A. H. AL-Abdaly, A., and D. K. K. Al-Ahmady. “Effect of the Hydraulic Detention Time and the Volumetric Ratio of Anaerobic to Aerobic Zone on the Efficiency of the Upgraded Activated Sludge Units Using (Bardenpho) System”. Al-Rafidain Engineering Journal (AREJ), vol. 22, no. 1, Feb. 2014, pp. 97-109, doi:10.33899/rengj.2014.87020.