A dual functional composite preparation for rapid deep removal of calcium ions and simultaneous pH adjustment

Abstract

The application discloses a kind of dual-function composite preparation of fast depth calcium ion removal and synchronous pH adjustment, belongs to sewage treatment preparation field.The novel dual-function composite preparation provided by the application utilizes the high concentration Ca 2+ In-situ induced crystallization and the buffering property of oxalic acid and phosphate, has the ability of fast depth removal Ca 2+ And pH adjustment;Dual-function composite preparation is put into the pressure filter liquid of water Ca 2+ Concentration 1800mg / L and pH=12.4, after standing and precipitating 30min, effluent Ca 2+ Concentration is less than 1000mg / L, and pH is less than 9.

Description

TECHNICAL FIELD

[0001] The present application relates to a dual-function composite preparation for rapid and deep removal of calcium ions and simultaneous pH adjustment, belonging to the field of sewage treatment preparations. BACKGROUND

[0002] The sludge treatment method in sewage treatment plants is mainly pressure filtration dewatering, and the moisture content of sludge after plate and frame pressure filtration dewatering is generally between 60-80%. In order to ensure the effect of plate and frame dewatering, iron salt and calcium salt dewatering preparations are needed, mainly "FeCl3+CaO". Iron salt and calcium salt dewatering preparations have the advantages of low cost, wide application range, simple operation, high dewatering efficiency and rate, obvious reduction effect, etc. Due to the addition of a large amount of CaO, the pressure filtrate produced by plate and frame dewatering also shows the characteristics of high pH, high Ca 2 + , high COD, high ammonia nitrogen, etc. If the complex composition of sludge pressure filtrate is not properly treated, it will cause serious secondary pollution to the environment.

[0003] In view of the problem of high Ca 2+ in the pressure filtrate, the chemical precipitation method is generally used at present, that is, CaCO3 is generated by adding Na2CO3 to remove Ca 2+ , but the cost of calcium removal is high and the effect is poor, and the Ca 2+ concentration is only reduced from 1800 mg / L to 1500 mg / L. Because the concentrations of Ca ions and carbonate ions in the pressure filtrate are uniform, CaCO3 nucleates uniformly, grows rapidly, and forms a large amount of CaCO3 precipitates at the micro-nano level. The settling velocity of these small CaCO3 precipitate particles is slow, which seriously restricts the hydraulic load of the calcium removal process section. The high Ca 2+ concentration of the effluent will cause serious scaling of the subsequent sewage treatment pipeline and facilities, which requires increased cleaning frequency, not only limiting the treatment capacity of the sewage treatment process, but also further increasing the operating cost. Therefore, how to quickly and deeply remove Ca 2+ has become an urgent problem to be solved in the field of sludge pressure filtrate treatment.

[0004] In addition, the pH of the pressure filtrate is generally about 12, which not only corrodes the pipeline, but also affects the microbial activity, and cannot be directly introduced into the biochemical treatment unit. Therefore, in the pressure filtrate treatment process, a pH adjustment tank needs to be added to adjust the pH to below 9 by adding sulfuric acid or hydrochloric acid before entering the biochemical unit. However, part of the undissolved CaCO3 precipitate will enter the pH adjustment tank, and the local pH reduction during the acid addition and pH adjustment process will cause the dissolution of CaCO3 and the release of Ca 2+The ions can significantly increase the total dissolved solids (TDS) index of sewage. The pH of the commonly used calcium removal agent Na2CO3 solution is also about 12, and the pH of the filter press filtrate does not change significantly before and after calcium removal.

[0005] Therefore, whether the pH can be adjusted synchronously has become a new direction for the development of calcium removal agents. It is urgent to develop a calcium removal agent that can quickly and deeply remove Ca 2+ The new dual-functional agent for synchronous pH adjustment can effectively solve the problems of high Ca 2+ and high pH in the sludge filter press filtrate. SUMMARY

[0006] [Technical problem]

[0007] The calcium removal of sludge filter press filtrate mainly relies on chemical precipitation, that is, CaCO3 is precipitated by using Na2CO3. However, the CaCO3 precipitate has slow settling speed, poor calcium removal effect and high cost;

[0008] During the adjustment of the sludge filter press filtrate with high pH, the local pH reduction can cause the dissolution of CaCO3, which not only increases the water treatment cost, but also introduces anions and dissolved Ca 2+ ions, which can significantly increase the total dissolved solids (TDS) index of sewage.

