Improved Biological Phosphorus Removal under Low Solid Retention Time Regime in Full-Scale Sequencing Batch Reactor

Enhanced biological phosphorus removal (EBPR) is an obscure but economical and helpful technology for removing phosphorus biologically from wastewater. A 3-MLD capacity pre-anoxic selector-attached sequencing batch reactor (SBR) treated municipal wastewater from the residents of IIT Roorkee. The treatment in the plant satisfied the effluent discharge standards in all respects except phosphorus, observed during an intensive two-year study. An elaborated 80-day study was performed to enhance and improve the plant's performance in terms of phosphorus removal specifically, with run 1: solid retention times (SRT) reduced from 56 to 20 days (t = 35 d), run 2: lowering the diffuser's running time from 15 min to 10 min in anoxic cum anaerobic selector chambers (dissolved oxygen (DO) concentration reduced to <0.15 mg/L) along with reducing SRT to 15 days (t = 25 d), and run 3:intensive reduction in SRT to <= 10 days (t = 20 d). During run 3, the increment in the enhanced biological phosphorus removal (EBPR) efficiency was three times that of the initial run ( eta(max)similar to 65%) with a readily biodegradable chemical oxygen demand to total phosphorus ratio (rbCOD/TP) of 7.8. The 16SrRNA sequencing revealed the microbial community structure before and after the changes in SRT and EBPR efficiencies, to correlate the biochemical processes and functional organisms.

Automated summary

Enhanced biological phosphorus removal (EBPR) is a cost-effective technology to remove phosphorus from wastewater. A 80-day study showed that reducing solid retention time and lowering dissolved oxygen concentration can significantly enhance EBPR efficiency.