Phosphorus and silicon removal method for acid catalyst wastewater

Abstract

The invention discloses a method for removing phosphorus and silicon from acid catalyst wastewater, which comprises the following steps: carrying out centrifugation or filter pressing separation on catalyst wastewater, introducing waste liquid into a subsequent wastewater treatment unit, adding electrolyte salt into the waste liquid, stirring until the electrolyte salt is completely dissolved, adding alkali into the waste liquid, regulating the pH value until the waste liquid is in a sol state, and carrying out solid-liquid separation on the sol-shaped waste liquid, and removing phosphorus in the wastewater, adding alkali into the separated wastewater, adjusting the pH value and the reaction temperature, removing silicon in the wastewater, carrying out solid-liquid separation, discharging the wastewater reaching the standard, and carrying out harmless treatment on the separated sludge. According to the method, the problem that phosphorus and silicon cannot be synchronously removed by an existing wastewater phosphorus and silicon removal method is solved, the total phosphorus in the wastewater is reduced to 3 mg / L or below, the silicon is reduced to 10 mg / L or below, and phosphorus and silicon are synchronously and efficiently removed.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment methods, and particularly relates to a method for removing phosphorus and silicon from acidic catalyst wastewater. Background Art

[0002] With the rapid development of the catalyst production industry, compounds such as aluminosilicates are widely used, and a large amount of silicon-containing wastewater is generated during the production of molecular sieves. Silicon mainly exists in two forms: (1) various amorphous colloidal silicon, that is, polymerization products of various polymeric silicon and silicon dioxide; (2) in the form of soluble silicon. In addition, in catalyst production, catalyst additives need to be added to adjust the acid-base activity, electronic and geometric structure of the catalyst, and improve the performance of the catalyst. Phosphorus-containing additives are one of them, but this makes the wastewater contain high concentrations of phosphorus. For catalyst wastewater mainly containing Al 3+ , PO4 3- ions and silicon, with a phosphorus content of 10000 - 15000 mg / L, a pH of 0.5 - 2.0, and a silicon content of more than 20000 mg / L, if not treated, it will cause a great impact on the subsequent sewage treatment system. Therefore, it is necessary to develop a rapid phosphorus and silicon removal technology for such wastewater.

[0003] The main silicon removal technologies include coagulation, microbubble flotation, electrocoagulation, ion exchange, etc. In actual applications, the coagulation method for silicon removal is mostly used. Mainly by adding lime, calcium salts, magnesium salts, iron salts, etc., and adding a certain amount of flocculant to remove silicon in the form of precipitation, but the silicon removal rate is low. The main phosphorus removal treatment technologies are chemical methods, biological methods, and adsorption methods. Among them, the chemical method is a phosphorus removal method with mature technology, having the advantages of simple operation, good phosphorus removal effect, and controllable cost; the biological method mainly uses processes such as A / O, A2 / O, SBR, etc. to treat low-concentration and organic phosphorus-containing wastewater; the adsorption method is to add an adsorbent with surface active groups to the phosphorus-containing wastewater, and the low-concentration phosphorus-containing wastewater is treated by the bonding action between the active groups and the phosphorus-containing groups. However, there are few reports on the treatment of ultra-high-concentration phosphorus and silicon-containing catalyst wastewater with a pH less than 2, a phosphorus content exceeding 10000 mg / L, and a silicon content exceeding 20000 mg / L. Therefore, it is urgent to develop an efficient method for removing phosphorus and silicon from wastewater. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for removing phosphorus and silicon from acidic catalyst wastewater, which solves the problem that the existing wastewater phosphorus and silicon removal methods cannot simultaneously achieve phosphorus and silicon removal.

[0005] The technical solution adopted by the present invention is as follows: a method for removing phosphorus and silicon from acidic catalyst wastewater. The catalyst wastewater is subjected to solid-liquid separation, and the waste liquid enters the subsequent wastewater treatment unit. An electrolyte salt is added to the waste liquid and stirred until completely dissolved. Then, an alkali is added to the waste liquid to adjust the pH until the waste liquid becomes sol-like. The sol-like waste liquid is subjected to solid-liquid separation to remove phosphorus from the wastewater. An alkali is added to the separated wastewater, and the pH and reaction temperature are adjusted to remove silicon from the wastewater. After solid-liquid separation, the up-to-standard wastewater is discharged, and the separated sludge is harmlessly treated.

