What are biological reactors?
Biological wastewater reactors (anaerobic and aerobic) makes use of certain microorganisms to assimilate organic matter for their own growth and thus removing soluble components from wastewater. The requirement for the successful application of this echnology is that the contaminants present in wastewater should be biodegradable.
Types of Biological Reactors
Biological reactors are classified based on different criteria-
Depending upon availability of oxygen, the biological reactors are classified as:
Aerobic, anaerobic, anoxic or facultative process.
Depending on the bacterial growth in the reactors, they can be classified as:
(a) Suspended growth process: Bacteria grow in suspension in the reactor without providing any media support such as activated sludge process, and
(b) Attached growth process: Here microorganism growth occurs as a biofilm on the media surface provided in the reactor such as trickling filters. This media could be made from broken gravels or rocks offering very high surface area per unit volume. The media could be fixed in the reactor, as in trickling filter, which is called as fixed film reactor or it could be moving media as used in moving bed bioreactor (MBBR).
Hybrid reactors are becoming increasingly popular as these make use of suspended growth as well as attached growth in the reactor to improve biomass retention and substrate removal kinetics such as submerged aerobic filters (SAF).
How many types of reactors used in Indian WTP?
A: Batch Reactor
In this type of reactor, the wastewater flow is not continuous and these reactors are operated as fill and draw type. The mode of operation of these reactors is batch mode with fill time, reaction time, and withdrawal time. The content may be completely mixed to ensure that no temperature or concentration gradient exists. All the elements in the reactor, under batch mode of operation, are exposed to treatment for the same duration of time for which the substrate is held in the reactor.
B:Plug-Flow (tubular flow) Reactor
In this type of reactor, the fluid particles flow through the tank and are discharged in the same sequence in which they enter the tank. The particles remain in the tank for a time same to theoretical detention time. No overtaking; no intermixing or dispersion takes place. Minimum longitudinal dispersion is considered and this type can occur in high length to width ratio of the tanks.
C:Continuous-flow Stirred Tank (Complete – mixed) reactor
In this reactor type, particles are dispersed throughout the tank as they enter the tank. The content in the reactor are completely mixed thus are homogeneous at all points in the reactor. This reactor can be made in square, circular or rectangular shape. The particles exit the tank in proportion to their statistical population.
D: Arbitrary Flow
Partial mixing between plug flow and completely mixing condition exists in this reactor. Each element of the incoming flow remains in the reactor for different duration of time. It is also called as dispersed flow and lies between ideal plug flow and ideal completely mixed reactor.
E: Packed Bed Reactor
Packing medium, such as, rock, slag, ceramic or synthetic plastic media are filled in these reactors. They can be anaerobic filter, when no air is supplied, or aerobic (trickling filter) when flow is intermittent or submerged aerobic filter when compressed air is supplied from the bottom.
F: Fluidized Bed Reactor
This reactor is similar to packed bed reactor except packing medium is expanded by upward movement of fluid (or air) than resting on each other in fixed bed. The porosity can be controlled by controlling flow rate of wastewater.
How can Netsol help?
Through the use of reactors in treatment of wastewater, it is possible to remove undesirable components and other water treatment services can be performed with the highest degree of efficiency.
Netsol Water have expertise in wide range of waste water treatment technologies. We can customize wastewater treatment plants that will cater to all your needs and at the same time effectively treat different types of wastewater. We are dedicated to provide hands on service, expert counselling and training to our valuable customers.