Revista de biorremediación y biodegradación

Abstracto

Decontamination of Domestic Wastewater Using Suspended Individual and Mixed Bacteria in Batch System

Ebtesam El Bestawy, Ahmed AL-Hejin, Ranya Amer and Rzaz Abdulrazaq Kashmeri 

The study aimed to investigate the ability of indigenous and/or exogenous free living bacteria either individual or as mixed culture to decontaminate raw domestic wastewater. Seven indigenous and two exogenous bacteria were selected and identified using traditional as well as molecular characterization, then used in the batch remediation system for seven days. Results indicated that the raw wastewater was relatively of high strength according to the levels of all the tested parameters. Treatment efficiency was time and bacterial species dependent. In general, the mixture of the tested bacteria considered the most efficient for the removal of all the tested parameters. Pseudomonas stutzeri (PS) was perfect for removing organic matter (BOD and COD) while the mixed culture considered the most efficient for removing fecal coliform (≈100%) brought them to safe (60, 100 mg/l and ≈ 0.0 CFU/ml respectively) discharge limits (MPL) stated by the Egyptian and Saudi Environmental laws that regulate discharging of domestic and industrial wastewater into fresh and saline open water. In addition, high removal efficiencies of TSS, FOG and TC recording 39.1, 90.0 and 99.0% respectively were achieved by B. amyloliquefaciens (S1), E. coli (Rz6) and the mixed culture respectively. However, their residuals still higher (23.3, 20 and 200 fold respectively) than their MPLs for the safe discharge due to the short treatment course. Therefore, longer treatment time and/or using biofilm of the selected bacteria are highly recommended to bring the contaminated domestic effluent it to the safe limits for the environment. The present study confirmed the ability of the selected bacteria for the removal of the target contaminants especially pathogenic bacteria (coliform) and thus can be manipulated efficiently to decontaminate polluted systems providing the optimum degradation conditions.