the subsequent added flocculant can be more conducive to flocculation.

[0037] In some embodiments, in step S2, the flocculant is polyaluminum chloride, and the adding amount is 80-120mg / L; and the precipitation time is 0.5-1h.

[0038] In some preferred embodiments, in step S2, the flocculant is polyaluminum chloride, and the adding amount is 100mg / L; and the precipitation time is 1h.

[0039] In the application, polyaluminum chloride is an inorganic polymer coagulant, and has excellent flocculation performance. By controlling the adding amount of the polyaluminum chloride and the precipitation time in the above range, the suspended solids in the reacted wastewater can be effectively precipitated, and the supernatant after precipitation is the wastewater treatment effluent.

[0040] The beneficial technical effects of the present application are: (1) the present application adopts the method of alkali modification calcination to treat clay minerals, so that the adsorption performance of the prepared alkali modification calcined clay minerals is greatly optimized, not only can adsorb suspended substances in wastewater, but also can adsorb chloride ions in wastewater; (2) the present application combines alkali modification calcined clay minerals with PS advanced oxidation technology, which not only removes part of the chloride ions in wastewater by using the adsorption of alkali modification calcined clay minerals, but also fully utilizes the role of PS advanced oxidation to efficiently degrade organic pollutants, and effectively improves the biodegradability of the treated wastewater through the synergistic effect of the two; (3) the method provided by the present application is suitable for relatively wide pH conditions, and has good treatment effect under acidic or neutral conditions; at the same time, it is suitable for different stages of wastewater treatment, which can be used for front-end pretreatment to reduce the subsequent treatment load, and can also be used for end-stage treatment to make the effluent meet the discharge requirements; (4) the method provided by the present application is simple to operate, convenient to manage, and stable in effect, and the clay minerals, sodium persulfate and ferrous sulfate used are low in price and low in operation cost, so the application prospect is good. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 The comparative results of chloride ion removal rate and COD removal rate of Example 1 and Comparative Example 1 are shown in the graph.

[0042] Figure 2 The structure schematic diagram of the pilot plant used for the pilot test of Example 16 is shown in the graph.

[0043] Figure 3 The chloride ion removal effect graph of the pilot test of Example 16 is shown in the graph.

[0044] Figure 4 The COD removal effect graph of the pilot test of Example 16 is shown in the graph.

[0045] Figure 5 The B / C effect graph of the pilot test of Example 16 is shown in the graph. DETAILED DESCRIPTION

[0046] In order to make the present application easier to understand, the present application will be further described in detail below in combination with examples, which only serve to illustrate the present application and do not limit the application scope of the present application. The raw materials or components used in the present application can be prepared by commercial means or conventional methods if not specifically stated.

[0047] Preparation Example 1: Preparation of alkali modification calcined clay minerals

[0048] (1) 140 g of bentonite and 60 g of kaolin were mixed uniformly to obtain a mixture of clay minerals, and the mass ratio of bentonite to kaolin in the mixture was 7:3;

[0049] (2) Put the clay mineral of step (1) into 1 mol / L sodium hydroxide solution completely, and seal and soak at room temperature for 24 h to obtain an alkali-modified clay mineral;

[0050] (3) Put the alkali-modified clay mineral obtained in step (2) into a vacuum drying oven, and vacuum dry at a constant temperature of 60°C, then put into a tube furnace, and heat to 550°C at a heating rate of 5°C / min under a nitrogen atmosphere, and keep for 2 h to calcine, then put into a pulverizer to stir to powder, and the powder particle size is about 2 μm, to obtain an alkali-modified calcined clay mineral.

[0051] Preparation Example 2: Preparation of an alkali-modified calcined clay mineral

[0052] The preparation process is basically the same as that in Preparation Example 1, except that 125 g of bentonite and 75 g of kaolin are mixed uniformly to obtain a mixture of clay minerals, and the mass ratio of bentonite to kaolin in the mixture is 5:3.

[0053] Preparation Example 3: Preparation of an alkali-modified calcined clay mineral

[0054] The preparation process is basically the same as that in Preparation Example 1, except that 160 g of bentonite and 40 g of kaolin are mixed uniformly to obtain a mixture of clay minerals, and the mass ratio of bentonite to kaolin in the mixture is 12:3 (4:1).

