CN1215993C - Batch type integrated membrane bioreactor - Google Patents

Abstract

The present invention belongs to the technical field of sewerage treatment and reclaimed water recycle in environment engineering, which is characterized in that an aerobic environment, an oxygen deficient environment and an anaerobic environment are realized in the same reaction tank so as to sufficiently remove nitrogen and phosphorus pollutants. A blower and a suction pump are synchronously started. The operation of organic matter degradation, ammonia and nitrogen nitration, and excessive phosphorus suction is completed in an aerobic stage. A time relay controls the blower and the suction pump to stop working, simultaneously, a lifting pump and a stirrer are started, the lifting pump pumps water with high flow quantity so as to provide sufficient carbon sources for denitrification, and a liquid level controller is used for controlling the lifting pump to stop working. After the blower stops working, dissolved oxygen is fast exhausted, and nitrate is in denitrification in an oxygen deficient stage so that the content of the nitrate is reduced. Phosphorus gathering bacteria sufficiently release phosphorus in an anaerobic stage. The rest sludge containing the phosphorus is periodically discharged to a sludge thickening tank by an air lifting pump so that the volume of sludge is reduced and supernatant fluid self flows to a regulation tank for retreatment. The present invention has the advantages of high capability of denitrification and phosphorus removal, simple flow path, convenient operation and low energy consumption, and can be used for treating and recycling sewage with high contents of nitrogen and phosphorus.

Description

Sequenced batch operation method to enhance the nitrogen and phosphorus removal function of membrane bioreactor

technical field

The invention belongs to the technical field of environmental engineering, relates to sewage treatment and reclaimed water technology, in particular to a method for realizing the denitrification and dephosphorization functions of a membrane bioreactor process.

Background technique

my country is one of the 13 water-poor countries in the world. In order to save precious water resources, reuse of reclaimed water is one of the effective ways. Studies at home and abroad have proved that the membrane bioreactor process that combines membrane filtration and biodegradation is an efficient and practical technology for sewage treatment and reclaimed water reuse, but the membrane bioreactor has insufficient nitrogen and phosphorus removal capabilities to meet Increasingly stringent water quality requirements.

Recycled sewage with high nitrogen and phosphorus content will cause the following main hazards when it is reused in industrial cooling water, industrial production water or municipal miscellaneous water: eutrophication of the receiving water body; lead to the propagation of biofouling in water pipelines and water equipment, resulting in blockage Or affect efficiency; increase the amount of disinfectant, while increasing the cost of water production, reduce the safety of water quality. In the "Comprehensive Wastewater Discharge Standard" (GB8978-1996), strict requirements for phosphate ≤ 0.5mg/L and ammonia nitrogen ≤ 15mg/L were put forward for the effluent quality of urban sewage secondary treatment plants.

The traditional A ² /O synchronous nitrogen and phosphorus removal process requires four pools: anaerobic tank, anoxic tank, aerobic tank and secondary sedimentation tank. The effluent from the aerobic tank needs to be partially circulated back to the anoxic tank by the return pump. , to realize the denitrification of the nitrifying liquid; the phosphorus-containing sludge in the secondary sedimentation tank needs to be partially circulated back to the anaerobic tank by the action of the sludge pump, so as to realize the full release of phosphorus by the phosphorus-accumulating bacteria. This process is complex, high energy consumption, difficult to operate and control, and the effluent of this process is the supernatant of the secondary sedimentation tank, the effluent water quality is poor, and cannot be reused as reclaimed water.

Contents of the invention

The purpose of the present invention is to provide a method for making the membrane bioreactor have the function of denitrification and phosphorus removal, and the required device is called sequence batch integrated membrane bioreactor. Using this method to design and build a membrane bioreactor will enable it to fully and effectively remove nitrogen and phosphorus pollutants on the basis of maintaining the original advantages, and it is simple to operate and easy to implement.

Realize the technical scheme that makes membrane bioreactor have denitrification and dephosphorization functional method described in the present invention is:

Add a mixer in the membrane bioreactor, use the liquid level controller and time relay to control the start-stop mode and running time of the four equipment of the mixer, the blower, the water inlet lift pump and the water outlet suction pump, and achieve good results in the same reaction tank. Oxygen, anoxic and anaerobic environments. During blower aeration, bubbles are generated by the inverted umbrella-type medium bubble aerator, which fully disturbs the membrane filaments and slows down membrane fouling, and at the same time provides sufficient oxygen to the activated sludge in the reaction tank to make it in an aerobic state, thereby reducing Bacteria cultivation degrades organic pollutants, nitrifying bacteria oxidize ammonia nitrogen to nitrate, and phosphorus accumulating bacteria absorb phosphorus excessively. When the blower stops aeration, the suction pump stops and the mixer starts to ensure that the activated sludge is in a suspended state and the mud and water in the reaction tank are evenly mixed. At the same time, the lifting pump feeds water with a large flow rate, and the water level of the reaction tank is restored to the highest water level in the shortest possible time, and the lifting pump is controlled by the liquid level controller to stop. That is, the opening of the lift pump is controlled by the time relay, while the stop is controlled by the liquid level controller. In a short period of time after the aeration is stopped, a large amount of water inflow provides sufficient electron donors for denitrification, without the need for additional carbon sources; and avoids the competition between denitrifying bacteria and phosphorus accumulating bacteria for organic substrates, ensuring good phosphorus removal Effect: The entry of a large amount of organic carbon can rapidly reduce dissolved oxygen and ensure sufficient anoxic and anaerobic time in the reaction tank. In the anoxic stage, denitrifying bacteria use carbon-containing organic matter in wastewater as a carbon source to convert nitrate into nitrogen and escape, thereby achieving complete denitrification. The concentration of nitrate gradually decreased and entered the anaerobic stage, and the phosphorus accumulating bacteria fully released phosphorus. After the aeration is stopped, organic matter will be further removed by denitrifying bacteria and phosphorus accumulating bacteria. After the anaerobic state is over, the blower is turned on through the time relay control, so that the activated sludge in the reaction tank enters the aerobic state again.

