Solid-liquid separation method for wall-breaking and cell-dissolving mixed liquid of excess sludge

Abstract

The invention relates to a solid-liquid separation method for residual sludge wall-breaking and cell-dissolving mixed liquid, which comprises the following steps: adding strong cationic polyquaternium into the residual sludge wall-breaking and cell-dissolving mixed liquid formed by enhanced ozone oxidation-anaerobic hydrolytic acidification reaction, and carrying out stirring demulsification reaction; after the demulsification reaction, adding an inorganic high-molecular coagulant and an organic high-molecular cationic flocculant, carrying out flocculent precipitation separation and phosphorus removal reaction, and at the moment, generating settled floccules from the residual sludge wall-breaking and cell-dissolving mixed liquid; the method comprises the following steps: carrying out solid-liquid separation on settled floccules, respectively returning solid-phase sludge to a biochemical pool or dehydrating the sludge and sending the sludge to a third party for treatment, adding sodium hypochlorite into a liquid phase, starting hydrodynamic cavitation, introducing ozone to carry out ammonia / amine nitrogen denitrification reaction, and finally converting to obtain a high-quality carbon source. According to the method disclosed by the invention, the high-efficiency solid-liquid separation of the residual sludge wall-breaking and cell-dissolving mixed solution is realized by adding a strong cation surface and interface active substance into the residual sludge wall-breaking and cell-dissolving mixed solution with a strong negative charge property.

Description

Technical Field

[0001] The present invention relates to a technology in the field of sewage treatment, in particular to a solid-liquid separation method for a residual sludge wall-breaking and cell-lysing mixed liquid. Background Art

[0002] The biological activated sludge process has become the most widely used sewage treatment technology due to its good treatment effect and convenient operation. However, the activated sludge process also produces a large amount of residual sludge while purifying sewage. After the residual sludge undergoes treatment such as enhanced ozone oxidation and cell lysis, a large amount of surface negatively charged substances will be formed. After anaerobic hydrolysis and acidification, the amount of surface negatively charged substances will be further enhanced, resulting in the formation of a broken cell lysis mixture with strong emulsion properties. For this type of broken cell lysis mixture with strong emulsion properties, the existing coagulation-flocculation technology cannot achieve solid-liquid separation at all. This seriously affects the reduction treatment of residual sludge and the development of resource utilization technology. This is also a difficult problem that needs to be solved urgently in the treatment of residual sludge. Summary of the Invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention proposes a method for solid-liquid separation of a residual sludge wall-breaking and cell-lysing mixed liquor, by adding a strong cationic surface active substance to the residual sludge wall-breaking and cell-lysing mixed liquor with strong negative charge properties, thereby achieving efficient solid-liquid separation of the residual sludge wall-breaking and cell-lysing mixed liquor.

[0004] The present invention is achieved through the following technical solutions:

[0005] The invention relates to a solid-liquid separation method for a residual sludge wall-breaking and cell-lysing mixed liquid. The method comprises the following steps: adding a strongly cationic polyquaternary ammonium salt to a residual sludge wall-breaking and cell-lysing mixed liquid formed by an enhanced ozone oxidation-anaerobic hydrolysis and acidification reaction, and performing a stirring and demulsification reaction; adding an inorganic polymer coagulant and an organic polymer cationic flocculant after the demulsification reaction to inhibit re-emulsification, and performing flocculation, sedimentation, separation, and phosphorus removal reactions, thereby generating settled flocs in the residual sludge wall-breaking and cell-lysing mixed liquid; performing solid-liquid separation on the settled flocs, and returning the solid-phase sludge to a biochemical tank or dehydrating the solid phase to be disposed of by a third party; adding sodium hypochlorite to the liquid phase, starting hydraulic cavitation, and then introducing ozone to form ClO·, thereby performing an ammonia / amine nitrogen denitrification reaction, and finally converting the resultant into a high-quality carbon source for sewage treatment.

[0006] The residual sludge wall-breaking and cell-lysing mixed liquid refers to the wall-breaking and cell-lysing mixed liquid obtained by introducing ozone into the residual sludge and simultaneously starting hydraulic cavitation, and then performing anaerobic hydrolysis and acidification after the ozone reaction is complete.

[0007] In the stirring demulsification reaction, the amount of the strong cationic polyquaternary ammonium salt added is 200-500 mg L -1The remaining sludge lysed cell mixture is stirred at 120 - 180 revolutions per minute for 1 - 2 minutes.

[0008] The strong cationic polyquaternary ammonium salt described above is poly(dimethyldiallylammonium chloride), polyquaternary ammonium salt, polyepichlorohydrin - dimethylamine, polyacrylamide quaternary ammonium salt, or a combination thereof.

