CN113121019A - Efficient low-energy-consumption EMBR biochemical treatment process and treatment system - Google Patents

Efficient low-energy-consumption EMBR biochemical treatment process and treatment system Download PDF

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CN113121019A
CN113121019A CN202110553204.8A CN202110553204A CN113121019A CN 113121019 A CN113121019 A CN 113121019A CN 202110553204 A CN202110553204 A CN 202110553204A CN 113121019 A CN113121019 A CN 113121019A
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biochemical
membrane
zone
aeration
water
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王益民
刘胜伟
马雪琳
陈珍珍
柳昊
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Shanghai Kaixin Isolation Technology Co ltd
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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
    • C02F3/30—Aerobic and anaerobic processes
    • C02F3/302—Nitrification and denitrification treatment
    • 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
    • C02F3/1236—Particular type of activated sludge installations
    • C02F3/1268—Membrane bioreactor systems
    • C02F3/1273—Submerged membrane bioreactors
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/16—Nitrogen compounds, e.g. ammonia
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/10—Biological treatment of water, waste water, or sewage

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  • Life Sciences & Earth Sciences (AREA)
  • Biodiversity & Conservation Biology (AREA)
  • Microbiology (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Activated Sludge Processes (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

The invention relates to an efficient low-energy-consumption EMBR biochemical treatment process and system. The sewage enters a biochemical anoxic zone and a biochemical aerobic zone in sequence for biochemical treatment; the nitrified liquid treated in the biochemical aerobic zone is refluxed to the biochemical anoxic zone in a large proportion through a gas stripping reflux device for biological denitrification, and the rest mixed liquid enters a high-efficiency precipitation zone for sludge precipitation treatment; and sewage treated in the sludge settling zone enters a membrane tank for treatment, an immersed membrane treatment unit is arranged in the membrane tank, membrane water production is realized by the immersed membrane treatment unit, and sludge obtained in the sludge settling zone and the membrane tank flows back to a biochemical aerobic zone through a gas stripping reflux device. Compared with the prior art, the invention integrates the advantages of a biochemical system, a membrane process and a physicochemical process. The biochemical system is optimized through an aeration system and a large-proportion backflow system, so that the operation energy consumption is greatly reduced; meanwhile, due to the arrangement of the high-efficiency sludge settling tank, the operation mode of the membrane process can be flexibly switched according to the quality of the incoming water, and different requirements can be met.

Description

Efficient low-energy-consumption EMBR biochemical treatment process and treatment system
Technical Field
The invention belongs to the technical field of sewage treatment, and particularly relates to a high-efficiency low-energy-consumption EMBR biochemical treatment process and system.
Background
The current mature and widely applied biological treatment technology in the market is mainly A2The conventional treatment process is well applied to various sewage plants all over the world at present.
However, under the condition of facing continuous improvement of the productivity and severely limiting the unit water consumption and the occupied area, the traditional biological treatment process also has a plurality of technical problems which are difficult to overcome, and the treatment process is urgently needed to be optimized. For example, in the traditional biological treatment process, the impact load on the system is large when the quality fluctuation of raw water is large; the traditional aeration device has low oxygen transfer efficiency, so that the energy consumption of a fan is overhigh; the MBR process fan has high operation energy consumption and poor process flexibility; when the quality of raw water has a large deviation from the design value and the denitrification requirement is very strict, the denitrification efficiency cannot be improved.
Chinese patent CN103011395A discloses a membrane bioreaction system, a mud-water separation device is arranged between an aerobic tank of a biological treatment unit and a membrane tank of an immersed membrane treatment unit, the mud-water separation device comprises a tank body, a first guide wall, a second guide wall, a third guide wall and an aeration device, an aeration device is arranged on one side of the bottom of the tank body, mud-water separation is realized in the system through a guide wall structure, the separated mud-water mixed liquid with higher concentration flows back to the biological treatment unit through a submersible pump, and the submersible pump for backflow of the mud-water mixed liquid with higher concentration needs to consume great energy.
Disclosure of Invention
Based on the current situation that high energy consumption is needed for sludge backflow in the sewage treatment process in the prior art, the invention provides an efficient low-energy consumption EMBR biochemical treatment process and a treatment system.
The purpose of the invention can be realized by the following technical scheme:
the invention firstly provides an efficient low-energy consumption EMBR biochemical treatment process, which comprises the following steps:
the sewage enters a biochemical anoxic zone and a biochemical aerobic zone in sequence for biochemical treatment;
the nitrifying liquid treated in the biochemical aerobic zone flows back to the biochemical anoxic zone for biological denitrification through a gas-lifting large-proportion reflux device, and the rest mixed liquid enters a high-efficiency precipitation zone for sludge precipitation treatment;
and sewage treated in the sludge settling zone enters a membrane tank for treatment, an immersed membrane treatment unit is arranged in the membrane tank, membrane water production is realized by the immersed membrane treatment unit, and sludge obtained in the sludge settling zone and the membrane tank flows back to a biochemical aerobic zone through a gas stripping reflux device.
In an embodiment of the invention, the gas stripping reflux device comprises a tank body, the tank body is provided with a feed inlet and a discharge outlet, a first wall body and a second wall body are arranged in the tank body, a feed area is arranged between the feed inlet and the first wall body, a discharge area is arranged between the discharge outlet and the second wall body, a gas stripping device is further arranged between the first wall body and the second wall body, and a gas stripping area is arranged between the first wall body and the second wall body.
The top of the first wall body exceeds the liquid level of the tank body, and a reserved hole is formed in the bottom of the first wall body and is not closed for water passing; a gap is reserved between the top of the second wall and the top of the tank body, and the bottom of the second wall is not crossed with water, namely the top of the second wall is lower than the liquid level;
the first wall body and the second wall body are arranged so that liquid in the feeding area enters the air stripping area from a reserved hole between the first wall body and the bottom of the tank body, and the air stripping device is used for driving material flow in the air stripping area to ascend and flows out of the reserved hole between the second wall body and the top of the tank body to the discharging area.
In one embodiment of the invention, due to the special design of the first wall, the second wall and the air stripping device, when air is introduced into the air stripping device, the air stripping can drive the water to move upwards while aerating because the density of the air is lower than that of the water, so that a micro negative pressure state is formed at the bottom; the water flow moves upwards through the bottom of the first wall body and then through the top of the second wall body. Under the drive of the gas, the water flow formed by the micro negative pressure formed at the lower left side enters and moves upwards due to low gas density, so that continuous water inlet and outlet are formed. The lifting height of the liquid level is controlled within 200mm from the design, and the energy consumption requirement is reduced to the minimum while the maximum reflux quantity is realized.
In one embodiment of the invention, the gas stripping device in the gas stripping reflux device comprises a gas stripping aeration pipeline and a fan for introducing gas into the gas stripping aeration pipeline.
In one embodiment of the invention, a first aeration device is arranged at the bottom of the biochemical anoxic zone, and a second aeration device is arranged at the bottom of the biochemical aerobic zone, wherein the first aeration device is used for stirring materials in the biochemical anoxic zone through gas, and the second aeration device is used for stirring materials in the biochemical aerobic zone through gas and introducing oxygen into the biochemical aerobic zone.
In one embodiment of the invention, the first aeration device adopts a perforated aeration pipe and maintains an anoxic state, and the second aeration device adopts microporous aeration to improve the oxygen transfer efficiency.
