In this paper, leather tanning wastewater treatment alternatives for protein recovery and nitrogen removal were studied. Experiments were conducted on various tanning wastewaters and also synthetic samples with reference amino acids related to proteins of leather tanning industry. Acidification permitted more than 90% protein removal at a pH value of 4.6 for sheepskin wastewater. Copper was the most effective metal facilitating 76% protein removal from sheepskin wastewater. Bovine leather wastewater proteins were removed up to 50% efficiency by acidification below pH 5.