Process for the purification of crude caprolactam

Disclosed is a process for recovering and purifying crude caprolactam from crude caprolactam-containing wastewaters consisting essentially of the steps: (a) obtaining a wastewater stream containing crude caprolactam from at least one process which by-produces a crude caprolactam-containing wastewater stream selected from caprolactam polymerization, catalytic cracking of polymers and oligomers of caprolactam, and thermoplastic processing of polycaprolactam; (b) mixing the crude caprolactam-containing wastewater stream with between 0.01 to 5% by weight, based on the crude caprolactam in the wastewater stream, of an acid; (c) subjecting the mixture of crude caprolactam-containing wastewater stream and acid obtained according to step (b) to purification distillation at a temperature of between 100 to 180 DEG C and a pressure of between 50 to 3000 Pa; and (d) obtaining purified crude caprolactam as a distillate from step (c).