The Effect of Natural Organic Matter Characteristic on Hardness Removal

• Main Authors: Yi-Chun Lin, 林怡君
• Other Authors: Chi-Wang Li
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/00232166904082235001

碩士 === 淡江大學 === 水資源及環境工程學系 === 92 === The characteristics of Natural organic matter (NOM), such as hydrophobicity/hydrophilicity might affect the efficiency of hardness removal, but was no the subject of research in the past. In this study, a natural water sample and commercial available humic acids (Aldrich humic acids, AHA) were fractionated into hydrophilic and hydrophobic components using XAD-8 resin adsorption technique. The fractionation samples before and after softening were analyzed using high performance liquid chromatography (HPLC) and fluorescence spectrophotometry. The EDTA titration method was employed to analyze the residual hardness. It was shown that the concentration of hydrophobic fraction NOM did not show any impact on the hardness removal. However, increasing the concentration of hydrophilic fraction NOM decreases the hardness removal efficiency. A linear correlation was found between the residual Ca concentration and the amount of hydrophilic NOM fraction added with R2 of 0.974. It was shown that 1 mg hydrophilic fraction can combine with approximately 39.6 mg Ca. HPLC analysis of the fractionated NOM shows that the hydrophobic fraction NOM was eluted during the first eight minutes, while the hydrophilic fraction NOM was eluted from 8 to 12 minutes. Fluorescence spectrophotometer analysis did not differentiate the hydrophobic fraction from hydrophilic fraction for the AHA sample. For the natural water samples, before softening the EEM value distribution of hydrophobic fraction are quite different form those for the unfractionated sample and hydrophilic fraction. After removing hardness from the unfractionated NOM sample, the residual NOM fraction of the sample has the fluorescence signature similar to that of the hydrophilic fraction, indicating that the hydrophobic fraction was selectively removed during softening process.