Applicability of plant-clay mineral composite for rapid algae removal from eutrophic freshwaters at the laboratory and field scales1

The global issue of water source eutrophication is exacerbated by increasing industrialization and urbanization, posing significant challenges for clean water management. Although strategies such as nutrient management and biomanipulation are employed, these methods often take longer to demonstrate effectiveness and indirectly work on algal blooms. This has led to the evaluation of eco-friendly technologies such as plant-mineral composites (PMCs) for faster and targeted control of algal proliferation and organic pollution. This study assessed the suitability of PMCs for rapid improvement of eutrophic water quality (focusing on algal control) and optimized their application methods at laboratory and field scales. Laboratory experiments were conducted to identify the critical factors influencing removal activity (RA), considering variables such as water temperature and light intensity. Field trials in reservoirs and a water treatment plant (WTP) explored the controlling factors influencing the RAs for various pollutants. Optimal conditions for maximizing PMC efficacy were determined using response surface methodology (RSM) and generalized linear models. RSM highlighted water temperature as a key factor influencing chlorophyll a RA in a unimodal manner, while demonstrating PMC's effectiveness across varying concentrations, depths, and pH levels. Results from the WTP emphasized the high PMC efficacy in humic matter-rich environments, and those from reservoirs consistently demonstrated PMC's effectiveness regardless of ambient water quality factors such as nutrient and conductivity levels. Comparative analyses indicated distinct PMC impact on algae-associated parameters, emphasizing its potential as an innovative solution for utilizing plant allelopathy and mineral adsorption for efficient algal bloom control and water quality enhancement.