科研之友
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摘要
To understand the characteristics of flux change and rainwater purification efficiency of the gravity-driven membrane (GDM) filtration process in long-term operation without any cleaning and maintenance, the GDM was operated for 240 days. The results showed that three different periods occurred during the long-term operation of the GDM, namely, the start-up period (0~8 d), the stabilization period (9~150 d) and the decline period (151~240 d). The permeate flux could stabilize at (8.85±0.74) L·(m2·h)?1 after 9 days operation, and the maximum stable operation time could reach 150 days without any cleaning and washing procedures. In addition, the influent water quality factors, including DO, pH, TOC and total plate counts, were the key factors affecting the stable flux, and their effects showed different patterns in both the stable and decline periods. During the stable period, the GDM setup could greatly remove the typical pollutants (including turbidity, color, TOC and total plate counts) in the rainwater, the effluent water quality met Chinese drinking water standards. However, during the decline period (151~240 days), the permeate flux decreased to 5.37 L·(m2·h)?1 and the total plate counts in the permeate could exceed the standards, so it was recommended to clean and maintain the GDM at the end of stable period (about 150 days) to recover the permeate as well as the function of water purification. Meanwhile, surface cleaning and manual backwashing could recover 80% of permeate flux. Accordingly, this study showed that GDM could stably purify the rainwater, and the permeate flux could recover by simple cleaning after long-term operation, which was suitable for the application in rural areas of China.
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