waste water purification

例句：

1. 1. The waste water is treated in a treatment plant.
   废水在处理厂被处理。
2. 2.The company has invested heavily in waste water treatment technology.
   该公司在废水处理技术方面投入了大量资金。
3. 3. The government has set up a special department to deal with the problem of waste water pollution.
   政府成立了一个专门部门来处理废水污染问题。