反渗透浓水预处理对气隙式膜蒸馏性能的影响  

Influence of pretreatment of reverse osmosis concentrate on performance of air gap membrane distillation process

作　　者：徐义明 何清凤[2,3] 黄晶晶 李凭力[2,3] 陈英才 吴浩赟[2,3] 陆晓咏 耿洪鑫[2,3] 黄益平 

机构地区：[1]中建安装工程有限公司,南京210046 [2]天津大学化工学院,天津300072 [3]天津市膜科学与海水淡化技术重点实验室,天津300072

出　　处：《膜科学与技术》2014年第3期86-91,共6页Membrane Science and Technology

摘　　要：针对含有Ca2＋、Mg2＋及SiO32-的反渗透（RO）浓水,提出了化学除硬→絮凝沉淀→离子交换→超滤处理的新型预处理流程.研究了该预处理方法对RO浓水中易结垢离子的去除效果,及其对气隙式膜蒸馏（AGMD）性能的影响.实验结果表明,经过该预处理过程后Ca2＋、Mg2＋和SiO32-的含量均低于5 mg/L.与常规的除硬处理不同,经过该预处理过程后,RO浓水中的难溶盐CaCO3、Mg （OH）2均未达到饱和,进行膜蒸馏浓缩时,不会立即在膜表面沉积.经预处理后,原RO浓水中的主要成分为NaCl,其可在膜蒸馏浓缩得到结晶固体.未经预处理的RO浓水浓缩7倍时,产水通量衰减了40.55％,电导率增大了22.71％,CODCr含量为40～60mg/L;对于预处理后的浓水,该衰减程度减小24.02％,且产水电导率保持相对稳定,COD含量低于10 mg/L,产水可以用作工业循环冷却水和工业洗涤水,经活性炭吸附后可用作锅炉用水.预处理后的RO浓水进入AGMD装置浓缩168 h,产水通量衰减缓慢,产水电导率一直维持在5 μS/cm以下,整个过程中COD均小于10mg/L.A novel pretreatment process for reverse osmosis concentrate was proposed which consisted of chemical removal of hard ions,coagulation and sedimentation,ions exchanges and ultrafiltration.Experiments were carried out to study the effects of pretreatment process on the removal of Ca2＋,Mg2＋ and SiO32-and on the performance of the air gap membrane distillation （AGMD）.The results showed that the contents of Ca2＋,Mg2＋ and SiO32-were all below 5 mg/L.Moreover,the insoluble salts such as CaCO3and Mg（OH）2 were unsaturated in the AGMD process.As a result,CaCO3 and Mg（OH）2 would not deposit on the surface of the membrane when the RO concentrate was processed in the AGMD module.After pretreatment,the main substance in the RO concentrate is NaCl which could be concentrated to crystalline form to obtain NaCl solid.When the concentrate factor reached 7,the novel pretreatment process could increase the permeate flux by 24.02％,the conductivity maintainedrelatively stable and the CODcx of the permeate was below 10 mg/L.As results,the permeate of the process could be used as circulating cooling water and washing water in industry.Moreover,after absorbed by activated carbon,the permeate water could be used as boiler water.The pretreated RO concentrate was concentrated continuously for 168 hours via AGMD.During the process,the permeate flux decreased slowly,the conductivity of the permeate was below 5 μS/cm and the CODcr of the permeate was below 10 mg/L.

关 键 词：RO浓水 气隙式膜蒸馏 预处理 产水通量 产水电导率 

分 类 号：TQ028.8[化学工程]