[0009] The inorganic polymer coagulant described above is polyferric sulfate or polyaluminum chloride, preferably polyferric sulfate, and its dosage is 300 - 800 mg / L. -1 The remaining sludge lysed cell mixture.

[0010] The organic polymer cationic flocculant described above is cationic polyacrylamide, and its dosage is 100 - 200 mg / L. -1 The remaining sludge lysed cell mixture.

[0011] For the flocculation precipitation separation described above, it is preferably stirred at 60 - 80 revolutions per minute for 3 - 5 minutes simultaneously.

[0012] The dosage of the sodium hypochlorite described above is 200 - 2000 mg / L. -1 Liquid phase.

[0013] The hydraulic cavitation rotation speed is 3000 revolutions per minute. -1 。

[0014] The flow rate of the ozone described above is 1 - 3 mg O3 / L. -1 Liquid phase per minute. -1 。

[0015] The reaction time of the ammonia / amine nitrogen denitrification reaction described above is 1 - 3 minutes.

[0016] Technical effect

[0017] The present invention realizes the demulsification of the cell wall lysate mixture of excess sludge by adding a strong cationic polyquaternary ammonium salt with a high cationic charge density and high molecular weight. Since the strong cationic polyquaternary ammonium salt can quickly neutralize the negatively charged particles or interfaces in the emulsion, it can rapidly destroy the double electric layer structure of the emulsion, promote the coalescence and separation of water droplets, thereby greatly reducing the stability of the emulsion; at the same time, the relatively high molecular weight of the strong cationic polyquaternary ammonium salt can connect multiple water droplets or particles together through bridging action to form larger aggregates and accelerate demulsification. On this basis, by adding an inorganic polymer coagulant and an organic polymer cationic flocculant to the cell wall lysate mixture of excess sludge after demulsification, the aggregation of suspended solids and colloidal particles is further promoted, thereby inhibiting the re-emulsification of the emulsion, completely eliminating the possibility of re-emulsification of the demulsified liquid, and realizing the functions of flocculation precipitation separation and phosphorus removal, achieving the triple effects of eliminating re-emulsification, flocculation precipitation and phosphorus removal; finally, using the formed ClO• / Cl• to oxidize ammonia nitrogen and organic amine nitrogen in the liquid phase to nitrogen, simplifies the process and realizes ammonia / amine nitrogen denitrification. Compared with the prior art, the cell wall lysate mixture of excess sludge is extremely easy to perform solid-liquid separation, and the obtained liquid-phase carbon source has a high concentration, high quality, low nitrogen content and low phosphorus content. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Example 1

[0020] This example includes the following steps:

[0021] Step 1: Put the excess sludge into a reaction vessel, introduce ozone, and the ozone flow rate is 2 mgO3 / L of wet sludge.min, and simultaneously start hydrodynamic cavitation with a hydrodynamic cavitation speed of 3000 revolutions / min and a reaction time of 40 min; after the ozone reaction is complete, introduce hydrolytic acidification bacteria and carry out anaerobic hydrolysis and acidification for 60 h to obtain a cell wall lysate mixture of excess sludge. -1 of wet sludge.min -1 After the ozone reaction is complete, introduce hydrolytic acidification bacteria and carry out anaerobic hydrolysis and acidification for 60 h to obtain a cell wall lysate mixture of excess sludge.

[0022] Step 2: Add 300 mg / L of polydimethyldiallylammonium chloride to the cell wall lysate mixture of excess sludge, stir at 150 revolutions / min for 1.5 minutes, and then add 600 mg / L of polyferric sulfate to the cell wall lysate mixture of excess sludge and 150 mg / L of cationic polyacrylamide to the cell wall lysate mixture of excess sludge -1 of the cell wall lysate mixture of excess sludge, stir at 150 revolutions / min for 1.5 minutes, and then add 600 mg / L of polyferric sulfate to the cell wall lysate mixture of excess sludge and 150 mg / L of cationic polyacrylamide to the cell wall lysate mixture of excess sludge -1 of the cell wall lysate mixture of excess sludge, 150 mg / L of cationic polyacrylamide -1The remaining sludge cell wall-breaking and cell lysis mixture is stirred at 70 rpm for 4 minutes, and the sedimentation time of the remaining sludge cell wall-breaking and cell lysis mixture is < 1 min; solid-liquid separation is carried out. The separated solid-phase sludge residue is refluxed to the biochemical pool or dehydrated and sent to a third party for disposal, and the water content of the dewatered mud cake after pressure filtration is < 65%. Sodium hypochlorite 1200 mg / L is added to the separated liquid phase -1 Liquid phase, and hydrodynamic cavitation is started again. The rotational speed of hydrodynamic cavitation is 3000 rpm -1 , and the ozone flow rate is 2.5 mg O3 / L -1 Liquid phase. min -1 , the reaction time is 2 min, and the ammonia / amine nitrogen denitrification reaction is carried out. After the liquid phase undergoes the denitrification reaction, it is converted into a high-quality carbon source for sewage treatment. Among them, the sludge is converted into dissolved chemical oxygen demand ~ 58%, and the ammonia nitrogen concentration in the liquid phase is 4.3 mg / L -1 , and the total phosphorus concentration is 5.2 mg / L -1 .

