A batch reaction system for simultaneously conducting reactions in at least two separate reactors (CSTR reactors), is provided wherein the at least two batch reactors, containing mixing means and a fluid inlet, a fluid feed common conduit is present for feed fluid to the reactors, which is connected to the inlet of each reactor of a fluid inlet conduits, and further includes a fluid discharge common conduit which is connected to the outlet of each reactor wherein in each fluid inlet conduit and/or in each fluid outlet conduit a non-return valve is arranged to prevent contamination but can provide simultaneous reactions wherein the reactors can be easily isolated from one another during reaction.