Method for controlling sludge bulking and realizing sludge granulation by using iron-carbon micro powder

Abstract

The invention discloses a method for controlling sludge bulking and realizing sludge granulation by using iron-carbon micro powder. The method comprises the following steps: crushing and grinding iron-carbon particles, and screening to obtain iron-carbon micro powder with the particle size of 50-200 microns; adding the iron-carbon micro powder into the expanded activated sludge system according to the adding amount of 0.5-5.0 kg / m < 3 >; and after addition, the sludge bulking phenomenon is rapidly controlled, and the sludge settling performance is obviously improved. Besides, the iron-carbon micro powder is used as a crystal nucleus, and the iron-carbon powder plays a micro-electrolysis role, so that the formation of the aerobic granular sludge is promoted, and meanwhile, the pollutant removal performance of the system is improved. The problem of sludge bulking in wastewater can be effectively solved, and the aerobic granular sludge with efficient treatment performance can be cultured.

Description

Technical Field

[0001] The invention belongs to the technical field of sludge treatment, and in particular relates to a method for controlling sludge swelling and realizing sludge granulation by utilizing iron-carbon micropowder. Background Art

[0002] The activated sludge process is currently the most widely used biological treatment method for wastewater at home and abroad. However, in actual engineering, sludge bulking is an inevitable problem in the activated sludge process. When sludge swells, it will lead to difficulties in separating mud and water in the secondary sedimentation tank and a large amount of sludge loss, which seriously affects the efficient and stable operation of the sewage treatment system. Sludge bulking is characterized by great harm, difficulty in control and long recovery period. Therefore, the problem of sludge bulking has always been an urgent problem to be solved in wastewater biological treatment. At present, the commonly used sludge bulking control measures are divided into two categories: adding chemicals and adjusting process operating conditions. Adding chemicals can quickly control sludge bulking, but it cannot completely solve the problem, and sludge bulking will still occur intermittently; although artificially adjusting the process operating conditions can fundamentally eliminate the sludge bulking problem, this process takes a long time and is difficult to control, and it is impossible to quickly restore the normal operation of the system.

[0003] Aerobic granular sludge (AGS) is an aggregate formed by self-agglomeration of activated sludge microorganisms under aerobic conditions. It is considered to be a new type of wastewater biological treatment technology with great application prospects. Compared with traditional activated sludge, AGS has the advantages of dense structure, good sedimentation, high biomass, tolerance to high organic load and toxic and hazardous substances. At present, the mechanism of aerobic granular sludge formation has not been clarified, and the filamentous bacteria hypothesis and the crystal nucleus hypothesis are generally accepted by researchers. The crystal nucleus hypothesis abstracts the formation of granular sludge as a crystallization process. The sludge will attach and grow on the surface of tiny inert substances, and gradually form aerobic granular sludge with these substances as the core. Therefore, in the sludge system, the addition of solid matter can promote the formation of aerobic granular sludge, improve the sedimentation performance of sludge, and thus solve the problem of sludge bulking. Summary of the invention

[0004] The purpose of the present invention is to provide a method for controlling sludge swelling and achieving sludge granulation by using iron-carbon micropowder to address the problems of poor sedimentation performance, difficulty in mud-water separation and sludge loss caused by sludge swelling in wastewater treatment.

[0005] To achieve the above objectives, the present invention provides the following technical solutions:

[0006] A method for controlling sludge bulking and achieving sludge granulation using iron-carbon micropowder comprises the following steps:

[0007] (1) Putting iron-carbon particles with a particle size of 5.0 to 7.0 mm into a grinder, crushing and grinding, and screening the ground powder through an 80-mesh sieve. The powder collected after screening is the iron-carbon fine powder;

[0008] (2) adding the iron-carbon powder to an activated sludge system with poor sludge settling properties or sludge bulking, and then operating the system according to the set operating conditions;

[0009] (3) After running for a period of time, the sludge volume index in the system decreases and aerobic sludge particles are formed.

