Treatment process for wastewater from N-(Phosphonomethyl)iminodiacetic acid production

Abstract

The invention discloses a method for treating PMIDA (N-(phosphonomethyl)iminodiacetic acid) production wastewater, which comprises the following steps: 1) the PMIDA production wastewater is sent into equipment with a compound evaporator and a vacuum system, and is separated into a saturated concentrated solution containing sodium chloride and evaporable water at a steam pressure of between 0.1 and 0.4MPa and a vacuum degree of between 0.05 and 0.08MPa; the concentrated solution containing the sodium chloride is cooled to crystallize the sodium chloride; and the solid-liquid separation is performed; 2) separating medium is sent into a curing container, a curing agent is added, and innoxious solid mud and a filtrate are obtained after the washing and filtration; 3) after the evaporable water and the filtrate are mixed, a neutralizing agent is used to adjust the pH value to between 6 and 8; 4) an oxidant is added in neutralized wastewater for oxidation; and 5) a treated oxidized liquid is aerated and then enters the prior biochemical system to obtain treated water. The method can greatly reduce the treatment cost for the PMIDA production wastewater, can also extract partial useful constituents in the PMIDA production wastewater, can be recycled, and is favorable for the environmental protection.

Description

Technical field: [0001] The invention relates to a treatment method of chemical production wastewater, in particular to a treatment method of diglyphosate production wastewater. Background technique: [0002] In the production process of using iminodiacetonitrile or iminodiacetic acid as raw material, alkali hydrolysis to synthesize iminodiacetic acid sodium salt, and then phosphonoformylation reaction to synthesize diglyphosate, the separated aqueous solution after the solid product of diglyphosate is separated , which is the waste water from the production of bis-glyphosate. Diglyphosate production wastewater contains 05-5% diglyphosate, 1-7% HCl, 0.5-5% phosphorous acid, 0.5-3% formaldehyde, 8-18% sodium chloride and the like. The waste water will pollute the environment due to direct discharge, and waste water treatment is required. [0003] There are the following three methods for the treatment of wastewater from the production of diglyphosate in the past: [0004] ...

AI Technical Summary

Problems solved by technology

[0007] 1) Incineration of waste water with fuel, the incineration operation is cumbersome, unstable, and the treatment cost is high;

[0008] 2) In the later stage of incineration, due to the sodium chloride in the waste water, the salt is easy to crystallize and accumulate on the wall of the incinerator. If the operation is not good, there is a danger of frying the furnace;

[0009] 3) Due to the incomplete combustion during the incineration process, the second polluted waste gas is generated. It is necessary to build a set of tail gas treatment system, and after treatment, it will be discharged up to the standard.

[0010] However, if the diglyphosate wastewater is treated by the above three methods to reach the discharge standard, a large treatment cost is required, which greatly increases the treatment cost of the diglyphosate production wastewater.