Guibai Li

Effects of natural organic matters molecular weight distribution on the immersed ultrafiltration membrane fouling of different materials

Abstract Effects of natural organic matter molecular weight (MW) distribution in source water on the reversible and irreversible fouling of immersed ultrafiltration membranes of three different materials were systematically investigated using representative sources of natural waters. It was found from the bench-scale tests that the organic matters of the MW lower than 1u2009K and higher than 30u2009KDa were the main substances that induced reversible fouling regardless of the materials, and that of MW between 1u2009K and 5u2009KDa could cause reversible fouling for polyvinylidene fluoride (PVDF) and polysulfone (PS) membrane. As for the irreversible fouling, small organic molecules of the MW lower than 1u2009KDa were the main part due to the hydrogen bonds. In addition, the organic matters of MW between 1u2009K and 3u2009KDa can induce irreversible fouling for polyvinyl chloride and PVDF membrane. Results of long-term filtration tests showed that PVDF membrane was more vulnerable to small organic molecules due to its high electroneg...

Reuse of PAC and alum sludge (RPAS) process: pretreatment to reduce membrane fouling

AbstractIn this study, a novel reuse of powdered activated carbon (PAC) and alum sludge (RPAS) process to reduce membrane fouling for drinking water treatment was evaluated by laboratory-scale experiments. As compared to coagulation, PAC combined with coagulation and reuse of alum sludge processes, RPAS process performed better in controlling trans-membrane pressure increase and reducing membrane resistances in both short-term and long-term periodical filtration. Removals of turbidity, DOC, UV254, BDOC and THMFP were 93.8, 37.3, 41.1, 83.0 and 57.9% on average by RPAS pretreatment, respectively. The results of fractionation of organic matters indicated that hydrophobic acids and hydrophilic matters were efficiently removed, while organic matters with the molecular weight (MW) more than 3u2009ku2009Da was well removed with a removal efficiency of 50.4%, and that of MW less than 1u2009ku2009Da were reduced by 32.6% by RPAS pretreatment, which could be attributed to the integration of PAC adsorption and the enhanced coagula...

Factors influencing critical flux of UF membrane in drinking water treatment

AbstractVery few fouling or even no fouling would happen when ultrafiltration (UF) was operated below the critical flux. Factors influencing the critical flux of UF for drinking water treatment were systematically investigated in both short-term and long-term tests. Results showed that critical flux could be increased by 5xa0L/m2xa0h by continuous aeration with the air flow rate of 10xa0m3/m2xa0h, and the same effect could be obtained by intermittent aeration with the air flow rate of 40xa0m3/m2xa0h which could not be further improved by increasing air flow rate. Intermittent filtration had no positive effect on improving critical flux, while intermittent filtration combined with aeration could effectively improve critical flux by 5xa0L/m2xa0h and reduce fouling a lot in long-term filtration. Critical flux could be increased by 10xa0L/m2xa0h when coagulation and sedimentation pretreatment was applied, and could be increased by 15xa0L/m2xa0h for combined process of coagulation combined with continuous aeration or coagulation comb...

Effect of aeration on the critical flux of immersed ultrafiltration membrane for drinking water treatment

To focus on the optimization of immersed ultrafiltration(UF) operation for drinking water treatment, critical flux of the UF membrane and the effect of aeration on it was investigated though the bench-scale experiments. Results show that a critical flux exists in the operation of UF, below which the fouling develops very slowly. The critical flux of UF membrane could be enhanced by both the continuous aeration and intermittent aeration, while the critical flux could not be increased when the aeration intensity exceed a range. It could be seen form the long period of operation that continuous aeration was more effective than intermittent aeration in controlling the membrane fouling.

Effect of operation conditions on fouling of immersed ultrafiltration membrane for drinking water treatment of surface water

Effect of operating conditions on the fouling of immersed ultrafiltration(UF) membrane for the Suzhou Internal River was investigated with a pilot scale study. Results show that fouling could be reduced by both the continuous aeration and intermittent aeration, while the aeration intensity should be selected reasonably. Fouling could be reduced by intermittent filtration only due to the decrease of the filtration duration, but the combination of aeration and intermittent filtration could have better control of fouling. The transmembrane pressure (TMP) of UF operation could be significantly reduced by coagulation pretreatment and the combination of coagulation, aeration and backwashing could have better mitigation of membrane fouling in the real application of immersed UF.