Difunctional compound preparation for rapidly and deeply removing calcium ions and synchronously adjusting pH

Abstract

The invention discloses a difunctional composite preparation capable of rapidly and deeply removing calcium ions and synchronously adjusting pH, and belongs to the field of sewage treatment preparations. The novel bifunctional composite preparation provided by the invention has the capability of rapidly and deeply removing Ca < 2 + > and adjusting pH by utilizing high-concentration Ca < 2 + > in-situ induced crystallization on the surface of the calcium ion-rich adsorbent powder and the buffering property of oxalic acid and phosphate radicals; the bifunctional composite preparation is put into a pressure filtrate with the influent Ca < 2 + > concentration of 1800 mg / L and the pH value of 12.4, and after static settlement is performed for 30 min, the effluent Ca < 2 + > concentration is lower than 1000 mg / L, and the pH value is lower than 9.

Description

Technical Field

[0001] The invention relates to a dual-function composite preparation for rapidly and deeply removing calcium ions and synchronously adjusting pH, belonging to the field of sewage treatment preparations. Background Art

[0002] The main method of sludge treatment in sewage treatment plants is filter press dehydration. The moisture content of sludge after plate and frame filter press dehydration is generally between 60% and 80%. In order to ensure the effect of plate and frame dehydration, it is necessary to add iron salt and calcium salt dehydration agents, mainly "FeCl 3 +CaO". Iron salt and calcium salt dehydration preparations have the advantages of low cost, wide application range, simple operation, high dehydration efficiency and rate, and obvious reduction effect. Due to the addition of a large amount of CaO, the filtrate produced by plate and frame dehydration also shows high pH and high Ca 2 + , high COD, high ammonia nitrogen and other significant characteristics. If the sludge filtrate with complex components is not properly handled, it will cause serious secondary pollution to the environment.

[0003] For high Ca in filtrate 2+ Problem, currently the chemical precipitation method is generally used, that is, adding Na 2 CO 3 Produces CaCO 3 It can be removed by precipitation, but the cost of calcium removal is high and the effect is poor. 2+ The concentration only dropped from 1800 mg / L to 1500 mg / L. Because the concentration of Ca ions and carbonate ions in the filtrate is evenly distributed, CaCO 3 Uniform nucleation and rapid growth to form a large number of micro-nanoscale CaCO 3 These smaller CaCO 3 The sedimentation speed of the precipitated particles is slow, which seriously restricts the hydraulic load of the decalcification process. 2+ The concentration will cause serious scaling of subsequent sewage treatment pipes and facilities, which requires increased cleaning frequency, which not only limits the treatment capacity of the sewage treatment process, but also further increases the operating cost. 2+ It has become an urgent problem that needs to be solved in the field of sludge filtrate treatment.

[0004] In addition, the pH of the filtrate is generally around 12, which will not only corrode the pipeline, but also affect the activity of microorganisms, and cannot directly enter the biochemical treatment unit. Therefore, during the filtrate treatment process, it is necessary to add a pH adjustment tank, add sulfuric acid or hydrochloric acid, and adjust the pH to below 9 before entering the biochemical unit. However, some unsettled CaCO 3 The precipitate will enter the pH adjustment tank. During the process of adding acid to adjust the pH, the local pH decrease will cause CaCO 3 Dissolves and releases Ca2+ ions. What is more noteworthy is that the acid addition process itself will increase a lot of treatment costs, while the anions introduced and dissolved Ca 2+ Ions will significantly increase the total dissolved solids (TDS) index of sewage. Currently commonly used decalcification agents Na 2 CO 3 The pH of the solution was also around 12, and there was no significant change in the pH of the filtrate before and after calcium removal.

[0005] Therefore, whether the pH can be adjusted simultaneously has become a new direction in the development of calcium removal preparations. It is urgent to develop a product that can quickly and deeply remove Ca 2+ A new dual-function agent that simultaneously adjusts pH to effectively solve the high Ca content of sludge press filtrate 2+ and high pH issues. Summary of the invention

[0006] [Technical issues]

[0007] The main method for removing calcium from sludge filtrate is chemical precipitation, which uses Na 2 CO 3 Produces CaCO 3 Precipitation, but CaCO 3 The sedimentation is slow, the calcium removal effect is poor and the cost is high;

[0008] During the high pH sludge press conditioning process, local pH reduction can lead to CaCO 3 dissolution, which not only increases the cost of water treatment, but also introduces anions and dissolved Ca 2+ Ions can significantly increase the total dissolved solids (TDS) content of wastewater.

[0009] [Technical solution]

[0010] In order to effectively solve the high Ca content of sludge filtrate 2+ and high pH problem, the present invention has developed a method with "fast and deep removal of Ca 2+ A novel compound preparation with dual functions of "purification and pH adjustment".

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

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

[0013] (2) Calcium ion-rich adsorbent powder, sodium carbonate, sodium hydrogen phosphate and oxalic acid are mixed to prepare a dual-functional composite preparation that simultaneously removes calcium ions and adjusts pH.

