Anoxic biological phosphorus uptake/release with high/low intracellular polymers

This study investigates the denitrification/phosphate uptake and denitrific ation/phosphate release characteristics among denitrifying phosphate accumu lating organisms (DNPAO), denitrifier, and nondenitrifying phosphate accumu lating organisms (non-DNPAO) in a biological nutrient removal process named TNCU-I, using a series of anoxic batch experiments with and without added acetate under high/low intracellular polymer conditions. The results showed 47% phosphate uptake in the anoxic tank of the TNCU-I process. Additionall y, due to the combined attribution of denitrifier and DNPAO, the experiment s with both added acetate and phosphate produced higher denitrification rat es than experiments with only acetate added. Furthermore, DNPAO contributed 42% of the denitrification reaction. The sludge exhibited simultaneous pho sphate uptake and release under anoxic conditions when acetate was added. W hen no acetate was added, the specific phosphate uptake rate for the high i ntracellular polymer level was higher than that found at the low intracellu lar polymer level. Moreover, the phosphate uptake rate of non-DNPAO was obs erved to be 2.46 times greater than that of the DNPAO. The phosphate uptake per unit polyhydroxyalkanoates (PHA) consumption (gamma (PO4/PHA)) for the nonDNPAO was 1.08 times greater than that of DNPAO. Thus, this study demon strates that the utilization efficiency of PHA by non-DNPAO is not signific antly different with the utilization efficiency of PHA by DNPAO.