Assessing wastewater stabilization ponds for agricultural use: a case study from Iran

This study was conducted out in the stabilization ponds of Birjand city for two seasons; autumn, 2007 and winter, 2008. For this reason, quality parameters, such as pH, TSS, BOD5, COD, total chloroform and pathogen egg in the influent and effluent of wastewater stabilization ponds, and heavy metals such as As, Hg, Pb, Cd, Zn and Cr in the effluent of wastewater were determined. The mean levels of these parameters were measured: 8.0 for pH, 76.2 mg/L for TSS, 68.67 mg/L for BOD5, 163.0 mg/L for COD, 1600 < MPN/100ml, while no mean level was found for pathogen egg. Also, the mean concentrations of heavy metals were measured: 0.091 mg/L for As, 0.005 mg/L for Hg, 0.001 mg/L for Cd, 0.020 mg/L for Zn and 0.125 mg/L for Cr. According to Standards of Environmental Protection Agency of Iran, the effluent of wastewater stabilization ponds is found to be useful for irrigation. The results also showed that the removal efficiencies of biological factors were high, so that the amounts of BOD5, COD and TSS were decreased 78.84%, 75.25% and 72.15% in the effluent of wastewater compared to the influent of wastewater.