Abstract

Due to the constantly increasing requirements and supervisory environmental agencies concerning the release of industrial effluents into receiving waters, industries are looking to properly treat their effluents and to achieve efficient removal of contaminants. The leather industry is responsible for the production of liquid effluents with high concentrations of pollutants since most of the process steps are carried out in an aqueous medium. Due to the changes in leather technologies in recent years, it is necessary to know and analyze how tannery effluents vary according to the processing steps performed in different tanneries. This may be used to plan and design unit operations in wastewater treatment plants. In order to contribute to this purpose, this study presents the characterization of raw tannery wastewater and provides and discusses an overview of effluent treatment plants and some particularities of them. The raw effluents were characterized by analysis of pH, turbidity, conductivity, chromium oxide, chlorides, total hardness, total Kjeldahl nitrogen (TKN), ammonia nitrogen, solids (total, suspended: fixed and volatile, dissolved: fixed and volatile), five-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), phosphorus and total organic carbon (TOC). The test results of the parameters for contaminants for each type of tannery are related to previous researches and discussed.