Abstract: A double alkali process employs limestone to regenerate spent sodium sulfite and then recirculates the unreacted limestone to attain a high internal stoichiometry and high limestone utilization. The regeneration of the sodium sulfite is carried out in a plurality of reactors and separation of the slurry from the reactors is carried out in at least one hydroclone. The at least one hydroclone has two primary functions: one to promote the reaction of Na.sub.2 SO.sub.3, which reduces the reactor volumes and reduces the temperature of conversion; and two to reduce the concentration of the limestone overflow, thus increasing the limestone utilization.

Abstract: There is provided a process for removing trinitrotoluene from waste water resulting from the manufacture of trinitrotoluene, the process comprising forming an admixture of the waste water and an amino group containing compound of the formula (C.sub.n H.sub.2n+1).sub.m (NH(CH.sub.2).sub.x).sub.y NH.sub.z, wherein n is 1 to 25, m is 1 to 3, x is 1 to 5, y is 0 to 5, z is 0 to 2 or the amine and a cationic compound of the formula (C.sub.n H.sub.2n+1).sub.4 N.sup.+ X.sup.-, wherein n is 1 to 25, and X.sup.- is Cl.sup.-, Br.sup.-, SO.sub.4 H.sup.- ; stirring the mixture to form a water insoluble reaction product of trinitrotoluene, and recovering the reaction product from the substantially trinitrotoluene free waste water.