[0010] Preferably, the main components of the iron-carbon fine powder are Fe and C, the mass ratio of Fe element to C element is 1:4, and the particle size of the iron-carbon fine powder is 50-200 μm.

[0011] Preferably, the volume index SVI of the activated sludge with poor sludge settling properties or sludge swelling is 30 Greater than 150mL / g.

[0012] Preferably, the iron-carbon powder is added during the aeration or anoxic stage of the activated sludge system to ensure that the iron-carbon powder can fully contact the activated sludge.

[0013] Preferably, the dosage of the iron-carbon powder in the activated sludge system is 0.5-5.0 kg / m 3 .

[0014] Preferably, the set working condition is to use wastewater to enter the activated sludge system for operation, and each cycle includes five stages: water inlet, aerobic, sedimentation, water outlet and idle.

[0015] Preferably, after stable operation, the sludge volume index SVI in the sludge system is 30 Less than 50mL / g, SVI5 / SVI 30 Greater than 0.90, sludge particle size is 0.2-1.3mm.

[0016] The beneficial effects of the present invention are:

[0017] (1) The present invention successfully inhibits sludge expansion by adding iron-carbon micropowder to an activated sludge system with poor settling performance or sludge swelling, thereby achieving control of sludge swelling, improving the settling performance of the sludge, and enabling the system to resume normal operation.

[0018] (2) The iron-carbon powder of the present invention can undergo micro-electrolysis to produce a series of by-products, such as Fe 2+ , Fe 3+ These by-products can serve as nuclei for microbial attachment and growth, while the Fe dissolved in the iron-carbon powder 2+ and Fe 3+It can stimulate microorganisms to secrete EPS, promote the aggregation of microorganisms, and contribute to the formation of aerobic granular sludge.

[0019] (3) The iron-carbon micropowder of the present invention can be used as a carrier for filamentous bacteria to attach, so that the filamentous bacteria can grow around the carrier, thereby inhibiting the disorderly reproduction and growth of the filamentous bacteria. While controlling sludge swelling, it promotes the formation of aerobic granular sludge, and improves the sludge settling performance and pollutant degradation effect of the wastewater biological treatment system.

[0020] (4) The present invention effectively controls the sludge bulking problem by adding iron-carbon micropowder, further realizes the cultivation of aerobic granular sludge, and provides a new idea for solving the sludge bulking problem in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of a device for controlling sludge swelling and realizing sludge granulation by using iron-carbon micropowder according to the present invention.

[0022] Figure 2 It is the SVI5 and SVI of the sludge in the reactor during operation. 30 's change graph.

[0023] Figure 3 It is a graph showing the change in the sedimentation ratio of sludge before and after adding iron-carbon micropowder. a, b and c are the sedimentation ratios of sludge within 5, 10 and 30 minutes respectively.

[0024] Figure 4 These are photos of the sludge in the reactor: a. Photo of iron-carbon powder; b. Microscope photo of the sludge without adding iron-carbon powder; c. Microscope photo of the sludge during the period of adding iron-carbon powder; d. Microscope photo of aerobic granular sludge during the stable period.

[0025] Among them: 1. water inlet tank; 2. water outlet tank; 3. water inlet pump; 4. water inlet; 5. air pump; 6. microporous aeration head; 7. reactor body; 8. electric control valve; 9. water outlet; 10. speed regulator; 11. paddle agitator; 12. glass rotor flowmeter; 13. iron-carbon micropowder. DETAILED DESCRIPTION

[0026] The following is a further description of the embodiments of the present invention through specific embodiments and the accompanying drawings. Those skilled in the art can more fully understand the present invention based on this specification. Based on the embodiments described in the present invention, all other embodiments obtained by those skilled in the art without creative work should belong to the scope of protection of the present invention.

[0027] Example 1

[0028] The invention controls sludge expansion by adding iron-carbon micropowder into the SBR reactor, thereby realizing the cultivation of sludge granulation.