[0055] Preparation Example 4: Preparation of an alkali-modified calcined clay mineral

[0056] The preparation process is basically the same as that in Preparation Example 1, except that the clay mineral in step (1) is 200 g of bentonite.

[0057] Preparation Example 5: Preparation of an alkali-modified calcined clay mineral

[0058] The preparation process is basically the same as that in Preparation Example 1, except that the concentration of the sodium hydroxide solution in step (2) is 2 mol / L.

[0059] Preparation Example 6: Preparation of an alkali-modified calcined clay mineral

[0060] The preparation process is basically the same as that in Preparation Example 1, except that the concentration of the sodium hydroxide solution in step (2) is 3 mol / L.

[0061] Preparation Example 7: Preparation of an alkali-modified calcined clay mineral

[0062] The preparation process is basically the same as that in Preparation Example 1, except that the concentration of the sodium hydroxide solution in step (2) is 0.5 mol / L.

[0063] Preparation Example 8: Preparation of alkali-modified calcined clay mineral

[0064] Preparation Example 9: Preparation of alkali-modified calcined clay mineral

[0065] The preparation process is basically the same as that of Preparation Example 1, except that the calcination in step (3) is performed by increasing the temperature to 650°C at a rate of 5°C / min and maintaining it for 2 h.

[0066] Preparation Example 10: Preparation of alkali-modified calcined clay mineral

[0067] The preparation process is basically the same as that of Preparation Example 1, except that the calcination in step (3) is performed by increasing the temperature to 750°C at a rate of 5°C / min and maintaining it for 2 h.

[0068] Example 1: Treatment of wastewater containing chlorine

[0069] To further analyze the synergistic treatment effect of alkali-modified calcined clay mineral and PS advanced oxidation, a pharmaceutical wastewater containing chlorine in Shijiazhuang (chloride ion concentration of 9000 mg / L, COD concentration of 900 mg / L) was taken as an example, and the following wastewater treatment experiments were carried out:

[0070] The alkali-modified calcined clay mineral prepared in Preparation Example 1, sodium persulfate and ferrous sulfate were simultaneously added into 200 mL of the above-mentioned actual wastewater diluted by 3 times (chloride ion concentration of 3000 mg / L, COD concentration of 300 mg / L), wherein the addition amount of alkali-modified calcined clay mineral was 5 g / L, the addition amount of sodium persulfate was 0.3 g / L, the addition amount of ferrous sulfate was 1.0 g / L, the mass ratio of sodium persulfate to ferrous sulfate was 3.3:1, and the mass ratio of ferrous sulfate to COD in wastewater was 1:1. Then, at room temperature, the reaction was carried out in a 250 mL conical flask on a six-connected stirrer at a speed of 200 r / min for 2 h to obtain the reacted wastewater. The pH value of the reacted wastewater was adjusted to 8.5 by sodium hydroxide solution, and then 20 mg of polyaluminum chloride (the concentration of polyaluminum chloride in wastewater was 100 mg / L) was added to assist precipitation. After 1 h of precipitation, the supernatant was the treated wastewater effluent.

[0071] Examples 2-10: Treatment of wastewater containing chlorine

[0072] The treatment process is basically the same as that of Example 1, except that the alkali-modified calcined clay mineral used in Examples 2-10 is the alkali-modified calcined clay mineral prepared in Preparation Examples 2-10, respectively.

[0073] Example 11: Treatment of wastewater containing chlorine

[0074] The treatment process is basically the same as that of Example 1, except that the addition amount of the alkali-modified calcined clay mineral is 8 g / L.

[0075] Example 12: Treatment of chlorinated wastewater

[0076] The treatment process is basically the same as that of Example 1, except that the addition amount of the alkali-modified calcined clay mineral is 3 g / L.

[0077] Example 13: Treatment of chlorinated wastewater

[0078] The treatment process is basically the same as that of Example 1, except that the addition amount of sodium persulfate is 0.3 g / L, the addition amount of ferrous sulfate is 0.6 g / L, the mass ratio of sodium persulfate to ferrous sulfate is 2:1, and the mass ratio of ferrous sulfate to COD in the wastewater is 1:1.

[0079] Example 14: Treatment of chlorinated wastewater

[0080] The treatment process is basically the same as that of Example 1, except that the addition amount of sodium persulfate is 0.3 g / L, the addition amount of ferrous sulfate is 1.5 g / L, the mass ratio of ferrous sulfate to sodium persulfate is 5:1, and the mass ratio of ferrous sulfate to COD in the wastewater is 1:1.