[0006] The characteristics of the technical solution adopted by the present invention also lie in:

[0007] Preferably, the method for removing phosphorus and silicon from acidic catalyst wastewater is specifically implemented according to the following steps:

[0008] (1) Perform solid-liquid separation on the wastewater to obtain waste liquid and sludge 1;

[0009] (2) Add an electrolyte magnesium salt to the waste liquid obtained in step (1), stir and homogenize, and carry out a polymerization inhibition reaction;

[0010] (3) Add an alkali to the waste liquid after the polymerization inhibition reaction in step (2) to adjust the pH value of the waste liquid and obtain a sol-like waste liquid;

[0011] (4) Perform solid-liquid separation on the sol-like waste liquid obtained in step (3) to obtain sludge 2 and separated wastewater;

[0012] (5) Add a magnesium salt to the separated wastewater obtained in step (4), adjust the reaction temperature and pH value, react with the silicon in the wastewater to obtain a white suspension, and carry out the removal of silicon;

[0013] (6) Perform solid-liquid separation after the silicon removal reaction to obtain sludge 3 and treated wastewater;

[0014] (7) Detect the wastewater after being treated in step (6). After reaching the standard, discharge the wastewater. If not up to the standard, return to step 2;

[0015] (8) Harmlessly treat the sludge 1, sludge 2, and sludge 3 separated in steps (1), (4), and (6).

[0016] Preferably, in step 1, the solid-liquid separation is carried out by centrifugation or pressure filtration, and the time for centrifugation or pressure filtration is 15 min to 45 min.

[0017] Preferably, the electrolyte magnesium salt in step 2 is at least one of MgCl 2 , MgSO 4 and Mg(NO 3 ) 2 , and preferably MgSO 4; the addition amount of the electrolyte magnesium salt is 3 g / L to 7 g / L; the temperature of the inhibition polymerization reaction is 20 °C to 35 °C, and the reaction time is 5 min to 30 min.

[0018] Preferably, in step 3, the way to adjust the pH is to add an alkaline compound and adjust the pH to 3 - 7; the alkaline compound is an alkali or an alkaline salt; the alkaline compound is at least one of an inorganic base and an organic base; specifically, it is at least one of sodium hydroxide, potassium hydroxide, and N-methyldiethanolamine.

[0019] Preferably, in step 4, the solid-liquid separation method is at least one of natural sedimentation, centrifugation, and pressure filtration.

[0020] Preferably, in step 5, the magnesium salt is added according to n(Mg):n(Si) = 1:5 - 7, the pH is adjusted to 8.5 - 10.5, the reaction temperature is 60 - 65 °C, the reaction process is accompanied by stirring, the stirring speed is 200 - 400 r / min, the reaction time is 1 - 2 h, and a white suspension is obtained.

[0021] Preferably, in step 6, the solid-liquid separation method is at least one of natural sedimentation, centrifugation, and pressure filtration.

[0022] Preferably, in step 7, the detection standard is that the total phosphorus in the wastewater drops below 3 mg / L and the silicon drops below 10 mg / L.

[0023] Preferably, the specific operation of the sludge harmless treatment in step 8 is as follows:

[0024] (1) Sludge 1 mainly contains silicon, and after dewatering it, it is transported out for utilization.

[0025] (2) Sludge 2 mainly contains phosphorus, and after dewatering it, it is treated as solid waste.

[0026] (3) Sludge 3 mainly contains silicon, and after dewatering it, it is treated as solid waste.

[0027] The beneficial effects of the present invention are:

[0028] The present invention provides a method for removing phosphorus and silicon from acidic catalyst wastewater, which solves the self-polymerization of ultra-high-concentration phosphorus- and silicon-containing catalyst wastewater with a pH less than 2, a phosphorus content exceeding 10,000 mg / L, and a silicon content exceeding 20,000 mg / L, enables the pH to be smoothly adjusted, reduces the total phosphorus content to below 3 mg / L through solid-liquid separation, and through adjusting the pH and reaction temperature, makes magnesium ions react with silicon to form magnesium silicate, and further removes silicon through solid-liquid separation, finally reducing the total phosphorus in the wastewater to below 3 mg / L and the silicon to below 10 mg / L, and achieving the efficient removal of phosphorus and silicon synchronously.

