A low-temperature-resistant activated sludge suitable for high-cold areas and a rapid cultivation method and application thereof

Abstract

The invention discloses low-temperature-resistant activated sludge applicable to alpine areas and a rapid cultivation method and application thereof, and relates to the technical field of sewage treatment. The invention discloses a low-temperature-resistant activated sludge cultivation method applicable to alpine areas, comprising the following steps: adding inoculated sludge into a sequencing batch activated sludge reactor, the reactor being operated in a water inlet-anoxia-aeration-sedimentation-drainage mode to domesticate the sludge, the water inlet pH being controlled between 7 and 8, the reactor being controlled at a temperature of 3 to 4°C throughout the operation, the reactor working process being water inlet for 15 to 20 minutes, anoxicity for 180 to 210 minutes, aeration for 350 to 360 minutes, sedimentation for 20 to 30 minutes, and drainage for 10 minutes; the drainage ratio being controlled between 30 and 50%, the aeration flow rate being 0.1 to 0.2 L / min, and domesticating continuously for 20 to 25 days to obtain the low-temperature-resistant activated sludge. The cultivation method provided by the present invention can realize the rapid cultivation of low-temperature activated sludge without the need to add additional low-temperature bacterial agents during the cultivation process, and the cultivated low-temperature activated sludge can achieve efficient nitrogen and phosphorus removal without the need to add carbon sources and phosphorus removal agents.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to low-temperature-resistant activated sludge suitable for high-cold areas, and a rapid cultivation method and application thereof. Background Art

[0002] my country's high-altitude cold regions are at low temperatures all year round, which makes the sewage temperature in the region (3~4℃) much lower than that in inland areas. The investigation found that the activated sludge process is a commonly used sewage treatment process in sewage treatment plants in high-altitude cold regions. When the water temperature is lower than 10℃, the metabolic capacity of microorganisms in the activated sludge for pollutants will decrease significantly, making it difficult for sewage to be discharged stably and meet standards. Among them, the inhibitory effect of low temperature on the removal efficiency of nitrogen compounds is particularly serious. Studies have found that the removal efficiency of nitrogen compounds by the activated sludge process is positively correlated with temperature. However, when the temperature drops to 5℃, the nitrifying bacteria and denitrifying bacteria in the activated sludge will enter a dormant state, which makes the removal efficiency of microorganisms for nitrogen compounds stop. More importantly, low temperature will also cause the sludge sedimentation to deteriorate, which can easily lead to the occurrence of sludge bulking.

[0003] In view of the technical bottlenecks faced by sewage treatment in high-cold areas, although existing studies have explored strategies and control methods for rapid cultivation of low-temperature sludge, the addition of bacterial agents is still the main cultivation method. At the same time, the cultivation method also uses a gradual cooling method to cultivate low-temperature sludge, which makes the sludge cultivation cycle require at least 3 to 4 months. More importantly, adding bacterial agents to the biochemical pool will not only greatly increase the difficulty of operation, but also increase the cost of sewage treatment, which is difficult to promote and apply in high-cold areas with weak economic foundation and operation and maintenance management capabilities. At the same time, in order to ensure the nitrification of activated sludge under low-temperature conditions, it is usually necessary to add fillers to the biochemical pool to ensure the nitrification reaction. However, the addition of fillers will not only increase the cost of sewage treatment, but also take a very long time to achieve the biofilm growth of nitrifying bacteria, and the mature biofilm has poor adaptability to temperature changes. Based on the drawbacks of existing cultivation measures, it is urgent to develop a low-temperature activated sludge cultivation method with a short cultivation cycle, strong low temperature resistance, low sludge concentration, strong decarbonization, phosphorus and nitrogen removal performance, strong polyphosphate effect, stable operation effect and strong impact resistance to meet the treatment of sewage in high-cold areas. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a low-temperature-resistant activated sludge suitable for use in high-cold areas and a rapid cultivation method and application thereof.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A low-temperature-resistant activated sludge cultivation method suitable for alpine areas comprises the following steps: adding inoculated sludge into a sequencing batch activated sludge reactor (SBR reactor), and the reactor is operated in a water inlet-anoxic-aeration-sedimentation-drainage mode to domesticate the sludge, wherein the pH of the water inlet is controlled between 7 and 8, the temperature of the reactor is controlled at 3 to 4°C during the whole operation, the working process of the reactor is water inlet for 15 to 20 minutes, anoxic for 180 to 210 minutes, aeration for 350 to 360 minutes, sedimentation for 20 to 30 minutes, and drainage for 10 minutes; the drainage ratio is controlled between 30 and 50%, the aeration flow rate is 0.1 to 0.2 L / min, and the activated sludge is obtained by continuous domestication for 20 to 25 days.

