Nitrogen removal from tannery wastewater by protein recovery

Nitrogen removal from wastewaters has gained importance in recent years. In this paper protein precipitation and recovery potential of leather tanning industry wastewaters were experimentally evaluated. A protein profile for all sources was prepared. Liming was determined to be the most important protein source. Composite samples were made up to assess the protein precipitation applications. Isoelectric pH precipitation yielded around 50% protein removal between the optimum pH interval of 2.1-3.8. FeCI₃ proved to be a very effective means of protein removal providing over 60% efficiency. Polyelectrolyte precipitation did not yield satisfactory results. Magnesium ammonium phosphate precipitation followed by acid precipitation of protein provided 85% ammonia removal in addition to 50% protein removal.