[0029] The present invention solves the problem of self - polymerization of acidic phosphorus - containing catalyst wastewater during the process of adjusting pH by adding alkali. By adding strong - electrolyte salts, the salt effect is utilized to prevent colloids from contacting, reducing the chance of collision and sedimentation, so that Al(OH) 2+ 、Al(OH) 2 + and AlO 2 - etc. exist in the form of monomers, thereby preventing the rapid self - polymerization of colloids, enabling the smooth adjustment of pH for strongly acidic high - concentration phosphorus - containing wastewater, and removing phosphorus in the wastewater in the form of sludge by adjusting the pH value and solid - liquid separation.

[0030] The present invention prevents the rapid self - polymerization of colloids by adding strong - electrolyte magnesium salts, enabling the smooth adjustment of pH for strongly acidic high - concentration phosphorus - containing wastewater, and finally removing phosphorus in the wastewater in the form of sludge. At the same time, it provides a magnesium source for subsequent silicon removal from wastewater. By reacting with soluble silicon in the wastewater to form magnesium silicate, the efficient removal of high - concentration silicon is achieved. Avoiding the re - addition of silicon - removal agents reduces the wastewater treatment and operation costs. The present invention reduces the phosphorus content in ultra - high - concentration phosphorus - and - silicon - containing catalyst wastewater above 10000 mg / L to below 3 mg / L and the silicon content to below 10 mg / L, simultaneously achieving the efficient removal of phosphorus and silicon from ultra - high - phosphorus - and - silicon - containing catalyst wastewater, dehydrating the sludge at the same time, reducing the external discharge volume, lowering the waste treatment cost, and finally harmlessly disposing of the sludge. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the process flow chart of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0033] The present invention discloses a method for removing phosphorus and silicon from acidic catalyst wastewater. The catalyst wastewater is separated by centrifugation or pressure filtration, and the waste liquid enters the subsequent wastewater treatment unit. An electrolyte salt is added to the waste liquid and stirred until completely dissolved. Then, alkali is added to the waste liquid to adjust the pH until the waste liquid becomes sol - like. The sol - like waste liquid is subjected to solid - liquid separation to remove phosphorus in the wastewater. Alkali is added to the separated wastewater, and the pH and reaction temperature are adjusted to remove silicon in the wastewater. After solid - liquid separation, the qualified wastewater is discharged, and the separated sludge is harmlessly treated.

[0034] This method solves the self - polymerization problem of ultra - high - concentration phosphorus - and - silicon - containing catalyst wastewater with a pH less than 2, a phosphorus content exceeding 10000 mg / L, and a silicon content exceeding 20000 mg / L. It enables the smooth adjustment of pH, reduces the total phosphorus content to less than 3 mg / L through solid - liquid separation, and by adjusting the pH and reaction temperature, makes magnesium ions react with silicon to form magnesium silicate, further removing silicon through solid - liquid separation. Finally, the total phosphorus in the wastewater is reduced to less than 3 mg / L and the silicon is reduced to less than 10 mg / L, achieving the efficient removal of phosphorus and silicon.

[0035] As Figure 1 shown, it is specifically implemented according to the following steps:

[0036] (1) Perform solid - liquid separation on the wastewater to obtain waste liquid and sludge 1; the solid - liquid separation is carried out by centrifugation or pressure filtration, and the time for centrifugation or pressure filtration is 15 min to 45 min;

[0037] (2) Add electrolyte magnesium salt to the waste liquid obtained in step (1), stir and homogenize, and carry out an inhibition polymerization reaction; the electrolyte magnesium salt is at least one of MgCl 2 , MgSO 4 and Mg(NO 3 ) 2 , preferably MgSO 4 ; the dosage of the electrolyte magnesium salt is 3 g / L to 7 g / L; the temperature of the inhibition polymerization reaction is 20 °C to 35 °C, and the reaction time is 5 min to 30 min;

[0038] (3) Add an alkali to the waste liquid after the inhibition polymerization reaction in step (2) to adjust the pH and obtain a sol - like waste liquid; the pH is adjusted by adding an alkaline compound and adjusting the pH to 3 - 7; the alkaline compound is an alkali or an alkaline salt; the alkaline compound is at least one of an inorganic base and an organic base; specifically, it is at least one of sodium hydroxide, potassium hydroxide, and N - methyldiethanolamine;