In one embodiment of the present invention, each of the first aeration apparatus and the second aeration apparatus includes an aeration line and a blower for introducing gas into the aeration line.
In one embodiment of the present invention, the stripping device, the first aeration device and the second aeration device in the stripping reflux device can adopt the following preferred design schemes:
the aeration pipelines in the air stripping device, the first aeration device and the second aeration device adopt low-flux high-efficiency aerators, and the unit ventilation volume is 0.5-1.0m3The ratio of the water to the water is/m/h; and fans in the air stripping device, the first aeration device and the second aeration device adopt high-efficiency single-stage high-speed centrifugal fans.
In one embodiment of the invention, an inclined plate or pipe is provided in the sludge settling zone.
In one embodiment of the present invention, an aeration pipe is provided at the bottom of the sludge settling zone for washing the inclined plate or the inclined pipe to prevent the inclined plate or the inclined pipe from being clogged.
In one embodiment of the invention, the submerged membrane treatment unit is selected from submerged ultrafiltration, SMF, or membrane bioreactor, MBR.
In one embodiment of the invention, if the suspended matter concentration of the produced water in the sludge settling zone is controlled to be more than 5000mg/L, the submerged membrane treatment unit selects a membrane bioreactor MBR, and the membrane process section operates according to the process mode of the MBR.
In one embodiment of the invention, if the suspended matter concentration of the produced water in the sludge settling zone is controlled within 100mg/L, the submerged membrane treatment unit selects submerged ultrafiltration (SMF), and the membrane process section operates according to the process mode of the submerged ultrafiltration (SMF).
In one embodiment of the invention, when the actual water quantity or water quality is far lower than the design in the early period, the operation mode of the immersed ultrafiltration SMF is adopted; when the actual water quantity or water quality reaches or slightly exceeds the original design standard, switching to an MBR operation mode; when the COD of the biochemical produced water reaches a certain bottleneck through biodegradation and can not be reduced any more and the water quality of the produced water needs to be improved, the mode is switched to the SMF mode.
In one embodiment of the invention, chemical agents are added into the membrane tank to form micro flocculation, and then membrane separation is directly carried out to further reduce COD and chroma so as to obtain water quality superior to biochemical and MBR produced water.
The invention also provides a high-efficiency low-energy-consumption EMBR biochemical treatment system, which comprises a biochemical anoxic zone, a biochemical aerobic zone, a sludge settling zone and a membrane pool which are sequentially connected, wherein the biochemical anoxic zone is used for carrying out anoxic treatment on sewage, the biochemical aerobic zone is used for carrying out aerobic treatment on the sewage, the sludge settling zone is used for carrying out sludge settling treatment on treatment liquid treated by the biochemical aerobic zone, the membrane pool is used for carrying out membrane treatment on the sewage treated by the sludge settling zone, an immersed membrane treatment unit is arranged in the membrane pool, and the immersed membrane treatment unit is used for realizing membrane water production;
the biochemical aerobic zone is also connected to the biochemical anoxic zone through an air stripping reflux device, and the air stripping reflux device between the biochemical aerobic zone and the biochemical anoxic zone is used for refluxing the nitrified liquid treated by the biochemical aerobic zone to the biochemical anoxic zone in a large proportion for biological denitrification;
the sludge settling zone and the membrane tank are also connected to a biochemical aerobic zone through a gas stripping reflux device;
and the gas stripping reflux device connected with the sludge settling zone and the membrane tank is used for refluxing the sludge in the sludge settling zone and the membrane tank to the biochemical aerobic zone.
In one embodiment of the invention, the gas stripping reflux device comprises a tank body, the tank body is provided with a feed inlet and a discharge outlet, a first wall body and a second wall body are arranged in the tank body, a feed area is arranged between the feed inlet and the first wall body, a discharge area is arranged between the discharge outlet and the second wall body, a gas stripping device is further arranged between the first wall body and the second wall body, a gas stripping area is arranged between the first wall body and the second wall body,
the top of the first wall body exceeds the liquid level of the tank body, and a reserved hole is formed in the bottom of the first wall body and is not closed for water passing; a gap is reserved between the top of the second wall and the top of the tank body, and the bottom of the second wall is not crossed with water, namely the top of the second wall is lower than the liquid level;
the first wall body and the second wall body are arranged so that liquid in the feeding area enters the air stripping area from a reserved hole between the first wall body and the bottom of the tank body, and the air stripping device is used for driving material flow in the air stripping area to ascend and flows out of the reserved hole between the second wall body and the top of the tank body to the discharging area.
In one embodiment of the invention, the gas stripping device in the gas stripping reflux device comprises a gas stripping aeration pipeline and a fan for introducing gas into the gas stripping aeration pipeline.
In one embodiment of the invention, a first aeration device is arranged at the bottom of the biochemical anoxic zone, and a second aeration device is arranged at the bottom of the biochemical aerobic zone, wherein the first aeration device is used for stirring materials in the biochemical anoxic zone through gas, and the second aeration device is used for stirring materials in the biochemical aerobic zone through gas and introducing oxygen into the biochemical aerobic zone for metabolism of microorganisms.
In one embodiment of the present invention, each of the first aeration apparatus and the second aeration apparatus includes an aeration line and a blower for introducing gas into the aeration line.
In one embodiment of the present invention, the stripping device, the first aeration device and the second aeration device in the stripping reflux device can adopt the following preferred design schemes:
the aeration pipelines in the air stripping device, the first aeration device and the second aeration device adopt low-flux high-efficiency aerators, and the unit ventilation volume is 0.5-1.0m3The ratio of the water to the water is/m/h; and fans in the air stripping device, the first aeration device and the second aeration device adopt high-efficiency single-stage high-speed centrifugal fans.
In one embodiment of the invention, an inclined plate or pipe is provided in the sludge settling zone.
In one embodiment of the present invention, an aeration pipe is provided at the bottom of the sludge settling zone for washing the inclined plate or the inclined pipe to prevent the inclined plate or the inclined pipe from being clogged.
In one embodiment of the invention, the submerged membrane treatment unit is selected from submerged ultrafiltration, SMF, or membrane bioreactor, MBR.
The invention adopts the air stripping reflux device to realize the reflux of the sewage and muddy water mixture, and replaces the problem of high energy consumption caused by the reflux realized by using a material delivery pump in the traditional process.
The reason that the energy consumption is reduced by adopting the gas stripping reflux device is illustrated by that the nitrified liquid treated in the biochemical aerobic zone flows back to the biochemical anoxic zone through the gas stripping reflux device:
in general, biological denitrification is realized by adopting an A/O (anoxic-aerobic) process, ammonia nitrogen in raw water is converted into nitrate nitrogen under the action of nitrifying bacteria in an aerobic environment by sewage, and then the mixed solution of the nitrate nitrogen flows back to an anoxic section and is mixed with the raw water under the action of denitrifying bacteria to realize the biological denitrification. The sludge reflux ratio for biological denitrification in the current design specifications is recommended to be 3-4 times, and the main reason is due to the limitation of denitrification efficiency, for example, 3 times Q of reflux has denitrification efficiency of 3/(1+3) ═ 75%; 4 times of Q, the denitrification efficiency is 80 percent (4/(1 + 4)); the denitrification efficiency of 5 times Q refluxing is 83 percent (5/(1 + 5)). When the reflux is increased from 3 times to 4 times, the theoretical denitrification efficiency is only improved by 5 percent; when the reflux is increased from 4 times to 5 times, the theoretical denitrification efficiency is only improved by 3 percent, and the marginal effect is reduced obviously.
