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Chu, Xuan-Quang,Kim, Jongwon,Park, Kyhyuk,Choi, Sungyong,Kim, Hyung-Soo IWA Publishing 2009 Water science & technology--water supply Vol.9 No.4
<P>The effects of coagulation pre-treatment on microfiltration process were investigated with the Nakdong River source water. In this study, the potential membrane-fouling materials presented in the raw water were mainly attributed to particulate matters and UV254-absorbing materials. Coagulation pre-treatment mitigated the effects of these components on membrane fouling because it induced a change in the characteristics of the cake layer and a decrease in the content of UV254-absorbing materials. Even though the coagulated suspensions were not removed before MF membrane filtration, their impact on resistance to filtration was insignificant when compared with that caused by the suspensions without pre-coagulation. However, insufficient dosages of coagulant or the improper controls of coagulation pH might cause severe membrane fouling in the treatment of low turbidity water (i.e. turbidity below 10 NTU). It appeared that a selection of coagulant dosage that focused on the reduction of specific cake resistance was possibly the best way to achieve the optimal condition in this study. Also, the coagulation pre-treatment process at pH values between 5.3 and 6.8 was found to be most effective in providing the lowest specific cake resistance as well as residual UV254 absorbance.</P>
( Nguyen Van Tuyen ),( Tran Hung Thuan ),( Chu Xuan Quang ),( Nhat Minh Dang ) 한국공업화학회 2023 공업화학 Vol.34 No.5
The effect of temperature and influent alkalinity/ammonia (K/A) ratio on the start-up of the partial nitrification (PN) process for an activated sludge-based domestic wastewater treatment was studied. Two different sequence batch reactors (SBR) were operated at 26 °C and 32 °C. The relationship between temperature and the concentration of free ammonia (FA) and free acid nitrite (FNA) was investigated. A stable PN process was achieved in the 32 °C reactor when the influent ammonium concentration was lower than 150 mg-N/L. In contrast, the PN process in the 26 °C reactor had a higher nitrite accumulation rate (NAR) and ammonium removal efficiency (ARE) when the influent ammonia concentration was increased to more than 150 mg-N/L. Then three different ranges of the K/A ratio were applied to an SBR reactor. In the K/A range of 2.48~1.65, the SBR reactor achieved the highest NAR ratio (75.78%). This ratio helps to achieve the appropriate level of alkalinity to maintain a stable pH and provide a sufficient amount of inorganic carbon source for the activity of microorganisms. At the same time, FA and FNA values also reached the threshold to inhibit nitrite-oxidizing bacteria (NOB) without a significant effect on ammonia-oxidizing bacteria (AOB). Results showed that the control of temperature and K/A ratio during the start-up period may be important in establishing a stable and steady PN process for the treatment of domestic wastewater.