Leather Tannery

Application of Ozone/AOP in Leather Tanning Industries

Leather tanning is conversion of animal skins or hides into leather and leather products. The industry applies numerous processes to raw skins and hides to produce leather for shoes, garments, upholstery, sporting goods, and a variety of other uses.


Micropollutants in the wastewater are originated from raw skins and hides, and the chemicals used in the processes. The most important toxic matter is chromium. The major sources of micropollutants are: syntans particularly based on naphthalene and phenol, biocides (important agents are pentachlorophenol, 2,4,6-trichlorophenol, cresol based biocides and 4-nitrophenol), and heavy metals used in metal-complex dyes. Due to the composition of tannery effluent COD removal never approaches to completion.


Evaluation of COD fractions of tannery effluent indicated that soluble inert and particulate inert COD fractions are 9 and 13 % of the total COD, respectively. Therefore, depending on the strength of tannery wastewater biological treatment effluent may not satisfy COD limits of 200–300 mg/L defined for direct discharge. That is why several stages of polishing treatment were accounted for as additional COD removal steps. Chemical oxidation methods have been successfully applied to leather tanning wastewater not only as a polishing treatment but also as a means of organic matter control and enhancement in the biodegradability.


Ozone is a powerful oxidant and has a great variety of application in both water and wastewater treatment. There are several applications of ozone in leather tanning industry wastewaters such as inert COD removal, oxidation prior to biological treatment to increase the biodegradability of wastewaters. Ozone is a powerful oxidant and has a great variety of application in both water and wastewater treatment. There are several applications of ozone in leather tanning industry wastewaters such as inert COD removal, oxidation prior to biological treatment to increase the biodegradability of wastewaters.