Sequential Batch Reactor (SBR) Technology

SBR is a Cyclic Activated Sludge process. It provides highest treatment efficiency possible in a single – step biological process. The proposed SBR System is operated in a batch reactor mode this eliminates all the inefficiencies of the continuous process. The complete process takes place in a single reactor, within which all biological treatment steps take place sequentially. No additional Settling Unit, Secondary Clarifier is required. The complete biological treatment is divided into Cycles with each Cycle is of 2‐4 hrs duration, during which all treatment steps take place. A basic Cycle comprises of the following phases which take place independently in sequence to constitute a Cycle and then gets repeated.

Standard Treatment Scheme

Manual Screening
Equalization & Cooling tank
pH Correction Dosing System
SBR Tank
Treated Water Tank

SBR Plant Picture

Filling /Aeration

This refers to the process loading time in the cycle. Loading occurs outside of the designated settle and decant sequences during which time influent is received into the basin through an admixture(selector)reactor. Biomass from the main aeration zone is admitted within fluent load in the biological selector hydrolysis reactor. Complete-mix reaction conditions prevail in the main reaction zone during this variable volume operational sequence, being typical of a fed‐batch reactor operation. Aeration can be regulated to maximize co‐current nitrification‐de‐nitrification that takes place and to insure the aerobic uptake of phosphorus previously released during anaerobic operation. The process typically employs a nominally constant rate of recycle from the main reaction zone that is pumped to a zone at the inlet end of the admixture reactor.

Settling

The air is turned off and influent to the reactor basin is stopped. During the first five minutes of this sequence, the residual mixing energy within the reaction basin is consumed. At this time gentle bio‐flocculation initially takes place, a solids‐liquid interface forms under partial hindered settling conditions. Rising of sludge does not occur.

Decanting

This sequence is an extension of the settle sequence and is also totally quiescent whereby a moving weir lowering decanter is used to take the operating liquid level in the basin to its designated bottom water level reference position. In this way supernatant is withdrawn from a subsurface position under laminar flow conditions. This allows optimum removal over the decant depth without entrainment of settled solids or floating debris. Upon completion of the supernatant liquid removal sequence, the moving weir decanter returns to its rest position located out of liquid. Completion of the decant sequence terminates the designated use of the basin as a stratified, interrupted inflow reactor. Typically, fill sequencing begins while the decanter is travelling to its upper rest position.

Standard Steps

Collection of the wastewater into the SBR Tanks
Aeration will be provided by fine bubble diffused aeration.
Compressed air will be provided by air blowers.
Clarification in the SBR Tanks.
Excess Settled sludge from the bottom of the SBR Tank will be wasted to the Sludge thickener.
The Sludge Wasting will be carried out via sludge Wasting Pumps.
Treated Effluent from SBR Tank will be dosed with Hypochlorite for disinfection before disposal.

Benefits of SBR System vs Activated Sludge

NO.	FEATURES	SEQUENTIAL BATCH PROCESS (SBR)	ACTIVATED SLUDGE PROCESS (ASP)
1	Treated Effluent Quality	The SBR utilizes batch kinetics; process reactions approach under high concentration gradients with no short-circuiting.	Utilizes Contiguous flow process. Generally Requires Additional filtration/tertiary treatment Step to achieve desired quality
2	MLSS Operating Range	4500 – 5000 mg/L	3500 – 4000 mg/L
3	Ability to adjust to variable hydraulic and pollutant loading	Very Good	Average
4	Resistance to Sludge Bulking	Cyclic & Batch conditions produce better settling sludge than continuous flow conditions.	Sludge Settleability is generally a concern
5	Secondary Clarifier Requirement	Not required. Aeration, Solid Separation & Clarification occur in the same vessel.	Separate clarifier needs to be provided.
6	Space Requirement/Area Footprint	Small as all necessary treatment operation takes place in a single vessel	Very High
7	System Flexibility	Greater System flexibility. The cycle format can be easily modified at any time to offset changes in process conditions, influent characteristics, or effluent objectives.	Lower system flexibility.

Advantages of World Technologies SBR System

World Technologies SBR offers a simple and most reliable method of Activated Sludge Waste Water Treatment that produces a tertiary quality effluent at the price of secondary treatment including nutrient removal. Simplifying factors which select WT’s SBR against other and conventional sequencing batch reactors are:

Proven Performance

Advanced secondary biological treatment – 95 to 98%
Nitrogen and Phosphorus removal
Tertiary Treatment (Disinfection)

High Flexibility

Consistently meeting effluent discharge limits, regardless of hydraulic and organic loads variations
Municipal, industrial and leachate wastewater, including retrofits
Cold and warm climate.

Simple Operation

Reliable fully automated process (SCADA/HMI display) ensuring low operational costs.

High Expertise / Experienced Team

World Technologies SBR requires the lowest investment and operating costs as compared to any other technology, when compared on a like to like basis, with respect to outlet parameters, MOC, Land required and Power consumed.