| Summary: | 碩士 === 嘉南藥理科技大學 === 環境工程與科學系暨研究所 === 97 === It is a common phenomenon that the existence of iron and manganese in groundwater for drinking water treatment. The iron and manganese will reduce disinfectant such as chlorine in water, therefore, the bacteria and biofilm will regrow in the water distribution pipe system if the iron and manganese were not treated properly in water treatment plant. As concentration of Fe and Mn in water are excess, the water becomes red-brown, and probably blockade water pipes in water supply system. In order to avoid these problems, the standards of drinking water quality in Taiwan are extremely strict, Fe is less than 0.3 mg/L and Mn is less than 0.05 mg/ L.
In this study, NaOCl, KMnO4 and MIOX were used to perform oxidation test under different operating conditions for two different iron and manganese concentrations source water. The oxidation sample was filtrated with 0.45 μm membrane and permeate was measured. Solid on the membrane from the iron and manganese oxidation was analyzed with SEM/EDS. The results show that iron oxidation reaction is faster than manganese. The oxidation of manganese is strongly correlated with pH. When pH value is higher than 8, the oxidation of manganese showed the positive effect.
The results also showed higher mixing intensity cause the worse removal efficiency of iron and manganese oxides when pH value more than 9. Iron oxidation is slow at low temperature and would residual higher iron concentration. When manganese exists alone in source water, the manganese best removal was observed at the dosage of 0.96 mg/L KMnO4. When iron and manganese were both exist in the water, 0.72 mg/L KMnO4 showed the highest removal efficiency. The manganese filtration removal efficiency is higher with the existence of iron than only manganese in the source water. It is estimated that iron and manganese co-precipitation to enhance remove manganese ion in water. KMnO4 overdosing would cause higher residual concentration of manganese. For the MIOX oxidation test, the optimal dosage is 5 mg/L, pH from 7 to 9. However, the require reaction time for MIOX needs more than 30 minutes to oxidize the iron and manganese.
Solid on the membrane from the iron and manganese oxides was analyzed with SEM/EDS. The results showed increased manganese solids composition percentage with higher iron and manganese oxidation efficiency. The results show higher oxidation efficiency could be proved by the lower residual manganese concentration in water.
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