[0039] (4) Perform solid - liquid separation on the sol - like waste liquid obtained in step (3) to obtain sludge 2 and separated wastewater; the solid - liquid separation method is at least one of natural sedimentation, centrifugation, and pressure filtration;

[0040] (5) Add magnesium salt to the separated wastewater obtained in step (4), adjust the reaction temperature and pH value, react with the silicon in the wastewater to obtain a white suspension, and remove silicon; add magnesium salt according to n(Mg):n(Si)=1:5 - 7, adjust the pH to 8.5 - 10.5, the reaction temperature is 60 - 65 °C, the reaction process is accompanied by stirring, the stirring speed is 200 - 400 r / min, and the reaction time is 1 - 2 h to obtain a white suspension;

[0041] (6) After the desilication reaction, solid-liquid separation is carried out to obtain sludge 3 and treated wastewater; the solid-liquid separation method is at least one of natural sedimentation, centrifugation, and pressure filtration;

[0042] (7) The treated product in step (6) is detected. After reaching the standard, the wastewater is discharged. If it does not meet the standard, it is returned to step 2; the detection standard is that the total phosphorus in the wastewater is reduced to less than 3 mg / L and the silicon is reduced to less than 10 mg / L;

[0043] (8) The separated sludge 1, sludge 2, and sludge 3 in steps (1), (4), and (6) are harmlessly treated;

[0044] Sludge 1 mainly contains silicon. After dehydration, it is transported out for utilization;

[0045] Sludge 2 mainly contains phosphorus. After dehydration, it is treated as solid waste;

[0046] Sludge 3 mainly contains silicon. After dehydration, it is treated as solid waste.

[0047] To make the objectives, technical solutions, and key points of the present invention clearer, the following further describes the specific implementation of the present invention in conjunction with the drawings and embodiments.

[0048] Example 1

[0049] Take catalyst wastewater with a pH value of 0.94, total phosphorus of 10885 mg / L, and silicon of 22450 mg / L; the wastewater is subjected to sludge separation for 30 min to obtain waste liquid and sludge 1, and the waste liquid enters the subsequent wastewater treatment unit; add MgSO 4 , with a dosage of 5 g / L, stir until completely dissolved, and react at 25 °C for 5 min; then add NaOH to adjust the pH value, stir while adding, and adjust the pH value to 5.0, and the wastewater becomes a white sol; carry out solid-liquid separation by filtration, and the separated wastewater enters the desilication reaction system; add MgSO 4 according to n(Mg):n(Si) = 1:5, and a total of 3.98 g / L of MgSO 4 is supplemented, adjust the pH to 8.5, the reaction temperature is 60 °C, the reaction process is accompanied by stirring, the stirring speed is 200 r / min, and the reaction time is 1 h to obtain a white suspension; carry out solid-liquid separation by filtration; the obtained sludge during the process is mixed and dehydrated for harmless disposal; the total phosphorus in the above-obtained filtrate is 2.84 mg / L and the silicon is 8.85 mg / L;

[0050] Sludge 1 mainly contains silicon. After dehydration, it is transported out for utilization;

[0051] Sludge 2 mainly contains phosphorus. After dehydration, it is treated as solid waste;

[0052] The sludge 3 mainly contains silicon, and after dehydration, it is treated as solid waste.

[0053] Example 2

[0054] Take the catalyst wastewater with a pH value of 0.94, total phosphorus of 10885 mg / L, and silicon of 22450 mg / L; perform sludge separation on the wastewater for 30 min to obtain waste liquid and sludge 1, and the waste liquid enters the subsequent wastewater treatment unit; add MgCl 2 to the waste liquid, with a dosage of 6 g / L, stir until completely dissolved, and react at 20 °C for 15 min; then add NaOH to adjust the pH value, stirring while adding, and adjust the pH value to 6.5, and the wastewater becomes a white sol state; perform solid-liquid separation by filtration, and the separated wastewater enters the silicon removal reaction system; add MgCl 2 in a ratio of n(Mg):n(Si) = 1:6, without additional supplementation of MgCl 2 , adjust the pH to 9, the reaction temperature is 60 °C, the reaction process is accompanied by stirring, the stirring speed is 300 r / min, and the reaction time is 1 h to obtain a white suspension. Perform solid-liquid separation by filtration; the sludge obtained during the process is mixed and dehydrated for harmless disposal. The total phosphorus in the above-mentioned obtained filtrate is 2.51 mg / L, and the silicon is 6.08 mg / L;

[0055] The sludge 1 mainly contains silicon, and after dehydration, it is transported out for utilization;

[0056] The sludge 2 mainly contains phosphorus, and after dehydration, it is treated as solid waste;

[0057] The sludge 3 mainly contains silicon, and after dehydration, it is treated as solid waste.

