2. Basics of oxidation and reduction reactor design

Oxidation or reduction reactions involve three types of reactor, depending on the state of the reactant and any catalyst under the conditions of use:

• single-phase reactor: the reagent is liquid (e.g. hydrogen peroxide, bleach);

• two-phase reactor: either the reactant is gaseous (oxygen, ozone) or the catalyst is solid (biological desulphation);

• three-phase reactor: the reactant is gaseous and the catalyst (biomass from biological processes) is in solid form (biofilm processes).

The basic design principles for redox reactors applied to water treatment are therefore in line with those for any chemical reactor