CN103145233A - Method for achieving fast cultivation of shortcut nitrifying granule sludge - Google Patents

Abstract

The invention belongs to the field of urban domestic sewage treatment and regeneration, and in particular relates to a rapid cultivation method of aerobic granular sludge with short-range nitrification performance. The invention adopts the method of gradually shortening the settling time, and operates the sequencing batch reactor (SBR) in the mode of fixing the aeration time and aeration volume, so as to rapidly cultivate the short-range nitrification granular sludge. After three stages of culture, granule formation, and granule maturity, the granulation of ordinary floc sludge was successfully realized within 20 days, and the nitrite accumulation rate (NAR) reached 80% within 80 days, with an average particle size of more than 800 μm and NH ₄ ⁺ -N removal rate is close to 100%, COD removal rate is 94%.

Description

A method for rapid cultivation of short-range nitrification granular sludge

technical field

The invention belongs to the field of urban domestic sewage treatment and regeneration, and in particular relates to a rapid cultivation method of aerobic granular sludge with short-range nitrification performance. the

Background technique

With the rapid development of science and technology, environmental problems represented by water pollution have become increasingly prominent, and the removal of ammonia nitrogen in wastewater has attracted the attention of many scholars. With the development of sewage treatment technology, many treatment methods have appeared today, among which biological denitrification technology has become a research hotspot in this field. the

Compared with the whole process of denitrification, the short-range denitrification can save 25% of the aeration volume in the nitrification stage, and can reduce the organic carbon source by 40% in the denitrification stage, and the short-range nitrification-denitrification biological denitrification process has the advantages of less alkalinity consumption and short reaction time It is considered to be a sustainable new technology for denitrification of sewage due to its characteristics of low yield and low sludge yield. In recent years, short-range denitrification has received extensive attention. The key to the realization and stable maintenance of short-cut denitrification is to terminate the nitrification process at the NO ₂ ^- -N stage, that is, short-cut nitrification. The control strategy to realize short-cut nitrification is of great significance for the wide application of short-cut nitrification and denitrification process in engineering practice.

In the 1990s, aerobic granular sludge technology appeared for the first time as a new sewage biological treatment technology. Aerobic granulation is considered to be a gradual change process from floc sludge to compact granules. Compared with flocculent activated sludge, granular sludge has the advantages of outstanding settling performance, high sludge density, high physical strength, high biomass and strong organic load bearing capacity. However, the start-up time of anaerobic granular sludge technology is relatively long,

The high operating temperature, unstable treatment of low-load sewage, and low efficiency in nitrogen and phosphorus removal have promoted people's research on aerobic granular sludge technology, and achieved a series of research results. Development of aerobic granular sludge biological nitrogen removal technology. Nitrifying granular sludge is a granular microbial aggregate formed by the aggregation and growth of a large number of nitrifying bacteria. It has a regular shape, compact structure, and excellent sedimentation performance. It has a high removal rate of ammonia nitrogen and can be used to treat high-concentration ammonia nitrogen wastewater. the

The combination of short-cut nitrification biological denitrification technology and aerobic granular sludge process is a new way to obtain stable short-cut nitrification. Nitrosifying granular sludge composed of ammonia oxidizing bacteria (AOB), nitrite oxidizing bacteria (NOB) and other heterotrophic bacteria has certain stability and can adapt to some variable environmental conditions. the

Contents of the invention

The purpose of the present invention is to provide a method capable of realizing rapid cultivation of short-range nitrification granular sludge. the

At a temperature of 20-30°C, the drainage ratio is 50-65%, the inoculation sludge is inoculated with the residual sludge of the urban sewage treatment plant, and the settling time is used as the selective pressure, and the method of gradually shortening the settling time is adopted, and artificial life is simulated. Sewage, cultivate aerobic granular sludge; run the sequencing batch reactor (SBR) with fixed aeration time and aeration volume to achieve short-range nitrification, and finally cultivate aerobic granular sludge with short-range nitrification performance. the