[0081] Example 15: Treatment of chlorinated wastewater

[0082] The treatment process is basically the same as that of Example 1, except that sodium hydroxide solution is used to adjust the pH value of the reaction wastewater to 10, and then 20 mg of polyaluminum chloride is added to assist precipitation.

[0083] Comparative Example 1: Treatment of chlorinated wastewater

[0084] Taking the chlorinated wastewater (chloride ion concentration of 9000 mg / L, COD concentration of 900 mg / L) of a pharmaceutical company in Shijiazhuang as an example, the following wastewater treatment experiments were carried out.

[0085] Sodium persulfate and ferrous sulfate were simultaneously added into 200 mL of the above-mentioned actual wastewater (chloride ion concentration of 3000 mg / L and COD concentration of 300 mg / L) diluted by 3 times, wherein the addition amount of sodium persulfate was 0.3 g / L, the addition amount of ferrous sulfate was 1.0 g / L, the mass ratio of sodium persulfate to ferrous sulfate was 3.3:1, and the mass ratio of ferrous sulfate to COD in the wastewater was 1:1. Then, at room temperature, the reaction was carried out in a 250 mL conical flask on a six-connected stirrer at a rotation speed of 200 r / min for 2 h to obtain the reacted wastewater. The pH value of the reacted wastewater was adjusted to 8.5 by using sodium hydroxide solution, and then 20 mg of polyaluminum chloride (the concentration of polyaluminum chloride in the wastewater was 100 mg / L) was added for auxiliary precipitation. After precipitation for 1 h, the supernatant was the treated wastewater effluent.

[0086] Test Example 1

[0087] The supernatant obtained after wastewater treatment in Examples 1-15 and Comparative Example 1 was detected for the COD concentration by using a COD rapid detector, and the chloride ion concentration was detected by using the national standard method (GB11896), and the chloride ion removal rate and the COD removal rate after treatment were calculated. The specific results are shown in Table 1, and the comparison results of the chloride ion removal rate and the COD removal rate of Example 1 and Comparative Example 1 are shown in Figure 1

[0088] Table 1

[0089]

[0090]

[0091] From Table 1 and Figure 1 It can be seen that, compared with the method of using PS advanced oxidation technology alone for treating chloride-containing wastewater in Comparative Example 1, the method of using the alkali-modified calcined clay mineral and PS advanced oxidation technology for cooperatively treating chloride-containing wastewater in Example 1 significantly improves the wastewater treatment effect, wherein the chloride ion removal rate is increased by about 15%, and the COD removal rate is increased by about 30%.

[0092] ​From the detection results of examples 1-4 in table 1, it can be seen that the alkali modified calcined clay mineral prepared by using a mixture of bentonite and kaolin as the clay mineral has better treatment effect when used in subsequent wastewater treatment, and when the mass ratio of bentonite and kaolin is 7:3, it helps to further improve the wastewater treatment effect. From the detection results of examples 1 and 6-7 in table 1, it can be seen that when the concentration of sodium hydroxide solution used for alkali modification of the clay mineral is 2 mol / L, the alkali modified calcined clay mineral prepared has better treatment effect when used in subsequent wastewater treatment. From the detection results of examples 1 and 8-10 in table 1, it can be seen that when the calcination temperature of the alkali modified clay mineral is 600℃, it helps to further improve the wastewater treatment effect.

[0093] From the detection results of examples 1 and 12-15 in table 1, it can be seen that when the addition amount of the alkali modified calcined clay mineral is 8 g / L, the mass ratio of ferrous sulfate to sodium persulfate is (3-4):1, and the pH value of the wastewater is adjusted to 8.0-9.0, it helps to improve the wastewater treatment effect.

