Effects of raw water and coagulant characteristics on the composition and physico-chemical properties of meso-particles remaining after coagulation

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K15127
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 22060:Environmental systems for civil engineering-related
• Research Institution: Chuo University
• Principal Investigator: DING QING 中央大学, 研究開発機構, 機構助教 (70837476)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: メソ粒子 / 膜目詰まり / ゼータ電位 / バイオポリマー / 凝集剤

Outline of Final Research Achievements

In drinking water treatment, it is important to control the meso-particles (20-500 nm) remaining after coagulation, since neutralization of meso-particles could improve the performance of the subsequent membrane filtration or sand filtration after coagulation. However, polyaluminum chloride, a commercially available coagulant in Japan, cannot neutralize meso-particles at the neutral pH normally used in water purification plants.
In this study, the results showed that the composition of meso-particles differed depending on the amount of coagulant addition. The reason why meso-particles cannot be charge-neutralized at neutral pH was found to be that meso-particles derived from raw water or coagulant are both negatively charged. In the future, it will be necessary to develop a coagulant that is positively charged at neutral pH, which can neutralize the meso-particle charge.

Free Research Field

土木環境システム

Academic Significance and Societal Importance of the Research Achievements

本研究では、メソ粒子の構成成分・物理化学特性を検討し、それらの凝集機構は既存の凝集機構とは異なることを示した。この結果は、既存の凝集理論を拡張し、メソからミリまでのすべての粒子を包含するような、新しい凝集理論の確立に有意義なものである。また、本研究の成果は、浄水処理における凝集－砂ろ過/膜ろ過プロセスの制御に参考になる。