A method for realizing rapid cultivation of short-course nitrification granular sludge, characterized in that: at a temperature of 20-30°C, the drainage ratio is 50-65%, and the residual sludge of urban sewage treatment plants is used as the inoculation sludge of the system, and the operation sequence Batch reactor, hereinafter referred to as reactor;

1) In the initial stage of cultivation, start the reactor with simulated domestic sewage, control the concentration of COD to 350-450mg/L, the concentration of NH ₄ ⁺ -N to 80-100mg/L, the MLSS of inoculated sludge to 3500-4500mg/L, and the SVI to 80~90mL/g; the system operates 3 cycles per day, each cycle is 7.5~8h, including water inflow for 3~6min, aerobic aeration for 7.2~7.5h, settling time for 12~16min, drainage for 3~6min, the remaining The time is the idle time, in which the aeration rate is 0.9-1.2L/h; at this stage, when the average particle size of the sludge in the system is more than 1.5 times the average particle size of the inoculated sludge, and the SVI value of the sludge continuously exceeds 4 The cycle is in a downward trend, and it is considered that the system has undergone a granulation process and entered the granule formation stage;

2) In the particle formation stage, the influent of the reactor is still simulated domestic sewage, the COD concentration is controlled at 350-450mg/L, the NH ₄ ⁺ -N concentration is 80-100mg/L, and the inoculation sludge MLSS is 3500-4500mg/L , SVI is 80-90mL/g; the system runs 3 cycles per day, each cycle is 7.5-8 hours, including water inflow for 3-6 minutes, aerobic aeration for 7.2-7.5 hours, sedimentation time shortened to 3-8 minutes, and drainage for 3-8 minutes 6min, and the remaining time is idle time, in which the aeration rate is 0.9-1.2L/h; at this stage, when the average particle size of the sludge in the system is more than 4.5 times the average particle size of the inoculated sludge, and the SVI value of the sludge is continuous If there is a downward trend for more than 4 cycles, it is considered that the system has entered the granule maturity stage;

3) In the particle maturity stage, the influent of the reactor is still simulated domestic sewage, the COD concentration is controlled at 350-450mg/L, the NH ₄ ⁺ -N concentration is 80-100mg/L, and the inoculation sludge MLSS is 3500-4500mg/L , SVI is 80-90mL/g; the system runs 3 cycles per day, each cycle is 7.5-8 hours, including water inflow for 3-6 minutes, aerobic aeration for 7.2-7.5 hours, sedimentation time shortened to 1.5-3 minutes, and drainage for 3-6 minutes 6min, and the remaining time is idle time, in which the aeration rate is 0.9-1.2L/h; at this stage, when the NH ₄ ⁺ -N value of the effluent is less than 1mg/L, and the NAR value is greater than 80%, it is considered that a stable At the same time, when the average particle size of the sludge in the system is more than 7 times the average particle size of the inoculated sludge, and the SVI value of the sludge is on a downward trend or remains unchanged for more than 4 consecutive cycles, the MLSS value continues More than 4 cycles show an upward trend, and it is considered that the short-course nitrification granular sludge culture is mature.

The present invention has the following beneficial effects:

1) The present invention successfully realizes the granulation of ordinary floc sludge within 20 days through three stages of initial cultivation, granule formation and granule maturity, and the average particle size increases by more than 4.5 times. From inoculation to aerobic granular sludge maturity within 80 days, the average particle size increases by more than 7 times, the removal rate of NH ₄ ⁺ -N is close to 100%, the removal rate of COD is more than 90%, and the NAR value is more than 80%.

2) The present invention gradually shortens the settling time as the selective pressure of the system, which helps to retain the sludge with good settling performance and elutriate the floc sludge with poor settling performance, promotes the sludge aggregation to facilitate granulation, and accelerates the granulation speed . In response to the short settling time, the content of inorganic matter in the sludge gradually increases, and the microorganisms will selectively accumulate some metal ions to increase their own density, thereby improving the compactness and settling performance of the sludge. the

3) The present invention operates the Sequencing Batch Reactor (SBR) by means of a fixed aeration time and aeration rate. Since the aeration time and aeration rate remain unchanged, the sludge in the reactor is continuously washed, resulting in nitrification Insufficient number of bacteria leads to incomplete nitrification reaction, which is equivalent to the incomplete oxidation of NH ₄ ⁺ -N and premature termination of aeration, resulting in the accumulation of NO ₂ ^- -N. Long-term incomplete nitrification inhibits the activity of NOB bacteria. At the same time, the particle shape of granular sludge is conducive to the attachment and enrichment of AOB bacteria. short-range nitrification.

