Performance Enhancement of Kality Wastewater Treatment Plant’s Up Flow Anaerobic Sludge Blanket Reactor Using Surface Response Methods

Abstract

The main aim of this study was to examine and optimize the performance of up flow anaerobic sludge blanket reactor (UASB) using the  surface response method-central composite design (RSM-CCD). The influences of several operational parameters were considered,  including temperature (0 to 30°C), organic loading rate (OLR) (1 to 3 kg COD/m³ ·d), pH (6.3 to 7.8), and hydraulic retention time (HRT) (4  to 12h). The pilot-scale reactor had a volume of 48.8 L. The RSM-CCD was used for the determination of the number of runs and the optimization of operational parameters. According to the derived model, the reactor exhibited optimal results under the following conditions: Temperature (23.0°C), OLR (2.3 kg COD/m³ ·d), pH (7.5), and HRT (11.4 h). Removals of 84.1 %, 99.9 %, and 100 % for chemical  oxygen demand (COD), total suspended solids (TSS), and volatile suspended solids (VSS), respectively, were achieved using the optimized  parameters. In comparison with the inlet concentrations, the outlet concentrations of volatile fatty acids (VFAs) and alkalinity decreased. Whereas, the outlet concentrations of sulfate ions increased, since the sulfur-reducing bacteria effect was hindered due to the anaerobic  condition of VFA and alkalinity. Even though the removal efficiency of the locally utilized wastewater treatment plant employing a UASB  reactor was set at 55 % and 70 % for COD and TSS, respectively, the experimental results showed that it was possible to achieve higher  removal efficiency at psychrophilic temperatures for unregulated sewage by optimizing controllable operational parameters.