[0058] Example 3

[0059] Take the catalyst wastewater with a pH value of 0.94, total phosphorus of 10885 mg / L, and silicon of 22450 mg / L; perform sludge separation on the wastewater for 20 min to obtain waste liquid and sludge 1, and the waste liquid enters the subsequent wastewater treatment unit; add Mg(NO 3 ) 2 to the waste liquid, with a dosage of 7 g / L, stir until completely dissolved, and react at 35 °C for 20 min; then add NaOH to adjust the pH value, stirring while adding, and adjust the pH value to 7.0, and the wastewater becomes a white sol state; perform solid-liquid separation by filtration, and the separated wastewater enters the silicon removal reaction system; add Mg(NO 3 ) 2 in a ratio of n(Mg):n(Si) = 1:7, and a total of Mg(NO 3 ) 20.91 g / L, adjust the pH to 10.5, the reaction temperature is 65 °C, the reaction process is accompanied by stirring, the stirring speed is 400 r / min, the reaction time is 2 h, and a white suspension is obtained; solid-liquid separation is carried out by filtration; the sludge obtained during the process is mixed and dehydrated for harmless treatment. The total phosphorus in the above-mentioned obtained filtrate is 2.35 mg / L, and the silicon is 5.22 mg / L;

[0060] Sludge 1 mainly contains silicon, which is dehydrated and then transported out for utilization;

[0061] Sludge 2 mainly contains phosphorus, which is dehydrated and then treated as solid waste;

[0062] Sludge 3 mainly contains silicon, which is dehydrated and then treated as solid waste.

[0063] Example 4

[0064] Take catalyst wastewater with a pH value of 1.63, total phosphorus of 14750 mg / L, and silicon of 24800 mg / L. The wastewater is subjected to sludge separation for 30 min to obtain waste liquid and Sludge 1, and the waste liquid enters the subsequent wastewater treatment unit; add MgSO 4 to the waste liquid, the dosage is 5 g / L, stir until completely dissolved, and react at 25 °C for 30 min; then add NaOH to adjust the pH value, stir while adding, and adjust the pH value to 6.0, and the wastewater becomes a white sol state; solid-liquid separation is carried out by filtration, and the separated wastewater enters the silicon removal reaction system; add MgSO 4 according to n(Mg):n(Si)=1:6, and a total of 3.27 g / L of MgSO 4 is added, adjust the pH to 8.5, the reaction temperature is 60 °C, the reaction process is accompanied by stirring, the stirring speed is 200 r / min, the reaction time is 1 h, and a white suspension is obtained; solid-liquid separation is carried out by filtration; the sludge obtained during the process is mixed and dehydrated for harmless treatment. The total phosphorus in the above-mentioned obtained filtrate is 2.95 mg / L, and the silicon is 9.77 mg / L;

[0065] Sludge 1 mainly contains silicon, which is dehydrated and then transported out for utilization;

[0066] Sludge 2 mainly contains phosphorus, which is dehydrated and then treated as solid waste;

[0067] Sludge 3 mainly contains silicon, which is dehydrated and then treated as solid waste.

