Suppressing transmembrane-pressure rise by pulse dosing of submicron super-fine powdered activated carbon: Effects of filtration flux, coagulant types, and coagulant-dose timing during precoating
Suppressing transmembrane-pressure rise by pulse dosing of submicron super-fine powdered activated carbon: Effects of filtration flux, coagulant types, and coagulant-dose timing during precoating
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DOI：
10.1016/j.jwpe.2022.103180
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发表时间：
2022-10
影响因子：
7
通讯作者：
Yuanjun Zhao;Y. Matsui;Y. Kinouchi;Takumu Seko;N. Shirasaki;T. Matsushita
中科院分区：
文献类型：
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作者：
Yuanjun Zhao;Y. Matsui;Y. Kinouchi;Takumu Seko;N. Shirasaki;T. Matsushita
最近发现，混凝预处理后以脉冲方式投加的亚微米粉末状活性炭（SSPAC，直径 200 nm）可有效减轻膜污染，从而抑制微滤过程中跨膜压力（TMP）的升高，因为 SSPAC 比传统 PAC 具有更高的吸附膜污染物（例如天然有机物）的能力，并且 SSPAC 在膜表面形成的预涂层可延缓膜污染。本研究研究了预涂过程中的过滤通量、混凝剂投加时间以及混凝剂类型对脉冲投加 SSPAC 抑制 TMP 升高的影响。 TMP 的上升对预涂期间的过滤通量不敏感。然而，SSPAC 的功效对混凝剂聚合氯化铝 (PACl) 的使用很敏感。与 SSPAC 的脉冲投加不同，混凝剂的脉冲投加会导致 SSPAC 的过度聚集和沉降，以及预涂层的形成不足。当在整个运行期间连续投加混凝剂时，可以获得最佳的过滤性能。在准备阶段使用处理过的水进行喂养也是有效的。对于硫酸化 PACl，高碱度 (70%) 因其高电荷中和能力而优于中等碱度 (50%)。同时，低至中碱度 (20-40%) 的非硫酸化 PACl 比零或高碱度 (70%) 更能有效抑制 TMP 上升。这种行为的解释是，随着碱度的增加，混凝剂的水解减少，但电荷中和作用变得更强。
Submicron-sized powdered activated carbon (SSPAC, diameter 200 nm) dosed in a pulse after coagulation pretreatment has recently been found to effectively mitigate membrane fouling and thus to suppress the rise of transmembrane pressure (TMP) in the microfiltration process because SSPAC has a higher capacity to adsorb membrane foulants, such as natural organic matter, than conventional PAC and a precoat layer formed by SSPAC on the membrane surface retards membrane fouling. This study investigated the effects of the filtration flux during precoating, the timing of coagulant dosing, and the types of coagulants on the suppression of TMP rise by pulse-dosed SSPAC. The TMP rise was insensitive to the filtration flux during precoating. However, the efficacy of the SSPAC was sensitive to the use of the coagulant polyaluminum-chloride (PACl). Unlike pulse dosing of SSPAC, pulse dosing of coagulant led to excessive aggregation and settling of SSPAC and insufficient formation of a precoating layer. The best filterability was achieved when the coagulant was dosed continuously in the entire operation period. It is also effective to use treated water for feeding during the preparation stage. For sulfated PACl, high basicity (70 %), with its high charge neutralization capacity, was preferred to medium basicity (50 %). Meanwhile, the TMP rise was more effectively suppressed by non-sulfated PACl with a low-to-medium basicity (20–40 %) than zero or high basicity (70 %). This behavior was explained by the fact that, as the basicity increases, hydrolysis of the coagulants is lessened, but the charge neutralization effect becomes stronger.