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

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

[0016] Optionally, the concentration of the calcium chloride solution is 4% to 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 calcium chloride solution, polyacrylamide coagulant aid solution and diatomaceous earth in step (1) is 500-1500 mL: 1-10 mL: 10-50 g;

[0021] Optionally, the usage ratio of calcium chloride solution, polyacrylamide coagulant aid solution and diatomaceous earth is 800-1200 mL: 3-8 mL: 15-30 g.

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

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

[0024] The third object of the present invention is to provide the application of any of the above methods or the above dual-functional composite preparations for simultaneously removing calcium ions and adjusting pH in the environmental field.

[0025] In one embodiment, applications in the environmental field include reduction of metal ions, adjustment of pH, and reduction of total dissolved solids.

[0026] The fourth object of the present invention is to provide a descaling agent prepared from the above-mentioned dual-functional composite preparation for simultaneously removing calcium ions and adjusting pH.

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

[0028] The dual-functional composite preparation solution and sewage are mixed in a volume ratio of 15 to 25:500 and precipitated;

[0029] Optionally, the concentration of the dual-functional composite formulation solution is 5-10% w / w.

[0030] [Beneficial Effects]

[0031] (1) It also solves the problem of high Ca in sludge filtrate 2+ And the high pH problem:

[0032] The novel dual-function composite preparation provided by the present invention utilizes the high concentration of Ca on the surface of the calcium ion-rich adsorbent powder to 2+ In-situ induced crystallization and buffering of oxalic acid and phosphate can rapidly remove Ca 2+ and pH adjustment capability; the dual-functional compound preparation is added to the influent Ca 2+ The filtrate with a concentration of 1800 mg / L and a pH of 12.4 was allowed to settle for 30 minutes and the effluent Ca 2+ The concentration is lower than 1000 mg / L and the pH is lower than 9.

[0033] (2) Simple operation and technical process:

[0034] The novel dual-functional composite preparation used in the present invention can adjust pH simultaneously, and there is no need to add a pH adjustment tank during the treatment of sewage and wastewater; compared with the control group using sodium carbonate, the pH of the filtrate almost changes before and after sodium carbonate decalcification, and acid needs to be added to reduce the pH to 9 before entering the biochemical pool, while the method of the present invention avoids this problem.

[0035] (3) Environmentally friendly and economically beneficial:

[0036] Compared with the reported sodium carbonate, the novel dual-functional composite preparation used in the present invention can effectively reduce the total dissolved solids (TDS) index of the filtrate. The product helps to carry out green and low-carbon treatment of sewage and wastewater, has significant environmental protection significance, and is suitable for large-scale promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a photo of the dual-functional composite formulation A in Example 1.

[0038] Figure 2 The calcium removal effect of the dual-functional composite preparation A in Example 2 and the sodium carbonate in Comparative Example 1.

[0039] Figure 3 The pH adjustment effect of the dual-functional composite preparation A in Example 2 and the sodium carbonate in Comparative Example 1.

[0040] Figure 4The TDS removal effect of the dual-functional composite preparation A in Example 2 and the sodium carbonate in Comparative Example 1.

[0041] Figure 5 The calcium removal and pH adjustment effects of the dual-functional composite preparations A, B and C in Examples 1, 3 and 4 are shown. DETAILED DESCRIPTION

[0042] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explaining the present invention and are not used to limit the present invention.

[0043] Test method:

[0044] pH Test:

[0045] SL1000 / 250 portable multi-parameter water quality analyzer was purchased from Hach Instruments, USA.

[0046] Calcium ion determination:

[0047] The determination was carried out according to the national standard “Determination of calcium in water - EDTA titration method” (GB 7476-87).

[0048] Total dissolved solids (TDS) determination:

[0049] The determination is carried out according to the weighing method in accordance with the national standard "Water quality - Determination of total dissolved solids - Standard test method for drinking water" (GBT5750.4-20068.1).

[0050] The raw materials used in the examples are:

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

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

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

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

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

[0056] Diatomaceous earth: SiO 2 Content>85%, commercially available.

[0057] The solutions involved in the embodiments and comparative examples without specifying the solvent are water as the solvent, and the % involved without specifying the meaning refers to the mass percentage w / w.

[0058] Example 1

[0059] A dual-functional composite preparation for rapid and deep removal of calcium ions and simultaneous pH regulation, the preparation steps are as follows:

[0060] (1) Prepare 1L of 5% calcium chloride solution, add 5mL of 0.02% PAM coagulant solution dropwise thereto, stir for 5 minutes, then continue to add 20g of diatomaceous earth, let it stand for adsorption for 1 hour, filter it, wash it with clean water, dry it at 60°C for 12 hours, grind it and pass it through an 80-mesh sieve 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-functional 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 rapidly and deeply removing calcium ions and simultaneously adjusting pH, using the bifunctional composite preparation A prepared in Example 1, the steps are as follows:

[0065] Weigh 5 g of composite 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, add them into 500 mL of filtrate wastewater with a calcium ion concentration of 1800 mg / L and pH = 12.4, respectively, 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 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) 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 soluble solids TDS was 8048 mg / L. When the dosage of the preparation A solution was 15 mL, 20 mL, and 25 mL, the outlet total soluble solids TDS were 6674 mg / L, 5862 mg / L, and 5698 mg / L, respectively, which significantly reduced the total soluble solids TDS.

