CN107235552B - Method for promoting granulation of flocculent activated sludge by applying nano magnet - Google Patents
Method for promoting granulation of flocculent activated sludge by applying nano magnet Download PDFInfo
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- CN107235552B CN107235552B CN201710601045.8A CN201710601045A CN107235552B CN 107235552 B CN107235552 B CN 107235552B CN 201710601045 A CN201710601045 A CN 201710601045A CN 107235552 B CN107235552 B CN 107235552B
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/02—Aerobic processes
- C02F3/12—Activated sludge processes
- C02F3/1205—Particular type of activated sludge processes
- C02F3/1215—Combinations of activated sludge treatment with precipitation, flocculation, coagulation and separation of phosphates
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/02—Aerobic processes
- C02F3/12—Activated sludge processes
- C02F3/1236—Particular type of activated sludge installations
- C02F3/1263—Sequencing batch reactors [SBR]
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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- C02F2203/00—Apparatus and plants for the biological treatment of water, waste water or sewage
- C02F2203/006—Apparatus and plants for the biological treatment of water, waste water or sewage details of construction, e.g. specially adapted seals, modules, connections
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Abstract
The invention relates to a method for promoting granulation of flocculent activated sludge by applying a nano magnet. The method comprises the following steps: mixing the flocculent activated sludge, the nano magnet and the sewage, and promoting the granulation of the flocculent activated sludge through the interaction between the nano magnet and the flocculent activated sludge; the granulation process is carried out at room temperature in cycles, and each cycle is fully aerated. The method can effectively shorten the granulation process of the activated sludge, and can effectively shorten the sludge granulation time by adding a small amount of nano magnets, thereby having low cost; and the obtained particles are more compact and have better stability. The method has simple process and mild reaction conditions, and can be carried out at normal temperature and normal pressure; is safe and harmless to the environment and is convenient for engineering application.
Description
Technical Field
The invention relates to a method for promoting granulation of flocculent activated sludge by applying a nano magnet, belonging to the technical field of environmental chemistry and wastewater treatment.
Background
Aerobic granular sludge is a special form of microorganism immobilization technology, and is a novel wastewater biological treatment technology which is started in recent years. The aerobic granular sludge is a biological aggregate which is formed by activated sludge microorganisms through self-immobilization and has a compact structure and a regular shape. Compared with flocculent activated sludge, the aerobic granular sludge has the advantages of compact structure, excellent settling property, various microbial populations and the like, has higher tolerance capacity to impact load, toxic substances, heavy metals and the like, and has better treatment effect on difficultly-degradable pollutants; the aerobic granular sludge is utilized to treat the sewage in the sequencing batch reactor, a secondary sedimentation tank and a sludge reflux system are not needed, the process is simple, the operation is flexible, the occupied area is small, and the investment and operation cost is low. The formation of sludge granules is affected by many factors, the process involving microbial growth and attenuation, mass transfer of oxygen and diffusion of substrates, etc., is very complex, which makes the sludge granulation process time-consuming and often takes several months. Such a long start-up time limits the industrial application of aerobic granular sludge, most of the current researches on aerobic granular sludge still stay in laboratories and pilot plant stages, only a few practical applications exist, many key technologies remain to be solved, and particularly how to shorten the time for converting activated sludge into aerobic granular sludge at a low cost, so that the problems of batch production, storage, transportation and the like in practical application become a hot point of the current researches. Therefore, speeding up the sludge granulation process at a lower cost, and thus shortening the granule formation time, is of great importance for the practical application of this technology.
At present, in the prior art, related researches on sludge granulation are carried out. For example, chinese patent document CN105731640A discloses a magnetite-enhanced bioelectrode-coupled UASB device and an operation method thereof; according to the invention, magnetite nanoparticles are added to strengthen direct electron transfer between microorganisms and electrodes, so that the rapid start of an anaerobic bioreactor, sludge granulation and improvement of productivity are finally realized; however, the invention combines the comprehensive action of the electric field and the magnetite, is more complicated, and has more consumption of the magnetite and higher cost. For another example, chinese patent document CN106396093A discloses a method for promoting granulation of activated sludge, in which modified nanospheres are added to an activated sludge system to promote granulation of sludge; the modified nanosphere is prepared by taking a surfactant, NaOH, an aqueous solution, tetraethoxysilane and a silicon source as main raw materials; the modified nanospheres can accelerate granulation process and promote continuous growth of granular sludge; however, the preparation method of the modified nanosphere is complicated, the consumption of the modified nanosphere is large, and the cost is high.
