return flow scavenging

例句：

1. 1. The return flow from the wastewater treatment plant is essential for maintaining water quality.
   来自污水处理厂的回流流量对于保持水质至关重要。
2. 2. The recirculation system in this industrial plant helps to reduce energy consumption and improve efficiency.
   这个工业工厂的循环系统有助于减少能源消耗和提高效率。
3. 3.Backflow can occur in pipes due to a blockage or when the pressure drops below the normal operating level.
   由于堵塞或压力低于正常操作水平，管道中可能会出现回流现象。