Hydrochloric acid recovery and separation method from waste liquid of N-phosphonomethyl iminodiacetic acid production

The process of separating and recovering hydrochloric acid from N-phosphono methyl imino diacetic acid producing effluent liquid includes the following steps: 1. steam heating at normal or reduced pressure to recover effluent liquid; and 2. continuous or intermittent rectification and separation of recovered effluent liquid in combined apparatus of anticorrosive stuffing tower, double-effect heat exchanger, re-boiler and condensator to obtain aldehyde and acid; or separation with four-stage reverse osmose membrane. The recovered hydrochloric acid and formaldehyde may be reused in the preparation of N-phosphono methyl imino diacetic acid, and this can reach the aims of lowering resource consumption and preventing environmental pollution.