Inhwan Hyun

Effects of rainfall characteristics on corrosion indices in Korean river basins

AbstractCorrosion indices have been widely used to assess water quality in countries such as the USA, Japan, France, and The Netherlands since Langelier first introduced this concept in 1936. The most commonly used corrosion indices are the Langelier saturation index (LSI), the Ryznar stability index (RSI), and the aggressiveness index (AI). Here, the changes in LSI, RSI, and AI due to corrosion factors such as pH, Ca hardness, and alkalinity were characterized according to the rainfall during the rainy season at four river basins in Korea. The results of a sensitivity analysis of corrosion indices with varying corrosion factors showed that pH had the greatest effect with a value of 0.1, which indicates that pH affects corrosion more than any other corrosion factor. By comparing the monthly pattern of corrosion factors at each river, it was found that pH and alkalinity decreased during the rainy season, whereas Ca hardness showed only subtle changes across the year. In addition, when comparing the relatio...

Application of peak load for industrial water treatment plant design

Peak load rate(i.e., maximum daily flow/average daily flow) has not been considered for industrial water demand planning in Korea to date, while area unit method based on average daily flow has been applied to decide capacity of industrial water treatment plants(WTPs). Designers of industrial WTPs has assumed that peak load would not exist if operation rate of factories in industrial sites were close to 100%. However, peak load rates were calculated as 1.10~2.53 based on daily water flow from 2009 to 2014 for 9 industrial WTPs which have been operated more than 9 years(9-38 years). Furthermore, average operation rates of 9 industrial WTPs was less than 70% which means current area unit method has tendency to overestimate water demand. Therefore, it is not reasonable to consider peak load for the calculation of water demand under current area unit method application to prevent overestimation. However, for the precise future industrial water demand calculation more precise data gathering for average daily flow and consideration of peak load rate are recommended.

The hydrodynamics of an ozone contactor with horizontal meandering flow to enhance disinfection efficiency

AbstractThe axial dispersion of an ozone contactor is known to influence Cryptosporidium parvum oocyst inactivation and bromate formation. While low dispersion is beneficial, an extent of dispersion is not specifically addressed for the design of a new ozone contactor. C. parvum oocyst inactivation, residual ozone, CT (i.e. Concentration × Time), and bromate formation were numerically simulated with diverse dispersion number (d), ranging from 0.01 to 5, using axial dispersion reactor model and kinetic parameters obtained from sand-filtered raw water under three pH and three temperature values. C. parvum oocyst inactivation was affected sensitively by the axial dispersion number especially at the region lower than 0.5. On the contrary, residual ozone, CT, and bromate formation were slightly influenced by dispersion number. The axial dispersion number of the full-scale ozone reactor with meandering horizontal flow was obtained with a tracer test. The equation for predicting the dispersion number of an ozone...