Evaluation of ozonation and cryptic growth for biosolids management in wastewater treatment

The ultimate disposal of biosolids has been and continues to be one of the most expensive problems faced by wastewater utilities. The objective of thi s research is to develop a process configuration for reducing the waste slu dge generation in an activated sludge plant by promoting cryptic growth con ditions (i.e., biomass growth on intracellular products). For this purpose, excess biosolids from a continuous flow activated sludge system were solub ilized using ozone as the cell lysis agent, and then returned to the aerati on tank. It is hypothesized that growth under such cryptic conditions will result in low net microbial yields, and hence, minimal net solids wastage. The results of these preliminary studies indicate that the proposed process configuration has the potential to reduce the waste sludge production by 4 0% to 60%. (C) 1999 Published by Elsevier Science Ltd on behalf of the IAWQ . All rights reserved.