Other oxidizing agents include: ozone, perhydrole (50% and 27%), potassium permanganate (it works already after a few minutes at concentrations of 10 mg/l. Most used as 6% solution),iron compounds (VI) and oxidizing chloride compounds, e.g.chloride dioxide. The introduction of chloride compounds for sludge intended for the use in agriculture or reclamation of soil is not recommended as chloride may react with organic compounds contained in the sludge, which form compounds potentially harmful for the environment (Zhang et al., 2013).