Abstract: This article details the principles of SBR process, and process startup, commissioning, operation and management issues in the analysis carried out in this regard for the design, construction, commissioning has a good reference value.
Keywords:: SBR process to run Summary
SBR is a Sequencing Batch Reactor (Sequencing Batch Reactor Activated Sludge Process) in short, is a way to run by intermittent aeration activated sludge wastewater treatment technology, also known as Sequencing Batch Reactor Activated Sludge Process.
Different from conventional sewage treatment process, SBR technology uses the time division mode of operation an alternative mode of operation of space separated, non-stable alternative to steady-state biochemical reactions and biochemical reactions, put it aside for an ideal alternative to the traditional dynamic precipitation precipitation. Its main feature is running on the orderly and intermittent operation, SBR technology is the core of SBR reaction tank, the pool set equalization, primary sedimentation, bio-degradable, 2 Shen functions in a pool, no sludge return system. It is these special characteristics make SBR process has the following advantages:
1, the ideal plug-flow process to drive biochemical reactions increased efficiency, pool anaerobic, aerobic at the turn of state, purification effect is good.
2, are stable operation of sewage in an ideal static state, precipitation, required a short time, high efficiency, good water quality.
3, resistance to shock loading, there are stranded in the handling of pool water and sewage are dilution, buffer effect, effective resistance to the impact of water and organic dirt.
4, process in the various processes in accordance with water quality, quantity adjustments, operation and flexible.
5, processing equipment, less simple structure, easy operation and maintenance management.
6, the reaction pool exists DO, BOD5 concentration gradient, effective control of activated sludge bulking.
7, SBR law system itself is also suitable for modular construction methods, which will help wastewater treatment plant expansion and transformation.
8, nitrogen and phosphorus removal, proper control operation mode to achieve aerobic, anoxic, anaerobic condition alternately, has a good effect of nitrogen and phosphorus removal.
9, process simple and low cost. There is only one of the main equipment, batch sequencing batch reactor, goes for the sedimentation tank, sludge return system, regulating pond, primary sedimentation tank can also be omitted, a compact layout, covers an area of province.
SBR system, the scope of application
As a result of technical characteristics, SBR system, and further broadens the use of activated sludge. On the recent technical conditions, SBR system is more suited to the following:
1) small and medium factories, mines and urban sewage and industrial waste water businesses, especially intermittent flow of changes in emissions and a larger place.
2) The need for a higher water quality of the places, such as scenic and tourist areas, lakes and estuaries and so on, not only to remove organic matter, also called effluent nitrogen and phosphorus to prevent eutrophication of rivers and lakes.
3) The water shortage areas. SBR system can be materialized in the biological treatment after treatment, no additional facilities, to facilitate water recycling.
4) The shortage of land areas.
5) built a continuous flow of sewage treatment plant transformation.
6) is very suitable for handling a small amount of water, intermittent discharge of industrial wastewater and scattered point source pollution control.
SBR design features, the main parameters
SBR design features
A run-cycle (T) to determine the
SBR operation cycle from water-filled time, reaction time, settling time, pumping water and mud time and idle time to determine. Water-filled time (tv) should be an optimal value. As noted above, water-filled time should be based on specific water quality and operation in the process of aeration method used to determine. When using a limited aeration mode, and the concentration of pollutants in water is high, water-filled time should be appropriate to take longer; as a non-limited aeration mode, and the concentration of pollutants in water is low, water-filled time can be appropriate to take shorter. Water-filled time normally take 1 ~ 4h. Reaction time (tR) is to determine the volume of SBR reactor, a very key process design parameters, the determination of its value during the operation also depends on the nature of sewage, sludge reactor concentration and aeration mode and other factors. For the domestic sewage waste water treatment easy class, the reaction time can take a shorter, instead of containing refractory materials or toxic substances, wastewater, the reaction time may be appropriate to take longer. Generally 2 ~ 8h. Precipitation drainage time (tS D) generally governed by 2 ~ 4h design. Idle time (tE) are generally governed by 2h design.
A cycle time tC ≥ tR + tS + tD
Number of cycles n = 24/tC
2, the reaction tank volume calculations
Assuming that each series of the volume of effluent for q, in each cycle of the sewage entering the reactor volume q / n * N. The volume of each reactor:
V: The capacity of the reactor
1 / m: discharge ratio
n: number of cycles (cycles / d)
N: the number of each series of reaction cell
q: for each series of sewage into the water (design maximum daily volume of effluent) (m3 / d)
3, aeration system
Sequencing batch reactor activated sludge process, the aeration device capabilities should be within the required aeration time be able to supply oxygen, in the design, high-load run-time per unit of influent BOD of 0.5 ~ 1.5kgO2/kgBOD , low-load run time of 1.5 ~ 2.5kgO2/kgBOD.
