Hydrolysis of particulate organics in activated sludge systems

Particulate matter constitute over 50% of the organic load in domestic wastewater. In activated sludge systems a portion of these particulates are hydrolysed and degraded. Experimental methods were developed and used for estimating the rate of hydrolysis of these particulates. These included ways to distinguish between biological and non-biological VSS in an activated sludge mixture. From batch experiments an average specific hydrolysis rate coefficient of 4.61 10 −4 l(mg day) −1 was obtained for raw primary suspended solids and 6.63 10 −4 l(mg day) −1 for non-settleable suspended solids. The specific hydrolysis rate coefficients for raw wastewater in continuous flow experiments was determined as 3.07 10 −3 l(mg day) −1, which is substantially higher than in batch tests.