[0068] Example 5

[0069] Take the catalyst wastewater with a pH value of 1.63, a total phosphorus content of 14,750 mg / L, and a silicon content of 24,800 mg / L. The wastewater is subjected to sludge separation for 45 minutes to obtain the waste liquid and sludge 1. The waste liquid enters the subsequent wastewater treatment unit; MgCl 2 is added to the waste liquid at a dosage of 7 g / L and stirred until completely dissolved. The reaction is carried out at 26 °C for 30 minutes; then NaOH is added to adjust the pH value while stirring. The pH value is adjusted to 3.0, and the wastewater becomes a white sol. Solid-liquid separation is carried out by filtration. After separation, the wastewater enters the silicon removal reaction system; MgCl 2 is added according to n(Mg):n(Si) = 1:7, and no additional MgCl 2 is required. The pH is adjusted to 9.5, the reaction temperature is 62 °C, the reaction process is accompanied by stirring at a stirring speed of 300 r / min, and the reaction time is 1.5 h to obtain a white suspension; solid-liquid separation is carried out by filtration; the sludge obtained during the process is mixed and dehydrated for harmless disposal. The total phosphorus in the obtained filtrate is 2.66 mg / L, and the silicon is 8.20 mg / L.

[0070] Example 6

[0071] Take the catalyst wastewater with a pH value of 1.63, a total phosphorus content of 14,750 mg / L, and a silicon content of 24,800 mg / L. The wastewater is subjected to sludge separation for 15 minutes to obtain the waste liquid and sludge 1. The waste liquid enters the subsequent wastewater treatment unit; Mg(NO 3 ) 2 is added to the waste liquid at a dosage of 3 g / L and stirred until completely dissolved. The reaction is carried out at 26 °C for 30 minutes; then NaOH is added to adjust the pH value while stirring. The pH value is adjusted to 7.0, and the wastewater becomes a white sol; solid-liquid separation is carried out by filtration. After separation, the wastewater enters the silicon removal reaction system; Mg(NO 3 ) 2 is added according to n(Mg):n(Si) = 1:7, and a total of 5.74 g / L of additional Mg(NO 3 ) 2 is added. The pH is adjusted to 10.5, the reaction temperature is 65 °C, the reaction process is accompanied by stirring at a stirring speed of 400 r / min, and the reaction time is 2 h to obtain a white suspension; solid-liquid separation is carried out by filtration; the sludge obtained during the process is mixed and dehydrated for harmless disposal. The total phosphorus in the obtained filtrate is 2.73 mg / L, and the silicon is 6.38 mg / L.

[0072] Comparative Example 1

[0073] Take the catalyst wastewater with a pH value of 0.94, a total phosphorus content of 10885 mg / L, and a silicon content of 22450 mg / L. The wastewater is subjected to sludge separation for 30 min to obtain waste liquid and Sludge 1, and the waste liquid enters the subsequent wastewater treatment unit. Add MgSO 4 to the waste liquid at a dosage of 2 g / L, stir until completely dissolved, and react at 25 °C for 5 min; then add NaOH to adjust the pH value while stirring, and adjust the pH value to 5.0. The wastewater becomes a white sol state; perform solid-liquid separation by filtration. After separation, the wastewater enters the silicon removal reaction system; adjust the pH to 8.5, the reaction temperature to 60 °C, stir during the reaction process with a stirring speed of 200 r / min, and the reaction time is 1 h. Perform solid-liquid separation by filtration; the sludge obtained during the process is mixed and dehydrated for harmless treatment; the total phosphorus in the above-mentioned obtained filtrate is 765.15 mg / L, and the silicon is 1885.66 mg / L.

[0074] The difference between Comparative Example 1 and Example 1 is that the dosage of MgSO 4 is different.

[0075] Comparative Example 2

[0076] Take the catalyst wastewater with a pH value of 0.94, a total phosphorus content of 10885 mg / L, and a silicon content of 22450 mg / L. The wastewater is subjected to sludge separation for 30 min to obtain waste liquid and Sludge 1, and the waste liquid enters the subsequent wastewater treatment unit; add MgCl 2 to the waste liquid at a dosage of 6 g / L, stir until completely dissolved, and react at 20 °C for 15 min; then add NaOH to adjust the pH value while stirring, and adjust the pH value to 6.5. The wastewater becomes a white sol state; perform solid-liquid separation by filtration. After separation, the wastewater enters the silicon removal reaction system; adjust the pH to 11.0, the reaction temperature to 60 °C, stir during the reaction process with a stirring speed of 300 r / min, and the reaction time is 1 h. Perform solid-liquid separation by filtration; the sludge obtained during the process is mixed and dehydrated for harmless treatment; the total phosphorus in the above-mentioned obtained filtrate is 2.45 mg / L, and the silicon is 524.02 mg / L.