[0009] [Technical solution]

[0010] In order to effectively solve the problems of high Ca 2+ and high pH in the sludge filter press filtrate, the present application develops a new composite agent with the dual functions of “quickly and deeply removing Ca 2+ and adjusting pH”.

[0011] The first object of the present application is to provide a method for preparing a dual-functional composite agent for removing calcium ions and adjusting pH, comprising the steps of:

[0012] (1) adding a polyacrylamide coagulant solution to a calcium chloride solution, stirring, adding diatomite, and standing; after standing, filtering, washing, drying, and grinding, a calcium ion-rich adsorbent powder is obtained;

[0013] (2) mixing the calcium ion-rich adsorbent powder, sodium carbonate, sodium hydrogen phosphate, and oxalic acid to prepare a dual-functional composite agent for removing calcium ions and adjusting pH.

[0014] In an embodiment, the concentration of the calcium chloride solution in step (1) is 0.1%~10%w / w;

[0015] Alternatively, the concentration of the calcium chloride solution is 1%~8%w / w;

[0016] Alternatively, the concentration of the calcium chloride solution is 4%~6%w / w.

[0017] In one embodiment, the concentration of the polyacrylamide coagulant aid solution in step (1) is 0.001% to 0.1% w / w;

[0018] Optionally, the concentration of the polyacrylamide coagulant aid solution is 0.01% to 0.1% w / w;

[0019] Optionally, the concentration of the polyacrylamide coagulant aid solution is 0.01% to 0.05% w / w.

[0020] In one embodiment, the ratio of the amount of calcium chloride solution, polyacrylamide coagulant aid solution and diatomite in step (1) is 500 to 1500 mL: 1 to 10 mL: 10 to 50 g;

[0021] Optionally, the ratio of the amount of calcium chloride solution, polyacrylamide coagulant aid solution and diatomite is 800 to 1200 mL: 3 to 8 mL: 15 to 30 g.

[0022] In one embodiment, the mass ratio of the calcium ion-rich adsorbent powder, sodium carbonate, sodium hydrogen phosphate and oxalic acid in step (2) is 1: 50 to 90: 5 to 25: 5 to 25.

[0023] The second object of the present application is to provide a dual-function composite preparation for simultaneously removing calcium ions and adjusting pH, prepared by any of the above-mentioned methods.

[0024] The third object of the present application is to provide the use of any of the above-mentioned methods or the above-mentioned dual-function composite preparation for simultaneously removing calcium ions and adjusting pH in the field of environment.

[0025] In one embodiment, the use in the field of environment includes reducing metal ions, adjusting pH, reducing total dissolved solids.

[0026] The fourth object of the present application is to provide a scale remover prepared from the above-mentioned dual-function composite preparation for simultaneously removing calcium ions and adjusting pH.

[0027] The fifth object of the present application is to provide a method for simultaneously improving the removal effect of calcium ions and total dissolved solids in wastewater and adjusting the pH of the wastewater, using the dual-function composite preparation of claim 6, the steps being as follows:

[0028] Mixing the dual-function composite preparation solution with wastewater at a volume ratio of 15 to 25: 500, and precipitating;

[0029] Optionally, the concentration of the dual-function composite preparation solution is 5 to 10% w / w.

[0030] [Beneficial effects]

[0031] (1)Simultaneously solve the problem of high Ca 2+ and high pH of sludge filter liquor:

[0032] The new type of bifunctional composite preparation provided by the application utilizes the high concentration of Ca 2+ on the surface of the calcium-rich ion adsorbent powder to induce crystallization in situ and the buffering property of oxalate and phosphate, has the ability to quickly and deeply remove Ca 2+ and adjust pH; when the bifunctional composite preparation is put into the filter liquor with a Ca 2+ concentration of 1800 mg / L and a pH of 12.4, after standing and precipitating for 30 min, the Ca 2+ concentration of the effluent is less than 1000 mg / L, and the pH is less than 9.

