Introduction: Can a River Clean Itself?
Let students find out through conversation by themselves that there are different self-purification processes in nature. However, if there is too much pollution or the pollution is man-made, water in nature cannot always purify itself. We need to purify water in treatment plants before it is discharged in natural streams.
Activities in this lesson
Discussion: Too Much Pollution / How to Increase Self-purification Capacity
When the level of pollution is high, there are two things that should be considered: to decrease the pollution intake and to increase the self-purification capacity of a water system.
- How can the self-purification capacity be increased (The riparian zone could be restored and enlarged. Wetlands could be restored. Wastewater treatment plans should be built. Smarter use of fertilizers in agriculture should be practised, etc.).