Generally, the circulating reflux of the nitrified liquid needs to be realized through a water pump, and the power cost for realizing the denitrification by improving the reflux ratio is higher. The minimum lift of the centrifugal pump is about 6m, the lift of the axial pump can be 2-3m (the minimum power is 7.5kw), and the conventional centrifugal pump has a large amount of loss on the lift. E.g. 5000m3D wastewater to achieve 3 times of reflux (Q: 630 m)3H), the annual power consumption is about 7.5 multiplied by 24 multiplied by 365 to 6.57 ten thousand KWH according to the axial flow pump with the lowest energy consumption of 7.5 kw; to achieve 5 times the reflux amount (Q: 1050 m)3H) with a power of 15kw and an electrical consumption of about 7.5 × 2 × 24 × 365 ═ 13.14 ten thousand KWH per year.
In order to avoid the marginal effect caused by high energy consumption of a reflux pump and large-proportion reflux required by denitrification, the invention adopts the gas stripping reflux device to realize high-efficiency gas stripping circulating reflux, and can greatly reduce energy consumption.
The invention adopts a gas stripping reflux device and a gas stripping system of 1000m3Flow rate is only 1.0m3The air flow of the fan per minute is converted into energy consumption of 1.5kwh, and the annual operating power consumption is as follows: 1.5 is multiplied by 24 and 365 is 1.3 ten thousand KWH, and the energy is saved by over 90 percent. It is worth mentioning that the oxygen dissolved in the wastewater by gas stripping can still be utilized by the following microorganisms, so that this part of the energy is not wasted at all. Because a huge reflux ratio can be provided, the denitrification efficiency is greatly improved without being limited by the reflux ratio.
Meanwhile, due to the huge reflux ratio provided by the circulating system, the system realizes the advantage of complete mixing, and the impact resistance of the system is greatly improved by responding to the fluctuation of the water quality of raw water.
When the air stripping reflux device is adopted to realize the reflux of the Sludge, an Enhanced-Cyclic Activated Sludge process (ECAST) is formed, and the operation energy consumption can be greatly reduced.
As is known, in the whole operation cost of a sewage plant, the power consumption occupies 50-60% of the operation cost of the water plant, and particularly, the fan adopted for aeration occupies 30-50% of the operation cost of the whole sewage plant, so that how to reduce the energy consumption of the fan of the sewage plant becomes the key for controlling the operation cost of the sewage plant, and the system effectively saves energy by more than 40% by adopting the following three ways:
1. the high-efficiency aeration system comprises: the test of the aeration system is carried out under the clear water condition of 6m water depth, and the deeper the water depth condition is, the higher the oxygen mass transfer efficiency of aeration is; the lower the aeration per unit membrane, the higher the oxygen mass transfer efficiency. At present, most of microporous aerators commonly used in the market are disc aerators and tubular aerators, and under the condition of 6m water depth, the oxygen mass transfer efficiency can reach 20-25%, and the unit ventilation volume is 4-8m3The ratio of the water to the water is/m/h. The high-efficiency dissolved oxygen aeration technology arranged in the system mainly adopts a low-flux high-efficiency aerator, and the unit ventilation volume is 0.5-1.0m3The oxygen mass transfer efficiency can be improved to 30-35% under the condition of 6m water depth, the oxygen transfer efficiency is improved by 30-50% through the optimization of aeration equipment, and the power of a fan is greatly reduced. Zhejiang Shaoxing certain printing and dyeing mill 5000m3The printing and dyeing wastewater is taken as an example (put into production), the oxygen transfer efficiency of the original aeration system is 20 percent, and the design is 2 tables with 42Nm3And the roots blower has the advantages of min (3 sets in total, 2 sets in 1 set), wind pressure of 7m, fan shaft power of 65kw and motor power of 75 kw. In 2017, the high-efficiency low-flux aeration system adopting the process has the oxygen transfer efficiency of 35 percent and the air quantity requirement of 42Nm3Min to 31Nm3And/min, the frequency of the fan is reduced from 48HZ to 38HZ, the shaft power is only 44kw, and the power consumption is greatly reduced.
2. High-efficient fan: the most mainstream fans applied in the current market are a multi-stage centrifugal fan and a Roots fan (or a screw fan), and if the fans are replaced by high-efficiency single-stage high-speed centrifugal fans, the structural forms of the fans are different, so that the fans are adoptedWith air bearings or magnetic bearings, the reactive loss of mechanical friction is eliminated, so that the power is greatly reduced. Zhejiang Shaoxing certain printing and dyeing mill 5000m3The original configuration is 42Nm through energy-saving transformation by taking the printing and dyeing wastewater of/d as an example3The Roots blower with the speed of min, wind pressure of 7m, fan shaft power of 65kw and motor power of 75kw is replaced by 31Nm3Min, wind pressure 7m, shaft power 38kw and motor power 44 kw.
3. Accurate dissolved oxygen control system: in the operation process, because the water volume loads in different time periods are different, if the operation is carried out according to the conventional fixed frequency, the excessive dissolved oxygen at the low load can be caused, and the energy consumption of the fan is wasted. Because the system adopts large circulation reflux control, the dissolved oxygen at each point is relatively uniform, and the adjustment of the fan according to the dissolved oxygen is very stable and easy to realize. The operation frequency of the fan is synchronously adjusted through the feedback control of dissolved oxygen, and the operation energy consumption can be saved by 5-10%.
Therefore, because a high-efficiency aeration system and a single-stage high-speed centrifugal fan are adopted, and a dissolved oxygen accurate control system is adopted, the power of a motor is reduced to 44kw from 2 original tables of 75kw, the shaft power is reduced to 38kw from 2 tables of 65kw, the average energy consumption is reduced to (65-38)/65-41.5%, and the running power consumption (65-38) and 2 × 24 × 365 is saved to 47.3 ten thousand kwh one year.
By effectively combining the methods, the aerodynamic consumption of the sewage plant can be reduced by 40-50%, and the electric energy consumption can be effectively reduced in the sewage plant.
In the invention, the surface load of the sedimentation tank is greatly improved by adding the inclined pipe/inclined plate in the sludge sedimentation zone, the surface load of the secondary sedimentation tank is 0.6-1.5m/h in the specification, and the actual design value is mostly 0.5-0.75 m/h. The surface load of the invention can be increased to 1.5-2.7m/h by adding the inclined tube, thus greatly reducing the occupied area. Meanwhile, in order to prevent the sludge from blocking the inclined plate, the bottom of the settling zone is provided with an aeration pipe, and the flushing inclined plate can be opened at regular time.
In general, in order to realize sludge-water separation of a biochemical system, either a traditional secondary sedimentation tank is selected for sludge-water separation, or an efficient MBR membrane process is selected for sludge-water separation. However, the traditional secondary sedimentation tank has low surface load and large occupied area, effluent suspended matters are not easy to control, and effluent quality is unstable; the effluent quality of the MBR process is guaranteed, but the equipment cost and the operation cost are increased. According to the invention, the high-flux low-energy-consumption EMBR process can be obtained by arranging the high-efficiency sedimentation tank. The efficient sludge sedimentation tank is arranged between the biochemical process and the membrane tank, and has the following advantages:
1. the high sludge concentration (6000-8000mg/L) of the biochemical system is maintained through the high-efficiency precipitation process, and the high sludge concentration is also obtained. Meanwhile, the sludge of the biochemical system can flow back through the high-efficiency sedimentation tank, the concentration value (such as 100-1000mg/L) of the sludge entering the membrane tank can be controlled, a small part of residual sludge enters the membrane tank, and the effluent is separated through the MBR to obtain the quality of the water produced by the MBR.