[0069] Comparative Example 1

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

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

[0072] Test results such as Figure 2 to Figure 4 As shown, 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 sodium carbonate preparation was 25 mL, the effluent Ca 2+ The concentration is 1495 mg / L, the effluent pH is 12.31, and the effluent total dissolved solids TDS is 7870 mg / L.

[0073] Comparative Example 2

[0074] On the basis of Example 1, the diatomaceous earth in step (1) was replaced by activated carbon, and the remaining steps were consistent with Example 1 to prepare a composite preparation.

[0075] Comparative Example 3

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

[0077] Comparative Example 4

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

[0079] Comparative Example 5

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

[0081] The composite preparations prepared in Comparative Examples 2 to 5 were used to test the Ca 2+ The effluent pH, calcium ion concentration and total dissolved solids (TDS) of the filtrate with a concentration of 1800 mg / L and pH = 12.4.

[0082] The results show that when the dosage of the composite preparation in comparative example 2 is 25 mL, the effluent Ca 2+ The concentration is 895 mg / L, the effluent pH is 8.78, the effluent total dissolved solids TDS is 6284 mg / L, and the calcium removal, pH adjustment and TDS removal performance are worse than those of the composite formulation A in Example 1.

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

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

[0085] When the dosage of the composite preparation of Comparative Example 5 was 25 mL, the effluent Ca 2+ The concentration is 1205 mg / L, the effluent pH is 9.32, and the effluent total dissolved solids TDS is 7751 mg / L. The calcium removal, pH adjustment and TDS removal performances are worse than those of the composite formulation A in 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 Example 1 to prepare a dual-functional composite preparation, which was named 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 Example 1 to prepare a dual-functional composite preparation, which was named Composite Preparation C.

[0090] The compound preparations B and C prepared in Examples 3 and 4 were taken, and the Ca content of 25 mL of 5% solution of preparations B and C was tested according to the method of Example 2. 2+ The results of the calcium ion removal effect and pH change of the filtrate with a concentration of 1800 mg / L and a pH of 12.4 are as follows: Figure 5 shown.

[0091] The results showed that the effluent Ca 2+ The concentrations were 770 mg / L and 872 mg / L respectively, and the effluent pH was 9.29 and 10.31 respectively. It can be seen that the rapid and deep removal of calcium ions and the synchronous regulation of pH were achieved.

[0092] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for preparing a dual-functional composite preparation for simultaneously removing calcium ions and adjusting pH, characterized in that: Includes steps: (1) adding a polyacrylamide coagulant solution to a calcium chloride solution, stirring, adding diatomaceous earth, and standing; after standing, filtering, washing, drying, and grinding to obtain a calcium ion-rich adsorbent powder; (2) Calcium ion-rich adsorbent powder, sodium carbonate, sodium hydrogen phosphate and oxalic acid are mixed to prepare a dual-functional composite preparation that simultaneously removes calcium ions and adjusts pH.

2. The method according to claim 1, characterized in that The concentration of the calcium chloride solution in step (1) is 0.1% to 10% w / w; Optionally, the concentration of the calcium chloride solution is 1% to 8% w / w; Optionally, the concentration of the calcium chloride solution is 4% to 6% w / w.

3. The method according to claim 1, characterized in that The concentration of the polyacrylamide coagulant aid solution in step (1) is 0.001% to 0.1% w / w; Optionally, the concentration of the polyacrylamide coagulant aid solution is 0.01% to 0.1% w / w; Optionally, the concentration of the polyacrylamide coagulant aid solution is 0.01% to 0.05% w / w.

4. The method according to claim 1, characterized in that In step (1), the dosage ratio of calcium chloride solution, polyacrylamide coagulant aid solution and diatomaceous earth is 500-1500 mL: 1-10 mL: 10-50 g; Optionally, the usage ratio of calcium chloride solution, polyacrylamide coagulant aid solution and diatomaceous earth is 800-1200 mL: 3-8 mL: 15-30 g.

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

6. A dual-functional composite preparation for simultaneously removing calcium ions and adjusting pH, prepared by the method according to any one of claims 1 to 5.

7. Use of the method according to any one of claims 1 to 5 or the dual-functional composite preparation for simultaneously removing calcium ions and adjusting pH according to claim 6 in the environmental field.

8. The use according to claim 7, characterized in that: Environmental applications include metal ion reduction, pH adjustment, and total dissolved solids reduction.

9. A descaling agent, characterized in that: The invention is prepared from the dual-functional composite preparation for simultaneously removing calcium ions and adjusting pH as described in claim 6.

10. A method for simultaneously improving the removal of calcium ions and total dissolved solids in sewage and adjusting the pH of sewage, characterized in that: Using the dual-functional composite preparation according to claim 6, the steps are as follows: The dual-functional composite preparation solution and sewage are mixed in a volume ratio of 15 to 25:500 and precipitated; Optionally, the concentration of the dual-functional composite formulation solution is 5-10% w / w.

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