Water quality transformation during the RO processes in the zero-liquid discharge system for coal chemical wastewater treatment
The long-term stability of the reverse osmosis(RO)system is crucial for achieving zero-liquid discharge of the coal chemical wastewater.This study focused on a zero-liquid discharge(ZLD)project located in northern China.The variations of the dissolved organic matter(DOM)during the multiple RO processes were investigated with a goal to identify the key organic compounds and evaluate the operational features and performance of the ZLD system.The results showed that the pretreatment could effectively decrease the hardness of wastewater,the removal other ions and pollutants mainly occurred at RO stage.The dominant DOM were aromatic proteins,humic substances,and soluble microbial metabolisms(SMP).Poor coagulation removal of SiO2 occurred at the pretreatment stage,and the removal efficiency was only 25.40％.SiO2 was mainly concentrated during RO processes,and the concentration factors at the 2nd-stage RO and high-efficiency reverse osmosis stage(HERO)were 5.36 and 3.83,respectively,indicating a high Si contamination potential on the membrane surface.The RO stage for reclaimed water mainly intercepted substances like humic substances and proteins,while the RO stage for salt concentration showed a poor rejection of tryptophan and SMP.Si and organic matters were identified as the main challenges in the ZLD process.Therefore,it is crucial to enhance the removal of DOM and Si at the pretreatment stage,to optimize the use of chemicals,and strengthen DOM and microorganism control in the whole system.These strategies are keys to improve the operational stability and membrane fouling mitigation.
coal chemical wastewaterROzero-liquid dischargespectrometryDOM
国家科技期刊平台
NSTL
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