Session XXIV Recovery of materials from wastewater & sludge – Sludge management Downstream processing for Polyhydroxyalkanoates from mixed microbial cultures: Study of microbial activity inhibition, polymer recovery and characterizations 1 L. Lorini, 1 F . Valentino, 1 G. Bifolchi, 1 A. Martinelli, 1 M. Majone 1 Department of Chemistry University of Rome La Sapienza laura.lorini@uniroma1.it
Polyhydroxyalkanoates (PHA) Product related Pro’s Family of copolymers with tunable composition Main constituent of several bioplastics Bio-based Bio-based feedstock and feedstock biodegradability Bio-PE Biopolym (PP/PVS), ers starch biobased blends, PET non PLA, PHA (Kunansudari, Exp Polym Let 2010) biodegradab biodegradabl le, recycling e, Biodegradable with organic mechanical commodity film recycling waste PE, PP, PS, PBAT, PBS, PVC, PET ecc. Packaging interlayer film PCL Biodegradabilit Specialty durables (such Oil-based plastics y as electronics) Slow C-release system for groundwater remediation Heraklion2019 28th June 2
PHA production from MMC and organic waste Organic fraction of municipal solid Activated sludge waste VFA (OFMSW) Stage II (SBR): Stage III: PHA Acidogenic biomass VFA MMC production Fermentation selection/ enrichment (ADF) PHA-rich Solid fraction Liquid fraction biomass PHA extraction Sludge from Anaerobic wastewater Digestion treatment plant PHA processing Energy Nutrients Biodegradab le 3 Heraklion2019 28th June bioplastics
Pilot platform Wastewater Treatment Plant in Treviso (North-East of Italy)
Aim of the study Optimization of a stabilization method Infmuence of pH ➔ H 2 SO 4 ; NaOH Oxidation➔ NaClO Excess of substrates Thermal treatments➔ oven dried at 70°C (with or without shock at 170°C) Innovative extraction and recovery methods Non-chlorinated solvent: ethyl acetate Characterization of extracted polymer: GC-FID ➔ purity, recovery yield and monomeric composition Capillary viscosimetry ➔ molecular weight DSC ➔ thermal properties Heraklion2019 28th June 5
Selection of PHA-producing biomass (SBR) Operative cycle (12 h) Feeding= 10 min Reaction 1= 140 min Withdrawal= 3 min Nitrogen feeding= 5 min Reaction 2= 562 min V = 1L Organic load rate (OLR) 4.25 gCOD/L d VFA (85% Acetic acid; 15% Propionic acid) T= 25°C Heraklion2019 28th June 6
PHA accumulation step • Batch reactor V= 0.5L Selection • 6h test (SBR) • Multispike strategy (85% Acetic acid; 15% Propionic acid) VF A PHA mgCOD/L PHA storing biomass PHA content 2500 2000 1500 PHA-rich Accumulati biomass 1000 on (Batch) 500 0 0 1 2 3 4 5 6 7 t (h) Heraklion2019 28th June 7
Stabilization tests PHA t /PHAend of accumulation 12000% 10000% 8000% 6000% P H A t / P H A e n d o f a c c u m u l a t i o n 4000% 2000% 0% 0 0,5 1 1,5 2 2,5 3 time (h) Two kinds of thermal 100% treatment 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Heraklion2019 28th June 8 End of batch test Centrifuged 170°C+70°C 70°C
Extraction and characterization 5 different batches ( Pilot scale Batches 11, 15, 19, 22, 24) and 1 batch ( Lab scale ) thermally stabilized Soxhlet extraction with CHCl 3 Oxidation with NaClO Mv (KDa) CHCl3 NaClO 200000 Purity (PHA %w/w) 95.3 % (CHCl 3 ); 150000 85.2 % (NaClO) 100000 Recovery yield (%w/w) 83.2 % (CHCl 3 ); 50000 87.4 % (NaClO) 0 B. 11 B. 15 B. 19 B. 22 B. 24 Lab scale Heraklion2019 28th June 9
Non-chlorinated solvent extraction Batch 11 thermally stabilized Extraction in a pressurized steel reactor with Ethyl acetate (100 and 125°C) for 1h Residues extracted with CHCl 3 Heraklion2019 28th June 10
Conclusions and future prospectives Thermal treatment applicable at pilot scale NaClO gave results comparable to traditional chloroform extraction Ethyl acetate selectively extracts shorter chains Evaluation of the efgects of thermal treatment on the polymer, in comparison with an acidifjcation method applied at pilot scale Optimization of Ethyl acetate extraction and use of other non-chlorinated solvents Heraklion2019 28th June 11
Thanks for your attention 12
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