[0077] The difference between Comparative Example 2 and Example 2 is that after entering the silicon removal reaction system, the pH is adjusted to 11.0, exceeding the pH for silicon removal reaction, resulting in poor silicon removal effect.

[0078] Comparative Example 3

[0079] Take the catalyst wastewater with a pH value of 0.94, a total phosphorus content of 10885 mg / L, and a silicon content of 22450 mg / L; the wastewater is subjected to sludge separation for 20 min to obtain waste liquid and Sludge 1, and the waste liquid enters the subsequent wastewater treatment unit; add Mg(NO 3 ) 2, the dosage is 7 g / L, stir until completely dissolved, and react at 35 °C for 20 min; then add NaOH to adjust the pH value, stirring while adding, and adjust the pH value to 2.8, and the wastewater becomes a white sol state; perform solid-liquid separation by filtration, and the separated wastewater enters the silicon removal reaction system; add Mg(NO 3 ) 2 according to n(Mg):n(Si) = 1:7, and a total of 0.91 g / L of Mg(NO 3 ) 2 is added, adjust the pH to 10.5, the reaction temperature is 65 °C, stir during the reaction, the stirring speed is 400 r / min, and the reaction time is 2 h to obtain a white suspension; perform solid-liquid separation by filtration; the sludge obtained during the process is mixed and dehydrated for harmless treatment. The total phosphorus in the above-mentioned filtrate is 5469.88 mg / L, and the silicon is 6.56 mg / L;

[0080] The difference between Comparative Example 3 and Example 3 is that: when removing phosphorus, the pH is adjusted to 2.8, which is lower than the pH of the phosphorus removal reaction, and the phosphorus removal effect is not good.

[0081] Comparative Example 4

[0082] Take catalyst wastewater with a pH value of 1.63, a total phosphorus of 14750 mg / L, and a silicon of 24800 mg / L. The wastewater is subjected to sludge separation for 30 min to obtain waste liquid and sludge 1, and the waste liquid enters the subsequent wastewater treatment unit; add NaOH to the waste liquid to adjust the pH value, stirring while adding, but the pH can only be adjusted to 2.3, and a large amount of precipitation will occur when adding more NaOH, and it is impossible to stir; perform solid-liquid separation by filtration, and measure the phosphorus content in the filtrate; the total phosphorus in the above-mentioned filtrate is 8656.03 mg / L, and the silicon is 11296.210 mg / L.

[0083] The difference between Comparative Example 4 and Example 4 is that: no magnesium salt is added during phosphorus removal, so the pH can only be adjusted to 2.3, a large amount of precipitation appears, and subsequent operations cannot be carried out.

[0084] From the results of the above examples and comparative examples, it can be seen that the present invention can solve the problem of self-polymerization during the process of adding alkali to adjust the pH. By adding strong electrolyte salts, the salt effect is used to prevent the colloids from contacting, reducing the chance of collision and sedimentation, so that Al(OH) 2+ 、Al(OH) 2 + and AlO 2 -They exist in the form of monomers, thus preventing the colloid from rapidly self-polymerizing, enabling the pH of the strongly acidic high-concentration phosphorus-containing wastewater to be adjusted smoothly. And through adjusting the pH value and solid-liquid separation, the phosphorus in the wastewater is reduced to below 3 mg / L. At the same time, it provides a magnesium source for subsequent silicon removal from the wastewater. By reacting with the soluble silicon in the wastewater, magnesium silicate is generated, achieving efficient removal of high-concentration silicon. Avoiding adding silicon-removing agents again reduces the wastewater treatment and operation costs. After treating the ultra-high-concentration phosphorus- and silicon-containing catalyst wastewater with a phosphorus content of over 10,000 mg / L, the phosphorus content is reduced to below 3 mg / L, and the silicon content is reduced to below 10 mg / L, simultaneously achieving efficient phosphorus and silicon removal from the ultra-high phosphorus- and silicon-containing catalyst wastewater. At the same time, the sludge is dehydrated, reducing the external discharge volume and lowering the waste treatment cost.