Disclosure of Invention
Aiming at the defects in the prior art that the conversion from flocculent activated sludge to aerobic granular sludge is long, the cost is high, and the practical application of the aerobic granular sludge is seriously hindered, the invention provides a method for promoting the granulation of the flocculent activated sludge by using a nano magnet. The method can promote the granulation of the activated sludge, promote the growth of microorganisms, improve the sewage treatment efficiency, is environment-friendly, is easy for engineering application and has lower cost.
Description of terms:
room temperature: have a well-known meaning, in particular from 15 to 35 ℃.
Nano magnet: the main components are iron and oxygen, wherein the iron is mainly present in the form of ferrous iron and ferric iron.
The technical scheme of the invention is as follows:
a method for promoting granulation of flocculent activated sludge by using a nano magnet comprises the following steps:
mixing the flocculent activated sludge, the nano magnet and the sewage, and promoting the granulation of the flocculent activated sludge through the interaction between the nano magnet and the flocculent activated sludge; the granulation process is carried out at room temperature in cycles, and each cycle is fully aerated.
According to the present invention, the flocculent activated sludge is activated sludge of a municipal sewage treatment plant or an industrial wastewater treatment plant.
According to the invention, the ratio of the mass of the flocculent activated sludge to the volume of the sewage is preferably 2500-6000 mg/L.
According to the invention, the ratio of the mass of the nano magnet to the volume of the sewage is 10-200 mg/L.
Preferably, the ratio of the mass of the nano magnet to the volume of the sewage is 20-60 mg/L.
According to the invention, the mass ratio of the nano magnet to the flocculent activated sludge is 1: 20-400.
According to the invention, the nano magnet is preferably a magnetic iron oxide nano microsphere. The magnetic iron oxide nano-microsphere can be obtained commercially or prepared according to the prior art.
According to the invention, the diameter of the nano magnet is 80-400nm, and the specific surface area is 10-30m2/g。
According to the invention, the sewage is urban domestic sewage containing NH with a concentration of 30-60mg/L4 +N, COD is 400-800 mg/L.
According to the invention, the aeration rate is preferably 0.1-0.5m3The aeration time in each period is 3.5 to 11.5 hours; the hydraulic retention time is 4-12 hours.
Preferably, the aeration rate is 0.1m3The aeration time in each period is 218 min; the hydraulic retention time was 8 hours.
Preferably, according to the invention, the room temperature is 20-30 ℃; most preferably 20-25 deg.c.
Preferably, according to the invention, the granulation process is carried out for 2 to 6 cycles per day, each cycle being 3.75 to 13 hours.
According to the present invention, it is preferable that each cycle further includes: the water inlet time is 3-18min, the standing time is 10-25min, and the water outlet time is 2-17 min.
Preferably, the water inlet time is 6min, the standing time is 12min, and the water outlet time is 4 min.
According to the invention, a preferable scheme is that the method for promoting the granulation of the flocculent activated sludge by using the nano magnet comprises the following steps:
inoculating flocculent activated sludge into a sequencing batch reactor, and introducing a mixed solution A of sewage and a nano magnet; the sequencing batch reactor operates at room temperature for 2-6 periods every day, and is fully aerated with aeration rate of 0.1-0.5m3H, aeration time is 3.5-11.5 hours, water inlet time is 3-18min, standing time is 10-25min, and water outlet time is 2-17 min; the hydraulic retention time is 4-12 hours; the inlet water is a mixed liquid B of sewage and the nano magnets, and the mass concentration of the nano magnets in the mixed liquid B is the same as that of the nano magnets in the mixed liquid A so as to keep the concentration of the nano magnets in the sequencing batch reactor unchanged.
According to the invention, the Sequencing Batch Reactor (SBR) is a prior art, and the Sequencing Batch Reactor is used for culturing aerobic granular sludge by activated sludge according to the prior art.
The existing Sequencing Batch Reactor (SBR) operates an activated sludge granulation culture system, the SBR Reactor is composed of an inner pipe and an outer pipe, air enters the Reactor through a microporous aeration head arranged at the center of the bottom of the Reactor by an air pump, the formed air flow pushes liquid and sludge in the Reactor to move upwards in the inner pipe, then moves downwards between the inner pipe and the outer pipe, and is pulled by the air flow to move upwards again after reaching the bottom of the Reactor, and mixed liquid can circularly flow between the inner pipe and the outer pipe and is uniformly mixed; water is fed into the bottom of the reactor through a peristaltic pump, the on-off of a water outlet is controlled by an electromagnetic valve, and the volume exchange rate is 50%; the water inlet, aeration, sedimentation and drainage time of the SBR reactor are automatically controlled by a double-time relay, and the water inlet is urban domestic sewage.
