This presentation describes the principle types of reactors used in unit operations and its working mechanism.

1. PRINCIPAL TYPES OF
REACTORS
Presentation by
VIJAYA SUBRAMANIAM P R
M.E Environmental Engineer
Kumaraguru College of Technology

2. REACTOR - Definition
Waste water treatment involving physical unit
operations, chemical and biological unit process
which is carried out in a vessel or tank which is called
a reactor.

3. PRINCIPAL TYPES OF REACTORS
 Batch Reactor
 Complete-mix Reactor [ Continuous-flow Stirred Tank Reactor
CSTR ]
 Plug Flow Reactor [ Tubular flow reactor ]
 Complete-mix Reactor in series.
 Packed Bed Reactor
 Fluidized Bed Reactor

4. Batch Reactor
 In batch reactor, the flow enters the reactor, it is treated and then it is
discharged and the cycle is repeated.
 The reactants are introduced into the reactor in batch.
 The liquid content of the reactor is mixed completely by stirrer.
 Suitable for small production rates and for long reaction time.

5. COMPLETE-MIX REACTOR
 Also called continuous flow stirred tank reactor [CSTR], in which reactants are
added and the products are removed, while the contents are inside the vessel
vigorous stirring is given by internal agitation.
 It may be employed in series or parallel.
 At steady state, the in-flow rate must be equal to the out-flow rate
 It is most commonly used in industrial processing where constant agitation is
required.
 Application : Aerated lagoons,
Activated sludge biological treatment.

6. PLUG-FLOW REACTOR
 Also called as tubular flow reactor.
 It consist of a hollow pipe or tube through which reactants flow.
 It is in the form of a tube wrapped around an acrylic mold which is encased in a tank.
 It has higher efficiency when compare to CSTR.
 Suitable for continuous production, large scale and for high temperature reactions.
 It may be of long open tanks or closed tubular reactors.
 Application : Natural treatment systems, Activated-sludge biological treatment

7. COMPLETE-MIX REACTORS IN SERIES
 The series of complete-mix reactors is used to model the flow regime
corresponding to the complete-mix and plug-flow reactors.
 If the series is composed of one reactor, the complete-mix condition prevails.
 If the series consists of an infinite number of reactors in series, then plug-
flow condition prevails.
 Application : In lagoon treatment systems, to stimulate ideal flow in plug-
flow reactors.

8. PACKED BED REACTORS
 It is filled with some type of packing materials like rocks, ceramics, plastics.
 Depending on the flow, it may be operated either up-flow or down-flow
mode.
 Dosing may be continuous or intermittent.
 Application : Trickling filter

9. FLUIDIZED-BED REACTOR
 It is similar to the packed-bed reactor, here the packing material is
expanded by the upward movement of fluid (air or water) through the bed.
 Application : Aerobic and anaerobic biological treatment.