A method for resolving sludge bulking in winter sewage treatment systems

Abstract

The present application relates to the field of sewage treatment, in particular to a method for solving sludge bulking of sewage treatment system in winter, comprising the following steps: 1, judging the cause of sludge bulking, detecting the sewage index, activated sludge index and reclaimed water quality index, and judging the degree of sludge bulking; 2, sludge bulking treatment, intermittent aeration and oxygenation according to the degree of sludge bulking, adding O3 to kill part of filamentous bacteria, adding wood ash, accelerant and organic biological complexing agent, increasing the adhesion of activated sludge and the number of microorganisms; 3, discharge activation, using a small low-voltage discharge device, passing a small current into the sewage tank, and exciting microbial activity through the current; 4, intermittent pumping of sewage, the step comprising starting the sewage pump, intermittent pumping of sewage, until the activated sludge settling ratio of the aerobic tank is greater than 40%. The present application has the advantages of simple operation, low investment and stable effect, and can solve the problem of sludge bulking of the sewage treatment system in a short time.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of sewage treatment, and particularly relates to a method for solving sludge bulking of a sewage treatment system in winter. BACKGROUND

[0002] In winter in the north, it is difficult to control the sewage treatment process, which causes deterioration of water quality and easy occurrence of sludge bulking. There are two types of sludge bulking, one is sludge filamentous bulking caused by reproduction of a large number of filamentous bacteria in activated sludge, and the other is non-filamentous bulking caused by a large amount of high-viscosity substances (such as a plurality of sugars formed by glucose, mannose, arabinose, rhamnose and deoxyribose) accumulated in the bacterial body of zooglea. Sludge bulking not only has a high occurrence rate but also is difficult to control, which has long plagued the stable operation of sewage treatment plants. At present, the main control methods for sludge bulking include adding various reagents such as flocculants, bactericides and lime, or setting a biological selector at the front end of the system to improve the process control conditions. These methods have the disadvantages of easy destruction of microbial activity, slow effect and long cycle, and it is difficult to quickly achieve the expected effect, especially when sludge bulking occurs in the sewage treatment system in winter in the north, which is affected by the air temperature and cannot be solved in time. SUMMARY

[0003] The main purpose of the present application is to provide a method for solving sludge bulking of a sewage treatment system in winter, which has the advantages of simple operation, low investment and stable effect, and can solve the sludge bulking of the sewage treatment system in a short time, solve the problems of long time, slow effect and long-term stop of equipment of the traditional sludge bulking treatment method.

[0004] In order to solve the above problems, the present application provides a method for solving sludge bulking of a sewage treatment system in winter, comprising the following steps:

[0005] (1) judging the degree of sludge bulking

[0006] detecting sewage indexes, activated sludge indexes and reclaimed water quality indexes, and judging the degree of sludge bulking according to the indexes;

[0007] (2) sludge bulking treatment

[0008] stopping sewage circulation, determining the aeration oxygenation amount according to the degree of sludge bulking, intermittently aerating the aerobic tank, and keeping the sewage temperature above 15℃;

[0009] then determining the O3 dosage in the treatment process according to the degree of sludge bulking, adding O3 after the aeration oxygenation is completed, starting the sludge reflux pump of the MBR tank, starting the sewage circulation, and killing part of the filamentous bacteria causing sludge bulking;

[0010] 6~12h after O3 sterilization, according to the sludge expansion degree, the prepared ash and microbial promoter is added into the sewage pool, then 2~4h later, according to the sludge expansion degree, a certain amount of organic biological compound is added into the aerobic tank, and the process is stabilized for 6~12h;

[0011] (3) Micro-current activation

[0012] A small low-voltage discharge device is used to pass micro-current into the sewage pool, the activity of microorganisms in low-temperature environment is excited by the current, 4~12h after the discharge is completed, the activated sludge settling ratio in the aerobic tank is detected, if the activated sludge settling ratio is less than 20%, steps 1~3 are repeated until the activated sludge settling ratio in the aerobic tank is greater than 30%;

[0013] (4) Intermittent pumping of sewage

[0014] The sewage pump of the adjusting tank is started, and sewage is intermittently pumped into the sewage treatment equipment from the outside until the activated sludge settling ratio in the aerobic tank is greater than 40% and the MLSS concentration is greater than 900 mg / L.

