ANALYSIS OF INFLUENCING FACTORS OF PHOSPHATE ENHANCED ABSORPTION IN BSBR PROCESS UNDER LOW CARBON SOURCE CONDITIONS

Compared with the traditional enhanced biological phosphorus removal(EBPR) process which achieves the enrichment and recovery of sludge phosphate through the flow process, the biofilm process can efficiently and synchronically remove and enrich phosphate in wastewater, thus has the potential to be applied to the mainstream process. Given the problem of high carbon source stimulation required for anaerobic phosphorus release by the biofilm process, the phosphorus storage of biofilm can be enhanced by optimizing the process conditions to strengthen the biofilm aerobic phosphorus uptake capacity, thus reducing the consumption of carbon source during anaerobic phosphorus release. In this paper, a biofilm sequencing batch reactor(BSBR) was used to investigate the response relationship between phosphorus storage and phosphorus concentration in the recovery tank under the addition of a low carbon source. The effects of dissolved oxygen, mixing strength and aerobic time on phosphate enhanced absorption were studied by orthogonal test. The results showed that when the temperature was(25±2) ℃ and the anaerobic external carbon source was(180±20) mg/L, the phosphorus concentration in the enrichment solution increased with the increase of phosphorus storage in the biofilm, up to 90.62 mg/L. Under the same phosphorus storage, the dissolved oxygen concentration increased from 2 mg/L to 8 mg/L, and the maximum phosphate absorption rate increased from 2.60 mg/(L·h) to 8.70 mg/(L·h). Orthogonal experiments showed that the order of influencing factors on phosphate enhanced absorption was dissolved oxygen>aerobic time>mixing intensity. When the dissolved oxygen concentration was 6 mg/L, the stirring speed was 200 r/min, and the aerobic time was 5 h, the phosphorus removal efficiency was up to 99.98%.