Kanokkan Pittayakool. Comparison of effects of hydraulic retention times and solid retention times on the performance of IFAS and as systems using synthetic wastewater. Master's Degree(Environmental Technology ). Mahidol University. Mahidol University Library and Knowledge Center. : Mahidol University, 2007.
Comparison of effects of hydraulic retention times and solid retention times on the performance of IFAS and as systems using synthetic wastewater
Abstract:
This study was conducted to investigate the performance of the Integrated Fixed Film
Activated Sludge (IFAS) technology for synthetic wastewater treatment at various hydraulic
retention times (HRTs) and solid retention times (SRTs). The IFAS system was compared in
parallel with a conventional Activated Sludge (AS) system to determine the COD removal
efficiencies and ammonia conversion or nitrification at 10, 8, and 6 hours HRTs and 8, 6, and
4 days SRTs.
The removal efficiencies of COD and TKN were in the ranges of 9496% and 97
98%, respectively in the conventional AS system, and in the ranges of 9596% and 9799%,
respectively in IFAS system. Although there were no differences of COD removal efficiencies
and nitrification between the IFAS and conventional AS systems in all experimental
conditions, there was apparently more biomass washout from the conventional AS system than
the IFAS system at low HRTs and SRTs. The biomass concentrations of the conventional AS
system were in the range of 23002500 mg/l, which was lower than that of IFAS system
(30004500 mg/l). Lower biomass concentrations in the conventional AS system was the
result of high effluent suspended solids concentrations; consequently, resulting in more loss of
biomass from the system, especially in the condition at 10 hours HRT with 4 days SRT, at 8
hours HRT with 6 and 4 days SRTs, and at the 6 hours HRT with all SRTs. Under the same
operating conditions, the IFAS system was more stabilized and could maintain high
performances until the SRT and HRT were 4 days and 6 hours, respectively. The failure of
the conventional AS system and the success of the IFAS system at the aforementioned
conditions clearly indicated that the IFAS system provides more capacity and stability than the
conventional AS system.
The experimental results clearly illustrated that the performance of the IFAS system
was higher than the conventional AS system in system stability as the IFAS system could
maintain the biomass within the system better than the conventional AS system. Therefore, the
capacity and stability of conventional AS system can be enhanced by applying the IFAS
technology