The reason why this method can strengthen the denitrification and dephosphorization function of the membrane bioreactor mainly lies in: adopting the sequence batch operation mode, so that the microorganisms are in an anoxic/anaerobic/aerobic alternate environment; Concentrated water intake ensures sufficient anoxic/anaerobic time; the period and exchange ratio can be simply adjusted according to the nitrogen and phosphorus content of the influent, with high flexibility.

Moreover, after the aeration is stopped in this method, the effluent peristaltic pump stops suction, so that the force of the substances in the mixed solution moving to the surface of the membrane filaments is weakened, and at the same time the mixer is started, which still has a disturbing effect on the membrane filaments, which is beneficial to the membrane filaments. Substances attached to the surface diffuse toward the mixed solution, thereby reducing membrane fouling.

The excess phosphorus-containing sludge in the reaction tank is regularly discharged to the sludge thickening tank by the air lift pump to concentrate and reduce the volume, and the supernatant is returned to the regulating tank for reprocessing. In the aeration stage of the blower, only need to open the valve on the branch road, the sludge can be lifted by air, and no additional power consumption is required.

The effect and benefit of the present invention are strong denitrification and dephosphorization capabilities, simple process, convenient operation and low energy consumption, and can be used to treat sewage with high nitrogen and phosphorus content, especially suitable for reclaimed water reuse projects.

Description of drawings

The accompanying drawing is a schematic diagram of the process flow of the sequencing batch integrated membrane bioreactor.

In the figure: (1) blower; (2) lifting pump; (3) mixer; (4) suction pump; (5) membrane module; (6) inverted umbrella type medium bubble aerator; (7) air lift pump (8) valve; (9) reaction pool; (10) regulating pool; (11) sludge thickening pool.

Detailed ways

The best embodiments of the method and device of the present invention will be described in detail below in conjunction with the accompanying drawings.

Example

The C/N ratio in domestic sewage is usually above 10:1. At this time, the time relay is set to switch every hour. If the influent C/N ratio is lower than 10:1, the time of the aerobic stage in the cycle can be extended to strengthen nitrification; at the same time, the water output in the aerobic stage can be increased to increase the short-term time of the anoxic/anaerobic stage The amount of organic carbon source entering the reactor strengthens the denitrification effect.

The process runs in cycles, and each cycle is divided into two phases, namely the aerobic phase and the anoxic/anaerobic phase. The air blower (1) and the suction pump (4) start synchronously. At this stage, only water is discharged, and no water is taken in. The water level of the reaction tank (9) drops, which is an aerobic stage. After 1 hour, controlled by the time relay, the air blower (1) and the suction pump (4) stop running, and at the same time, the lifting pump (2) and the mixer (3) start synchronously. The lift pump (2) feeds water with a large flow rate, and the water level of the reaction tank (9) is restored to the highest water level in the shortest possible time. The stop of the lift pump (2) is controlled by the liquid level controller. This is anaerobic/anaerobic stage. After 2 hours, the mixer (3) is controlled by the time relay to stop, and simultaneously the blower (1) and the suction pump (4) are restarted to complete a cycle. When the blower is aerated, the valve (8) is opened regularly, and the excess sludge containing phosphorus is discharged to the sludge concentration tank (11) by the air lift pump (7), the sludge is concentrated at the bottom of the tank, and the supernatant is returned to the adjustment tank (10) reprocessing. The automatic control system of the invention is simple and easy to implement, and can make the membrane bioreactor have excellent nitrogen and phosphorus removal capabilities.

Claims (4)

1. A method that adopts the sequential batch mode of operation to strengthen the denitrification and dephosphorization function of membrane bioreactor, its characteristics are as follows: 1) The process operates periodically, and each cycle is divided into two stages, namely the aerobic stage and the anoxic/anaerobic stage; 2) The blower and the water outlet suction pump are started synchronously. At this stage, only water is discharged, no water is taken in, and the water level of the reaction tank drops. This is the aerobic stage; 3) After the aerobic stage is completed, the blower and the suction pump stop running under the control of the time relay. At the same time, the water inlet lift pump and the mixer start synchronously; The pool water level returns to the highest water level, and the stop of the lift pump is controlled by the liquid level controller. This is the stage of anoxic and anaerobic; 4) After the anoxic/anaerobic stage is completed, the mixer is stopped by the time relay control, and at the same time the blower and the water outlet suction pump are restarted to complete a cycle. 2. A method for strengthening the denitrification and phosphorus removal function of membrane bioreactors according to claim 1, characterized in that: the initial concentration of water in the deficient/anaerobic section does not stop in one cycle. Water ingress occurred. 3. A method for strengthening membrane bioreactor denitrification and phosphorus removal by adopting sequence batch operation mode according to claim 1, characterized in that: said membrane bioreactor is an ultrafiltration or microfiltration membrane module At the bottom of the square activated sludge tank, there is an aerator under the membrane module. 4. according to claim 1, a kind of method adopting sequence batch mode of operation to strengthen the denitrification and dephosphorization function of membrane bioreactor is characterized in that: the residual sludge containing phosphorus is discharged to the sludge thickening tank by the air lift pump, The sludge is concentrated at the bottom of the tank, and the supernatant is returned to the regulating tank for further processing.