Rasoul Khusravi, Maryam Khodadadi, Abdolmajid Gholizadeh, Ehsan Abouee Mehrizi, Taher Shahriary and Abdoljavad Shahnia
Wastewater stabilization ponds (WAPs) are one of the simplest techniques available for the treatment of municipal wastewater which eventually benefit from the simplicity and reliability of their operation. Although many WAPs have been established and made operational, but still the dynamics of pollutants in these systems are not well understood and this can lead to improper design and poor removal efficiency of pollutants and also operational problems. Since in the most used wastewater treatment stabilization ponds, the removal of organic matter (BOD5) is the primary goal of design systems, so preliminary determination of BOD5 removal kinetics and wastewater flow pattern is often required. In this study, to analysis of kinetic data, four kinetic models that can be used in the WAPs have been compared. The studied models combine the different kinetics of Monod and First order kinetic models with continuous stirred-tank reactor (CSTR) and plug flow regimes. Finally, the models were analyzed using statistical parameters. The combined model of the Monod’s kinetic equation and plug flow pattern presented nearest mathematical relationship between theoretical and actual data of WAPs. In the three hybrid models except the Monod and plug flow, BOD5 removal coefficients decreased with increasing BOD5 loading. About the prediction of organic materials removal in WAPs, a significant relationship between the ratio of BOD / COD and removal coefficients was not found, suggesting that the decomposition of organic matter in the stabilization ponds are not susceptible rather than organic waste nature.