3.1.2. Steady state operation and biological efficiency Throughout the operation, no consequential variance in the pH (7.5–8.5) and temperature (18–23 °c) were observed.
The uninterrupted operation time began at an MLSS concentration of 6.6 g/L Fig. 5. Turbidity (visual) comparison of treated wastewater and raw wastewater.
(day 60) which was stable for the whole period of the experiment(day 60–120).
This has been interpreted as a sign of the reduced biomass in the MBR systems.
The minor change in the temperature throughout the operation was because of the significant level of ambient air that was pumping into the system and their temperature changes during the experiment.
The effluent quality throughout the operation was regularly checked.
The operation conditions and the monitoring were separated into three time periods: days 0–25, 25–45, and 45–60 (see Table 3).
The result shows that the mean removal of COD throughout the operation was in the range of 76–82%. The reported COD elimination in MBR studies is usually high (>99%).
The proportionately lower COD elimination in this study is linked to the high feed concentration as well as the presence of troublesome biodegradable, rebellious organics and growth restrainingmaterials in the actual refinery wastewater.
An even lower biodegradation (