SMALL ACTIVATED-SLUDGE PERFORMANCE AND VIABILITY CHARACTERISTICS UNDER INTERMITTENT AND REDUCED FLOWS

Small activated sludge systems operate in transient states under inter mittent and variable flows. Simulations for such a treatment plant in a summer house site operating on a seasonal basis is investigated for system performance and viability using the five component inert solubl e substrate generation model. The results have revealed that the viabi lity drops to zero within the first month after the cessation of the f eed for intermittently loaded systems that are fed during the summer m onths, while it never reaches that value for systems operating all yea r round with reduced flows off season. Restartup is compulsory for the intermittent loadings while the system adapts itself in a stepwise ma nner for the year round operation. Other factors being comparable, con ventional operation with shorter sludge ages may be preferable since v iability of the sludge is higher and the effluent COD is comparable.