Evaluation of Mixing and Performance of Lab-Scale Upflow Anaerobic Sludge Blanket Reactors Treating Domestic Wastewater

by Abdur Rahman Quaff, Lecturer; Dept. of Civil Engineering, Motilal Nehru National Institute of Technology (MNNIT), Allahabad 211004, India., arquaff@gmail.com,
Saumyen Guha, (corresponding author), Associate Professor; Dept. of Civil Engineering, Indian Institute of Technology, Kanpur 208016, India, sguha@iitk.ac.in,

Serial Information: Issue 5, Pg. 322-331

Document Type: Journal Paper

Abstract: The effects of varying hydraulic retention time (HRT) and associated upflow velocity on mixing and reactor performance were evaluated in five lab-scale upflow anaerobic sludge blanket (UASB) reactors treating real domestic wastewater. The mixing and transport studies were carried out with the help of tracer experiments at various HRTs using a pulse tracer input. A number of existing models were assessed for the analysis of the time series of observed tracer concentrations. The plug-flow reactor (PFR) model with two-zone dispersion better simulated the time series of tracer concentrations at all HRTs than other models, such as single compartment dispersion, completely mixed flow reactors (CMFRs) in series, and a combination of CMFR and PFR. The dispersion coefficients obtained from the two-zone dispersion model correlated well with the dispersion analysis expression for flow in a circular cylinder, and the correlation can be used for the prediction of dispersion in a UASB reactor. The analysis of reactor performance data indicated that reduction of dispersion owing to decrease in the upflow velocity resulted in increased sulfidogenic activity in the reactor. This was attributed to the inability of the sulfate reducers to colonize in the reactor at high upflow velocity and mixing condition.

Subject Headings: Anaerobic processes | Waste treatment | Soil mixing | Laboratory tests | Municipal wastewater | Wastewater treatment | Sludge | Probe instruments | Flow simulation | Model analysis | Hydraulics | Time series analysis | Simulation models |

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