[0029] Devices that use iron-carbon micropowder to control sludge bulking and achieve sludge granulation, such as Figure 1 As shown, it includes a reactor body 7, a paddle stirrer 11 is provided on the top of the reactor body 7, the reactor body is connected to a water inlet unit, a water outlet unit, a stirring unit and an aeration unit, a water inlet 4 is provided at the bottom of the reactor and a microporous aeration head 6 is provided on the inner side of the bottom, and a water outlet 9 is provided along the middle of the outer wall of the reactor.

[0030] The water inlet tank 1 stores the actual printing and dyeing wastewater, and the wastewater in the water inlet tank 1 is pumped into the reactor from the water inlet 4 of the reactor through the water inlet pump 3. The water outlet 9 is connected to the electric control valve 8 through a pipeline, and the electric control valve 8 is connected to the water outlet tank 2 for draining the reactor.

[0031] The aeration unit includes an air pump 5, a glass rotor flowmeter 12 connected to the air pump 5 through a pipeline, and a microporous aeration head 6 connected to the glass rotor flowmeter 12 through a pipeline. The microporous aeration head 6 is arranged on the inner side of the bottom of the reactor 7 to supply oxygen to the reactor.

[0032] The stirring unit includes a paddle agitator 11 and a speed regulator 10 electrically connected to the paddle agitator 11; wherein the speed regulator 10 controls the rotation speed of the paddle agitator 11, and the paddle agitator provides a certain hydraulic shear force to prevent the iron-carbon micropowder from depositing at the bottom, promotes the collision and agglomeration of the iron-carbon micropowder with the sludge, and helps the granulation of the sludge.

[0033] Based on the above device, a method for controlling sludge swelling and achieving sludge granulation using iron-carbon micropowder is provided, and the specific process of the method includes the following steps:

[0034] The activated sludge from the aerated biochemical tank of a textile printing and dyeing wastewater treatment plant was inoculated into the reactor 7. First, the activated sludge was poured into a 50-mesh screen to remove large particles of inorganic impurities, and then the sieved sludge was poured into the reactor 7. The initial activated sludge concentration was 4000 mg / L, and the SVI 30 It is 121.71mL / g.

[0035] The reactor is operated with actual printing and dyeing wastewater, and the water inlet pump 3 is started to allow the wastewater to enter the reactor 7 through the water inlet pipe. The water quality of the inlet water is: TN concentration is 75.32-84.54 mg / L, COD concentration is 819.32-973.28 mg / L, NH4 + -N concentration is 25.95~29.38mg / L, NO3 - The -N concentration was 31.33-46.15 mg / L, the pH was 7.0-8.0, and the temperature of the reactor was controlled at 37±2 degrees Celsius.

[0036] The reactor adopts a batch operation mode. From the first water inlet to the second water inlet, one operation cycle is considered. Each operation cycle includes five stages: water inlet, aeration, sedimentation, drainage and idleness.

[0037] The printing and dyeing wastewater stored in the water inlet tank 1 enters the reactor 7 from the bottom of the reactor 7 in a plug flow manner through the water inlet pump 3. The water inlet time is 60 minutes. During the water inlet, the reactor is in anoxic state. Then, the air pump is started to enter the aerobic stage, and the aeration time is 240 to 360 minutes. The aeration volume is controlled at 1.0 to 1.5 L / min by the glass rotor flowmeter 12. While aerating, the paddle stirrer 11 is turned on, and the speed of the paddle stirrer 11 is controlled to be 140 to 200 r / min by the speed regulator 10, and the stirring time is the same as the aeration time. After the aeration is completed, the sedimentation stage is entered, and the sedimentation is 45 to 5 minutes. After the sedimentation is completed, the wastewater is made to flow out from the inside of the reactor 7 through the outlet 9 in the middle of the reactor 7 through the electric control valve 8, and the water outlet time is 5 minutes. After the water outlet is completed, the reactor is in an idle state, and the idle time is 10 to 50 minutes. After the idle stage is completed, the next cycle is run.

