The ruling on the purification of impure fertilizers after being treated with chemical substances

Question:
He says: Honorable Shaykh, may Allah grant you success, if impure fertilizers are treated with chemical substances, do they become pure in this case?

Answer:
This is a matter where they now say that sewage is purified. The issue of purifying and treating sewage is such that it returns to its original state. Impurity is a matter of scholarly disagreement today. Some say that if the impurities are removed and the water returns to its state—having no color, taste, or smell of impurity—then it becomes pure, and it is permissible to use it. The jurists, and what is in the *Zad* text that you have, states that if the removal of the smell, taste, or odor is due to the treatment of this, it is not permissible. However, if it disappears on its own without treatment, if the signs of impurity disappear by themselves and the water returns to its natural state, there is no harm. But if its removal is through treatment and manufacturing, it is not permissible according to the school of thought.