[0015] Preferably, the sewage indicators include dissolved oxygen concentration, pH, temperature, C / N ratio, the activated sludge indicators include sludge load (F / M), sludge volume index (SVI), and the reclaimed water quality indicators include pH, COD, ammonia nitrogen, total nitrogen, and total phosphorus concentration, etc., and the sludge expansion degree is divided into mild, moderate, and severe.

[0016] Preferably, in step (1), the mild indicator range is: dissolved oxygen concentration (0.5 mg / L~1.0 mg / L), pH (5~6, 8~9), temperature (15℃~20℃), C / N ratio (5~10), sludge load (F / M≥0.2 kg / kg.d), sludge volume index (200<SVI<300), and ≤2 items of reclaimed water COD, ammonia nitrogen, total nitrogen, and total phosphorus indicators are not up to standard.

[0017] The moderate indicator range is: dissolved oxygen concentration (0.2 mg / L~0.5 mg / L), pH (4~5, 9~10), temperature (10℃~15℃), C / N ratio (2~5), sludge load (0.1 kg / kg.d <F / M<0.2 kg / kg.d), sludge volume index (300<SVI<400), and ≥2 items of reclaimed water COD, ammonia nitrogen, total nitrogen, and total phosphorus indicators are not up to standard.

[0018] The severe indicator range is: dissolved oxygen concentration (<0.2 mg / L), pH (≤5, ≥9), temperature (<10℃), C / N ratio (<2), sludge load (F / M<0.1 kg / kg.d), sludge volume index (SVI≥400), and ≥3 items of reclaimed water COD, ammonia nitrogen, total nitrogen, and total phosphorus indicators are not up to standard.

[0019] Preferably, in the step (2), the mild sludge bulking treatment method is: aeration time lasts for 6-12h, O3 dosage is 0.1-1mg / L / h, the dosage of wood ash and microbial promoter is 0.001%-0.005% of the volume of the sewage treatment equipment, the dosage of organic biological complexing agent is 0.001%-0.01% of the volume of the sewage treatment equipment; the moderate sludge bulking treatment method is: aeration time lasts for 12-24h, O3 dosage is 1-5mg / L / h, the dosage of wood ash and microbial promoter is 0.005%-0.01% of the volume of the sewage treatment equipment, the dosage of organic biological complexing agent is 0.01%-0.03% of the volume of the sewage treatment equipment; the severe sludge bulking treatment method is: aeration time lasts for 24-48h, O3 dosage is 5-20mg / L / h, the dosage of wood ash and microbial promoter is 0.01%-0.02% of the volume of the sewage treatment equipment, the dosage of organic biological complexing agent is 0.03%-0.05% of the volume of the sewage treatment equipment.

[0020] Preferably, in the step (2), the sludge reflux pump works for 1-3min, and stops for 10-20min.

[0021] Preferably, in the step (3), the low-voltage discharge device is direct current, and contains multiple positive and negative electrodes, the positive electrode material is graphite mesh, and the negative electrode material is copper mesh.

[0022] Preferably, in the step (4), 2%-8% of the designed treatment capacity is intermittently pumped into the sewage.

[0023] Preferably, the aeration device operates for 15-40min, stops for 5-15min, the aeration intensity is 5-15m 3 / m 2 h, and the dissolved oxygen content of the activated sludge is 2.0mg / L-3.5mg / L.

[0024] Preferably, the wood ash is wood ash containing CaCl2, the microbial promoter is phytic acid, and the mass ratio of CaCl2, wood ash and phytic acid is (0.01-0.1):1:(0.0001-0.001).

[0025] Preferably, the organic biological complexing agent is composed of a carbon source, a strain and chitosan, the carbon source is flour and glucose, the strain is phosphorus-removing bacteria, ammonia-nitrogen-removing bacteria and total-nitrogen-removing bacteria, and the chitosan is chitin or shrimp and crab shells, and the mass ratio of the carbon source, the strain and the chitosan is (500-2000):(0.5-8):(0.5-10).

[0026] Preferably, the low-voltage discharge device discharges during the operation of the sludge backflow pump, and the discharge process lasts for 5-20 s and the current density is 5-150 mA / m2.