Description of drawings

Fig. 1 is a graph showing the variation of sludge characteristics during the experiment of the present invention. At the end of the experiment, the sludge MLSS reached 6440mg/L, SVI was 21mL/g, and the sedimentation performance was significantly improved. the

Fig. 2 is the change curve of nitrification characteristics during the experimental process of the present invention. From the 66th d, the NH ₄ ⁺ -N concentration in the effluent is lower than 0.5mg/L, the NH ₄ ⁺ -N removal rate is close to 100%, the NAR value rises steadily, and reaches 83%.

Fig. 3(a) is a scanning electron microscope image of the appearance of the short-course nitrification granular sludge cultivated by the method of the present invention. the

Fig. 3(b) is an internal scanning electron micrograph of the short-range nitrification granular sludge cultivated by the method of the present invention. the

The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto. the

Detailed ways

Embodiment 1:

SBR reactor is adopted, with a height of 50cm, a diameter of 23.5cm, and an effective volume of 21L. It is made of plexiglass. A row of sampling ports with a spacing of 10cm is set on the vertical direction of the reactor wall, and a sludge discharge pipe is provided at the bottom. The drainage ratio 60%. The rubber microporous aeration disc is used as the aerator, and the air blowing is used for aeration, and the rotameter controls the aeration volume to keep it constant at 1L/h. The temperature in the reactor is controlled by a temperature controller and kept at 25-28°C. The operation of the SBR reactor realizes the automatic control of the reaction process through the time program controller, and runs 3 cycles a day, each cycle is 8h. The influent is artificially simulated domestic sewage, with sodium acetate as the organic carbon source, the corresponding COD concentration is 400mg/L, and the NH ₄ ⁺ -N concentration is 80mg/L. The MLSS of the inoculated sludge was 4030mg/L, the SVI was 89mL/g, and the average particle size was 106.56μm.

In the initial cultivation stage, each cycle includes 5 minutes of water inflow, 7.5 hours of aerobic aeration, 15 minutes of sedimentation, 5 minutes of drainage and 5 minutes of idle time. In the initial stage, the MLSS of the inoculated sludge was high and the aeration time and aeration volume were sufficient so that NH ₄ ⁺ -N was almost completely oxidized, and the effluent concentration was lower than 2mg/L. On the 6th day of operation, the nitrite accumulation rate (NAR) increased to 20%. Because a large amount of sludge with poor settling performance was washed out by the system, the MLSS value of the sludge decreased, but the SVI value was always on a downward trend. When the average particle size is 216.52 μm, the system enters the particle formation stage.

The particle formation stage, starting from the 7th day, each cycle includes 5 minutes of water intake, 7.5 hours of aerobic aeration, 3 minutes of sedimentation, 5 minutes of drainage and 17 minutes of idle time. On the 20th day of operation, due to the elutriation of part of the sludge, the number of AOB bacteria in the system decreased, so that the concentration of NH ₄ ⁺ -N in the effluent increased slightly, but it was lower than 5mg/L, and the NAR value of the system rose to more than 30%. , due to the presence of a large amount of floc sludge in the reactor, the sludge settleability has not been significantly improved. Although the sludge SVI value continues to decrease, it is still above 70mL/g, and the sludge color has changed from yellowish brown to light. Yellow, and fine sandy granular sludge appears, with an average particle size of 480.74 μm, indicating that the system has entered a mature stage.