[0023] Control Example 1

[0024] As a control, under the condition that other conditions in Example 1 remain unchanged, strong cationic polyquaternary ammonium salt (polydimethyldiallylammonium chloride), inorganic polymer coagulant (polyferric sulfate), and organic polymer cationic flocculant (cationic polyacrylamide) are not added. Finally, the sedimentation time of the remaining sludge cell wall-breaking and cell lysis mixture is > 1 h, and the water content of the dewatered mud cake after barely pressure filtration is > 90%. The sludge is converted into dissolved chemical oxygen demand ~ 51%, and the ammonia nitrogen concentration in the liquid phase is 4.3 mg / L -1 , and the total phosphorus concentration is 92.3 mg / L -1 .

[0025] Control Example 2

[0026] As a control, under the condition that other conditions in Example 1 remain unchanged, inorganic polymer coagulant (polyferric sulfate) and organic polymer cationic flocculant (cationic polyacrylamide) are not added. The sedimentation time of the remaining sludge cell wall-breaking and cell lysis mixture is > 30 min. The settled remaining sludge cell wall-breaking and cell lysis mixture is left standing for 48 h, and the solid-liquid stratification of the remaining sludge cell wall-breaking and cell lysis mixture is not obvious (partially restored to the characteristics of an emulsion); at this time, it is stirred at 150 rpm for 1.5 minutes, and then polyferric sulfate 600 mg / L -1 Remaining sludge cell wall-breaking and cell lysis mixture, cationic polyacrylamide 150 mg / L -1 Remaining sludge cell wall-breaking and cell lysis mixture is stirred at 70 rpm for 4 minutes, and the sedimentation time of the remaining sludge cell wall-breaking and cell lysis mixture is < 3 min.

[0027] Example 2

[0028] The difference between this embodiment and Embodiment 1 is that in Step 2, 200 mg / L of polyepichlorohydrin-dimethylamine is added to the mixed solution of lysed residual sludge formed by enhanced ozone oxidation-anaerobic hydrolysis acidification -1 to the mixed solution of lysed residual sludge, stir at 180 r / min for 1 minute, and then add 300 mg / L of polyaluminum chloride -1 to the mixed solution of lysed residual sludge, 200 mg / L of cationic polyacrylamide -1 to the mixed solution of lysed residual sludge, stir at 60 r / min for 3 minutes, and the sedimentation time of the mixed solution of lysed residual sludge < 1.5 min; perform solid-liquid separation, the separated solid-phase sludge residue is refluxed to the biochemical pool or dehydrated and sent to a third party for disposal, and the moisture content of the dewatered sludge cake after pressure filtration < 65%. 200 mg / L of sodium hypochlorite is added to the separated liquid phase -1 to the liquid phase, and hydrodynamic cavitation is started again, with a hydrodynamic cavitation speed of 3000 r / min -1 , an ozone flow rate of 1 mg O3 / L -1 per liter of liquid phase.min -1 , with a reaction time of 1 min, perform ammonia / amine nitrogen denitrification reaction. After the denitrification reaction of the liquid phase, it is converted into a high-quality carbon source for sewage treatment, in which about 57% of the sludge is converted into dissolved chemical oxygen demand, the ammonia nitrogen concentration in the liquid phase is 7.5 mg / L -1 , and the total phosphorus concentration is 5.8 mg / L -1 .

