Assessment of Biodegradability of Synthetic Tanning Agents Used in Leather Tanning Process

---The goal of this research was to assess the biodegradability of two synthetic tanning agents (syntans), Phenol condensation product and Nitrogen containing resin using Respirometry. The evaluation involved the analysis of oxygen uptake rate (OUR), profiles by respirometry. The study was conducted with different syntan concentrations of 50mg/L, 100mg/L, 150mg/L and 200mg/L. The oxygen uptake rate (OUR) of mixed liquid is 60 mg/L h with 50mg/L phenol condensation product and is found to be higher than with the concentrations 100, 150 and 200 mg/L h. The percent chemical oxygen demand (%COD) removal was decreased with increased syntan concentration indicating high rates of biodegradation at low concentration and toxicity impacts or low rates of biodegradation at higher concentrations. Whereas the Nitrogen Containing Resin showed complete inhibition on oxygen uptake rate of mixed liquor at all concentrations and very low % COD removals as well showing less biodegradability or potential toxic impact on the activated sludge.