The Treatment Of Saline Glycol Wastewater By Membrane Distillation Crystallization

Nowadays,with the increasing attention of environment protection across the world,the treatment and recycle of saline organic wastewater has been focused by various researchers.Saline glycol wastewater from deep water gas field is a typical saline organic wastewater which is produced by the addition of anti-hydrating agent(EG).Currently,this saline glycol wastewater is recycled by evaporation crystallization process.However,there are two main problems: firstly,the operating temperature for this process is pretty high and the loss of EG for the high temperature is huge.Secondly,the supersaturation in crystallization process is uncontrollable and the separation of crystals from the crystallizing solution is pretty hard.To overcome these drawbacks,the membrane distillation crystallization technology had been applied to reduce energy consume,EG loss,and produce the crystal production with uniform distribution and completely surface morphology.In the study,membrane distillation process had been used to concentrate the saline glycol wastewater,the permeate flux had been measured both in experiment and theory.Besides,the separation efficiency and long term stability has been detected.In the crystallization process,some basic crystallization data had been measured,such as solubility and supersolubility.Moreover,the influence of membrane,temperature and EG content on the crystal distribution and surface morphology had been studied.The mechanism of membrane crystallization had been proposed in this study through the analysis of force field and the mathematical criterion to judge whether the crystal will slide and detach from the membrane surface had been raised.The proposed crystal growth and nucleation mechanism had been tested by the direct observation experiment and some advantages involving membrane crystallization had been explained by the mechanism.In addition,based on the criterion,some membrane module parameters had been evaluated providing some theory introduce to the industry production.