title: Moving towards sustainable resources: Recovery and fractionation of nutrients from dairy manure digestate using membranes.
abstract: The fractionation of nitrogen (as ammonia/ammonium) and phosphorus (as phosphate ions) present in the dairy manure digestate was investigated using a nanofiltration membrane NF270. The filtration and separation efficiencies were correlated to pH across the range 3 < pH < 11. Filtration at pH 11 enabled higher permeate flux of 125-150 LMH at 20 bar, however rejection of ammonia was high at 30-36% and phosphate was 96.4-97.2%. At pH 3 and pH 7, electrostatic charge effects led to higher permeation of ammonium and thus more efficient separation of nitrogen. The rejection of phosphorus was relatively constant at any given pH and determined as 83% at pH 3, 97% at pH 7 and 95% at pH 11. The fractionation of nitrogen and phosphorus from complex aqueous solutions was demonstrated to be highly dependent on the charge of the membrane and ionic speciation. Solutions rich in nitrogen (as ammonia/ammonium) were obtained with almost no phosphorus present (<1 ppm) whilst the purification of the PO4-P was achieved by series of diafiltration (DF) operations which further separated the nitrogen. The separation of nutrients benefited from an advantageous membrane process with potential added value for a wide range of industries. The analysis of the process economics for a membrane based plant illustrates that the recovery of nutrients, particularly NH3-N, may be commercially feasible when compared to manufactured anhydrous NH3.
authors.affiliation: Centre for Complex Fluid Processing (CCFP), Systems and Process Engineering Centre, College of Engineering (SPEC), Swansea University, Swansea, SA2 8PP, UK. Electronic address: Michael.l.gerardo@gmail.com.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Gerardo
authors.affiliation: Centre for Water Advanced Technologies and Environmental Research (CWATER), College of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PP, UK.
authors.forename: Nasser H M
authors.initials: NH
authors.lastname: Aljohani
authors.affiliation: Centre for Complex Fluid Processing (CCFP), Systems and Process Engineering Centre, College of Engineering (SPEC), Swansea University, Swansea, SA2 8PP, UK; Centre for Water Advanced Technologies and Environmental Research (CWATER), College of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PP, UK.
authors.forename: Darren L
authors.initials: DL
authors.lastname: Oatley-Radcliffe
authors.affiliation: Centre for Complex Fluid Processing (CCFP), Systems and Process Engineering Centre, College of Engineering (SPEC), Swansea University, Swansea, SA2 8PP, UK; Centre for Water Advanced Technologies and Environmental Research (CWATER), College of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PP, UK.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Lovitt
mesh_terms: D000641:Ammonia / Q000032:analysis / Q000302:isolation & purification; D000818:Animals; D002417:Cattle; D005591:Chemical Fractionation / Q000295:instrumentation* / Q000379:methods; D003612:Dairying; D005240:Feasibility Studies; D005308:Fertilizers / Q000032:analysis; D005374:Filtration / Q000191:economics / Q000295:instrumentation* / Q000379:methods; D006863:Hydrogen-Ion Concentration; D008372:Manure / Q000032:analysis*; D008567:Membranes, Artificial; D036103:Nanotechnology; D010710:Phosphates / Q000032:analysis / Q000302:isolation & purification; D010758:Phosphorus / Q000032:analysis / Q000302:isolation & purification; D059027:Recycling; D015203:Reproducibility of Results
chemical_list: D005308:Fertilizers; D008372:Manure; D008567:Membranes, Artificial; D010710:Phosphates; D010758:Phosphorus; D000641:Ammonia
keywords: Digestate; Membrane filtration; Nutrient recovery; Process economics