[0007] Among them, the MLSS of inoculated sludge was between 5000~5250 mg / L, and the MLVSS was between 2630~2920 mg / L.

[0008] When the reactor is influent, the carbon-nitrogen ratio of the wastewater is 5, the influent ammonia nitrogen concentration is 40~50 mg / L, the COD concentration is 200~250 mg / L, and the total phosphorus concentration is 2~3 mg / L.

[0009] Sodium bicarbonate is added as an acid-base buffer when water enters the reactor, sodium acetate is used as a carbon source, ammonium chloride is used as a nitrogen source, and potassium dihydrogen phosphate is used as a phosphorus source.

[0010] Preferably, trace elements are added when the reactor is fed with water, and 0.5 mL of trace elements are added to 1 L of wastewater.

[0011] The dissolved oxygen concentration during the aeration stage was controlled at 5~6 mg / L.

[0012] During the activated sludge cultivation period, the physical properties of the sludge are regularly analyzed, including: MLSS, MLVSS, SVI 30 and sludge morphology and structure; analyze the inlet and outlet water quality every day, including: COD, ammonia nitrogen, total nitrogen and total phosphorus content; as the reaction proceeds, SVI 30 It will gradually drop from the initial 400~500 mL / g to below 200 mL / g; scanning electron microscopy was used to observe the aggregation and appearance of microorganisms in the activated sludge.

[0013] When the system has a COD, ammonia nitrogen and total phosphorus removal rate of 95% and a total nitrogen removal rate of 70% for at least 2 to 3 weeks, the operation cycle will be shortened to 4 to 5 hours.

[0014] The second aspect of the present invention provides low-temperature resistant activated sludge suitable for use in high-cold areas, which is prepared by the above-mentioned preparation method.

[0015] A third aspect of the present invention provides an application of low-temperature resistant activated sludge suitable for low-temperature sewage treatment in high-cold areas.

[0016] By precisely controlling the culture parameters such as time control, aeration volume, carbon-nitrogen ratio, etc. at each stage of the reactor, the dormant state of nitrifying bacteria and denitrifying bacteria at 5°C can be broken, so that nitrifying bacteria and denitrifying bacteria still have high activity at 3-4°C and become dominant species during the culture process. At the same time, the process of the present invention can also increase the relative abundance of nitrifying bacteria and denitrifying polyphosphate bacteria, with the highest increase reaching 117.15%.

[0017] Among them, stirring begins after the reactor is filled with water until the aerobic stage is finished. On the one hand, it increases the cold resistance of microorganisms; on the other hand, it forms heavy sludge to improve the sedimentation of sludge. Cultivation in a low-temperature environment can promote the secretion of extracellular polymers of microorganisms in the sludge. On the one hand, the secreted extracellular polymers can promote the aggregation of microorganisms in the sludge. After the microorganisms aggregate, they promote the electron transfer between microorganisms through group response, conductive pili and flagella, thereby promoting the denitrification reaction; on the other hand, extracellular polymers can be used as a carbon source to promote the stability of the denitrification reaction during sewage treatment. Increasing the dissolved oxygen concentration in the water body during the aeration stage is conducive to promoting the growth of low-temperature resistant heterotrophic nitrification-aerobic denitrification bacteria, ensuring the nitrogen removal efficiency of activated sludge in a low-temperature environment.

[0018] The beneficial effects of the present invention are:

[0019] The cultivation method provided by the present invention can realize the simultaneous nitrification and denitrification of low-temperature activated sludge without adding low-temperature bacterial agents and fillers during the cultivation process, and the accumulation of excessive intermediate products is avoided without the addition of exogenous agents. Through strict control of cultivation parameters, the activated sludge obtained after 20 to 25 days of cultivation can form a short-range nitrification and denitrification reaction during sewage treatment, shorten the reaction time of the anoxic stage, and has a very strong phosphorus removal effect, which can greatly shorten the sludge discharge cycle and sludge discharge volume; the aggregation of different microorganisms in the activated sludge can increase the sedimentation of the sludge; the microorganisms with nitrification, denitrification and polyphosphate effects in the cultivated activated sludge are in a dominant position, and their relative abundance exceeds 50%, and it has the advantages of strong low temperature resistance and high pollutant removal efficiency.

[0020] Compared with other cultivation methods, the cultivation method of the present invention can significantly improve the removal efficiency of ammonia nitrogen and total nitrogen at 3-4°C, and the removal rates of ammonia nitrogen and total nitrogen are increased by 50.74% and 70.24%, respectively. The successfully domesticated activated sludge can ensure the stable nitrification reaction at low temperature, and can achieve stable and standard discharge of nitrogen and phosphorus without the need for additional addition of external carbon sources and phosphorus removal agents during sewage treatment, greatly reducing the cost of sewage treatment.