The invention has the following beneficial effects:
(1) the nano magnet has unique super paramagnetic property and certain adsorption effect; the specific surface area effect of the nano magnet can influence the flocculation performance of the activated sludge when the nano magnet coexists with the activated sludge, so that the aerobic granulation process is accelerated; the nano magnet has biocompatibility, so that the nano magnet can coexist with activated sludge without generating biotoxicity; the surface functional groups make the nano magnet hydrophilic, can play a role of a matrix when coexisting with the activated sludge, and can react with the groups of the activated sludge, so that the conversion of the activated sludge from flocs to particles is promoted; and the obtained particles are more compact and have better stability.
(2) On the premise of keeping the treatment effect, the nano-magnet can be well dispersed in a flocculent activated sludge system and can be converted into iron ions to be used as trace elements for microorganisms, so that the granulation process is effectively promoted. Therefore, the method has the characteristics of high efficiency and safety by using the nano magnet to promote the granulation of the aerobic sludge.
(3) The nano magnet is easy to purchase, safe and harmless to the environment, and convenient for engineering application.
(4) The invention directly applies the nano magnet to the process of promoting sludge granulation, and adds a small amount of nano magnet, thus effectively shortening the sludge granulation time, having low cost, high efficiency, safety and mild conditions, and being capable of being used at normal temperature and normal pressure. The low operating cost of the method is mainly reflected in the consumption of iron. For example, the method can obtain obvious promotion effect by adding 0.25g of nano magnet into a sewage treatment system with an effective volume of 5L each time, and has the advantages of less iron consumption and lower cost.
Drawings
FIG. 1 is a scanning electron microscope image of a nanomagnet used in example 1 of the present invention.
FIG. 2 is a graph showing the effect of the sludge granulation process in test example 1.
Detailed Description
The invention is further illustrated by the following examples, but the scope of the invention as claimed is not limited to the scope described in the detailed description.
The raw materials used in the embodiment of the invention are all commercial products, and the used equipment is conventional equipment.
In the embodiment, all reactors used for sewage treatment are Sequencing Batch Reactors (SBR), which are conventional water treatment equipment purchased in the market;
the SBR reactor is composed of an inner pipe and an outer pipe, air enters the reactor through a microporous aeration head arranged at the center of the bottom of the reactor by an air pump, the formed air flow pushes liquid and sludge in the reactor to move upwards in the inner pipe, then the air flow moves downwards between the inner pipe wall and the outer pipe wall, the liquid and the sludge are pulled by the air flow to move upwards again after reaching the bottom of the reactor, and mixed liquid can flow circularly between the inner pipe wall and the outer pipe wall and is uniformly mixed; water is fed into the bottom of the reactor through a peristaltic pump, the opening and closing of a water outlet are controlled by an electromagnetic valve, the volume exchange rate is 50%, and the effective volume is 5L; the water inlet, aeration, sedimentation and drainage time of the SBR reactor are automatically controlled by a double-time relay.
The flocculent activated sludge in the examples is derived from aeration tanks of municipal sewage treatment plants.
In the embodiment, the municipal domestic sewage is taken from a regulating reservoir of a municipal sewage treatment plant, and the regulating reservoir contains NH with the concentration of 40mg/L4 +N, COD is about 500 mg/L.
The nano-magnet used in the examples is available from Shanghai Aladdin Biotechnology Ltd, with a particle size of about 200nm and a specific surface area of 15m2/g。
Example 1
A method for promoting granulation of flocculent activated sludge by using a nano magnet comprises the following steps:
inoculating flocculent activated sludge into a sequencing batch reactor, and introducing 5L of mixed liquor of urban domestic sewage and a nano magnet (the concentration of the nano magnet in the mixed liquor is 50mg/L) to ensure that the concentration of the sludge in the sequencing batch reactor is 4000mg/L and the concentration of the nano magnet is 50 mg/L; the reactor is operated at 25 deg.C according to cycle, the operation conversion of each stage in the reactor cycle is controlled by time relay, and the reactor is operated for 6 cycles every dayThe force retention time (HRT) is 8 hours, each period is 4 hours, and the period comprises water inlet time of 6min, aeration time of 218min, standing time of 12min and water outlet time of 4 min; in each period, aeration is carried out by an air compressor, and the aeration rate is maintained at 0.1m3H; the inlet water in each period is a mixed liquid of urban domestic sewage and the nano magnet (the concentration of the nano magnet in the mixed liquid is 50mg/L), so that the concentration of the nano magnet in the sequencing batch reactor is maintained at 50 mg/L. The efficiency of degrading pollutants in wastewater is improved. The reactor was stable after 10 days.
