Notice of Retraction MF for Treatment of Iron Contaminated Underground Water and Fouling Countermeasures

A hybrid process of pre-aeration followed with microfiltration (MF) was investigated for treatment of iron-polluted underground water. The microfiltration used a tubular membrane made from novel material of ultrahigh molecular weight polyethylene (UHMWPE). The results showed that at initial stage, more than 90% of iron was removed by the pre-aeration/MF process, the removal rate being 40~60% higher than using MF alone. After 60 days, with ferruginous activated biofilm formed over the membrane surface, iron removal rate reached over 90% even with MF alone. Iron concentration in the effluent was below 0.1 mg/L, meeting the Standard for Drinking Water Sanitary of China. Turbidity removal was over 95% no matter pre-aeration was used or not, keeping the turbidity in the filtrate always under 0.2 NTU. Pre-aeration/MF process could efficiently remove poisonous and harmful trace pollutants, with removal rates of TOC, UV254 and UV410 being 41.5% 82.1% and 88.7% respectively. Inorganic matters such as Fe were the main contributors to the membrane fouling at beginning, but ferruginous activated biofilm and cake layer contribute much by the end of the experiment. The membrane contaminants could be effectively removed by hydraulic flush with fresh water combined with soak in dilute HCI solution.