Claims

1. Method for removing phosphorus and silicon from acidic catalyst wastewater, Characterized in that, The catalyst wastewater is subjected to solid-liquid separation, and the waste liquid enters the subsequent wastewater treatment unit. An electrolyte salt is added to the waste liquid and stirred until completely dissolved. Then an alkali is added to the waste liquid to adjust the pH until the waste liquid becomes sol-like. The sol-like waste liquid is subjected to solid-liquid separation to remove phosphorus in the wastewater. An alkali is added to the separated wastewater, and the pH and reaction temperature are adjusted to remove silicon in the wastewater. The up-to-standard wastewater is discharged after solid-liquid separation, and the separated sludge is harmlessly treated.

2. The method for removing phosphorus and silicon from acidic catalyst wastewater according to claim 1, Characterized in that, It is specifically implemented according to the following steps: (1) The wastewater is subjected to solid-liquid separation to obtain waste liquid and sludge 1; (2) An electrolyte magnesium salt is added to the waste liquid obtained in step (1), and stirred and homogenized and subjected to a polymerization inhibition reaction; (3) An alkali is added to the waste liquid after the polymerization inhibition reaction in step (2) to adjust the pH value of the waste liquid to obtain a sol-like waste liquid; (4) The sol-like waste liquid obtained in step (3) is subjected to solid-liquid separation to obtain sludge 2 and separated wastewater; (5) A magnesium salt is added to the separated wastewater obtained in step (4), and the reaction temperature and pH value are adjusted to react with silicon in the wastewater to obtain a white suspension for silicon removal; (6) After the silicon removal reaction, solid-liquid separation is carried out to obtain sludge 3 and treated wastewater; (7) The treated wastewater in step (6) is detected. After reaching the standard, the wastewater is discharged. If not up to the standard, it returns to step 2; (8) The sludge 1, sludge 2 and sludge 3 separated in steps (1), (4) and (6) are harmlessly treated.

3. The method for removing phosphorus and silicon from acidic catalyst wastewater according to claim 2, Characterized in that, In step 1, the solid-liquid separation is carried out by centrifugation or pressure filtration, and the centrifugation or pressure filtration time is 15 min to 45 min.

4. The method for removing phosphorus and silicon from acidic catalyst wastewater according to claim 2, Characterized in that, In step 2, the electrolyte magnesium salt is MgCl 2 , MgSO 4 and Mg(NO 3 ) 2 at least one of them, preferably MgSO 4 ; the addition amount of the electrolyte magnesium salt is 3 g / L to 7 g / L; the temperature of the inhibition polymerization reaction is 20 °C to 35 °C, and the reaction time is 5 min to 30 min.

5. The method for removing phosphorus and silicon from acidic catalyst wastewater according to claim 2, Characterized in that, In step 3, the pH is adjusted by adding an alkaline compound and adjusting the pH to 3 to 7; the alkaline compound is an alkali or an alkaline salt; the alkaline compound is at least one of an inorganic base and an organic base; specifically at least one of sodium hydroxide, potassium hydroxide, and N-methyldiethanolamine.

6. The method for removing phosphorus and silicon from acidic catalyst wastewater according to claim 2, Characterized in that, In step 4, the solid-liquid separation method is at least one of natural sedimentation, centrifugation, and pressure filtration.

7. The method for removing phosphorus and silicon from acidic catalyst wastewater according to claim 2, Characterized in that, In step 5, the magnesium salt is added according to n(Mg):n(Si)=1:5 to 7, the pH is adjusted to 8.5 to 10.5, the reaction temperature is 60 to 65 °C, the reaction process is accompanied by stirring, the stirring speed is 200 to 400 r / min, and the reaction time is 1 to 2 h to obtain a white suspension.

8. The method for removing phosphorus and silicon from acidic catalyst wastewater according to claim 2, Characterized in that, The solid-liquid separation method in the step 6 is at least one of natural sedimentation, centrifugation, and pressure filtration.

9. The method for removing phosphorus and silicon from acidic catalyst wastewater according to claim 2, characterized in that the detection standard in the step 7 is that the total phosphorus in the wastewater is reduced to below 3 mg / L and the silicon is reduced to below 10 mg / L.

10. The method for removing phosphorus and silicon from acidic catalyst wastewater according to claim 2, characterized in that the specific operation of the sludge harmless treatment in the step 8 is as follows: (1) The sludge 1 mainly contains silicon, and after dehydration, it is transported out for utilization; (2) The sludge 2 mainly contains phosphorus, and after dehydration, it is treated as solid waste; (3) The sludge 3 mainly contains silicon, and after dehydration, it is treated as solid waste.

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