In the sequencing batch reactor activated sludge process, because in the same reaction to the aeration tanks for activated sludge and sedimentation, aeration devices must be easy to plug in, taking into account the mixing reactor performance. Aeration systems are commonly used in gas-liquid mixing jet, mechanical stirring type, perforated aeration tube, porous aerator, jet aeration general election because there are mixed without aeration the role of fashion, while avoiding congestion.
4, drainage system
⑴ supernatant exclusion devices should be able to set the drainage time, the activated sludge does not occur the case of floating discharge supernatant methods are gravity discharged exhaust emission and water pumps.
⑵ exhaust devices for the prevention of supernatant failure, accidents should be set to use drainage.
⑶ in the supernatant discharge devices should be equipped with anti-scum out of institutions.
Sequencing batch reactor activated sludge drain discharge device in settling period, should be discharged with the separation of activated sludge supernatant, and have the following characteristics:
1) should be able to neither disturbance precipitated sludge, sludge will not go up, according to the provisions of the flow discharge supernatant. (Quantitative drainage)
2) In order to obtain the clear treated water after the separation, should be close to the surface of the water catchment agencies and can be discharged with the supernatant after the water level changes in drainage. (Follow the water level of performance)
3) drainage and drainage to stop the action to be carried out smoothly, action accurate, durable and reliable. (Reliability)
Drainage of the structure, according to the different movements the way, there are float-type, machine type, and not to lift the fixed.
5, mud Equipment
Design of sludge dry solids = design volume of sewage influent SS concentration * Design * Sludge Yield / 1000
In the high-load operation (0.1 ~ 0.4 kg-BOD/kg-ss * d) when the flow of sludge production per 1 kgSS produce 1 kg terms, in the low-load operation (0.03 ~ 0.1 kg-BOD/kg-ss * d) when the inflow of 1 kgSS each calculation produces 0.75 kg.
In response to the pool to set a simple sludge thickening tank, able to obtain 2 ~ 3% of the concentrated sludge. As the sequencing batch reactor activated sludge process without primary sedimentation tank, easily more debris flows, sludge pumps should be easy to plug the pump.
SBR design of the main parameters
Sequencing Batch Reactor design parameters, we must take into account the geographical features and treatment plant design conditions (land area, maintenance and management to deal with water quality objectives, etc.) the appropriate determination.
The design parameters for facilities design shall be subject to the following values:
BOD-SS loading (kg-BOD/kg-ss * d) 0.03 ~ 0.4
MLSS (mg / l) 1500 ~ 5000
Emission ratio (1 / m) 1 / 2 ~ 1 / 6
Safety height ε (cm) (activated sludge interface and above the minimum water depth) 50 or more
Sequencing batch reactor activated sludge method is a different according to the organic load from the low-load (equivalent to oxidation ditch) to the high-load (equivalent to the standard activated sludge method) can run within the framework of the method. Sequencing batch reactor activated sludge BOD-SS loading, due to the aeration time as the reaction time to consider, define the following formula:
QS: sewage into the water (m3 / d)
CS: The average influent BOD5 (mg / l)
CA: The average MLSS concentration in aeration tanks mixture (mg / l)
V: volume of aeration tank
e: aeration time than e = n * TA/24
n: number of cycles TA: a cycle of aeration time
Sequencing batch reactor activated sludge process is based on the load conditions of each cycle, the reaction tank volume of sewage into the water ratio and the daily number of cycles to determine, in addition, the sequencing batch reactor activated sludge process as a result pool easy to maintain good MLSS concentration, so the changes through the MLSS concentration can also be adjusted organic load. Furthermore, due to aeration time easy to adjust, so by changing the aeration time, organic load can be adjusted.
In the denitrification and desulfurization targets, in addition to organic load, he also must discharge ratio, the number of periods, daily aeration time for research.
In the land area of restricted facilities, suitable for high load operation, the influent flow rate variation in a small load of small-scale facilities, the best low-load operation. Therefore, an effective way is to put into production during the initial phase in the low-load operation, and as the volume of water increases, it can be a high load operation.
Characteristics under different load conditions
Organic load conditions (flow conditions) high load operation with low load operation
Intermittent intermittent water inlet, continuous
Operating conditions BOD-SS loading (kg-BOD/kg-ss * d) 0.1 ~ 0.4 0.03 ~ 0.1
Large number of cycles (3 ~ 4), small (2 ~ 3)
Discharge than the size of the
Handling characteristics of organics removal of treated water BOD