How can we treat heavy metals in rivers and streams?
Chemicals can be used to treat heavy metals.
Let me start with Metal (+2) (such as zinc) and Ca(OH)2 in water.
At the end of reaction,
Metal + Ca(OH)2 --> Me(OH)2 +
Now you have solid form (of Me(OH)2).
You can also use chemical oxidation, using hydrogen peroxide and ultraviolet light, ozone, etc. to remove heavy metals in water.