[0027] Compared with the prior art, the method has the advantages and positive effects that by adding wood ash, strains, carbon sources and microbial adhesives and using the low-voltage discharge device to discharge to stimulate microbial activity and by reasonably adjusting the operation parameters of each system, the problem of sludge bulking in sewage treatment can be quickly solved; the running time of the sewage treatment system is reduced, the problem of long processing time and high cost of the traditional sewage treatment system is solved, and the problem of incomplete treatment is solved; the method does not need to add coagulants such as iron salt and aluminum salt, and the damage of the coagulants to the active sludge and water quality in the sewage is reduced; the method is simple and easy to operate, does not need other chemical agents, and only needs a small amount of O3 to quickly solve the problem of sludge bulking, restore the ecological balance of microorganisms, and realize the normal operation of the sewage treatment system in a short time. The method is suitable for treating sludge bulking in the sewage treatment system in winter in the north. DETAILED DESCRIPTION

[0028] In the following, the application will be described in detail by way of exemplary embodiments. It should be understood, however, that the elements, structures and features of one embodiment can be advantageously combined with elements, structures and features of other embodiments without further description. EMBODIMENT

[0029] A method for solving the problem of sludge bulking in a sewage treatment system in winter is carried out in a sewage treatment device, and the sewage treatment device comprises a regulating tank, an aerobic tank, an anaerobic tank and an MBR tank. The regulating tank is communicated with the anaerobic tank through a sewage pump, the anaerobic tank is communicated with the aerobic tank through a self-flow hole, the aerobic tank is communicated with the MBR tank through a self-flow hole, and the MBR tank is communicated with the anaerobic tank through a sludge backflow pump. An ozone disinfection device is installed in the sludge backflow pipe, and a low-voltage discharge device is placed in the aerobic tank and the anaerobic tank.

[0030] The method specifically comprises the following steps:

[0031] 1. Determine the cause of sludge bulking

[0032] The sewage index, active sludge index and reclaimed water quality index are detected, and the degree of sludge bulking is determined according to the indexes. The sewage index includes dissolved oxygen concentration, pH, temperature and C / N ratio, the active sludge index includes sludge load (F / M) and sludge volume index (SVI), and the reclaimed water quality index includes pH, COD, ammonia nitrogen, total nitrogen and total phosphorus concentration, etc. The degree of sludge bulking is divided into mild, moderate and severe.

[0033] The mild index range is: dissolved oxygen concentration (0.5 mg / L~1.0 mg / L), pH (5~6, 8~9), temperature (15℃~20℃), C / N ratio (5~10), sludge load (F / M≥0.2 kg / kg.d), sludge volume index (200<SVI<300), and ≤2 items of the indexes such as reclaimed water COD, ammonia nitrogen, total nitrogen, total phosphorus are not up to standard;

[0034] The moderate index range is: dissolved oxygen concentration (0.2 mg / L~0.5 mg / L), pH (4~5, 9~10), temperature (10℃~15℃), C / N ratio (2~5), sludge load (0.1 kg / kg.d <F / M<0.2 kg / kg.d), sludge volume index (300<SVI<400), and ≥2 items of the indexes such as reclaimed water COD, ammonia nitrogen, total nitrogen, total phosphorus are not up to standard;

[0035] The severe index range is: dissolved oxygen concentration (<0.2 mg / L), pH (≤5, ≥9), temperature (<10℃), C / N ratio (<2), sludge load (F / M<0.1 kg / kg.d), sludge volume index (SVI≥400), and ≥3 items of the indexes such as reclaimed water COD, ammonia nitrogen, total nitrogen, total phosphorus are not up to standard;

[0036] In the embodiment, the sewage dissolved oxygen concentration is 1.0 mg / L, pH=8~9, temperature is 13℃, C / N ratio=5.2, sludge load (F / M)=0.3 kg / kg.d, sludge volume index (SVI)=261, and the total nitrogen of the reclaimed water is not up to standard.

