Study of Performance of Completely Mixed Activated Sludge Process with Varying Hydraulic Retention Time (HRT) and Solid Retention Time (SRT) Using Lab-scale Plant

Bijay Thapa, Nawa Raj Khatiwada, Anish Ghimire, Bikash Adhikari, Rabin Malla


Hydraulic Retention Time (HRT) and Solid Retention Time (SRT) are two major parameters for the performance of the activated sludge process. The present study was aimed at studying the performance of the activated sludge process with varying SRT and HRT using a laboratory-scale plant. The wastewater was synthesized at the laboratory. HRT of 1, 2, 4, 8 and 12 hours were used and SRT of 5 days, 7.5 days and 10 days were used for the study. The performance was found to increase with increasing HRT and SRT. An Analysis of Variance (ANOVA) test was used to confirm the variation. For SRT of 5 days, the performance for Chemical Oxygen Demand (COD) removal increased from 12.9% to 88.4% for an increase in HRT from 1 hr. to 12 hrs. Similarly, for Total Kjeldahl Nitrogen (TKN), the removal increased from 10.8% to 72.1%. Likewise, the performance for COD removal increased from 12.5% to 90.9%, whereas the removal of TKN increased from 10.1% to 85.2% for SRT of 7.5 days. The COD removal increased from 13.8% to 93.4% and TKN removal increased from 9.6% to 90.2% for SRT of 10 days.


Activated Sludge Process; Lab-scale Plant; COD Removal; TKN Removal; Synthetic Wastewater

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Journal of Development Innovations

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