sand-gravel filter

例句：

1. 1.The sand-gravel filter is used to remove fine particles from the water.
   沙砾过滤器用于从水中去除细颗粒物。
2. 2.The sand-gravel filter is an essential part of the wastewater treatment system.
   沙砾过滤器是废水处理系统的重要组成部分。
3. 3.The sand-gravel filter is designed to prevent sediment from entering the clean water supply.
   沙砾过滤器设计用来防止沉积物进入清洁的供水系统中。