[0038] This embodiment is operated in two stages. The first stage is operated for 40 days, 3 cycles per day, 8 hours per cycle, including 60 minutes of water inlet, 360 minutes of aerobic, 45 minutes of sedimentation, 5 minutes of water outlet and 10 minutes of idle time. The second stage is operated for 4 cycles per day, 6 hours per cycle, including 60 minutes of water inlet, 240 minutes of aerobic, 5 minutes of water outlet. According to the sludge settling properties, the sedimentation time is gradually shortened from 45 minutes to 5 minutes, and the idle time is correspondingly extended from 10 minutes to 50 minutes.

[0039] In the first stage of this embodiment, no iron-carbon powder is added, and iron-carbon powder is added in the second stage. In the second stage, iron-carbon powder is added to the reactor. During the aeration stage, 2.5 g of iron-carbon powder is directly added to the reactor each time, and the concentration of iron-carbon powder in the reactor is finally 5.0 g / L.

[0040] During this embodiment, the sedimentation of the sludge was observed regularly, and the settling time was adjusted according to the sedimentation property of the sludge. At the same time, the sludge was examined under a microscope to observe the morphological changes of the sludge.

[0041] In the first stage of this example, the sludge settling performance is poor, the sludge in the reactor is mainly filamentous or flocculent sludge, and there is less agglomerated sludge, which may be the main reason for the poor sludge settling performance. 30When the concentration is greater than 150 mL / g, the sludge is in a swelling state. The experiment entered the second stage and began to add iron-carbon powder. The addition of iron-carbon powder significantly improved the sedimentation performance of the sludge. Subsequently, the sedimentation time was shortened from 45 min to 5 min. Shortening the sedimentation time increases the selection pressure, allowing light sludge to be discharged from the reactor and retaining heavy sludge, which increases the sludge aggregates in the reactor and is conducive to granulation.

[0042] In this embodiment, the sedimentation performance of the sludge is changed by adding iron-carbon micropowder, and the sludge granulation is promoted by shortening the sedimentation time. The sedimentation time is shortened from 45 minutes to 5 minutes in the second stage. Figure 2 As shown, the SVI5 and SVI of the sludge in the reactor 30 They decreased from the initial 226.39mL / g and 121.71mL / g to 37.19mL / g and 35.33mL / g at 120 days, respectively. As for the changes in the SVI values ​​of the sludge without and with the addition of iron-carbon micropowder, it can be seen that the SVI value of the sludge gradually decreased during the addition of iron-carbon micropowder, the sedimentation performance of the sludge was significantly improved, and the sludge swelling phenomenon in the reactor was significantly weakened. At the same time, after the addition of iron-carbon micropowder, the SVI5 / SVI of the sludge 30 The ratio gradually increased. When the experiment was run for 96 days, the SVI5 / SVI 30 The ratio is 0.92. During the 96th to 120th day of operation, the SVI5 / SVI of the sludge 30 All of them are greater than 0.90. This shows that the addition of iron-carbon micropowder promotes the formation of aerobic granular sludge. Therefore, the addition of iron-carbon micropowder can effectively control sludge expansion and is conducive to the cultivation of aerobic granular sludge.

[0043] like Figure 3 As shown in the figure, the sedimentation ratio of the sludge after adding iron-carbon powder is compared. Figure 3 a and Figure 3 b It can be seen that after adding iron-carbon micropowder, the sludge settling ratios SV5 and SV10 within 5min and 10min were 65% and 52% respectively, while the SV5 and SV10 of the sludge without adding iron-carbon micropowder were 90% and 84% respectively. This shows that adding iron-carbon micropowder can quickly improve the settling property of sludge in a short time. Figure 3 c It can be seen that the SV30 of the sludge with iron-carbon micropowder added within 30 minutes is 32%, and the SV30 of the sludge without iron-carbon micropowder added is 57%. The addition of iron-carbon micropowder significantly improves the sedimentation of the sludge, which is conducive to the subsequent cultivation of aerobic granular sludge.

