A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Technology

Thesis (M.Eng.) - Asian Institute of Technology,1987

Experiments with synthetic waste as substrate showed that Intermittent flow system (IFS) had better performance than Continuous flow system (CFS) in activated sludge process. Even though effluent FTOC was better in IFS than CFS for same HRT and COD loading, sludge settlability was the. important parameter that gave the advantage to IFS over CFS . This research study ascertain that IFS could be operated without sludge bulking problem and better effluent qualities compared with CFS, where poor settlability and sludge bulking were often the operational problems, particularly at short HRTs and high volumetric loadings . IFS could be operated at HRT range of 4.74 h to 18 . 95 hand loading range of 0.42 to 2.41 kg COD/m3 .d with F/M ratio ranging from 0 . 42 to 1.10 g COD/g MLVSS . d. Treatability of waste with different cycle time (or different HRT) showed that shorter aeration period such as 1 1/2 to 2 h was enough to achieve about 92% COD removal efficiency with good sludge settlability. Higher unit oxygen uptake rate in IFS over CFS indicated that high microorganisms activity in IFS than CFS. Better effluent quality of IFS over CFS indicated that intermittent activated sludge process could be adopted to meet the stringent effluent standard.