膜组合工艺处理含铁填埋场渗滤液及膜污染分析

Treatment of iron containing landfill leachate and membrane fouling analysis by membrane combined process

在某含铁渗滤液卷管式反渗透(STRO)应急减量项目运行期间,膜组件流道内生成不明胶状物,造成了严重的膜污染。通过胶状物酸溶分析及膜酸洗水水质分析,发现该胶状物的生成与水质中的高含铁量相关,同时对膜片的扫描电镜分析进一步证实了膜面发生的污染为有机物-铁的复合污染。根据该污染机理对渗滤液开展浸没式微滤及PAC混凝沉淀预处理中试验证实验。实验结果可得,浸没式微滤对原水总铁的去除率约为50%,然而STRO系统在70%回收率下处理微滤产水的污染周期仅为60 h,换用碟管式反渗透(DTRO)后可将污染周期延长至120 h;采用1500 mg/L PAC加药量的混凝沉淀工艺对总铁有80%的去除率,且混凝产水对后端STRO污染趋势显著降低,STRO在70%回收率下污染周期大于200 h,并在提高膜回收率至75%后STRO污染周期依然超过120 h。综合分析可得STRO、DTRO对浓水侧浓水的铁耐受质量浓度分别为8、16 mg/L左右。现场可根据实际需求采用浸没式微滤+DTRO或PAC混凝沉淀+STRO的组合工艺,保证整体工艺的稳定运行。

During the processing of iron containing leachate emergency treatment case with the spacer tube reverse osmosis(STRO)process,a type of unknown colloids were generated in the channel of membrane module and caused serious membrane pollution.Through the acid dissolution analysis of colloid and the water quality analysis of acid membrane-cleaning water,it was found that the formation of colloid was related to the high iron content of the leach⁃ate.Additionally,the membrane SEM analysis further confirmed that the pollution on the membrane surface was a kind of mixed pollution with organic matter and iron.According to their pollution mechanism,the verification experi⁃ments of immersion microfiltration pretreatment and PAC coagulation sedimentation pretreatment for the leachate were carried out.The experimental result showed that submerged microfiltration could remove almost 50%total iron of the leachate.However,the pollution cycle of STRO system in treating microfiltration produced water at 70%re⁃covery was only 60 h.Only when changing to disk tube reverse osmosis(DTRO)system could extend the pollution cycle to 120 h.Concurrently,the coagulation sedimentation process with 1500 mg/L PAC dosage had an 80%total iron removal rate of the leachate,and the pollution trend of STRO treating coagulation produced water was signifi⁃cantly reduced.The pollution cycle of STRO was more than 200 h under 70% recovery,and the system recovery could be further improved to 75% with a pollution cycle exceeding 120 h.Comprehensive analysis showed that the iron tolerance mass concentration of STRO and DTRO at membrane concentrated side was about 8 mg/L and 16 mg/L respectively.The combined process of immersion microfiltration+DTRO or PAC coagulation sedimentation+STRO could be adopted on site based on the actual needs to ensure the stable operation of the whole process.