Development of reaction model for coagulation with considering the characteristics of varying components in natural waters

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K04752
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22060:Environmental systems for civil engineering-related
• Research Institution: Kumamoto University
• Principal Investigator: Ito Hiroaki 熊本大学, くまもと水循環・減災研究教育センター, 助教 (80637182)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 凝集 / 天然有機物 / 水中金属 / 鉱物粒子

Outline of Final Research Achievements

Dynamic light scattering can observe particles in a relatively short time. However, it was shown that dynamic light scattering is not as accurate as the nanoparticle tracking analysis method unless the concentration of the substances is high.
Ca was shown to form aggregates of organic matter (humic substances, sugars, and proteins, except for lipids (dodecanoic acid)), and clay minerals (kaolinite) by cross-linking. Humic substances were shown to reduce the size of Fe(III) aggregates under both low ionic strength and high Ca concentration conditions. Both high ionic strength and high Ca concentration had a limited effect on promoting Fe(III) aggregation. It was suggested that clay minerals are possibly a decisive factor in the large-scale aggregation of Fe(III) that occurs in natural seawater.

Free Research Field

水環境工学

Academic Significance and Societal Importance of the Research Achievements

環境水中で生じる凝集は，種々の物質の生残性と流動性を大きく決定づけており，水産学・環境衛生・地球科学等の各分野の問題に関わる。例えば，Fe(III)は河川水等の淡水が海水と混合すると大規模な凝集を生じ，この凝集に巻き込まれる有機物や毒性物質の移動先が影響を受ける。これまでに，各分野で凝集に重要なメカニズムが示されてきたが，環境中に見られる幅広い種類の物質の凝集を定量的に推定するための知見は限られている。本研究では，複数の物質が相互に関わる凝集反応を調べることで，実環境中環境中において生じる凝集の主要因を推定するための知見を得ることができた。