The particle maturation stage starts from the 21st day, and each cycle includes 5 minutes of water inflow, 7.5 hours of aerobic aeration, 2 minutes of sedimentation, 5 minutes of drainage and 18 minutes of idle time. The shorter settling time caused the sludge with poor settling property to flow out with the effluent, and the MLSS showed a downward trend. On the 47th day, MLSS dropped to 1020mg/L, and the concentration of NH ₄ ⁺ -N in the effluent reached 17.38mg/L because the aeration time and aeration volume remained unchanged. With the increase of culture time, MLSS increased continuously, and the concentration of NH ₄ ⁺ -N in effluent decreased continuously. On the 66th day, the MLSS reached about 3000mg/L, and the effluent NH ₄ ⁺ -N was lower than 2mg/L again. After that, it further decreased until the 80th day, when the effluent NH ₄ ⁺ -N was lower than 0.5 mg/L, the removal rate of NH ₄ ⁺ -N was close to 100%, at this time the NAR value was close to 80%, and the average particle size of the sludge in the reactor was 856.56 μm, the short-course nitrification granular sludge culture is mature, and the NAR value reaches 83% at the end of the experiment, and a stable short-course nitrification is formed in the system.

The short-course nitrification granular sludge was cultivated and matured within 80 days, and the pollutants in the system were effectively removed. The COD removal rate reached 94%, the NO ₃ ^- -N removal rate reached 83%, and the NH ₄ ⁺ -N removal rate was close to 100%.

Claims (1)

1. method that realizes short distance nitration granule sludge fast culture, it is characterized in that: at 20～30 ℃ of temperature, the draining ratio is 50～65%, take the excess sludge of municipal sewage plant as the seed sludge of system, the operation sequencing batch reactor is hereinafter to be referred as reactor;

1) the initial-stage culture stage, adopt simulated domestic wastewater to start reactor, controlling COD concentration is 350～450mg/L, NH ₄ ⁺-N concentration is 80～100mg/L, and seed sludge MLSS is 3500～4500mg/L, and SVI is 80～90mL/g; System moves 3 cycles every day, and each cycle 7.5～8h comprises into water 3～6min, aerobic aeration 7.2～7.5h, and sedimentation time is made as 12～16min, draining 3～6min, be idle mixing time remaining time, wherein aeration rate is 0.9～1.2L/h; In this stage, when intrasystem mud median size is more than 1.5 times of seed sludge median size, and the SVI value of mud surpasses continuously 4 cycles and is in downtrending, thinks that pelletising process has occured in system, enters the particle formation stages;

2) particle formation stages, the water inlet of reactor are still simulated domestic wastewater, and controlling COD concentration is 350～450mg/L, NH ₄ ⁺-N concentration is 80～100mg/L, and seed sludge MLSS is 3500～4500mg/L, and SVI is 80～90mL/g; System moves 3 cycles every day, and each cycle 7.5～8h comprises into water 3～6min, aerobic aeration 7.2～7.5h, and sedimentation time shortens to 3～8min, draining 3～6min, be idle mixing time remaining time, wherein aeration rate is 0.9～1.2L/h; This stage, when mud median size in system is more than 4.5 times of seed sludge median size, and the SVI value of mud to surpass continuously 4 cycles on a declining curve, think that system enters the particle stage of maturity;

3) the particle stage of maturity, the water inlet of reactor is still simulated domestic wastewater, and controlling COD concentration is 350～450mg/L, NH ₄ ⁺-N concentration is 80～100mg/L, and seed sludge MLSS is 3500～4500mg/L, and SVI is 80～90mL/g; System moves 3 cycles every day, and each cycle 7.5～8h comprises into water 3～6min, aerobic aeration 7.2～7.5h, and sedimentation time shortens to 1.5～3min, draining 3～6min, be idle mixing time remaining time, wherein aeration rate is 0.9～1.2L/h; This stage is as water outlet NH ₄ ⁺-N value is less than 1mg/L, and the NAR value is greater than 80%, thinks to have formed stable short distance nitration in reactor; Meanwhile, when mud median size in system is more than 7 times of seed sludge median size, and the SVI value of mud is in downtrending or remains unchanged over 4 cycles continuously, and it is in rising trend that the MLSS value surpasses 4 cycles continuously, thinks that the cultivation of short distance nitration granule sludge is ripe.

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