title: Response of a sludge-minimizing lab-scale BNR reactor when the operation is changed to real primary effluent from synthetic wastewater.
abstract: The activated sludge process is the most widely used treatment method for municipal wastewater. However, the excessive amount of biomass generated during the process is a major drawback. Earlier studies using the activated sludge process running in a biomass fasting and feasting mode demonstrated both nutrient removal and a minimization of biomass production. However, these studies were conducted using synthetic wastewater. In this study, we report findings from a lab-scale sludge-minimizing biological nutrient removing (BNR) reactor when its operation was changed from synthetic to real wastewater (primary effluent). Two lab-scale sequencing batch reactors, one in sludge minimization mode (hereafter called modified-SBR), and the other in conventional activated sludge mode (referred as control-SBR), were operated for more than 300 days. Both reactors were started and operated with synthetic feed. Gradually the feed to both reactors was changed to 100% primary effluent collected from a local full-scale wastewater treatment plant. Irrespective of the feed composition, more than 98% NH3-N removal was recorded in both SBRs. However, while 89% of the total dissolved phosphorus was removed from the 100% synthetic feed, only 80% of the total dissolved phosphorus was removed from the 100% primary effluent in both SBRs. The overall observed sludge reduction in the modified-SBR as compared to the control-SBR also decreased from 65% to 39% when the feed was changed from 100% synthetic to 100% primary effluent. The specific oxygen uptake rate for the modified-SBR was 80% higher than that for the control-SBR when the SBRs were fed with primary effluent wastewater. The modified-SBR showed a greater diversity of ammonia-oxidizing bacteria (AOBs) with synthetic wastewater as well as during the transition period than the control-SBR. Yet when the reactors were running on 100% real wastewater, only Nitrosomonas europaea/eutropha were identified in both SBRs. The nitrite-oxidizing bacterial community and the polyphosphate accumulating organisms (PAOs) responded in a similar way in both SBRs.
authors.affiliation: Department of Civil & Environmental Engineering, University of Utah, Salt Lake City, United States.
authors.forename: Pei
authors.initials: P
authors.lastname: Huang
authors.affiliation: Department of Civil & Environmental Engineering, University of Utah, Salt Lake City, United States. Electronic address: ram.goel@utah.edu.
authors.forename: Ramesh
authors.initials: R
authors.lastname: Goel
mesh_terms: D001419:Bacteria / Q000254:growth & development; D018533:Biomass; D019149:Bioreactors; D010758:Phosphorus / Q000378:metabolism; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology; D014865:Waste Disposal, Fluid / Q000379:methods; D062065:Wastewater / Q000737:chemistry*; D018508:Water Purification / Q000379:methods
chemical_list: D010758:Phosphorus; D012722:Sewage; D062065:Wastewater
keywords: Biological nutrients removal; Nitrifiers; PAO; Primary effluent wastewater; Sludge minimization