Aggregation and settling characteristics of particulate matter and DOM in a southern China reservoir: Influence of hydraulic conditions and dosing methods

Abstract

For the in-situ treatment process of landscape waters, ponds, reservoirs and other water bodies, there is a significant deviation between the experiment results and the actual treatment effect due to volume amplification effect. Therefore, this study systematically explored the influence of hydraulic conditions, dosing frequency, dosing intervals of coagulant, and coagulant dilution multiples on the removal efficiency of particulate and organic matter on a large scale to precisely simulate the practical treatment situation. Results showed that dosing intervals and dosing frequency played an important role in the aggregation and settling process of particulate matter by influencing the energy barrier between particles, while hydraulic conditions affected the structure and settling characteristics of flocs. The overall trend of the total organic matter was consistent with that of particulate matter. However, only the freshly formed aluminum hydroxide precipitates had adsorption activity to humic substances. The adsorption could be completed rapidly so that hydraulic conditions had no influence on the aggregation process of humic substances. While during stirring and aging process, humic substances was found to be released due to the polymerization and crystallization of aluminum precipitates. From the results of pilot tests, a treatment strategy was implemented for a reservoir in southern China and the ideal treatment effect was achieved. This study provided theoretical foundation and design guidance for the in-situ coagulation treatment of landscape waters, ponds and reservoirs.