2. The submerged ultrafiltration SMF process can be operated at low sludge concentration, thereby greatly improving the operating flux of the membrane and reducing the operating energy consumption thereof. In a certain printing and dyeing wastewater project in Zhejiang, the operation flux of the membrane is improved from 15LMH to about 20LMH by the arrangement of the efficient sedimentation tank, and the water production flux performance is improved by 33%. When the investment cost is converted into the investment cost of a new project, the cost of the membrane product can be reduced by about 30 percent, and the investment cost is greatly reduced.
3. When the effluent quality requirement is high, the effluent suspended matter concentration of the high-efficiency sedimentation tank is controlled, the sludge in the sedimentation tank is totally refluxed, and the residual sludge is discharged into the membrane tank. Chemical agents are added into the membrane tank, and after micro flocculation is generated, the micro flocculation is directly separated through an MBR membrane, so that the water quality of product water is further improved, and residual sludge is directly concentrated and then discharged.
In conclusion, the efficient and low-energy-consumption EMBR process can be obtained through the arrangement of efficient precipitation.
In the invention, through the optimized design and control of the process, the membrane process can be seamlessly switched between the immersed ultrafiltration SMF process and the membrane bioreactor MBR process.
In general, RO process is mostly used for desalination in order to realize reuse of reclaimed water. Before the RO, the membrane at ultrafiltration level is mostly needed to be pretreated, and the processes such as external ultrafiltration UF, submerged ultrafiltration SMF or membrane bioreactor MBR process are usually adopted.
Compared with pressure type ultrafiltration, the submerged type ultrafiltration SMF is characterized in that a membrane is placed in a membrane pool by submerged type ultrafiltration, the requirement of water inflow is wider than that of pressure type ultrafiltration UF, and the pollution resistance is strong. The membrane has high water yield and low operation energy consumption, but compared with MBR, the membrane has low requirement on the concentration of influent suspended matters and weak anti-pollution capability.
The membrane bioreactor MBR is mainly applied to a sewage treatment process, and the membrane separation technology is organically combined with the traditional wastewater biological treatment technology, so that the solid-liquid separation efficiency is greatly improved; meanwhile, the generation amount of excess sludge is reduced by reducing the F/M ratio, so that a plurality of outstanding problems existing in the traditional activated sludge method are solved, but the membrane flux is lower, and the operation energy consumption is higher.
Meanwhile, in the beginning of design, a plurality of sewage plants are difficult to determine the real and accurate water quality and water quantity, and great difficulty is brought to the operation of the sewage plants. The actual water quantity or water quality in the early stage of operation may be far lower than the design standard under normal conditions; in the actual operation process, the deviation between the actual inlet water quality and the designed water quality is large, and the uncertainty of the system in operation and the flexibility of operation need to be fully considered.
The invention can control the suspended matter concentration of the effluent of the high-efficiency sedimentation tank through the optimized design and the process control, so that the membrane process can operate under different suspended matter concentrations to adapt to different process conditions.
a) If the concentration of suspended matters in the precipitated water is controlled to be more than 5000mg/L, the membrane process section operates according to the MBR process mode, scrubbing, backwashing and chemical cleaning are carried out at regular time, and the produced water enters the subsequent advanced treatment process section.
b) If the concentration of suspended matters in the water produced by precipitation is controlled within 100mg/L, most of sludge flows back to the front section of the biochemical system through the sedimentation tank, the operation flux of the membrane can be greatly improved, and the operation energy consumption is reduced. According to the scheme, after the Zhejiang dyeing wastewater is reformed, the SMF mode is switched to the immersed ultrafiltration SMF mode. The running flux is improved from 15LMH to 20LMH, and the productivity is improved by 33%; meanwhile, the continuous operation of the aeration fan is changed into 1 hour of every 3 hours, and the operation energy consumption is reduced by 75 percent.
The optimal design of the biochemical system and the seamless switching of the membrane process can effectively cope with the working condition of large variation range of the concentration of suspended matters.
When the actual water quantity or water quality is far lower than the design in the previous period, the operation mode of the immersed ultrafiltration SMF can be adopted. Activated sludge is intercepted by the efficient sedimentation tank, and the concentration of low suspended matters in the effluent is controlled, so that the operation condition of obtaining SMF is adopted, the low aeration rate can be adopted, the quality of the produced water can meet the pretreatment requirement of reuse water, and the operation cost can be effectively reduced; when the actual water quantity or water quality reaches or slightly exceeds the original design standard (especially total nitrogen), the MBR operation mode can be switched. The sludge concentration in the biochemical tank is increased in advance through the high-efficiency sedimentation tank, the microorganism concentration is further increased through an MBR process, and the sludge load of the system is reduced. Meanwhile, the denitrification capability of the system can be improved through multi-point water inlet and multi-stage large-proportion circulating reflux in the ECAST system.
When the COD of the biochemical produced water reaches a certain bottleneck through biodegradation and can not be reduced any more and the water quality of the produced water needs to be improved, the mode can be switched to the SMF mode.
According to the invention, ECAST can be independently operated, sludge of a biochemical system flows back through the high-efficiency sedimentation tank, effluent enters the membrane tank, chemical agents are added into the membrane tank to form micro flocculation, and then the micro flocculation is directly separated, so that COD and chromaticity can be further reduced, and the water quality superior to that of biochemical and MBR produced water is obtained.
The invention discloses an efficient and low-energy-consumption EMBR biochemical treatment process (eco Membrane Biological Reactor), which mainly comprises a biochemical treatment Enhanced circulating Activated Sludge process ECAST (Enhanced-Cyclic Activated Sludge Technology) and a Membrane process Membrane Bioreactor (MBR) Technology, and realizes the optimization and upgrading of a water treatment process flow.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. the invention adopts the air stripping reflux device, realizes the large-proportion reflux from the biochemical aerobic zone to the biochemical anoxic zone on the basis of unique air stripping circulating reflux without adding power equipment, can realize the high-efficiency low-energy-consumption denitrification, and simultaneously, the large-proportion reflux can greatly improve the shock resistance of the system.
2. The invention adopts the high-efficiency bottom aeration technology and the use of the high-efficiency single-stage high-speed centrifugal fan, thereby greatly reducing the operation energy consumption of the sewage plant.
3. The efficient sedimentation tank can greatly reduce investment and energy consumption, improve surface load, control the concentration of suspended matters in produced water and provide more possibility for a subsequent membrane process by arranging the efficient sludge sedimentation tank.
4. In the process, the produced water suspended matters in the high-efficiency sedimentation tank are detected and controlled, and the seamless switching of the immersed ultrafiltration SMF process and the membrane bioreactor MBR process can be effectively switched.
5. The invention adds chemical agent in the membrane pool, which can realize the advanced treatment of the membrane process.
6. The pump is not needed in other links except for the immersed membrane treatment unit, so that a large amount of energy consumption is saved.