[0044] like Figure 4 As shown in the figure, the changes before and after adding iron-carbon powder are compared in combination with the sludge morphology. Figure 4 b and Figure 4c It can be seen that when no iron-carbon powder was added, the sludge was mainly flocculent sludge, with a large amount of filamentous sludge, fewer sludge aggregates and loose sludge structure; when iron-carbon powder was added, the sludge adhered to the iron-carbon powder and grew and tightly surrounded the iron-carbon powder, the flocculent sludge in the reactor decreased, the granular sludge increased, and relatively complete aerobic granular sludge appeared. Figure 4 d It can be seen that during the stabilization period of aerobic granular sludge, the shape of granular sludge gradually becomes regular and the structure becomes dense. In addition, with the formation of granular sludge, the filamentous sludge gradually decreases and the sludge particle size increases.

[0045] In the present invention, firstly, the addition of iron-carbon powder can make microorganisms attach, grow and surround the surface of the microorganisms, serving as the core of aerobic granular sludge, and promoting the formation of aerobic granular sludge. Secondly, the iron-carbon powder can perform micro-electrolysis in the activated sludge system to produce Fe 2+ , Fe 3+ and its by-products such as sediments, which can also serve as carriers for microbial attachment. 2+ and Fe 3+ It can promote the secretion of EPS by microorganisms, which can promote the aggregation of microorganisms and accelerate the formation of aerobic granular sludge.

[0046] The present invention can effectively solve the problem of sludge swelling in wastewater, and at the same time utilizes iron-carbon micropowder as crystal nuclei to cultivate aerobic granular sludge, which provides a new idea for solving sludge swelling and cultivating aerobic granular sludge, and provides an application basis for dealing with the problem of sludge swelling in actual engineering.

[0047] The specific embodiments described above are merely examples of the method of the present invention and its core concept. It should be noted that a person skilled in the art may make various improvements or modifications to the present invention without departing from the principles of the present invention or exceeding the scope defined by the claims of the present invention.

Claims

1. A method for controlling sludge bulking and achieving sludge granulation using iron-carbon micropowder, characterized in that: The following steps are involved: (1) Putting iron-carbon particles with a particle size of 5.0 to 7.0 mm into a grinder, crushing and grinding, and screening the ground powder through an 80-mesh sieve. The powder collected after screening is the iron-carbon fine powder; (2) adding the iron-carbon powder to an activated sludge system with poor sludge settling properties or sludge bulking, and then operating the system according to the set operating conditions; (3) After running for a period of time, the sludge volume index in the system decreases and aerobic sludge particles are formed.

2. The method according to claim 1, characterized in that The main components of the iron-carbon fine powder are Fe and C, the mass ratio of Fe element to C element is 1:4, and the particle size of the iron-carbon fine powder is 50-200 μm.

3. The method according to claim 1, characterized in that The volume index SVI of the activated sludge with poor sludge settling performance or sludge swelling 30 Greater than 150mL / g.

4. The method according to claim 1, characterized in that The iron-carbon micropowder is added during the aeration or anoxic stage of the activated sludge system to ensure that the iron-carbon micropowder can fully contact with the activated sludge.

5. The method according to claim 1, characterized in that The dosage of the iron-carbon powder in the activated sludge system is 0.5-5.0 kg / m 3 .

6. The method according to claim 1, characterized in that The set working condition is to use wastewater to enter the activated sludge system for operation, and each cycle includes five stages: water inlet, aerobic, sedimentation, water outlet and idle.

7. The method according to claim 1, characterized in that Sludge volume index SVI in the sludge system after stable operation 30 Less than 50mL / g, SVI5 / SVI 30 Greater than 0.90, sludge particle size is 0.2-1.3mm.

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