[0021] At 3~4℃, low-temperature activated sludge can be cultivated after 20~25 days of acclimatization. Compared with the existing cultivation technology, the cultivation period can be shortened by 30~45 days. The acclimatized low-temperature activated sludge can ensure that the sewage stably reaches the Class A discharge standard at extremely low sludge concentration. The removal rates of COD, ammonia nitrogen and total phosphorus exceed 95%, and the removal rate of total nitrogen exceeds 70%. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a scanning electron microscope photo of mature activated sludge obtained on the 25th day of cultivation;

[0023] Figure 2 This is the screening and growth statistics of microbial communities in activated sludge after the 25th day;

[0024] Figure 3 It is the statistical chart of COD removal rate during the cultivation process;

[0025] Figure 4 This is a statistical chart of ammonia nitrogen removal rate during the cultivation process;

[0026] Figure 5 This is a statistical chart of total nitrogen removal rate during the cultivation process;

[0027] Figure 6 This is a statistical chart of total phosphorus removal during the cultivation process;

[0028] Figure 7 This is a statistical chart of the data when two types of activated sludge are used for sewage treatment. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0030] A rapid cultivation method for low-temperature resistant activated sludge suitable for high-cold areas:

[0031] (1) Flocculent activated sludge from a municipal sewage treatment plant at room temperature was added to a sequencing batch reactor as inoculum sludge. Before use, the inoculum sludge was filtered using a 100-mesh steel sieve to remove large particles of impurities in the sludge. The MLSS of the inoculum sludge was between 5000 and 5250 mg / L, and the MLVSS was between 2630 and 2920 mg / L, where MLSS is the sludge concentration and MLVSS is the volatile suspended solids concentration.

[0032] (2) The effective volume of the SBR reactor is 10 L, the width is 20 cm, the height is 35 cm, and there is a stirrer in the reactor. The SBR reactor operates in the mode of water inlet-anoxic-aeration-sedimentation-drainage. During the operation of the reactor, water inlet, drainage, stirring and aeration are realized through an automatic control system. The pH of the inlet water is controlled between 7 and 8. During the operation of the reactor, it is placed in a refrigerator at 3 to 4 ° C. The inlet water tank is also placed in a refrigerator at 3 to 4 ° C. The startup conditions of the reactor are water inlet for 15 to 20 min, anoxic for 180 to 210 min, aeration for 350 to 360 min, sedimentation for 20 to 30 min, and drainage for 10 min. The initial cycle operation time is controlled at 9.5 to 10.5 h. In the later stage of operation, when the COD, ammonia nitrogen and total phosphorus removal rates reach 95% and the total nitrogen removal rate reaches 70% within at least 2 to 3 weeks, the operation cycle is shortened to 4 to 5 h, and the entire cultivation cycle is 20 days. The drainage ratio is controlled between 30~50%, and the aeration flow rate is 0.1~0.2 L / min.

[0033] (3) According to the water quality of influent sewage in alpine areas, simulated wastewater was prepared. The carbon-nitrogen ratio of the wastewater was 5, the influent ammonia nitrogen concentration was 40-50 mg / L, the COD concentration was 200-250 mg / L, the total phosphorus concentration was 2-3 mg / L, and a certain amount of sodium bicarbonate was added as an acid-base buffer. The influent used sodium acetate as the carbon source, ammonium chloride as the nitrogen source, and potassium dihydrogen phosphate as the phosphorus source. Among them, 0.5 mL of trace elements was added to 1 L of wastewater.

[0034] (4) In the early stage of activated sludge cultivation, the physical properties of sludge are analyzed regularly, including: MLSS, MLVSS, SVI 30 and sludge morphology and structure, and analyze the inlet and outlet water quality every day, including: COD, ammonia nitrogen, total nitrogen and total phosphorus. As the reaction proceeds, SVI 30 It will gradually decrease from the initial 400-500 mL / g to below 200 mL / g; Scanning electron microscopy can be observed that microorganisms in activated sludge will secrete extracellular polymers to promote the aggregation of microorganisms, improve the sedimentation and cold resistance of microorganisms, and the surface of microorganisms will become smoother; with the optimization of sludge sedimentation performance, the sedimentation time will be gradually shortened from 30 min to 15 min, and then with the SVI 30 A further decrease in the value reduces the precipitation time to 5 min.

[0035] (5) Stirring should be started immediately after the SBR reactor is filled with water and the stirring should be continued until the aerobic stage is completed. The stirring rate should be controlled at 60-70 rpm / min.