[0033] (2) The operation technical process is simple:

[0034] The new type of bifunctional composite preparation used in the application can simultaneously adjust pH, and no pH adjusting tank is needed in the process of treating sewage and waste water; compared with the comparative group using sodium carbonate, the pH of the filter liquor almost does not change before and after calcium removal by sodium carbonate, and acid needs to be added to reduce the pH to 9 so as to enter the biochemical tank, while the method of the application avoids this problem.

[0035] (3) Environment-friendly and economic benefits:

[0036] Compared with the reported sodium carbonate, the new type of bifunctional composite preparation used in the application can effectively reduce the total dissolved solids (TDS) index of the filter liquor, the product is helpful for green and low-carbon treatment of sewage and waste water, has significant environmental protection significance, and is suitable for large-scale promotion. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is a photo of the bifunctional composite preparation A in Example 1.

[0038] Figure 2 It is the calcium removal effect of the bifunctional composite preparation A in Example 2 and sodium carbonate in Comparative Example 1.

[0039] Figure 3 It is the pH adjustment effect of the bifunctional composite preparation A in Example 2 and sodium carbonate in Comparative Example 1.

[0040] Figure 4 It is the TDS removal effect of the bifunctional composite preparation A in Example 2 and sodium carbonate in Comparative Example 1.

[0041] Figure 5 It is the calcium removal and pH adjustment effect of the bifunctional composite preparations A, B and C in Examples 1, 3 and 4. DETAILED DESCRIPTION

[0042] The following describes the preferred embodiments of the present application, and it should be understood that the embodiments are for better explaining the present application and are not intended to limit the present application.

[0043] Test method:

[0044] pH test:

[0045] SL1000 / 250 portable multi-parameter water quality analyzer, purchased from the United States Hashi Instrument Co.

[0046] Calcium ion determination:

[0047] Determination according to the national standard "Determination of calcium in water EDTA titration method" (GB 7476-87).

[0048] Determination of total dissolved solids (TDS):

[0049] Determination according to the national standard "Determination of total dissolved solids in water Standard test method for drinking water" (GBT5750.4-20068.1) weighing method.

[0050] Raw materials used in the examples:

[0051] Calcium chloride: analytical pure, commercially available.

[0052] Sodium carbonate: analytical pure, commercially available.

[0053] Sodium hydrogen phosphate: analytical pure, commercially available.

[0054] Oxalic acid: analytical pure, commercially available.

[0055] Polyacrylamide (PAM): 2 million molecular weight, commercially available.

[0056] Diatomite: SiO2 content > 85%, commercially available.

[0057] The solutions involved in the examples and comparative examples are water as the solvent if the solvent is not specified, and the % is mass percentage w / w if the meaning is not specified.

[0058] Example 1

[0059] A dual-function composite preparation for quickly and deeply removing calcium ions and simultaneously adjusting pH, the preparation steps are as follows:

[0060] (1) Prepare 1L of 5% calcium chloride solution, add 5mL of 0.02% PAM coagulant solution to it, stir for 5min, then continue to add 20g of diatomite, stand for 1h for adsorption, then filter, wash with water, dry at 60℃ for 12h, grind and pass through an 80 mesh screen to obtain a calcium ion-rich adsorbent powder;

[0061] (2) 1 g of calcium ion-rich adsorbent powder, 50 g of sodium carbonate, 25 g of sodium hydrogen phosphate, and 25 g of oxalic acid were mixed thoroughly, ground, and passed through an 80-mesh sieve to obtain a dual-function composite preparation, which was named Composite Preparation A.

[0062] The appearance of compound medicine A is as follows Figure 1 shown.

[0063] Example 2

[0064] A sewage treatment method for rapid and deep removal of calcium ions and simultaneous pH adjustment is provided, using the dual-functional composite preparation A prepared in Example 1, and the steps are as follows:

[0065] Weigh 5 g of compound preparation A, add 95 mL of water to prepare a 5% preparation A solution; take 15 mL, 20 mL and 25 mL of 5% preparation A solution, respectively, add 500 mL of press filtrate wastewater with a calcium ion concentration of 1800 mg / L and a pH of 12.4, let it stand and settle for 30 minutes, take the supernatant, and monitor the effluent pH, calcium ion concentration and total dissolved solids (TDS).

[0066] The test results are as follows Figure 2 、 Figure 3 、 Figure 4 shown.