In summary, the following steps: the efficient EMBR process of the invention integrates the advantages of a biochemical system, a membrane process and a physicochemical process. The biochemical system is optimized through an aeration system and a large-proportion backflow system, so that the operation energy consumption is greatly reduced; meanwhile, due to the arrangement of the high-efficiency sludge sedimentation tank, the operation mode of the membrane process can be flexibly switched according to the quality of the incoming water; when the COD and the chromaticity of the produced water have higher requirements, the quality of the product water can be further improved through the separation effect of a physicochemical process and a membrane process by adding a chemical agent, and the method can adapt to different requirements.
Drawings
FIG. 1 is a schematic structural diagram of an efficient and low-energy-consumption EMBR biochemical treatment system in example 1 of the present invention.
FIG. 2 is a schematic diagram of the configuration of the stripping reflux unit of the present invention. The direction of the arrows in fig. 2 indicates the direction of liquid flow.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
Example 1
Referring to fig. 1, the embodiment provides a high-efficiency low-energy-consumption EMBR biochemical treatment system, which includes a biochemical anoxic zone 1, a biochemical aerobic zone 2, a sludge settling zone 3 and a membrane tank 4, which are connected in sequence, where the biochemical anoxic zone 1 is used for anoxic treatment of sewage, the biochemical aerobic zone 2 is used for aerobic treatment of sewage, the sludge settling zone 3 is used for sludge settling treatment of treatment liquid treated by the biochemical aerobic zone 2, the membrane tank 4 is used for membrane treatment of sewage treated by the sludge settling zone 3, an immersed membrane treatment unit 6 is arranged in the membrane tank 4, and the immersed membrane treatment unit 6 is used for realizing membrane water production;
the biochemical aerobic zone 2 is also connected to the biochemical anoxic zone 1 through a gas stripping reflux device 5, and the gas stripping reflux device 5 between the biochemical aerobic zone 2 and the biochemical anoxic zone 1 is used for refluxing the nitrified liquid treated by the biochemical aerobic zone 2 to the biochemical anoxic zone 1;
the sludge settling zone 3 and the membrane tank 4 are also connected to the biochemical aerobic zone 2 through a gas stripping reflux device 5;
and the gas stripping reflux device 5 connected with the sludge settling zone 3 and the membrane tank 4 is used for refluxing the sludge in the sludge settling zone 3 and the membrane tank 4 to the biochemical aerobic zone 2.
Referring to fig. 2, in the present embodiment, the stripping reflux unit 5 includes a tank 51, the tank 51 is provided with a feed inlet and a discharge outlet, a first wall 52 and a second wall 53 are arranged in the tank 51, a feed area 55 is arranged between the feed inlet and the first wall 52, a discharge area 56 is arranged between the discharge outlet and the second wall 53, a stripping unit 54 is further arranged between the first wall 52 and the second wall 53, a stripping area 57 is arranged between the first wall 52 and the second wall 53,
the top of the first wall 52 exceeds the liquid level of the pool body 51, and the bottom is not closed and provided with a reserved hole for water passing; a gap is reserved between the top of the second wall 53 and the top of the tank body 51, and the bottom of the second wall 53 is not crossed with water, namely the top of the second wall 53 is lower than the liquid level;
the first wall 52 and the second wall 53 are arranged so that the material flow in the feeding area 55 enters the stripping area 57 from a reserved hole between the first wall 52 and the bottom of the tank body 51, and the stripping device 54 is used for driving the material flow in the stripping area 57 to ascend and flow out to the discharging area 56 from a reserved hole between the second wall 53 and the top of the tank body 51.
In this embodiment, the gas stripping device 54 in the gas stripping reflux device 5 includes a gas stripping aeration line and a blower for introducing gas into the gas stripping aeration line.
In this embodiment, a first aeration device 7 is disposed at the bottom of the biochemical anoxic zone 1, a second aeration device 8 is disposed at the bottom of the biochemical aerobic zone 2, the first aeration device 7 is used for stirring materials in the biochemical anoxic zone 1 through gas, and the second aeration device 8 is used for stirring materials in the biochemical aerobic zone 2 through gas and introducing oxygen into the biochemical aerobic zone 2.
In this embodiment, each of the first aeration apparatus 7 and the second aeration apparatus 8 includes an aeration pipeline and a blower for introducing gas into the aeration pipeline.
In this embodiment, the following preferred design schemes are adopted for the air stripping device 54, the first aeration device 7 and the second aeration device 8 in the air stripping reflux device 5: the aeration pipelines in the air stripping device 54, the first aeration device 7 and the second aeration device 8 adopt low-flux high-efficiency aerators, and the unit ventilation volume is 0.5-1.0m3The ratio of the water to the water is/m/h; the fans in the air stripping device 54, the first aeration device 7 and the second aeration device 8 adopt high-efficiency single-stage high-speed centrifugal fans. In this embodiment, an inclined plate or pipe 9 is provided in the sludge settling zone 3.
In this embodiment, an aeration pipe is provided at the bottom of the sludge settling zone 3 for washing the inclined plate or inclined pipe 9 to prevent the inclined plate or inclined pipe 9 from being clogged.
In this embodiment, the submerged membrane treatment unit 6 is selected from submerged ultrafiltration SMF or membrane bioreactor MBR.
Referring to fig. 1, this embodiment further provides a high-efficiency and low-energy-consumption EMBR biochemical treatment process, including the following steps:
the sewage enters a biochemical anoxic zone 1 and a biochemical aerobic zone 2 in sequence for biochemical treatment;
the nitrifying liquid treated in the biochemical aerobic zone 2 flows back to the biochemical anoxic zone 1 through the gas stripping reflux device 5, and the rest mixed liquid enters the high-efficiency precipitation zone 3 for sludge precipitation treatment;
the sewage treated by the sludge settling zone 3 enters a membrane tank 4 for treatment, an immersed membrane treatment unit 6 is arranged in the membrane tank 4, membrane water production is realized by the immersed membrane treatment unit 6, and the sludge obtained in the sludge settling zone 3 and the membrane tank 4 flows back to the biochemical aerobic zone 2 through an air stripping reflux device 5.
In this embodiment, due to the special design of the first wall 52, the second wall 53 and the stripping device 54 in the stripping reflux device 5, when air is introduced into the stripping device 54, air stripping can drive water to move upwards during aeration because the density of the air is lower than that of the water, so that a micro negative pressure state is formed at the bottom; after the water flow moves upwards, the water flow can only move towards the second wall 53 because the first wall 52 blocks the water flow. Under the drive of the gas, the water flow formed by the micro negative pressure formed at the lower left side enters and moves upwards due to low gas density, so that continuous water inlet and outlet are formed. The lifting height of the liquid level is controlled within 200mm from the design, and the energy consumption requirement is reduced to the minimum while the maximum reflux quantity is realized.
In this embodiment, the first aeration device 7 adopts perforation aeration to maintain an anoxic state, and the second aeration device 8 adopts micropore aeration to maintain an aerobic state, so as to improve oxygen transfer efficiency.
In this embodiment, if the concentration of suspended solids in the water produced by the sludge settling zone 3 is controlled to be above 5000mg/L, the submerged membrane treatment unit 6 selects the membrane bioreactor MBR, and the membrane process section operates according to the MBR process mode.
In this embodiment, if the concentration of suspended matters in the water produced in the sludge settling zone 3 is controlled within 100mg/L, the submerged ultrafiltration SMF is selected by the submerged membrane processing unit 6, and the membrane process section operates according to the submerged ultrafiltration SMF process mode.
