[Startup, stable operation and process failure of EBPR system under the low temperature and low dissolved XXXX condition].

@entity26 @entity4613 @entity3542 @entity1507 @entity3151 @entity121
A sequencing batch reactor (SBR) was started up and operated with alternating anaerobic/oxic (An/O) to perform enhanced biological @entity3151 removal (EBPR) under the condition of 13-16 degrees C. The results showed that under the condition of low temperature, the EBPR system was successfully started up in a short time (<6 d). The reactor achieved a high and stable @entity3151 removal performance with an influent @entity4613 concentration of 20 mg x L(-1) and the dissolved @entity26 (DO) concentration of 2 mg x L(-1). The effluent @entity4613 concentration was lower than 0.5 mg x L(-1). It was found that decreasing DO had an influence on the steady operation of EBPR system. As DO concentration of aerobic phase decreased from 2 mg x L(-1) to 1 mg x L(-1), the system could still perform EBPR and the @entity3151 removal efficiency was greater than 97.4%. However, the amount of @entity4613 released during anaerobic phase was observed to decrease slightly compared with that of 2 mg x L(-1) @entity121 . Moreover, the @entity3151 removal performance of the system deteriorated immediately and the effluent @entity4613 concentration couldn't meet the national integrated wastewater discharge standard when DO concentration was further lowered to 0.5 mg x L(-1). The experiments of increasing DO to recover @entity3151 removal performance of the EBPR suggested the process failure resulted from low DO was not reversible in the short-term. It was also found that the batch tests of anoxic @entity3151 uptake using @entity3542 and @entity1507 as electron acceptors had an impact on the stable operation of EBPR system, whereas the resulting negative influence could be recovered within 6 cycles. In addition, the mixed liquid suspended solids (MLSS) of the EBPR system remained stable and the sludge volume index (SVI) decreased to a certain extend in a long run, implying long-term low temperature and low @entity121 favored the sludge sedimentation.
