I remember from my environmental studies that there were certain toxic substances and heavy metals in sludge used as agricultural fertiliser that could affect plants and their products. Is this true and if so, what is the safe way of treating sewage for use as fertiliser?
I remember from my environmental studies that there were certain toxic substances and heavy metals in sludge used as agricultural fertiliser that could affect plants and their products. Is this true and if so, what is the safe way of treating sewage for use as fertiliser?