[0067] Outlet pH, calcium ion concentration, etc. Figure 2 、 Figure 3 As shown, the results show that for the influent Ca 2+ The concentration of the filtrate was 1800 mg / L and the pH was 12.4. When the dosage of the preparation A solution was 15 mL, 20 mL and 25 mL, the effluent Ca 2+ The concentrations were 987 mg / L, 875 mg / L and 633 mg / L, respectively, and the effluent pH was 11.91, 10.44 and 8.33, respectively, achieving rapid and deep removal of calcium ions and synchronous regulation of pH.

[0068] Total dissolved solids (TDS) such as Figure 4 As shown, the results show that for the influent Ca 2+ The filtrate had a concentration of 1800 mg / L and a pH of 12.4, and the inlet total dissolved solids (TDS) was 8048 mg / L. When the dosage of Preparation A solution was 15 mL, 20 mL, and 25 mL, the outlet total dissolved solids (TDS) were 6674 mg / L, 5862 mg / L, and 5698 mg / L, respectively, significantly reducing the total dissolved solids (TDS).

[0069] Comparative Example 1

[0070] The press filtrate treatment experiment was carried out using commercial sodium carbonate as a decalcification agent, as follows:

[0071] Take 5g of sodium carbonate preparation, add 95mL of water, and prepare a 5% sodium carbonate solution; take 25mL of the 5% sodium carbonate solution and add it to 500mL of press filtrate sewage with a calcium ion concentration of 1800mg / L and pH=12.4, let it stand for 30min, then take the supernatant, and monitor the effluent pH, calcium ion concentration, and total dissolved solids (TDS).

[0072] The test results are shown in Table 1. Figures 2 to 4 As shown in Table 1, when the calcium ion concentration of the press filtrate is 1800mg / L and the pH is 12.4, and the sodium carbonate preparation dosage is 25mL, the effluent calcium ion concentration is 1495mg / L, the effluent pH is 12.31, and the effluent total dissolved solids (TDS) is 7870mg / L. 2+ 2+ The test results are shown in Table 1.

[0073] Comparative Example 2

[0074] On the basis of Example 1, replace the diatomite in step (1) with activated carbon, and the remaining steps are consistent with Example 1, to prepare a composite preparation.

[0075] Comparative Example 3

[0076] On the basis of Example 1, omit the PAM coagulant solution in step (1), and the remaining steps are consistent with Example 1, to prepare a composite preparation.

[0077] Comparative Example 4

[0078] On the basis of Example 1, replace the PAM in step (1) with sodium alginate, and the remaining steps are consistent with Example 1, to prepare a composite preparation.

[0079] Comparative Example 5

[0080] On the basis of Example 1, replace the 1g of calcium ion-rich adsorbent powder in step (2) with 1g of diatomite, and the remaining steps are consistent with Example 1, to prepare a composite preparation.

[0081] Take the composite preparations prepared in Comparative Examples 2-5, and according to the method of Comparative Example 1, test the effluent pH, calcium ion concentration, and total dissolved solids (TDS) of 25mL of 5% composite preparation solution on press filtrate with a calcium ion concentration of 1800mg / L and pH=12.4. 2+

[0082] The results show that when the dosage of the composite preparation of Comparative Example 2 is 25mL, the effluent calcium ion concentration is 895mg / L, the effluent pH is 8.78, and the effluent total dissolved solids (TDS) is 6284mg / L, which is poorer than the composite preparation A of Example 1 in terms of calcium removal, pH adjustment, and TDS removal performance. 2+ ​​​

[0083] When the dosage of the composite preparation of Comparative Example 3 was 25 mL, the effluent Ca 2+ The concentration was 1032 mg / L, the effluent pH was 9.02, the effluent total dissolved solids (TDS) was 6858 mg / L, and the calcium removal, pH adjustment and TDS removal performances were poorer than those of the composite preparation A of Example 1.

[0084] When the dosage of the composite preparation of Comparative Example 4 was 25 mL, the effluent Ca 2+ The concentration was 823 mg / L, the effluent pH was 8.65, the effluent total dissolved solids (TDS) was 5720 mg / L, and the calcium removal, pH adjustment and TDS removal performances were poorer than those of the composite preparation A of Example 1.