In the embodiment, when the actual water quantity or water quality is far lower than the design in the previous period, an operation mode of immersed ultrafiltration SMF is adopted; when the actual water quantity or water quality reaches or slightly exceeds the original design standard, switching to an MBR operation mode; when the COD of the biochemical produced water reaches a certain bottleneck through biodegradation and can not be reduced any more and the water quality of the produced water needs to be improved, the mode is switched to the SMF mode.
In the embodiment, chemical agents are added into the membrane tank to form micro flocculation, and then membrane separation is directly carried out to further reduce COD and chroma so as to obtain water quality superior to biochemical and MBR produced water.
In the embodiment, the air stripping reflux device 5 is adopted to realize the reflux of the sewage and muddy water mixture, and the problem of high energy consumption caused by the fact that a material conveying pump is required to realize the reflux in the traditional process is solved.
The reason that the energy consumption is reduced by adopting the gas stripping reflux device 5 of the invention is illustrated by that the nitrified liquid treated in the biochemical aerobic zone 2 flows back to the biochemical anoxic zone 1 through the gas stripping reflux device 5:
in general, biological denitrification is realized by adopting an A/O (anoxic-aerobic) process, ammonia nitrogen in raw water is converted into nitrate nitrogen under the action of nitrifying bacteria in an aerobic environment by sewage, and then the mixed solution of the nitrate nitrogen flows back to an anoxic section and is mixed with the raw water under the action of denitrifying bacteria to realize the biological denitrification. The sludge reflux ratio for biological denitrification in the current design specifications is recommended to be 3-4 times, and the main reason is due to the limitation of denitrification efficiency, for example, 3 times Q of reflux has denitrification efficiency of 3/(1+3) ═ 75%; 4 times of Q, the denitrification efficiency is 80 percent (4/(1 + 4)); the denitrification efficiency of 5 times Q refluxing is 83 percent (5/(1 + 5)). When the reflux is increased from 3 times to 4 times, the theoretical denitrification efficiency is only improved by 5 percent; when the reflux is increased from 4 times to 5 times, the theoretical denitrification efficiency is only improved by 3 percent, and the marginal effect is reduced obviously.
Generally, the circulating reflux of the nitrified liquid needs to be realized through a water pump, and the power cost for realizing the denitrification by improving the reflux ratio is higher. The minimum lift of the centrifugal pump is about 6m, and the lift of the axial pump can be adjustedIn order to achieve 2-3m (the minimum power is 7.5kw), the conventional centrifugal pump has a large loss on the lift. E.g. 5000m3D wastewater to achieve 3 times of reflux (Q: 630 m)3H), the annual power consumption is about 7.5 multiplied by 24 multiplied by 365 to 6.57 ten thousand KWH according to the axial flow pump with the lowest energy consumption of 7.5 kw; to achieve 5 times the reflux amount (Q: 1050 m)3H) with a power of 15kw and an electrical consumption of about 7.5 × 2 × 24 × 365 ═ 13.14 ten thousand KWH per year.
In order to avoid the marginal effect caused by high energy consumption of a reflux pump and large-proportion reflux required by denitrification, the invention adopts the gas stripping reflux device to realize high-efficiency gas stripping circulating reflux, and can greatly reduce energy consumption.
In the embodiment, a gas stripping reflux device and a gas stripping system are adopted, wherein the gas stripping system is 1000m3Flow rate is only 1.0m3The air flow of the fan per minute is converted into energy consumption of 1.5kwh, and the annual operating power consumption is as follows: 1.5 is multiplied by 24 and 365 is 1.3 ten thousand KWH, and the energy is saved by over 90 percent. It is worth mentioning that the oxygen dissolved in the wastewater by gas stripping can still be utilized by the following microorganisms, so that this part of the energy is not wasted at all. Because a huge reflux ratio can be provided, the denitrification efficiency is greatly improved without being limited by the reflux ratio.
Meanwhile, due to the huge reflux ratio provided by the circulating system, the system realizes the advantage of complete mixing, and the impact resistance of the system is greatly improved by responding to the fluctuation of the water quality of raw water.
In the embodiment, when the air stripping reflux device is adopted to realize the reflux of the Sludge, an Enhanced-Cyclic Activated Sludge process (ECAST) is formed, and the operation energy consumption can be greatly reduced.
As is known, in the whole operation cost of a sewage plant, the power consumption occupies 50-60% of the operation cost of the water plant, and particularly, the fan adopted for aeration occupies 30-50% of the operation cost of the whole sewage plant, so that how to reduce the energy consumption of the fan of the sewage plant becomes the key for controlling the operation cost of the sewage plant, and the system effectively saves energy by more than 40% by adopting the following three ways:
1. the high-efficiency aeration system comprises: the aeration system was tested at 6m water depthThe test is carried out under the water condition, and the deeper the water depth condition is, the higher the oxygen mass transfer efficiency of aeration is; the lower the aeration per unit membrane, the higher the oxygen mass transfer efficiency. At present, most of microporous aerators commonly used in the market are disc aerators and tubular aerators, and under the condition of 6m water depth, the oxygen mass transfer efficiency can reach 20-25%, and the unit ventilation volume is 4-8m3The ratio of the water to the water is/m/h. The high-efficiency dissolved oxygen aeration technology arranged in the system mainly adopts a low-flux high-efficiency aerator, and the unit ventilation volume is 0.5-1.0m3The oxygen mass transfer efficiency can be improved to 30-35% under the condition of 6m water depth, the oxygen transfer efficiency is improved by 30-50% through the optimization of aeration equipment, and the power of a fan is greatly reduced. Zhejiang Shaoxing certain printing and dyeing mill 5000m3The printing and dyeing wastewater is taken as an example (put into production), the oxygen transfer efficiency of the original aeration system is 20 percent, and the design is 2 tables with 42Nm3And the roots blower has the advantages of min (3 sets in total, 2 sets in 1 set), wind pressure of 7m, fan shaft power of 65kw and motor power of 75 kw. In 2017, by adopting the high-efficiency low-flux aeration system, the oxygen transfer efficiency reaches 35 percent, and the air quantity requirement is 42Nm3Min to 31Nm3And/min, the frequency of the fan is reduced from 48HZ to 38HZ, the shaft power is only 44kw, and the power consumption is greatly reduced.
2. High-efficient fan: the most mainstream fans applied in the current market are a multi-stage centrifugal fan and a Roots fan (or a screw fan), and if the fans are replaced by high-efficiency single-stage high-speed centrifugal fans, because the structural forms of the fans are different, an air bearing or a magnetic suspension bearing is adopted, and the reactive loss of mechanical friction is not available, so the power is greatly reduced. Zhejiang Shaoxing certain printing and dyeing mill 5000m3The original configuration is 42Nm through energy-saving transformation by taking the printing and dyeing wastewater of/d as an example3The Roots blower with the speed of min, wind pressure of 7m, fan shaft power of 65kw and motor power of 75kw is replaced by 31Nm3Min, wind pressure 7m, shaft power 38kw and motor power 44 kw.
3. Accurate dissolved oxygen control system: in the operation process, because the water volume loads in different time periods are different, if the operation is carried out according to the conventional fixed frequency, the excessive dissolved oxygen at the low load can be caused, and the energy consumption of the fan is wasted. Because the system adopts large circulation reflux control, the dissolved oxygen at each point is relatively uniform, and the adjustment of the fan according to the dissolved oxygen is very stable and easy to realize. The operation frequency of the fan is synchronously adjusted through the feedback control of dissolved oxygen, and the operation energy consumption can be saved by 5-10%.
