title: Integration of biopolymer production with process water treatment at a sugar factory.
abstract: The present investigation has focused on generating a surplus denitrifying biomass with high polyhydroxyalkanoate (PHA) producing potential while maintaining water treatment performance in biological nitrogen removal. The motivation for the study was to examine integration of PHA production into the water treatment and residuals management needs at the Suiker Unie sugar beet factory in Groningen, the Netherlands. At the factory, process waters are treated in nitrifying-denitrifying sequencing batch reactors (SBRs) to remove nitrogen found in condensate. Organic slippage (COD) in waters coming from beet washing is the substrate used for denitrification. The full-scale SBR was mimicked at laboratory scale. In two parallel laboratory scale SBRs, a mixed-culture biomass selection strategy of anoxic-feast and aerobic-famine was investigated using the condensate and wash water from Suiker Unie. One laboratory SBR was operated as conventional activated sludge with long solids retention time similar to the full-scale (SRT >16 days) while the other SBR was a hybrid biofilm-activated sludge (IFAS) process with short SRT (4-6 days) for the suspended solids. Both SBRs were found to produce biomass with augmented PHA production potential while sustaining process water treatment for carbon, nitrogen and phosphorus for the factory process waters. PHA producing potential in excess of 60 percent g-PHA/g-VSS was achieved with the lab scale surplus biomass. Surplus biomass of low (4-6 days) and high (>16 days) solids retention time yielded similar results in PHA accumulation potential. However, nitrification performance was found to be more robust for the IFAS SBR. Assessment of the SBR microbial ecology based on 16sDNA and selected PHA synthase genes at full-scale in comparison to biomass from the laboratory scale SBRs suggested that the full-scale process was enriched with a PHA storing microbial community. However, structure-function relationships based on RNA levels for the selected PHA synthases could not be established and, towards this ambition, it is speculated that a wider representation of PHA synthesases would need to be monitored. Additionally at the factory, beet tail press waters coming from the factory beet residuals management activities are available as a carbon source for PHA accumulation. At pilot scale, beet tail press waters were shown to provide a suitable carbon source for mixed culture PHA production in spite of otherwise being of relatively low organic strength (≤ 10 g-COD/L). A copolymer of 3-hydroxybutyrate with 3-hydroxyvalerate (PHBV with 15% HV on a molar basis) of high thermal stability and high weight average molecular mass (980 kDa) was produced from the beet tail press water. The mixed culture accumulation process sustained PHA storage with parallel biomass growth of PHA storing bacteria suggesting a strategy to further leverage the utilization of surplus functional biomass from biological treatment systems. Integration of PHA production into the existing factory water management by using surplus biomass from condensate water treatment and press waters from beet residuals processing was found to be a feasible strategy for biopolymer production.
authors.affiliation: AnoxKaldnes AB, Klosterängsvägen 11A, 22647 Lund, Sweden.
authors.forename: Simon
authors.initials: S
authors.lastname: Anterrieu
authors.affiliation: AnoxKaldnes AB, Klosterängsvägen 11A, 22647 Lund, Sweden.
authors.forename: Luca
authors.initials: L
authors.lastname: Quadri
authors.affiliation: Bioclear BV, Rozenburglaan 13, 9704 CG Groningen, The Netherlands.
authors.forename: Bert
authors.initials: B
authors.lastname: Geurkink
authors.affiliation: Bioclear BV, Rozenburglaan 13, 9704 CG Groningen, The Netherlands.
authors.forename: Inez
authors.initials: I
authors.lastname: Dinkla
authors.affiliation: AnoxKaldnes AB, Klosterängsvägen 11A, 22647 Lund, Sweden.
authors.forename: Simon
authors.initials: S
authors.lastname: Bengtsson
authors.affiliation: AnoxKaldnes AB, Klosterängsvägen 11A, 22647 Lund, Sweden.
authors.forename: Monica
authors.initials: M
authors.lastname: Arcos-Hernandez
authors.affiliation: AnoxKaldnes AB, Klosterängsvägen 11A, 22647 Lund, Sweden.
authors.forename: Tomas
authors.initials: T
authors.lastname: Alexandersson
authors.affiliation: AnoxKaldnes AB, Klosterängsvägen 11A, 22647 Lund, Sweden.
authors.forename: Fernando
authors.initials: F
authors.lastname: Morgan-Sagastume
authors.affiliation: AnoxKaldnes AB, Klosterängsvägen 11A, 22647 Lund, Sweden.
authors.forename: Anton
authors.initials: A
authors.lastname: Karlsson
authors.affiliation: AnoxKaldnes AB, Klosterängsvägen 11A, 22647 Lund, Sweden.
authors.forename: Markus
authors.initials: M
authors.lastname: Hjort
authors.affiliation: AnoxKaldnes AB, Klosterängsvägen 11A, 22647 Lund, Sweden.
authors.forename: Lamija
authors.initials: L
authors.lastname: Karabegovic
authors.affiliation: AnoxKaldnes AB, Klosterängsvägen 11A, 22647 Lund, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Magnusson
authors.affiliation: AnoxKaldnes AB, Klosterängsvägen 11A, 22647 Lund, Sweden.
authors.forename: Peter
authors.initials: P
authors.lastname: Johansson
authors.affiliation: AnoxKaldnes AB, Klosterängsvägen 11A, 22647 Lund, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Christensson
authors.affiliation: AnoxKaldnes AB, Klosterängsvägen 11A, 22647 Lund, Sweden. Electronic address: alan.werker@anoxkaldnes.com.
authors.forename: Alan
authors.initials: A
authors.lastname: Werker
mesh_terms: D000641:Ammonia / Q000302:isolation & purification; D057919:Biological Oxygen Demand Analysis; D018533:Biomass; D001704:Biopolymers / Q000096:biosynthesis*; D019149:Bioreactors / Q000382:microbiology; D001709:Biotechnology / Q000379:methods*; D002241:Carbohydrates / Q000032:analysis*; D007220:Industrial Waste; D009584:Nitrogen / Q000302:isolation & purification; D010802:Phylogeny; D010865:Pilot Projects; D054813:Polyhydroxyalkanoates; D012995:Solubility; D018508:Water Purification
chemical_list: D001704:Biopolymers; D002241:Carbohydrates; D007220:Industrial Waste; D054813:Polyhydroxyalkanoates; D000641:Ammonia; D009584:Nitrogen