[0029] Embodiment 3

[0030] The difference between this embodiment and Embodiment 1 is that in Step 2, 500 mg / L of quaternary ammonium salt of polyacrylamide is added to the mixed solution of lysed residual sludge formed by enhanced ozone oxidation-anaerobic hydrolysis acidification -1 to the mixed solution of lysed residual sludge, stir at 120 r / min -1 for 2 minutes, and then add 800 mg / L of polyferric sulfate -1 to the mixed solution of lysed residual sludge, 100 mg / L of cationic polyacrylamide -1 to the mixed solution of lysed residual sludge, stir at 80 r / min -1 for 5 minutes, and the sedimentation time of the mixed solution of lysed residual sludge < 1 min; perform solid-liquid separation, the separated solid-phase sludge residue is refluxed to the biochemical pool or dehydrated and sent to a third party for disposal, and the moisture content of the dewatered sludge cake after pressure filtration < 65%. 2000 mg / L of sodium hypochlorite is added to the separated liquid phase -1 to the liquid phase, and hydrodynamic cavitation is started again, with a hydrodynamic cavitation speed of 3000 r / min -1 , an ozone flow rate of 3 mg O3 / L -1 per liter of liquid phase.min-1 , with a reaction time of 3 min, the ammonia / amine nitrogen denitrification reaction is carried out. After the denitrification reaction of the liquid phase, a high-quality carbon source for sewage treatment is converted, in which the sludge is converted into dissolved chemical oxygen demand ~58%, and the ammonia nitrogen concentration in the liquid phase is 2.3 mg L -1 , and the total phosphorus concentration is 3.7 mgL -1 .

[0031] The above specific embodiments can be locally adjusted in different ways by those skilled in the art without departing from the principles and purposes of the present invention. The protection scope of the present invention is subject to the claims and is not limited by the above specific embodiments, and all implementation solutions within its scope are subject to the present invention.

Claims

1. A method for solid-liquid separation of a remaining sludge cell wall-breaking and cell lysis mixture, characterized in that, Add a strong cationic polyquaternary ammonium salt to the remaining sludge cell wall-breaking and lysis mixture formed by enhanced ozone oxidation-anaerobic hydrolysis acidification reaction, and carry out a stirring demulsification reaction; after the demulsification reaction, add an inorganic polymer coagulant and an organic polymer cationic flocculant, and carry out flocculation precipitation separation and phosphorus removal reaction. At this time, a sedimentation floc is generated from the remaining sludge cell wall-breaking and lysis mixture; after solid-liquid separation of the sedimentation floc, the solid-phase sludge residue is refluxed to the biochemical pool or dehydrated and sent to a third party for disposal; add sodium hypochlorite to the liquid phase, start hydrodynamic cavitation, and then introduce ozone to form ClO• to carry out ammonia / amine nitrogen denitrification reaction, and finally obtain a high-quality carbon source for sewage treatment.

2. The solid-liquid separation method of the remaining sludge cell wall breaking and lysis mixture according to claim 1, characterized in that, The remaining sludge cell wall-breaking and lysis mixture mentioned above refers to: ozone is introduced into the remaining sludge and hydrodynamic cavitation is started synchronously. After the ozone reaction is complete, the cell wall-breaking and lysis mixture obtained after anaerobic hydrolysis acidification.

3. The solid-liquid separation method of the residual sludge cell wall breaking and cell lysis mixed solution according to claim 1, characterized in that For the stirring demulsification reaction described above, the addition amount of the strong cationic polyquaternary ammonium salt is 200~500 mg / L -1 The remaining sludge cell wall-breaking and cell lysis mixture, and stir at 120~180 revolutions per minute for 1-2 minutes.

4. The method for solid-liquid separation of the remaining sludge cell wall-breaking and cell lysis mixture according to claim 1 or 3, characterized in that The strong cationic polyquaternary ammonium salt mentioned above is selected from poly(dimethyldiallylammonium chloride), polyquaternary ammonium salt, polyepichlorohydrin-dimethylamine, polyacrylamide quaternary ammonium salt or a combination thereof.

5. The solid-liquid separation method of the remaining sludge cell wall breaking and cell lysis mixture according to claim 1, characterized in that, The inorganic polymer coagulant used is polyferric sulfate or polyaluminum chloride, and its dosage is 300~800 mg / L -1 The mixed liquid of lysed residual sludge 6. The solid-liquid separation method of the residual sludge cell wall breaking and cell lysis mixture according to claim 1, characterized in that, The organic polymer cationic flocculant used is cationic polyacrylamide, and its dosage is 100-200 mg / L. -1 The mixed solution of lysed excess sludge.

7. The solid-liquid separation method of the residual sludge cell wall breaking and cell lysis mixture according to claim 1, characterized in that, For the flocculation precipitation separation, stir at 60-80 revolutions per minute for 3-5 minutes simultaneously.

8. The solid-liquid separation method of the residual sludge cell wall breaking and cell lysis mixture according to claim 1, characterized in that, The dosage of sodium hypochlorite described is 200~2000 mg / L -1 Liquid phase.

9. The solid-liquid separation method of the residual sludge cell wall breaking and cell lysis mixture according to claim 1, characterized in that, The flow rate of the ozone is 1 to 3 mg O3 / L -1 liquid phase min -1 .

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