Method for recovering cyanide and ammonia nitrogen in acrylic nitrile waste water using membrane absorption method

Abstract

The invention relates to a method for recovering high-concentration cyanide and ammonia nitrogen in acrylonitrile waste water by utilization of the membrane absorption method. The method adopts the double-circulation process to adjust the pH value of the waste water to between 11 and 12 at first; the waste water enters into a tube pass of a hydrophobic hollow-fiber membrane after undergoing sand filtration and micro-filtration (MF) in turn to remove suspended particles; volatile NH3 gas in the waste water generates neutralization reaction with a H2SO4 solution on a boundary surface of the hollow-fiber membrane and an absorption liquid, and nonvolatile (NH4)2SO4 is generated and recovered; due to the hydrophobicity of the membrane, water and other nonvolatile substances are still kept in the waste water; and after the high-concentration ammonia nitrogen is recovered by the membrane absorption method, the pH value of the waste water is adjusted to between 5 and 6, an NaOH solution is used as the absorption liquid of HCN, and then the membrane absorption process is repeated. The membrane absorption method is simple and convenient to operate, has low energy consumption, can recover useful substances, and changes the high-cost treatment condition of the acrylonitrile waste water in the prior art to a certain degree.

Description

technical field [0001] The invention belongs to the technical field of water pollution control, and in particular relates to a method for recovering high-concentration cyanide and ammonia nitrogen in acrylonitrile wastewater by using a hydrophobic gaseous membrane absorption method. This method can change the current high-cost treatment status of acrylonitrile wastewater to a certain extent. Background technique [0002] Acrylonitrile (AN for short), structural formula CH 2 =CH-CN is an important organic chemical raw material widely used in many industrial fields such as synthetic fiber, synthetic chemistry and synthetic rubber. In recent years, with the development of acrylic fiber, ABS / AS, acrylamide and other downstream products of propylene oxide, the demand for acrylonitrile in the world has been increasing. The production process of acrylonitrile is mainly the propylene ammoxidation method (Sohio method), which uses propylene, ammonia and air as raw materials, and ob...

AI Technical Summary

Problems solved by technology

The incineration method needs to consume a large amount of auxiliary fuel oil, which is a great waste of limited energy; the pressurized hydrolysis method has low polymer removal efficiency, and the wastewater after hydrolysis with alkali needs a large amount of water to dilute and neutralize with acid before entering Wastewater treatment plants; the wet oxidation method has high requirements on equipment materials, large one-time investment, and needs supporting removal of heavy metal ions (such as Cu 2+ Catalyst) device

At present, all manufacturers at home and abroad basically choose to add auxiliary fuel oil incineration. The treatment cost per ton of wastewater is between 200 and 300 yuan. There are many disadvantages such as large equipment investment, high operating costs, and secondary pollution.