[0037] 2. Sludge expansion treatment

[0038] The steps include stopping the sewage pump of the equipment, stopping the sewage circulation, determining the aeration oxygenation amount according to the sludge expansion degree, adjusting the parameters of the air blower, intermittently aerating the aerobic tank, making the activated sludge mixed uniformly and in the oxygen-rich state, and keeping the sewage temperature above 15℃. The aeration equipment runs for 15 min~40 min, stops for 5 min~15 min, and the aeration intensity is 5~15 m 3 / m 2 h, so as to ensure that the dissolved oxygen content of the activated sludge is 2.0 mg / L~3.5 mg / L;

[0039] Subsequently, the O3 dose in the treatment process is determined according to the sludge expansion degree, O3 is added after the aeration oxygenation is completed, the sludge reflux pump of the MBR tank is started, the sewage circulation is started, the reflux sewage is disinfected by using the ozone generator, and part of the filamentous bacteria causing the sludge expansion is killed; the sludge reflux pump works for 1~3 min, and pauses for 10 min~20 min;

[0040] O3 sterilization after 6~12h detection of O3 residual concentration in sewage, up to standard according to sludge expansion degree, to the sewage pool adding the prepared ash and microbial promoter, then interval 2~4h according to sludge expansion degree, to the aerobic tank adding a certain amount of organic biological complexing agent, stable 6~12h. Ash is CaCl2 containing ash, microbial promoter is phytic acid, organic biological complexing agent is composed of carbon source, strain and chitosan, carbon source is flour and glucose, strain is phosphorus removal bacteria, ammonia nitrogen removal bacteria, total nitrogen removal bacteria; chitosan is chitin or shrimp and crab shell; CaCl2, ash and phytic acid mass ratio is (0.01~0.1):1:(0.0001~0.001), carbon source, strain, chitosan mass ratio is (500~2000):(0.5~8):(0.5~10).

[0041] Mild sludge bulking treatment method is: aeration time lasts for 6~12h, O3 dosage is 0.1~1mg / L / h, ash and microbial promoter dosage is 0.001%~0.005% of the volume of sewage treatment equipment, organic biological complexing agent dosage is 0.001%~0.01% of the volume of sewage treatment equipment;

[0042] Moderate sludge bulking treatment method is: aeration time lasts for 12~24h, O3 dosage is 1~5mg / L / h, ash and microbial promoter dosage is 0.005%~0.01% of the volume of sewage treatment equipment, organic biological complexing agent dosage is 0.01%~0.03% of the volume of sewage treatment equipment;

[0043] Severe sludge bulking treatment method is: aeration time lasts for 24~48h, O3 dosage is 5~20mg / L / h, ash and microbial promoter dosage is 0.01%~0.02% of the volume of sewage treatment equipment, organic biological complexing agent dosage is 0.03%~0.05% of the volume of sewage treatment equipment.

[0044] In this embodiment, the aeration equipment running time is 15min, the stop time is 15min, the aeration intensity is 8m 3 / m 2 h, the activated sludge dissolved oxygen content is 2.0mg / L~3.5mg / L, the sludge reflux pump working time is 1min, the pause time is 20min, the aeration time lasts for 6h, O3 dosage is 0.1mg / L / h, ash and microbial promoter dosage is 0.001% of the volume of sewage treatment equipment, CaCl2, ash, phytic acid and sewage ratio is 0.01:1:0.0001, organic biological complexing agent dosage is 0.003% of the volume of sewage treatment equipment, carbon source, strain, chitosan dosage ratio is 800:2:3, stable 6h.

[0045] 3, microcurrent activation

[0046] Using small low-voltage discharge equipment, a micro-current is passed into the sewage pool, and the activity of microorganisms in a low-temperature environment is excited by the current. The low-voltage discharge equipment is direct current, and contains multiple positive and negative electrodes. The positive electrode material is graphite mesh, and the negative electrode material is copper mesh. 4-12 hours after the discharge ends, the activated sludge settling ratio in the aerobic tank is detected. If the activated sludge settling ratio in the aerobic tank is less than 20%, steps 1-3 are repeated until the activated sludge settling ratio in the aerobic tank is greater than 30%. The low-voltage discharge equipment discharges during the operation of the sludge reflux pump. The discharge process lasts for 5-20 seconds at a time, and the current density is 5-150 mA / m 2 ;

[0047] In this embodiment, the discharge process lasts for 5 seconds at a time, and the current density is 30 mA / m 2 . 6 hours after the discharge ends, the activated sludge settling ratio in the aerobic tank is greater than 30%.

