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• Main Authors: Wei-Hsiu Wang, 王偉修
• Other Authors: Hsuan-Hsien Yeh
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/09156648745448686146

碩士 === 國立成功大學 === 環境工程學系碩博士班 === 91 === In advanced water treatment, membrane filtration has been used widely throughout the world. It can be used to remove suspended solids, organics, inorganic salts and microorganism, and to control disinfections-by products (DBPs) effectively. As a matter of fact, coagulation and sedimentation in conventional process can be replaced with membrane process to improve the potability of drinking water. Besides, the membrane process has many advantages, such as small footprint, easy expansion and uncomplicated control, etc. However, the major problem encounters in membrane process for water treatment is fouling. Fouling will increase the chemical cleaning frequency, therefore, not only decrease productivity, but also shorten membrane lifespan and increase cost. In this research, the fouling phenomena of microfiltration（MF） membrane were studied. The interactions among colloidal particles, calcium ion, and dissolved organics, such as salicylic acid, humic acid and, alginic acid on MF fouling were focused. This was to simulate the scenario of source water from an eutrophic surface reservoir in south Taiwan, with the co-existance of hardness and algae bloom. The alginic acid is to represent the extracellular organic matter（EOM）from algal. The salicylic acid and humic acid are to simulate low and high MW natural organic matter（NOM）, respectively. The colloidal particles employed were latex particles, with diameter of 0.05, 0.1 and 0.8 μm. The MF membrane used was made from polyvinylidenefluoride（PVDF）, with average diameter of 0.1 μm. First, the effect of single substance on fouling was studied. Next, feed water with dual substances, namely alginic acid with Ca, alginic acid with colloidal particles, and colloidal particles with Ca were explored. And, finally, it was the feed water with the simultaneous existance of the three catagories of substances. The results show that alginic acid fouled the membrane, mainly at low pH. When Ca was added into the alginic acid solution, fouling was aggravated, probably due to the complexation between Ca and alginic acid, and also the the bridging between alginic acid and MF membrane. For sole colloidal particle system, latex particle with diameter closed to the pore size（0.1 μm）of MF membrane showed severe fouling. However, adding Ca could alleviate fouling caused by 0.1 μm diameter latex particle. This was dut to the aggregation of 0.1 μm particle by Ca. Alginic acid also have coagulation function on colloidal particles; however, when the amount of alginic acid is in excess compare to that of colloidal particles, the free alginic acid may foul the membrane severely. If the feed water contained alginic acid, Ca, and colloidal particle simultaneously, the fouling was most severe. In this situation, calcium played an import role, as it would promote the adsorption of alginic acid on colloidal particles, and also the deposition of particles on membrane surface. In conclusion, EOM have a significant effect on MF membrane fouling, especially when Ca and colloidal particles also exit at the same time. For preventing fouling, EOM, Ca, and colloidal particles should be removed to certain extecd before the water is fed into the membrane.