Abstract
The study aimed to investigate decontamination of domestic wastewater using bacterial consortium biofilm consisted of four strains (Pseudomonas stutzeri M15-10-3 (PS), Bacillus sp. OU-40 (Rz6), Bacillus amyloliquefaciens T004 (S1) and Bacillus cereus OPP5 (Rz7)). Bacterial mixed culture fixed on gravels was tested continuously at different flow rates (100, 150 and 200 mL/h) for 5 working hours where samples were collected on hourly interval. Raw wastewater samples were collected from the drainage network. Wastewater quality parameters including pH, temperature, dissolved oxygen (DO: 5-9 mg/L), total suspended solids (TSS: 140-155 mg/L), total dissolved solids (TDS: 390-420 mg/L), biochemical oxygen demand (BOD: 111-120 mg/L), chemical oxygen demand (COD: 350-448 mg/L), fat, oil and grease (FOG: 34-38 mg/L), bacterial total viable count (TVC: 4.00 x 10(6) and 16.0 x 10(7)), total coliform (TC) and fecal coliform (FC) were determined before and after treatment and the removal efficiencies (REs) were calculated. As a general trend, the RE of all the tested parameters increased with increasing the exposure time and decreased with increasing the flow rate. The highest achieved REs by the proposed biofilm system were 86.0%, 84.0%, 83.7%, 98.5%, 27%, 99.8%, 100% and 98.8% for TSS, BOD, COD, FOG, TDS, TVC, TC and FC after 5 running hours at the lowest tested flow rate (100 mL/h) except for FOG (150 mL/L). Treatment using the biofilm system has decreased all the tested pollutants to much lower levels than the maximum permissible limits for safe discharge into open environments. Results of the present study confirmed that the proposed biofilm system using a composite culture is highly active, very promising, renewable and recommended cheap biotechnology for the treatment of wide range of contaminated domestic wastewater.