[0036] (6) An aeration plate is set at the bottom of the SBR reactor, and a constant pressure aeration pump is used in conjunction with the aeration plate for aeration. The aeration volume is adjusted by a rotor flow meter, and the dissolved oxygen concentration is strictly controlled at 5-6 mg / L. If the ammonia nitrogen concentration in the inlet water is too high, nitrate nitrogen will accumulate in the system. At this time, the drainage ratio is adjusted by starting and stopping the drainage valve.

[0037] By strictly controlling the parameters of each stage of the SBR reactor operation, activated sludge with good sewage treatment effect can be obtained after 20 days of continuous cultivation. If the cultivation is continued to 25 days, the total nitrogen removal effect of the activated sludge will be better. The low-temperature activated sludge after cultivation and acclimatization can ensure the stable discharge of sewage at 3~4 ℃, and its effluent COD, ammonia nitrogen, total nitrogen and total phosphorus concentrations are less than 20 mg / L, 0.5 mg / L, 10 mg / L and 0.1 mg / L. At the same time, the sedimentation of the sludge is also greatly improved. Compared with traditional activated sludge, the sedimentation of the sludge is improved by more than 100%. The scanning electron microscope photo of the mature activated sludge obtained on the 25th day of cultivation is shown in the figure. Figure 1 Screening and growth of microbial communities in activated sludge after 25 days Figure 2 As shown in Figure 2, the removal rates of COD, ammonia nitrogen, total nitrogen and total phosphorus during the culture process are as follows: Figure 3-6 .

[0038] test:

[0039] The activated sludge obtained by the cultivation method of the present invention was subjected to low-temperature sewage treatment below 10°C, and the control group was subjected to sewage treatment by using activated sludge cultivated in a step-by-step cooling manner (from 25°C to 8°C). The sewage treatment data of the two groups are shown in FIG. Figure 7 .

[0040] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A method for rapid cultivation of low-temperature resistant activated sludge suitable for high-cold areas, characterized in that: The following steps are involved: Inoculated sludge was added to the sequencing batch activated sludge reactor, and the reactor was operated in the mode of water inlet-anoxic-aeration-sedimentation-drainage for sludge domestication, wherein the inlet pH was controlled between 7 and 8, the temperature of the reactor was controlled at 3-4°C throughout the operation, the working process of the reactor was water inlet for 15-20 minutes, anoxic for 180-210 minutes, aeration for 350-360 minutes, sedimentation for 20-30 minutes, and drainage for 10 minutes; the drainage ratio was controlled between 30-50%, the aeration flow rate was 0.1-0.2 L / min, and the initial cycle operation time was controlled at 9.5-10.5 hours. When the COD, ammonia nitrogen and total phosphorus removal rates of the system reached 95% and the total nitrogen removal rate reached 70% within at least 2-3 weeks, the operation cycle was shortened to 4-5 hours, and the continuous domestication was carried out for 20-25 hours. d to obtain activated sludge; the MLSS of the inoculated sludge is between 5000 and 5250 mg / L, and the MLVSS is between 2630 and 2920 mg / L; when the reactor is influent, the carbon-nitrogen ratio of the wastewater is 5, the ammonia nitrogen concentration of the influent is 40 to 50 mg / L, the COD concentration is 200 to 250 mg / L, and the total phosphorus concentration is 2 to 3 mg / L; the dissolved oxygen concentration in the aeration stage is controlled at 5 to 6 mg / L.

2. The activated sludge cultivation method according to claim 1, characterized in that: When water enters the reactor, sodium bicarbonate is added as an acid-base buffer, sodium acetate is used as a carbon source, ammonium chloride is used as a nitrogen source, and potassium dihydrogen phosphate is used as a phosphorus source.

3. The activated sludge cultivation method according to claim 1, characterized in that: Trace elements were added when the reactor was fed with water, and 0.5 mL of trace elements was added to 1 L of wastewater.

4. The activated sludge cultivation method according to claim 1, characterized in that: During the activated sludge cultivation period, the physical properties of the sludge are regularly analyzed, including: MLSS, MLVSS, SVI 30 and sludge morphology and structure; analyze the inlet and outlet water quality every day, including: COD, ammonia nitrogen, total nitrogen and total phosphorus content; as the reaction proceeds, SVI 30 It will gradually drop from the initial 400~500 mL / g to below 200 mL / g; scanning electron microscopy was used to observe the aggregation and appearance of microorganisms in the activated sludge.

5. A low-temperature resistant activated sludge suitable for use in high-cold areas, characterized by: The method is prepared by any one of claims 1 to 4.

6. Use of the low-temperature-resistant activated sludge suitable for cold regions as claimed in claim 5 in low-temperature sewage treatment.

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