Sludge disintegration model with finite disintegration rate

Fahad Saif Al Saadi, Mark I. Nelson, A. L. Worthy


The activated sludge process is the most widely used biological wastewater treatment method for domestic and industrial wastewaters. One drawback of this process is the production of `sludge'. The expense for treating excess sludge accounts for 50-60% of the operating costs in a wastewater treatment plant. Traditional methods for disposing of excess sludge are increasingly regulated due to environmental concerns about the presence of potentially toxic elements in the sewage sludge. A promising method to reduce excess sludge production is to increase its biodegradability by disintegrating it within the bioreactor. We extend an earlier model by allowing the sludge disintegration reactions to occur at a finite rate. Furthermore, we include a more realistic model for the hydrolysis of particulate matter by allowing the rate of hydrolysis to saturate at high particulate concentrations. We analyze the steady-state operation of an activated sludge system incorporating a sludge disintegration unit to prevent excess sludge production.

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