[0085] When the dosage of the composite preparation of Comparative Example 5 was 25 mL, the effluent Ca 2+ The concentration was 1205 mg / L, the effluent pH was 9.32, the effluent total dissolved solids (TDS) was 7751 mg / L, and the calcium removal, pH adjustment and TDS removal performances were poorer than those of the composite preparation A of Example 1.

[0086] Example 3

[0087] On the basis of Example 1, the formula of step (2) was changed to 1 g of calcium ion-rich adsorbent powder, 70 g of sodium carbonate, 15 g of sodium hydrogen phosphate and 15 g of oxalic acid, and the remaining steps were consistent with those of Example 1, to prepare a dual-functional composite preparation, which was named as composite preparation B.

[0088] Example 4

[0089] On the basis of Example 1, the formula of step (2) was changed to 1 g of calcium ion-rich adsorbent powder, 90 g of sodium carbonate, 5 g of sodium hydrogen phosphate and 5 g of oxalic acid, and the remaining steps were consistent with those of Example 1, to prepare a dual-functional composite preparation, which was named as composite preparation C.

[0090] The composite preparations B and C prepared in Examples 3 and 4 were detected for the ion removal effect of Ca 2+ The concentration of the pressure filter liquid calcium was 1800 mg / L and the pH was 12.4, and the results are shown in Table 2. Figure 5

[0091] The results showed that the effluent Ca 2+ The concentrations were 770 mg / L and 872 mg / L, respectively, and the effluent pHs were 9.29 and 10.31, respectively, which indicated that the rapid and deep removal of calcium ions and the simultaneous adjustment of pH were achieved.

[0092] ​Although the present application has been disclosed in its preferred embodiments with reference to the accompanying drawings, it is not intended to limit the present application thereto, and various modifications and alterations can be made thereto by those skilled in the art without departing from the spirit and scope of the present application, and the scope of protection of the present application should be defined by the appended claims.

Claims

1. A method of preparing a bifunctional complex formulation for simultaneous removal of calcium ions and pH adjustment, characterized by, The method comprises the steps of: (1) adding a polyacrylamide coagulant solution to a calcium chloride solution, stirring, adding diatomite, and standing; after standing, filtering, washing, drying, and grinding to obtain a calcium ion-rich adsorbent powder; (2) mixing the calcium ion-rich adsorbent powder, sodium carbonate, sodium hydrogen phosphate, and oxalic acid to obtain a dual-function composite preparation for simultaneously removing calcium ions and adjusting pH.

2. The method of claim 1, wherein, The concentration of the calcium chloride solution in step (1) is 0.1%-10% w / w.

3. The method of claim 2, wherein, The concentration of the calcium chloride solution is 1%-8% w / w.

4. The method of claim 3, wherein, The concentration of the calcium chloride solution is 4%-6% w / w.

5. The method of claim 1, wherein, The concentration of the polyacrylamide coagulant solution in step (1) is 0.001%-0.1% w / w.

6. The method of claim 5, wherein, The concentration of the polyacrylamide coagulant solution is 0.01%-0.1% w / w.

7. The method of claim 6, wherein, The concentration of the polyacrylamide coagulant solution is 0.01%-0.05% w / w.

8. The method of claim 1, wherein, The ratio of the amount of the calcium chloride solution, the polyacrylamide coagulant solution, and the diatomite in step (1) is 500-1500 mL: 1-10 mL: 10-50 g.

9. The method of claim 8, wherein, The ratio of the amount of the calcium chloride solution, the polyacrylamide coagulant solution, and the diatomite is 800-1200 mL: 3-8 mL: 15-30 g.

10. The method of claim 1, wherein, The mass ratio of the calcium ion-rich adsorbent powder, sodium carbonate, sodium hydrogen phosphate, and oxalic acid in step (2) is 1: 50-90: 5-25: 5-25.

11. The dual-function composite preparation for simultaneously removing calcium ions and adjusting pH prepared by the method of any one of claims 1-10.

12. A method for simultaneously improving the removal of calcium ions and total dissolved solids and adjusting the pH of wastewater, characterized by, The dual-function composite preparation of claim 11 is used as follows: The dual-function composite preparation solution is mixed with sewage at a volume ratio of 15-25: 500 to precipitate.

13. The method of claim 12, wherein, The concentration of the dual-function composite preparation solution is 5-10% w / w.

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