Dept. of Civil and Environmental Engineering, Carleton University, 1125 Colonel by Drive, Ottawa, ON, K1S 5B6, Canada.
Dept. of Civil, Geological and Mining Engineering, Polytechnique, C.P. 6079 Succursale Centre-Ville, Montreal, QC, H3C 3A7, Canada.
Chemosphere. 2019 Jul;226:668-677. doi: 10.1016/j.chemosphere.2019.03.188. Epub 2019 Apr 1.
This study investigates chemical cleaning mechanisms of a tubular ceramic UF membrane. The effect of cleaner type (ozone (O), sodium hypochlorite (NaOCl) and sodium hydroxide (NaOH)), clean in place (CIP) pH (11 vs. 12), and cleaning sequence on the removal of irreversible fouling of hydrophobic (humic acids) and hydrophilic (alginate with and without calcium (alginate + Ca and alginate - Ca, respectively)) NOM fractions were investigated. Results showed that different NOM types responded differently to chemical cleaning. Alginate-Ca and humic acids were equivalently removed by NaOCl or NaOH whereas a lower cleaning efficiency of alginate + Ca was observed. Increasing the pH of NaOCl and NaOH CIP increased the removal of the chemically reversible fouling index (UMFI). The efficiency of NaOCl was always lower than that of NaOH at the same pH, which was attributed to surface tension (λ) differences in the CIP water and potential differences in cleaning mechanism. The ceramic UF CIP cleaning using O (0.50 mg O/mgC) for 1 h demonstrated higher cleaning efficiency for humic acids and alginate ± Ca, (%UMFI > 98%), than NaOCl or NaOH alone (%UMFI>80%). The O CIP was as effective as 4 h cleaning using a sequential NaOH/NaOCl or combined NaOCl + NaOH CIP.
本研究考察了管状陶瓷 UF 膜的化学清洗机制。考察了清洁剂类型（臭氧 (O)、次氯酸钠 (NaOCl) 和氢氧化钠 (NaOH)）、原位清洗 (CIP) pH 值（11 与 12）和清洗顺序对疏水性（腐殖酸）和亲水性（海藻酸钠加钙和去钙（海藻酸钠 + Ca 和海藻酸钠 - Ca）NOM 分数的不可逆污染去除的影响。结果表明，不同的 NOM 类型对化学清洗的反应不同。海藻酸钠 - Ca 和腐殖酸可通过 NaOCl 或 NaOH 等效去除，而海藻酸钠 + Ca 的去除效率较低。增加 NaOCl 和 NaOH CIP 的 pH 值可提高化学可逆污染指数 (UMFI) 的去除率。在相同 pH 值下，NaOCl 的效率始终低于 NaOH，这归因于 CIP 水中的表面张力 (λ) 差异和清洗机制中的潜在差异。使用 O (0.50 mg O/mgC) 进行 1 小时的陶瓷 UF CIP 清洗，对腐殖酸和海藻酸盐 ± 钙的清洗效率更高（%UMFI > 98%），优于单独使用 NaOCl 或 NaOH（%UMFI > 80%）。O CIP 与 4 小时使用 NaOH/NaOCl 或组合 NaOCl + NaOH CIP 的清洗效果相当。
