Performance evaluation of aerobic reactor and Sarcocornia perennis to reduce the COD and chloride of effluents from tanning sheepskins

Tannery is an industry that generates wastewater characterised by high levels of organic matter, chrome, dissolved solids, sulphides and high salinity. The aim of this work was to evaluate at laboratory scale, the decrease of chemical oxygen demand (COD) and salinity from effluents from tanning sheepskins, using physical chemical methods in primary treatment, and bioreactor and wetlands for secondary and tertiary treatment, respectively. Effluents were collected from tanning processes of sheepskins carried out on the Center of Research and Technology on leather tannery plant, La Plata, Argentina. Conventional primary treatments selecting coagulants and flocculants were employed. For secondary treatment, batch bioreactors were designed, and the maximum COD removal was 60-70%. For the tertiary treatment, wetlands at laboratory scale were employed. In this test wetlands were filled with granite stone, with and without the plant Sarcocornia perennis, and COD decreased on average by 64% additional and chlorides concentration decreased by around 15%.