ABSTRACT
The generation of a sludge which exhibits good settlement properties, is a most important consideration in the design and operation of all activated sludge systems. This chapter presents a design procedure based on material balances, active biomass, floc-loading parameters, biosorptive capacity with related biosorptive regeneration criteria, and biomass zone settling velocity. Variable volume or cyclically operated activated sludge technology has emerged as a viable alternative to the use of constant volume, constantly aerated conventional activated sludge methodology. Long sludge age systems operating at low temperatures treating domestic wastes and systems treating essentially carbohydrate wastes having a high soluble organic content are typical situations where bulking sludge is frequently encountered. Cyclic systems by virtue of their mode of operation offer a simple and efficient methodology for combined or single sludge nitrification and denitrification. Internal wastewater carbonaceous organic compounds are used as the hydrogen acceptor in the denitrification sequence.
