双膜法处理化工废水过程中反渗透膜污染研究

Research on reverse osmosis membrane fouling during the treatment of chemical wastewater by double membrane method

基于反渗透(RO)膜的双膜组合工艺被广泛应用于废水回用处理,研究了不同RO组合工艺(UF-RO、UF-NF-RO、UF-RO-RO)对化工废水主要污染物的处理效能。通过对不同RO组合工艺处理化工废水过程中膜通量变化、出水中荧光类有机物、膜表面有机和无机污染物含量和成分的分析,揭示了RO膜污染层的形貌和特性。研究结果表明,UF-RO和UF-NF预处理可以一定程度上减缓RO膜通量的下降,但连续运行8 h后RO膜通量仍然严重下降,出水COD、TP、TN均较低,TN去除率均大于95%。废水中荧光类有机物经UF-RO、UF-NF-RO和UF-RO-RO处理后显著减少,主要是由于RO对废水中有机物的截留作用。RO膜表面的污染物主要包括无机污染物质(如钙和镁)以及蛋白质类有机污染物,且有一定量的累积,证明UF、NF、RO等预处理后仍存在污染物质能够在后续RO表面积累,导致严重的膜污染问题。

The double-membrane combination process based on reverse osmosis(RO)membrane is widely used in wastewater reuse treatment.The treatment efficiency of different RO combination processes(UF-RO,UF-NF-RO,UF-RO-RO)on the main pollutants of chemical wastewater was studied.The morphology and characteristics of the membrane pollution layer were revealed by analyzing the membrane flux in the process of chemical wastewater treat-ment by different RO combination processes,the amount,content and composition of fluorescent organic matter in the effluent,organic and inorganic pollutants on the membrane surface.The results showed that UF-RO and UF-NF pretreatment could slow down the decline of RO membrane flux,but the membrane flux was still serious after 8 hours.The COD,TP,and TN of effluent were all low,and the TN removal rate was greater than 95%,when the chemical water was treated by double membrane methods.Fluorescent organic matter was significantly reduced in the effluent after UF-RO,UF-NF-RO and UF-RO-RO treatment,mainly due to RO interception of organic matter from wastewater.The pollutants on the surface of the RO membrane mainly included inorganic pollutants(such as calcium and magnesium)and protein-based organic pollutants,and there was a certain amount of accumulation on the subsequent RO surface,which proved that there were still pollutants after UF,NF,RO and other pretreatments,leading to serious membrane fouling problems.