USE OF POWDERED CLAY TO UPGRADE ACTIVATED-SLUDGE PROCESS

Two experimental pilot plant units were run. The first unit was an upg raded activated sludge system with powdered clay addition (PC). The se cond one was a conventional activated sludge plant, run as a control u nit (CU). The main objective of this study was to confirm the enhanced performances of upgraded PC unit, particularly as far as sludge settl ing characteristics and increased nitrification capacity are concerned . The experimental results showed that the application of this techniq ue for overloaded plants upgrading resulted in a decrease of applied s ludge loading, an increase of solids flow loading, a very low value of SVI and an enhanced nitrification capacity. Moreover, plant volume co uld be reduced by 30% compared to a conventional activated sludge proc ess. The presence of powdered clay improves also physical characterist ics of the excess sludge, namely its thickening capacity and dry solid s content.