[0048] 4. Turn on the adjusting tank sewage pump, and intermittently pump sewage from the outside into the sewage treatment equipment. The sewage is intermittently pumped in at 5% of the designed treatment capacity until the activated sludge settling ratio in the aerobic tank is greater than 40% and the MLSS concentration is greater than 900 mg / L.

[0049] In this embodiment, the activated sludge settling ratio in the aerobic tank is greater than 40%, and the MLSS concentration is greater than 900 mg / L.

[0050] After running for 4 days, the quality of the reclaimed water was determined, and the results are shown in Table 1.

[0051] Table 1: Sewage detection indicators Embodiment

[0052] The difference between this embodiment and embodiment 1 is that the sewage treatment system operating parameters, ozone dosage, and organic biological composite agent dosage in the steps are different.

[0053] In step 1, the dissolved oxygen concentration of the sewage is 0.18 mg / L, the pH is greater than or equal to 9, the temperature is 9.8°C, the C / N ratio is 1.78, the sludge load (F / M) is 0.08 kg / kg.d, the sludge volume index (SVI) is 780, and the ammonia nitrogen, total nitrogen, and total phosphorus in the reclaimed water do not meet the standards.

[0054] In step 2, the aeration equipment operates for 40 minutes and stops for 5 minutes, and the aeration intensity is 10 m 3 / m 2h, the active sludge dissolved oxygen content 2.0 mg / L~3.5 mg / L, sludge reflux pump working time 3 min, pause time 10 min, aeration time continues 48 h, O3 dosage is 10 mg / L / h, grasswood ash and microbial promoter dose is 0.015% of the volume of the sewage treatment equipment, the ratio of CaCl2, grasswood ash, phytic acid and sewage is 0.08:1:0.0002, the organic biological compound agent dosage is 0.04% of the volume of the sewage treatment equipment, the carbon source, strain, chitosan dosage ratio is 1500:5:8, and it is stable for 12 h.

[0055] In step 3, the discharge process lasts for 20 s, the current density is 120 mA / m 2 , 8 h after the discharge, the activated sludge settling ratio (SVI) in the oxygen pool is greater than 30%;

[0056] In step 4, the outside intermittently pumps sewage into the sewage treatment equipment, and the sewage is intermittently pumped according to 8% of the design processing capacity until the activated sludge settling ratio in the aerobic tank is greater than 40% and the MLSS concentration is greater than 900 mg / L;

[0057] After running for 4 days, the reclaimed water quality is determined, and the results are shown in Table 2:

