## 1 Introduction  
Harmful algae bloom problems are becoming more serious with increasing frequency and quantity in the aquatic environment [1]. Especially in drinking water sources in Korea, the problem is significant because of the impact of the harmful algal on the water treatment performance [2]. An algal bloom event results in the release of geosmin, 2-methylisoborneol (2-MIB) and taste and odor (T&O)compounds from the algal cells during and after bloom events. The toxic and/or odorous metabolites produced by these blooms impact the drinking water quality. Odors of organic compounds produced by algae are characterized as earthy and musty/camphorous. Odors of such compounds can be easily sensed by the human nose even at extremely low concentrations, e.g., concentrations as low as 4.0 and 8.5 ng/L for geosmin and 2-MIB, respectively [3].  
Various mitigation methods for algae and T&O problems have been examined, including coagulation, filtration, potassium permanganate, chlorine and ozone treatments [4; 5; 6]. Among those processes, the coagulation stage is recommended for removal of algae to ensure minimal impact on subsequent processes and prevent the release of the toxic or T&O compounds from cell destruction [7]. However, some of the most commonly used coagulants (e.g., aluminum salts) have disadvantages, such as production of harmful sludge and residuals in the treated water, which can be harmful to human health [8; 9].  
In practice, owing to the variability in water quality and low degradability of certain compounds, achieving the desired water quality by using a single conventional method for removal of algae, geosmin, and 2-MIB is difficult. Implementation of nontoxic and easy-to-use treatment methods to protect drinking water from algal-bloom-related problems is needed. Therefore, the water industry is exploring alternatives to replace Al-based coagulants and ways to strengthen methods that combine coagulation and advanced oxidation processes (AOPs). One effort that has been made in this context is the investigation of the use of a new coagulant that is based on a plant-mineral composite (PMC) for water treatment [10], which was selected to reduce the aluminum sludge and residuals and evaluated for treatment of algae and dissolved organic matters (DOMs) in a lab-scale batch system and a pilot-scale flowing system (109 m\({}^{3}\)/h). The pilot facility was installed at a water intake station from Han-river in Korea. The PMC-based coagulant consists of mixtures of indigenous plant extracts (e.g., _Camelia sinensis_, _Quercus acutissima_, and _Castanea crenata_) and minerals (e.g., loess, quartz porphyry, and natural zeolite) [10]. In reservoir water treatment, PMC performance was found to be effective in removing chlorophyll-a (88-98%), phytoplankton (84-92%) and zooplankton [11]. Moreover, about 70% removal efficiency of turbidity and suspended solids was also reported in the reservoir water [11]. In the present study, the algae and its metabolite removal efficiencies in the drinking water system of PMC based coagulation process were evaluated. For the case that required higher removal efficiency of T&O compounds, UV based AOPs, i.e., UV/H\({}_{2}\)O\({}_{2}\) and UV/Cl\({}_{2}\) processes, were also evaluated as a following processes of the PMC coagulation process. The geosmin and 2-MIB removal efficiencies could be enhanced through several options like simultaneous application of various AOPs, achieving safety and subsequent suitability of the drinking water [12; 13]. UV-based AOPs are well-established processes which have been implemented worldwide and have distinct benefits for simple installation and small footprint.  
The aim of this study was (1) to evaluate the PMC for removal of algae, turbidity, dissolved organic matter and mechanism of coagulation; (2) to evaluate the combination process of PMC coagulation with UV-based AOPs to remove T&O compounds.