Therefore, because a high-efficiency aeration system and a single-stage high-speed centrifugal fan are adopted, and a dissolved oxygen accurate control system is adopted, the power of a motor is reduced to 44kw from 2 original tables of 75kw, the shaft power is reduced to 38kw from 2 tables of 65kw, the average energy consumption is reduced to (65-38)/65-41.5%, and the running power consumption (65-38) and 2 × 24 × 365 is saved to 47.3 ten thousand kwh one year.
By effectively combining the methods, the aerodynamic consumption of the sewage plant can be reduced by 40-50%, and the electric energy consumption can be effectively reduced in the sewage plant.
In the embodiment, the surface load of the sedimentation tank is greatly improved by adding the inclined pipe/inclined plate in the sludge sedimentation area, the surface load of the secondary sedimentation tank is 0.6-1.5m/h in the specification, and the actual design value is mostly 0.5-0.75 m/h. In the method, the surface load can be increased to 1.5-2.7m/h by adding the inclined tube, so that the floor area is greatly reduced. Meanwhile, in order to prevent the sludge from blocking the inclined plate, the bottom of the settling zone is provided with an aeration pipe, and the flushing inclined plate can be opened at regular time.
In general, in order to realize sludge-water separation of a biochemical system, either a traditional secondary sedimentation tank is selected for sludge-water separation, or an efficient MBR membrane process is selected for sludge-water separation. However, the traditional secondary sedimentation tank has low surface load and large occupied area, effluent suspended matters are not easy to control, and effluent quality is unstable; the effluent quality of the MBR process is guaranteed, but the equipment cost and the operation cost are increased. In the embodiment, the high-flux and low-energy-consumption EMBR process can be obtained by arranging the high-efficiency sedimentation tank. The efficient sludge sedimentation tank is arranged between the biochemical process and the membrane tank, and has the following advantages:
1. the high sludge concentration (6000-8000mg/L) of the biochemical system is maintained through the high-efficiency precipitation process, and the high sludge concentration is also obtained. Meanwhile, the sludge of the biochemical system can flow back through the high-efficiency sedimentation tank, the concentration value (such as 100-1000mg/L) of the sludge entering the membrane tank can be controlled, a small part of residual sludge enters the membrane tank, and the effluent is separated through the MBR to obtain the quality of the water produced by the MBR.
2. The submerged ultrafiltration SMF process can be operated at low sludge concentration, thereby greatly improving the operating flux of the membrane and reducing the operating energy consumption thereof. In a certain printing and dyeing wastewater project in Zhejiang, the operation flux of the membrane is improved from 15LMH to about 20LMH by the arrangement of the efficient sedimentation tank, and the water production flux performance is improved by 33%. When the investment cost is converted into the investment cost of a new project, the cost of the membrane product can be reduced by about 30 percent, and the investment cost is greatly reduced.
3. When the effluent quality requirement is high, the effluent suspended matter concentration of the high-efficiency sedimentation tank is controlled, the sludge in the sedimentation tank is totally refluxed, and the residual sludge is discharged into the membrane tank. Chemical agents are added into the membrane tank, and after micro flocculation is generated, the micro flocculation is directly separated through an MBR membrane, so that the water quality of product water is further improved, and residual sludge is directly concentrated and then discharged.
In conclusion, the efficient and low-energy-consumption EMBR process can be obtained through the arrangement of efficient precipitation.
In this embodiment, the membrane process can be seamlessly switched between the submerged ultrafiltration SMF and membrane bioreactor MBR processes by optimal design and control of the process.
In general, RO process is mostly used for desalination in order to realize reuse of reclaimed water. Before the RO, the membrane at ultrafiltration level is mostly needed to be pretreated, and the processes such as external ultrafiltration UF, submerged ultrafiltration SMF or membrane bioreactor MBR process are usually adopted.
Compared with pressure type ultrafiltration, the submerged type ultrafiltration SMF is characterized in that a membrane is placed in a membrane pool by submerged type ultrafiltration, the requirement of water inflow is wider than that of pressure type ultrafiltration UF, and the pollution resistance is strong. The membrane has high water yield and low operation energy consumption, but compared with MBR, the membrane has low requirement on the concentration of influent suspended matters and weak anti-pollution capability.
The membrane bioreactor MBR is mainly applied to a sewage treatment process, and the membrane separation technology is organically combined with the traditional wastewater biological treatment technology, so that the solid-liquid separation efficiency is greatly improved; meanwhile, the generation amount of excess sludge is reduced by reducing the F/M ratio, so that a plurality of outstanding problems existing in the traditional activated sludge method are solved, but the membrane flux is lower, and the operation energy consumption is higher.
Meanwhile, in the beginning of design, a plurality of sewage plants are difficult to determine the real and accurate water quality and water quantity, and great difficulty is brought to the operation of the sewage plants. The actual water quantity or water quality in the early stage of operation may be far lower than the design standard under normal conditions; in the actual operation process, the deviation between the actual inlet water quality and the designed water quality is large, and the uncertainty of the system in operation and the flexibility of operation need to be fully considered.
In the embodiment, the concentration of suspended matters in the effluent of the high-efficiency sedimentation tank can be controlled through optimal design and process control, and the membrane process can operate under different suspended matter concentrations to adapt to different process conditions.
a) If the concentration of suspended matters in the precipitated water is controlled to be more than 5000mg/L, the membrane process section operates according to the MBR process mode, scrubbing, backwashing and chemical cleaning are carried out at regular time, and the produced water enters the subsequent advanced treatment process section.
b) If the concentration of suspended matters in the water produced by precipitation is controlled within 100mg/L, most of sludge flows back to the front section of the biochemical system through the sedimentation tank, the operation flux of the membrane can be greatly improved, and the operation energy consumption is reduced. According to the scheme, after the Zhejiang dyeing wastewater is reformed, the SMF mode is switched to the immersed ultrafiltration SMF mode. The running flux is improved from 15LMH to 20LMH, and the productivity is improved by 33%; meanwhile, the continuous operation of the aeration fan is changed into 1 hour of every 3 hours, and the operation energy consumption is reduced by 75 percent.
The optimal design of the biochemical system and the seamless switching of the membrane process in the embodiment can effectively cope with the working condition of large concentration variation range of suspended matters.
When the actual water quantity or water quality is far lower than the design in the previous period, the operation mode of the immersed ultrafiltration SMF can be adopted. Activated sludge is intercepted by the efficient sedimentation tank, and the concentration of low suspended matters in the effluent is controlled, so that the operation condition of obtaining SMF is adopted, the low aeration rate can be adopted, the quality of the produced water can meet the pretreatment requirement of reuse water, and the operation cost can be effectively reduced; when the actual water quantity or water quality reaches or slightly exceeds the original design standard (especially total nitrogen), the MBR operation mode can be switched. The sludge concentration in the biochemical tank is increased in advance through the high-efficiency sedimentation tank, the microorganism concentration is further increased through an MBR process, and the sludge load of the system is reduced. Meanwhile, the denitrification capability of the system can be improved through multi-point water inlet and multi-stage large-proportion circulating reflux in the ECAST system.
When the COD of the biochemical produced water reaches a certain bottleneck through biodegradation and can not be reduced any more and the water quality of the produced water needs to be improved, the mode can be switched to the SMF mode.
In the embodiment, ECAST can be independently operated, sludge of a biochemical system flows back through the high-efficiency sedimentation tank, effluent enters the membrane tank, chemical agents are added into the membrane tank to form micro flocculation and then are directly separated, COD (chemical oxygen demand) and chromaticity can be further reduced, and the water quality superior to that of biochemical and MBR (membrane bioreactor) produced water is obtained.
