What is SBR?
General SBRs are a variation of the activated-sludge process. They differ from activated-sludge plants because they combine all of the treatment steps and processes into a single basin, or tank, whereas conventional facilities rely on multiple basins
How to design Sequencing Batch Reactors (SBR)?
A step by step guide for calculating size and capacity of tank or a reactor:
a. Hydraulic, organic, nitrogen, and phosphorus loading are the essential criteria for tank design. Section 82.32 of the Domestic Wastewater Facilities Manual should be followed for setting these settings. The tank size, cycle frequency, rate of draw and outflow of treated effluent, and total oxygen demand are all determined using these parameters. When it comes to nitrogen removal, temperature is a crucial factor to consider.
b. The effective part of the tank (the volume between the lowest operating level and the highest level, allowing for at least 18" of freeboard) should be sized to hold the volume of the peak hourly flow received during the portion of the SBR(s) cycle time when no forward flow will occur, or the volume of one batch, whichever is greater. Furthermore, side stream/recycle flows should be factored into the sizing.
c. The hydraulic capacity of the plant should be calculated based on handling 100% of the maximum monthly average flow.
d. Without advancing cycles, the basins should be sized to treat 100 percent of the maximum day dry weather flows. To ensure biomass retention and treatment stability, cycles may be accelerated to handle maximum day wet weather peak flows.
e. At all plants, dividing the needed aeration tank volume into two or more units should be considered. To meet applicable effluent limitations and reliability criteria, total aeration tank volume should be distributed across two or more units capable of independent operation for facilities designed to receive a maximum monthly average flow of 50,000 GPD or higher.
f. A pre-equalization tank can be added to a single SBR reactor. The pre-equalization tank should be large enough to handle the peak flow that may occur during a cycle's nonfill period.
g. Prior to the SBR tanks, the flow division control facilities should be constructed for maximum operation and maintenance convenience, flexibility, consistency of maximum effluent quality, and ease of future unit installation. If more than one basin is given, automatic influent valves or dedicated influent pumps should be provided for each basin. To enable for servicing, each of these valves should have a means of isolation and/or bypass.
h. Based on the maximum daily BOD-5 load to the aeration tank, the volumetric loading of the aeration tank should not exceed 15 lb. BOD-5/day/1000 ft3 [0.24 kg BOD-5/(m3d)].
With sufficient rationale and computations, higher loadings may be permissible.
i. Reactor layout at low or lowest water levels, MLSS concentrations should be in the range of 2,000 mg/L to 5,000 mg/L. Other values could be acceptable if they are justified.
j. A method should be given for completely draining each reactor of all grit, debris, liquid, and sludge.
k. In normal operation, automatic influent valves should be employed to control fill to tanks in or out of service.
l. In single tank SBR designs, influence baffling should be added to ensure physical isolation of the influent from the decanter, or if peak wet weather flows are expected to induce design cycle advancement. An influent manifold, instead, might be used to distribute the influent without disturbing the sludge blanket.
{At design peak hourly flow, average horizontal velocities through each baffle wall or manifold aperture should not exceed 1 ft./sec and the influent wastewater should be directed into the baffling or manifoldblanket of sludge}.
m. While SBR systems should be designed to interrupt flow during the SETTLE and DECANT phases, they can also be configured to function as a continuous influent feed system.In this situation, the reactor should have a length-to-width ratio of at least 3:1, with maximum inlet and output separation.
n. Inter-reactor overflow to another SBR tank or a storage tank should be supplied for each reactor.
o. At a minimum water level and maximum monthly average flow, the detention duration should be at least 12 hours.
p. Decanter system head needs, operating depth changes, operation during stream flooding heights, future plant expansions, and the possibility of treatment units or pumps being out of service should all be factored into hydraulic grade line calculations.
q. The following mechanical requirements must be considered at a minimum:
1. SBRs with one or two basins should be equipped with equipment that can be accessed from the top or side of the basin for inspection, routine maintenance, and operation without dewatering the basins.
2. With a basin out of service, a full description of how the in-basin equipment may be serviced while still processing at least 75% of the maximum monthly average flow and peak daily load is required. If more than two basins are necessary to meet this need, each basin should have its own blower and mixing system.
r. The bottom of the tank should slope towards a drain or sump. For upkeep, circular basins should be slanted towards the centre. Rectangular basins should have a modest incline to one corner to enable for hosing down.
s. Structures with a common wall should be built to withstand the loads that occur when one basin is full and another is empty.
t. The SBR's walls should all be watertight and resist buoyant upliftempty.
u. A tank's side water depth should be at least 9 feet.
v. At the maximum liquid level, the tank should have a minimum freeboard of 18 inches.
For design and manufacture of SBR’s or any other treatment plant, contact Netsol Water for further information.
Netsol Water is Greater Noida-based leading water & wastewater treatment plant manufacturer. We are industry's most demanding company based on client review and work quality. We are known as best commercial RO plant manufacturers, industrial RO plant manufacturer, sewage treatment plant manufacturer, Water Softener Plant Manufacturers and effluent treatment plant manufacturers. Apart from this 24x7 customer support is our USP. Call on +91-9650608473, or write us at enquiry@netsolwater.com for any support, inquiry or product-purchase related query.
