title: Control of nitrification/denitrification in an onsite two-chamber intermittently aerated membrane bioreactor with alkalinity and carbon addition: Model and experiment.
abstract: Denitrifying membrane bioreactors (MBRs) are being found useful in water reuse treatment systems, including net-zero water (nearly closed-loop), non-reverse osmosis-based, direct potable reuse (DPR) systems. In such systems nitrogen may need to be controlled in the MBR to meet the nitrate drinking water standard in the finished water. To achieve efficient nitrification and denitrification, the addition of alkalinity and external carbon may be required, and control of the carbon feed rate is then important. In this work, an onsite, two-chamber aerobic nitrifying/denitrifying MBR, representing one unit process of a net-zero water, non-reverse osmosis-based DPR system, was modeled as a basis for control of the MBR internal recycling rate, aeration rate, and external carbon feed rate. Specifically, a modification of the activated sludge model ASM2dSMP was modified further to represent the rate of recycling between separate aerobic and anoxic chambers, rates of carbon and alkalinity feed, and variable aeration schedule, and was demonstrated versus field data. The optimal aeration pattern for the modeled reactor configuration and influent matrix was found to be 30 min of aeration in a 2 h cycle (104 m3air/d per 1 m3/d average influent), to ultimately meet the nitrate drinking water standard. Optimal recycling ratios (inter-chamber flow to average daily flow) were found to be 1.5 and 3 during rest and mixing periods, respectively. The model can be used to optimize aeration pattern and recycling ratio in such MBRs, with slight modifications to reflect reactor configuration, influent matrix, and target nitrogen species concentrations, though some recalibration may be required.
authors.affiliation: Civil, Architectural, and Environmental Engineering, University of Miami, PO Box 248294, Coral Gables, FL 33124-0630, USA. Electronic address: m.perera@miami.edu.
authors.forename: Mahamalage Kusumitha
authors.initials: MK
authors.lastname: Perera
authors.affiliation: Civil, Architectural, and Environmental Engineering, University of Miami, PO Box 248294, Coral Gables, FL 33124-0630, USA. Electronic address: jenglehardt@miami.edu.
authors.forename: James D
authors.initials: JD
authors.lastname: Englehardt
authors.affiliation: Department of Civil and Environmental Engineering, University of California Davis, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: George
authors.initials: G
authors.lastname: Tchobanoglous
authors.affiliation: Bio-Microbics, 8450 Cole Parkway, Shawnee, KS 66227, USA.
authors.forename: Reza
authors.initials: R
authors.lastname: Shamskhorzani
mesh_terms: D019149:Bioreactors; D002244:Carbon; D058440:Denitrification; D058465:Nitrification; D009584:Nitrogen; D012722:Sewage; D014865:Waste Disposal, Fluid
chemical_list: D012722:Sewage; D002244:Carbon; D009584:Nitrogen
keywords: Aeration; Denitrification; Direct potable reuse; Membrane bioreactor; Model; Nitrification