Modelling of Phosphorus Release and Substrate Uptake by Activated Sludge under Anaerobic Conditions

Abstract

In order to obtain information about the effects of several factors on phosphorus release and substrate uptake under anaerobic conditions, and also to develop the kinetic model for high polymeric substrate, batch experiments were undertaken using the sludge acclimated in sequencing batch reactors. The main results are as follows : ( 1 ) The specific rates of phosphorus release (SRP) and substrate uptake (SRS) in the case using soluble starch were larger than those of polypeptone. ( 2 ) The unuptakeable COD of soluble starch was smaller than that of polypeptone under anaerobic conditions. ( 3 ) In the case using high polymeric substrate, the ΔTPl/ΔCODl ratio increased with time. The increase rate of ΔTPl/ΔCODl ratio of polypeptone was larger than that of soluble starch. ( 4 ) The higher the added substrate concentration was, the larger SRP and SRS of the initial stage were. ( 5 ) The content of unreleasable phosphorus of sludge A and B, C, and D were 24, 19, and 22 mgP/gSS, respectively. ( 6 ) A model system to express the phosphorus release and substrate uptake was presented based on these results. In this model system, the SRS was expressed by an unsaturation degree of accumulated substrate, uptakeable CODl, and an amount of releasable phosphorus in sludge floe. The SRP was expressed by an amount of accumulated substrate and the content of releasable phosphorus.