In this example, as shown in fig. 1, the scanning electron micrograph of the nanomagnet is a spherical particle having a particle diameter of about 200nm as seen from fig. 1.
Example 2
A method for promoting granulation of flocculent activated sludge using nanomagnets, the steps being as described in example 1, except that: the concentration of the nano magnet in the sequencing batch reactor is 10 mg/L.
Example 3
A method for promoting granulation of flocculent activated sludge using nanomagnets, the steps being as described in example 1, except that: the concentration of the nano magnet in the sequencing batch reactor is 100 mg/L.
Example 4
A method for promoting granulation of flocculent activated sludge using nanomagnets, the steps being as described in example 1, except that: the concentration of the nano magnet in the sequencing batch reactor is 200 mg/L.
Comparative example 1
A method of granulating a flocculent activated sludge, the steps being as described in example 1, except that: no nanomagnet was added.
Test example 1
The particle size of the particles in the reactors of example 1 and comparative example 1 was measured in real time and the results are shown in fig. 2. In FIG. 2, the abscissa is the number of days and the ordinate is the average particle diameter (in mm) of the formed particles; as shown in FIG. 2, the addition of the nano-magnet can effectively shorten the sludge granulation time.
Test example 2
The time for forming particles having a particle size of more than 0.5mm in the reactors of examples 1 to 4 and comparative example 1 was measured, and the results are shown in Table 1.
TABLE 1 aerobic sludge granulation formation time table under different nano-magnet dosages
As can be seen from Table 1, the present invention can effectively shorten the sludge granulation time with a smaller amount of nano-magnet.
Claims (1)
1. A method for promoting granulation of flocculent activated sludge by using a nano magnet comprises the following steps:
inoculating flocculent activated sludge into a sequencing batch reactor, and introducing a mixed solution A of sewage and a nano magnet; the sequencing batch reactor is operated for 6 periods at 25 ℃ per day, each period is 4 hours, each period is fully aerated, and the aeration rate is 0.1m3H, aeration time is 218min, water inlet time is 6min, standing time is 12min, and water outlet time is 4 min; the hydraulic retention time is 8 hours; the inlet water is a mixed solution B of sewage and nano magnets, and the mass concentration of the nano magnets in the mixed solution B is the same as that of the nano magnets in the mixed solution A so as to keep the concentration of the nano magnets in the sequencing batch reactor unchanged;
the mass of the flocculent activated sludge and the volume ratio of the sewage are 4000 mg/L; the mass of the nano magnet and the volume ratio of sewage are 50 mg/L; the mass ratio of the nano magnet to the flocculent activated sludge is 1: 80; the nano magnet is magnetic iron oxide nano microsphere with particle size of 200nm and specific surface area of 15m2/g。
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| CN108726669A (en) * | 2018-04-20 | 2018-11-02 | 温州大学苍南研究院 | A kind of method that magnetic activated sludge process synchronizes a variety of non-steroidal estrogenics of removal |
| CN112624327B (en) * | 2020-12-18 | 2021-12-07 | 中国农业大学 | Method for promoting formation of anaerobic granular sludge |
| CN114315442B (en) * | 2022-01-26 | 2022-10-04 | 中国农业科学院农业资源与农业区划研究所 | Method for strengthening carbon-nitrogen conversion in composting process based on magnet particles |
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| CN102849849A (en) * | 2012-10-22 | 2013-01-02 | 山东大学 | Method for treating urban domestic sewage based on magnetic nanomaterial reinforced activated sludge |
| CN106365307A (en) * | 2016-11-09 | 2017-02-01 | 成都信息工程大学 | Magnetic nano-silicon-based aerobic granular sludge and culture method and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102849849A (en) * | 2012-10-22 | 2013-01-02 | 山东大学 | Method for treating urban domestic sewage based on magnetic nanomaterial reinforced activated sludge |
| CN106365307A (en) * | 2016-11-09 | 2017-02-01 | 成都信息工程大学 | Magnetic nano-silicon-based aerobic granular sludge and culture method and application thereof |
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