Contaminant rejection in the presence of humic acid by membrane distillation for surface water treatment
Contaminant rejection in the presence of humic acid by membrane distillation for surface water treatment
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DOI：
10.1016/j.memsci.2017.07.013
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发表时间：
2017-11-01
影响因子：
9.5
通讯作者：
Chew, Jia Wei
中科院分区：
文献类型：
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作者：
Han, Le;Xiao, Tong;Chew, Jia Wei
膜蒸馏(MD)是一种很有前途的高纯度分离方法，如饮用水所需的分离。MD在地表水或地下水处理方面的好处尚未实现，因此腐植酸和钙的存在对其他基于膜的过程是有害的。因此，本研究调查了MD在含有腐植酸、氯化钙和氯化钠的典型饲料中拒绝各种污染物，即布洛芬、硼和砷的效果。所调查的饲料范围从去离子水到模拟地表水的合成饲料，再到新水盐水(即来自新加坡当地废水处理厂的反渗透浓缩物)。结果一致地表明，在不同浓度的腐植酸和钙以及不同的pH值下，整个实验过程中渗透通量恒定，电导率低，这意味着膜污染和润湿可以忽略不计。此外，对硼和砷的完全排斥也实现了，而对布洛芬的排斥约为90%。在渗透液中检测到非挥发性布洛芬和腐植酸，表明膜具有疏水作用。最后，进行了成本分析，以评估MD与传统的纳滤(NF)工艺。尽管MD目前的成本高于纳滤膜，但(I)专为MD量身定做的改进膜的可用性和低成本加热将使成本至少降至纳滤膜的成本，以及(Ii)MD的性能在长时间持续通量方面更优越，能够处理污染物浓度更高的饲料，并具有更好的渗透质量。
Membrane distillation (MD) is a promising means for high-purity separations like those needed for potable water. The benefits of MD have not been realized for the treatment of surface or ground water, whereby the presence of both humic acid and calcium are detrimental to other membrane-based processes. Accordingly, this study investigated the efficacy of MD in rejecting various contaminants, namely, ibuprofen, boron and arsenic, in the presence of typical feeds comprising humic acid, calcium chloride and sodium chloride. Feeds investigated ranged from DI water to synthetic feeds mimicking surface water to NEWater brine (i.e., reverse osmosis concentrate from a local wastewater treatment plant in Singapore). Results consistently indicate constant permeate fluxes and low conductivities throughout the experiments with varying concentrations of humic acid and calcium, along with varying pH values, which implies negligible membrane fouling and wetting. Also, complete rejections of boron and arsenic were achieved, while rejection of ibuprofen was approximately 90%. The detection of the non-volatile ibuprofen and humic acid in the permeate suggests some hydrophobic interactions with the membrane. Finally, a cost analysis was carried out to evaluate MD against the conventional nanofiltration (NF) process. Although MD is currently at a higher cost than NF, (i) the availability of improved membranes tailored for MD and low-cost heat would decrease costs to at least those of NF, and (ii) the performance of MD is superior in terms of sustained flux over prolonged periods, capable to treat feeds with higher concentrations of foulants, and better permeate quality.