Noubaria canal water was improved through a new constructed biofilm treatment system to reduce chemical addition. This system included sedimentation tanks and biological aerated filter (BAF) under full aeration condition. In the present investigation, gravel (2 5 mm) was selected as a filtering material for removal of pollutant due to it is local and stable materials and has biofilm formation possibility. This study aimed to evaluate the role of influent quality, operation modes and retention times on the removal efficiency of different pollutants as result of BAF treatment system on canal water during 2 years of operation. After biofilm formation, (60 days), the different algal species with gravel filter medium were reduced by 84%, 91% and 93% under flow rates 0.05, 0.025, and 0.017 L/sec, respectively. Also, results showed that, biological aerated filter system and flow rate of 0.05 L/sec could successfully improve water quality as indicated by reduction in concentrations of turbidity, suspended solids, COD, and BOD5. The combination of three treatment stages was almost totally responsible for the overall observed reduction. The effluent water can be safely used in domestic and industrial activities.
Key words: Noubaria canal water, biological aerated filter, algal and microbial indicators
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