[0058] Table 2 Sewage detection index

[0059] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this, any skilled person in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for resolving sludge bulking in a winter sewage treatment system, characterized by, The method comprises the following steps: (1) judging the sludge bulking degree The sewage index, activated sludge index and reclaimed water quality index are detected, the sewage index includes dissolved oxygen concentration, pH, temperature and C / N ratio, the activated sludge index includes sludge load F / M and sludge volume index SVI, and the reclaimed water quality index includes pH, COD, ammonia nitrogen, total nitrogen and total phosphorus concentration; the degree of sludge bulking is judged according to the indexes, and the degree of sludge bulking is divided into mild, moderate and severe; The mild index range is: dissolved oxygen concentration 0.5 mg / L-1.0 mg / L, pH 5-6 or 8-9, temperature 15℃-20℃, C / N ratio 5-10, sludge load F / M≥0.2 kg / kg.d, sludge volume index 200<SVI<300, and ≤2 items of the reclaimed water COD, ammonia nitrogen, total nitrogen and total phosphorus indexes are substandard; The moderate index range is: dissolved oxygen concentration 0.2 mg / L-0.5 mg / L, pH 4-5 or 9-10, temperature 10℃-15℃, C / N ratio 2-5, sludge load 0.1 kg / kg.d The severe index range is: dissolved oxygen concentration <0.2 mg / L, pH≤5 or pH≥9, temperature <10℃, C / N ratio <2, sludge load F / M<0.1 kg / kg.d, sludge volume index SVI≥400, and ≥3 items of the reclaimed water COD, ammonia nitrogen, total nitrogen and total phosphorus indexes are substandard; (2) sludge bulking treatment Stop the sewage circulation, determine the aeration oxygenation amount according to the sludge bulking degree, intermittently aerate the aerobic tank, and keep the sewage temperature above 15℃; Then, determine the O3 dosage in the treatment process according to the sludge bulking degree, add O3 after the aeration oxygenation is completed, start the sludge reflux pump of the MBR tank, start the sewage circulation, and kill part of the filamentous bacteria causing the sludge bulking; 6-12 hours after the O3 sterilization, add the prepared wood ash and microbial promoter into the sewage tank according to the sludge bulking degree, then add the organic biological compound agent into the aerobic tank at intervals of 2-4 hours according to the sludge bulking degree, and stabilize for 6-12 hours; The mild sludge bulking treatment mode is that: the aeration time lasts for 6-12 hours, the O3 dosage is 0.1-1 mg / L / h, the wood ash and microbial promoter dosage is 0.001%-0.005% of the volume of the sewage treatment equipment, and the organic biological compound agent dosage is 0.001%-0.01% of the volume of the sewage treatment equipment; The moderate sludge bulking treatment mode is that: the aeration time lasts for 12-24 hours, the O3 dosage is 1-5 mg / L / h, the wood ash and microbial promoter dosage is 0.005%-0.01% of the volume of the sewage treatment equipment, and the organic biological compound agent dosage is 0.01%-0.03% of the volume of the sewage treatment equipment; The heavy sludge expansion treatment method is that the aeration time lasts for 24-48h, the O3 dosage is 5-20mg / L / h, the dosage of wood ash and microbial promoter is 0.01%-0.02% of the volume of the sewage treatment equipment, the dosage of organic biological compound agent is 0.03%-0.05% of the volume of the sewage treatment equipment, the working time of the sludge reflux pump is 1-3min, and the pause time is 10-20min. (3) Micro-current activation Using small low-voltage discharge equipment, the sewage pool is passed through a small current, the low-voltage discharge equipment discharges during the operation of the sludge reflux pump, and the discharge process lasts for 5-20s once, and the current density is 5-150mA / m 2 The activity of microorganisms in a low-temperature environment is excited by electric current, and after 4-12 hours after the discharge is completed, the settling ratio of activated sludge in the aerobic tank is detected, if the settling ratio of activated sludge is less than 20%, steps 1-3 are repeated until the settling ratio of activated sludge in the aerobic tank is greater than 30%. (4) Intermittent pumping of sewage The sewage pump of the adjusting tank is started, and sewage is intermittently pumped into the sewage treatment equipment from the outside until the activated sludge settling ratio of the aerobic tank is greater than 40% and the MLSS concentration is greater than 900mg / L.

2. The method for resolving winter sludge bulking in wastewater treatment systems of claim 1, wherein, In the step (3), the low-voltage discharge device is direct current, and contains multiple positive and negative electrodes, the positive electrode material is graphite mesh, and the negative electrode material is copper mesh.

3. The method for resolving winter sludge bulking in wastewater treatment systems of claim 1, wherein, In the step (4), the sewage is intermittently pumped according to 2%-8% of the designed treatment capacity.

4. The method for resolving winter septic system sludge bulking according to claim 1, wherein, The aeration equipment runs for 15-40 minutes, stops for 5-15 minutes, and the aeration intensity is 5-15 m 3 / m 2 h, and the dissolved oxygen content of the activated sludge is ensured to be 2.0-3.5 mg / L.

5. The method for resolving winter septic system sludge bulking of claim 1, wherein, The wood ash is wood ash containing CaCl2, the microbial promoter is phytic acid, and the mass ratio of CaCl2, wood ash and phytic acid is (0.01-0.1):1:(0.0001-0.001).

6. The method for addressing winter septic system sludge bulking according to claim 1, wherein, The organic biological compound agent is composed of a carbon source, a strain and chitosan, the carbon source is flour and glucose, the strain is phosphorus-removing bacteria, ammonia nitrogen-removing bacteria and total nitrogen-removing bacteria; The chitosan is chitin or shrimp and crab shells, and the mass ratio of the carbon source, the strain and chitosan is (500-2000):(0.5-8):(0.5-10).