The filler used in the lake water purification project is generally selected according to the specific situation. Common fillers include activated carbon, slag, zeolite, ceramsite, expanded perlite, etc. These fillers have different physical and chemical properties and can be treated for different water quality issues.
Among them, activated carbon is a commonly used water treatment material, which has a well-developed pore structure and adsorption properties, and can effectively remove harmful substances such as organic matter, heavy metal ions and pigments in water. Slag can use its large specific surface area and pore structure to adsorb and filter suspended solids and organic matter in water. Zeolite is a natural mineral, and its internal pores and surface active sites can effectively remove nutrients such as ammonia nitrogen and phosphorus from water. Ceramsite is a porous ceramic material with good adsorption properties on its surface, which can remove organic matter and heavy metal ions in water. Expanded perlite can take advantage of its large surface area and good adsorption properties to remove suspended solids and organic matter in water. 
When selecting fillers, the specific conditions of the lake and the treatment objectives need to be considered. For example, if the water quality of the lake has a high content of organic matter and heavy metal ions, materials with strong adsorption properties such as activated carbon and ceramsite can be selected. If the lake water quality has a high nutrient content, materials with good ion exchange properties, such as zeolite and slag, can be selected. At the same time, it is also necessary to consider factors such as the cost and treatment effect of the filler to achieve the dual goals of economy and environmental protection.