[0094] Example 16

[0095] To further analyze the pilot scale application of the method of removing chlorine ions in industrial wastewater by using the composite alkali modified calcined clay mineral and PS advanced oxidation technology, a pharmaceutical wastewater in Shijiazhuang was taken as an example, and a pilot device was built in a sewage plant. The structure of the pilot device is shown in Figure 2 The alkali modified calcined clay mineral prepared in preparation example 1 was selected for pilot scale test. The influent amount of the pilot device was 1.6-2.0 m 3 / h, the daily operation time was 8-10 h, the actual water treatment amount per day was 15-20 m 3 / d, the dosing amount of each reagent in the pilot test is shown in table 2, and the operation effect of the pilot test is shown in Figures 3-5 (Wherein the first 20 days only used PS advanced oxidation technology for wastewater treatment, and the last 40 days added alkali modified calcined clay mineral and PS advanced oxidation technology for wastewater treatment). Figure 3 The chlorine ion removal effect diagram of the pilot test is Figure 4 The COD removal effect diagram of the pilot test is Figure 5 The B / C (biodegradability ratio, i.e. the ratio of BOD to COD) effect diagram of the pilot test is

[0096] It can be seen from Figure 3 that the original wastewater chlorine ion concentration is about 8000-9000 mg / L, the effluent chlorine ion concentration after PS advanced oxidation technology treatment is about 7500-8000 mg / L, and the chlorine ion removal rate is about 5%. After 20 days of treatment with the addition of alkali modified calcined clay mineral, the chlorine ion concentration is about 6800-7200 mg / L, and the chlorine ion removal rate can be increased by about 15%, reaching about 20%. FromFigure 4 It can be seen that the original wastewater COD concentration is about 750-950 mg / L, and the effluent COD concentration is about 400-500 mg / L after the PS advanced oxidation technology treatment, and the COD removal rate is about 40%. After adding the alkali modified calcined clay mineral for 20 days, the COD concentration is about 250-300 mg / L, and the COD removal rate can be increased by about 25%, reaching 65-70%. It can be seen that the original wastewater B / C average is 0.07, and the effluent B / C average is 0.332. After the alkali modified calcined clay mineral cooperates with the PS advanced oxidation technology treatment, the wastewater biodegradability is obviously improved. Figure 5

[0097] It should be noted that the above-described embodiments are only used to explain the present application and do not constitute any limitation on the present application. The present application is described by referring to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than limiting words. The present application can be modified as specified within the scope of the claims of the present application, and the present application can be revised within the scope and spirit of the present application. Although the present application described therein relates to specific methods, materials and embodiments, it does not mean that the present application is limited to the specific examples disclosed therein, on the contrary, the present application can be extended to all other methods and applications with the same function.​

Claims

1. A method for treating chlorinated wastewater by alkali-modified calcined clay mineral in conjunction with advanced oxidation, characterized in that, The method comprises the following steps: S1, adding an alkali-modified calcined clay mineral, a persulfate salt and a ferrous salt into chlorinated wastewater to react, to obtain reacted wastewater; S2, adjusting the pH of the reacted wastewater to alkaline, and then adding a flocculant to assist precipitation, thereby removing organic matter and chloride ions in the wastewater, and obtaining supernatant as treated effluent of the wastewater; The preparation method of the alkali-modified calcined clay mineral comprises the following steps: T1, soaking a clay mineral in a sodium hydroxide solution to obtain an alkali-modified clay mineral; T2, vacuum drying the alkali-modified clay mineral, calcining it in an inert atmosphere, and crushing it to obtain an alkali-modified calcined clay mineral; The clay mineral is a mixture of bentonite and kaolin, and the mass ratio of bentonite to kaolin in the mixture is (5-10):(2-4). The concentration of sodium hydroxide in the sodium hydroxide solution is 1-3 mol / L, and / or the soaking time is 18-24 h.

2. The method of claim 1, wherein, The calcination is performed at a temperature rising rate of 3-8 ℃ / min to 550-650 ℃ for 2-3 h.

3. The method according to claim 1 or 2, characterized in that, In step S1, the addition amount of the alkali-modified calcined clay mineral in the chlorinated wastewater is 5-10 g / L.

4. The method according to claim 1 or 2, characterized in that, In step S1, the mass ratio of the ferrous salt to the persulfate salt is (2-5):1, and the mass ratio of the persulfate salt to COD in the chlorinated wastewater is (0.5-1.5):

1.

5. The method according to claim 1 or 2, characterized in that, In step S1, the reaction is performed under stirring for 2-3 h.

6. The method of claim 1 or 2, wherein, In step S2, the pH of the adjusted wastewater is 8.0-9.

0.

7. The method of claim 1 or 2, wherein, In step S2, the flocculant is polyaluminum chloride, and the addition amount is 80-120 mg / L; the precipitation time is 0.5-1 h.

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