Methods
Chemical agents
Potassium permanganate (〖"KMnO" 〗_"4" )
Potassium permanganate (〖"KMnO" 〗_"4" ); Nasr. Co., Cairo, Egypt. A stock solution of 〖"KMnO" 〗_"4" was prepared by dissolving 1 g of 〖"KMnO" 〗_"4" in 1 L of reagent grade water. 〖"KMnO" 〗_"4" dosed at 2.5 ppm (mg/l), calculated according to potassium permanganate demand average of the experimental tanks 0.5 mg/l +2 mg/l according to