Chemicals in the factory's sewage system have changed the ecology of the whole area.
这座工厂排出的化学物质改变了整个地区的生态.
A pipe for carrying off water or sewage.
排水管排水或污水的管子
The grave problem of public hygiene is connected with the inefficient sewage system of the city.
公共卫生方面的严重问题与该城低效率的污水处理系统有关。