The study investigated the recovery potential of phosphorus from supernatant enriched with phosphorus by aluminum and ferric salts

as well as the effects on the performance of mainstream biological phosphorus systems. Two parallel SBR reactors were designed

which used aluminum and ferric salts as flocculants to illustrate the influence on the performances of wastewater treatment

sludge

and phosphorus recovery. Results indicated that the maximum release rates of phosphorus in anaerobic stage of the two systems could be 2.58 and 2.63 times of the influent phosphorus

and the average recovery contents of the influent phosphorus resources by aluminum and ferric salts in a cycle were 1.57 times and 2.68 times. In addition

the COD removal efficiency was not significantly affected by the stripping treatment. Due to the stripping operation

the intracellular polyphosphate particle content in PAOs decreased

the ability of phosphorus release declined

and the phosphorus removal by microorganism was inhibited. Therefore

the removal rates of phosphorus in the two systems declined after stopping sidestream stripping. Owing to the lower removal rate

the aluminum salt system could be recovered in a shorter time

while the ferric salt need a longer time. In sidestream stripping period

a little residue of Al3+ and Fe3+ promoted the increase of extracellular polymeric substances produced by microorganism. The contents of EPS in the aluminum salt system and the ferric salt system increased by 62.93% and 94.52%

respectively. In summary

though the content of phosphorus recovery in aluminum salt system was smaller than that of the ferric salt system

the restoration capability was stronger

and the effect on the ability of biological phosphorus removal in mainstream system was less

which were more beneficial for the long-term recovery of phosphorus.