Sequencing batch membrane biofilm reactor for simultaneous nitrogen and phosphorus removal: Novel application of membrane‐aerated biofilm

Abstract

A sequencing batch membrane biofilm reactor (SBMBfR) was developed for simultaneous carbon, nitrogen, and phosphorus removal from wastewater. This reactor was composed of two functional parts: (1) a gas-permeable membrane on which a nitrifying biofilm formed and (2) a bulk solution in which bacteria, mainly denitrifying polyphosphate-accumulating organisms (DNPAOs), were suspended. The reactor was operated sequentially under anaerobic condition and then under membrane aeration condition in one cycle. During the anaerobic period, organic carbon was consumed by DNPAOs; this was accompanied by phosphate release. During the subsequent membrane aeration period, nitrifying bacteria utilized oxygen supplied directly to them from the inside of the membrane. Consequently, the nitrite and nitrate products diffused into the bulk solution, where they were used by DNPAOs as electron acceptors for phosphate uptake. In a long-term sequencing batch operation, the mean removal efficiencies of total organic carbon (TOC), total nitrogen (T-N), and total phosphorus (T-P) under steady-state condition were 99%, 96%, and 90%, respectively. In addition, fluorescence in situ hybridization (FISH) clearly demonstrated the difference in bacterial community structure between the membrane biofilm and the suspended sludge: ammonia-oxidizing bacteria belonging to the Nitrosomonas group were dominant in the region adjacent to the membrane throughout the operation, and the occupation ratio of the well-known polyphosphate-accumulating organism (PAO) Candidatus "Accumulibacter phosphates" in the suspended sludge gradually increased to a maximum of 37%.

Applicability of a Sequencing Batch Membrane Biofilm Reactor for Simultaneous Nitrogen and Phosphorus Removal from Low C/N Ratio Wastewater

“…Specific nitrification rates at C/N ratios of 2.3 and 3.5 were 2.5 g-N/m 2 /day and 2.3 g-N/m 2 /day, respectively, suggesting marginal effect of PAOs outcompeting the nitrifying bacteria at a higher C/N ratio. The specific nitrification rates are comparable with those previously reported (Terada et al, 2006). Taken together, oxygen via membrane aeration was preferentially utilized for nitrification, corroborating that biofilm on a membrane was a spot for nitrification in SBMBfRs.…”

“…5 indicates that PAOs were predominant in activated sludge throughout the SBMBfR operation, accounting up to over 20 -30% of the total bacteria. These abundances were comparable with the previous studies harnessing DNPAOs in single-stage N and P removal systems (e.g., Terada et al, 2006). The PAO abundance decreased with a decrease in C/N ratio in the synthetic wastewater, suggesting that a lower C/N ratio in wastewater is not favorable for PAO growth.…”

“…Especially, a sequencing batch reactor (SBR) technology is suitable to achieve a small foot-print reactor system. Above all, a sequencing batch membrane biofilm reactor (SBMBfR) is one of the promising technologies in the sense that simultaneous nitrogen and phosphorus (N and P) removal is feasible (Terada et al, 2006). An SBMBfR is comprised of a fibrous-composite matrix of a gas-permeable membrane, on which nitrifying biofilm grows, and activated sludge where denitrifying polyphosphate-accumulating organisms (DNPAOs) are predominant.…”

Membrane-Aerated Biofilms for High Rate Biotreatment: Performance Appraisal, Engineering Principles, Scale-up, and Development Requirements

“…A techno-economic model would form an important input into scale-up design strategies. Improvements in MABR performance may also be gained by further exploration of non-continuous operation, such as sequencing batch MABRs 41,[73][74][75] , or by novel hybrid designs that combine the MABR with other technologies [38][39][40][41][42] . There is also a continuing need for basic research into fundamental mechanisms governing MABR performance.…”

Model‐based comparative performance analysis of membrane aerated biofilm reactor configurations

“…To-date, laboratory and pilot-scale investigations have focused on several application areas, for example, total nitrogen removal (Hibiya et al, 2003;Terada et al, 2006), simultaneous carbonaceous/nitrogen removal (Semmens et al, 2003;Timberlake et al, 1988), high strength carbonaceous removal and the treatment of volatile organic wastewater constituent .…”