Assessment of energy-saving strategies and operational costs in full-scale membrane bioreactors.
The energy-saving strategies and operational costs of stand-alone, hybrid, and dual stream full-scale membrane bioreactors (MBRs) with capacities ranging from 1100 to 35,000 m(3) day(-1) have been assessed for seven municipal facilities located in Northeast Spain. Although hydraulic load was found to be the main determinant factor for the energy consumption rates, several optimisation strategies have shown to be effective in terms of energy reduction as well as fouling phenomenon minimization or preservation. Specifically, modifications of the biological process (installation of control systems for biological aeration) and of the filtration process (reduction of the flux or mixed liquor suspended solids concentration and installation of control systems for membrane air scouring) were applied in two stand-alone MBRs. After implementing these strategies, the yearly specific energy demand (SED) in flat-sheet (FS) and hollow-fibre (HF) stand-alone MBRs was reduced from 1.12 to 0.71 and from 1.54 to 1.12 kW h(-1) m(-3), respectively, regardless of their similar yearly averaged hydraulic loads. The strategies applied in the hybrid MBR, namely, buffering the influent flow and optimisation of both biological aeration and membrane air-scouring, reduced the SED values by 14%. These results illustrate that it is possible to apply energy-saving strategies to significantly reduce MBR operational costs, highlighting the need to optimise MBR facilities to reconsider them as an energy-competitive option.
LEQUIA, Institute of the Environment, University of Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain. Electronic address: sara.gabarron@lequia.udg.cat.
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Gabarrón
UNESCO-IHE Institute for Water Education, Westvest 7, 2611 AX Delft, The Netherlands. Electronic address: g.ferrero@unesco-ihe.org.
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Ferrero
LEQUIA, Institute of the Environment, University of Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain. Electronic address: montse.dalmau@lequia.udg.cat.
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Dalmau
LEQUIA, Institute of the Environment, University of Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain. Electronic address: quim@lequia.udg.cat.
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Comas
LEQUIA, Institute of the Environment, University of Girona, Campus Montilivi, E-17071 Girona, Catalonia, Spain; ICRA (Catalan Institute for Water Research), Scientific and Technological Park of the University of Girona, H2O Building, c/Emili Grahit 101, E17003 Girona, Spain. Electronic address: irodriguezroda@icra.cat.
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Rodriguez-Roda
D019149:Bioreactors / Q000191:economics; D003246:Conservation of Energy Resources; D003365:Costs and Cost Analysis; D005374:Filtration / Q000295:instrumentation / Q000379:methods; D008567:Membranes, Artificial; D014865:Waste Disposal, Fluid / Q000191:economics / Q000295:instrumentation / Q000379:methods
D008567:Membranes, Artificial
Energy efficiency; Membrane bioreactor; OPEX; Wastewater