Effect of Magnesium Iron Content on the Biological Phosphorus Removal System in SBR
镁离子浓度对SBR生物除磷系统的影响

This study investigated the effect of magnesium iron content on the enhanced biological phosphorus removal system, which performed differently at magnesium content of 0mg/L, 8mg/L and 24mg/L (R1-R3). The results indicated appropriate Mg addition could enrich phosphorus accumulating organisms and keep stable running. During the steady state period, phosphorus removal rate declined to below 50% gradually, moreover, the system tended to deteriorate with the shortage of magnesium in R1.However, the system with appropriate magnesium kept the higher phosphorus removal rate (more than 90%). The statistical analysis of the experimental data also showed a strong correlation between Mg and phosphorus concentrations in R2 and R3, the ratios of Mg and P were 0.29-0.59 and 0.25-0.54 in two reactors respectively. In the anaerobic phase of EBPR, the magnesium content, the absolute value of ORP and the phosphates release had a correlation. Meanwhile, magnesium was released together with phosphates in the anaerobic phase, and that would uptake under aerobic conditions. Thus it was obvious that magnesium played a key role on the biological phosphorus removal system.