The embodiment discloses an efficient and low-energy-consumption EMBR biochemical treatment process (eco Membrane Biological Reactor) which mainly comprises a biochemical treatment Enhanced circulating Activated Sludge process ECAST (Enhanced-Cyclic Activated Sludge Technology) and a Membrane process Membrane Bioreactor (MBR) Technology, and realizes the optimization and upgrading of a water treatment process flow.
The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.

Claims (10)

1. An efficient low-energy-consumption EMBR biochemical treatment process is characterized by comprising the following steps:
the sewage enters a biochemical anoxic zone (1) and a biochemical aerobic zone (2) in sequence for biochemical treatment;
the nitrifying liquid treated in the biochemical aerobic zone (2) flows back to the biochemical anoxic zone (1) through the gas stripping reflux device (5), and the rest mixed liquid enters the high-efficiency precipitation zone (3) for sludge precipitation treatment;
the sewage after the sludge settling zone (3) is treated enters a membrane tank (4) for treatment, an immersed membrane treatment unit (6) is arranged in the membrane tank (4), membrane water production is realized by the immersed membrane treatment unit (6), and the obtained sludge in the sludge settling zone (3) and the membrane tank (4) flows back to a biochemical aerobic zone (2) through a gas stripping reflux device (5).
2. The high-efficiency low-energy-consumption EMBR biochemical treatment process according to claim 1, characterized in that the air stripping reflux device (5) comprises a tank body (51), the tank body (51) is provided with a feeding port and a discharging port, a first wall body (52) and a second wall body (53) are arranged in the tank body (51), a feeding area (55) is arranged between the feeding port and the first wall body (52), a discharging area (56) is arranged between the discharging port and the second wall body (53), an air stripping device (54) is further arranged between the first wall body (52) and the second wall body (53), an air stripping area (57) is arranged between the first wall body (52) and the second wall body (53),
the top of the first wall body (52) exceeds the liquid level of the tank body (51), and a reserved hole is formed in the bottom of the first wall body and is not closed for water passing; a gap is reserved between the top of the second wall body (53) and the top of the tank body (51), and the bottom of the second wall body is not crossed with water;
the first wall body (52) and the second wall body (53) are arranged so that the material flow of the feeding area (55) enters the stripping area (57) from a reserved hole between the first wall body (52) and the bottom of the tank body (51), and the stripping device (54) is used for driving the material flow of the stripping area (57) to ascend and flow out to the discharging area (56) from a reserved hole between the second wall body (53) and the top of the tank body (51);
the gas stripping device (54) comprises a gas stripping aeration pipeline and a fan used for introducing gas into the gas stripping aeration pipeline.
3. A high-efficiency low-energy-consumption EMBR biochemical treatment process according to claim 1, wherein a first aeration device (7) is arranged at the bottom of the biochemical anoxic zone (1), a second aeration device (8) is arranged at the bottom of the biochemical aerobic zone (2), the first aeration device (7) is used for realizing the stirring of materials in the biochemical anoxic zone (1) through gas, and the second aeration device (8) is used for realizing the stirring of materials in the biochemical anoxic zone (2) through gas on one hand and introducing oxygen into the biochemical aerobic zone (2) on the other hand.
4. A high-efficiency low-energy-consumption EMBR biochemical treatment process according to claim 3, characterized in that the first aeration device (7) and the second aeration device (8) comprise aeration pipelines and fans for introducing gas into the aeration pipelines;
the aeration pipelines in the air stripping device (54), the first aeration device (7) and the second aeration device (8) adopt aerators, and the unit ventilation volume is 0.5-1.0m3/m/h；
The aeration pipe of the first aeration device (7) is a perforated aeration pipe, and the aeration pipelines in the air stripping device (54) and the second aeration device (8) are microporous aeration pipes;
the fans in the air stripping device (54), the first aeration device (7) and the second aeration device (8) adopt single-stage high-speed centrifugal fans.
5. A high efficiency and low energy consumption EMBR biochemical treatment process according to claim 1, characterized in that an inclined plate or tube (9) is arranged in the sludge settling zone (3).
6. A high efficiency and low energy consumption EMBR biochemical treatment process according to claim 1, characterized in that an aeration pipe is arranged at the bottom of the sludge settling zone (3) for washing the inclined plate or pipe (9) to prevent the inclined plate or pipe (9) from being blocked.
7. A high efficiency and low energy consumption EMBR biochemical treatment process according to claim 1, wherein the submerged membrane treatment unit (6) is selected from submerged ultrafiltration SMF or membrane bioreactor MBR.
8. The high-efficiency low-energy-consumption EMBR biochemical treatment process according to claim 7, characterized in that, if the suspended matter concentration of the produced water in the sludge settling zone (3) is controlled above 5000mg/L, the immersed membrane treatment unit (6) selects MBR, and the membrane process section operates according to the MBR process mode;
if the concentration of suspended matters in the produced water of the sludge settling zone (3) is controlled within 100mg/L, the immersed membrane treatment unit (6) selects immersed ultrafiltration SMF, and the membrane process section operates according to the process mode of the immersed ultrafiltration SMF.
9. The high-efficiency low-energy-consumption EMBR biochemical treatment process according to claim 7, characterized in that, when the actual water quantity or water quality is far lower than the design in the previous period, the operation mode of the immersed ultrafiltration SMF is adopted; when the actual water quantity or water quality reaches or slightly exceeds the original design standard, switching to an MBR operation mode; when the COD of the biochemical produced water reaches a certain bottleneck through biodegradation and can not be reduced any more and the water quality of the produced water needs to be improved, the mode is switched to the SMF mode.
10. The high-efficiency low-energy-consumption EMBR biochemical treatment system is characterized by comprising a biochemical anoxic zone (1), a biochemical aerobic zone (2), a sludge settling zone (3) and a membrane pool (4) which are sequentially connected, wherein the biochemical anoxic zone (1) is used for carrying out anoxic treatment on sewage, the biochemical aerobic zone (2) is used for carrying out aerobic treatment on sewage, the sludge settling zone (3) is used for carrying out sludge settling treatment on treatment liquid treated by the biochemical aerobic zone (2), the membrane pool (4) is used for carrying out membrane treatment on sewage treated by the sludge settling zone (3), an immersed membrane treatment unit (6) is arranged in the membrane pool (4), and the immersed membrane treatment unit (6) is used for realizing membrane water production;
the biochemical aerobic zone (2) is also connected to the biochemical anoxic zone (1) through an air stripping reflux device (5), and the air stripping reflux device (5) between the biochemical aerobic zone (2) and the biochemical anoxic zone (1) is used for refluxing the nitrified liquid treated by the biochemical aerobic zone (2) to the biochemical anoxic zone (1) in a large proportion for biological denitrification;
the sludge settling zone (3) and the membrane tank (4) are also connected to the biochemical aerobic zone (2) through a gas stripping reflux device (5);
and the gas stripping reflux device (5) connected with the sludge settling zone (3) and the membrane tank (4) is used for refluxing the sludge in the sludge settling zone (3) and the membrane tank (4) to the biochemical aerobic zone (2).
CN202110553204.8A 2021-05-20 2021-05-20 Efficient low-energy-consumption EMBR biochemical treatment process and treatment system Pending CN113121019A (en)

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