Resource recovery using enriched purple phototrophic bacteria in an outdoor flat plate photobioreactor: Suspended vs. attached growth

Gabriel Capson-Tojo; Albie Zuo Meng Gan; Pablo Ledezma; Damien J Batstone; Tim Hülsen

doi:10.1016/j.biortech.2023.128709

Resource recovery using enriched purple phototrophic bacteria in an outdoor flat plate photobioreactor: Suspended vs. attached growth

Bioresour Technol. 2023 Apr:373:128709. doi: 10.1016/j.biortech.2023.128709. Epub 2023 Feb 6.

Authors

Gabriel Capson-Tojo¹, Albie Zuo Meng Gan², Pablo Ledezma², Damien J Batstone², Tim Hülsen³

Affiliations

¹ Australian Centre for Water and Environmental Biotechnology, The University of Queensland, Brisbane, QLD 4072, Australia; CRETUS Institute, Department of Chemical Engineering, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain; INRAE, Univ Montpellier, LBE, 102 Avenue des Etangs, 11100 Narbonne, France. Electronic address: gabriel.capson-tojo@inrae.fr.
² Australian Centre for Water and Environmental Biotechnology, The University of Queensland, Brisbane, QLD 4072, Australia.
³ Australian Centre for Water and Environmental Biotechnology, The University of Queensland, Brisbane, QLD 4072, Australia; Fouling Doctors, Brisbane, QLD 4108, Australia.

PMID: 36754239
DOI: 10.1016/j.biortech.2023.128709

Abstract

Purple phototrophic bacteria (PPB) can produce single-cell protein from wastewater at high yields. Growing in a biofilm vs suspended can improve product quality and consistency. This study compares suspended and attached growths of enriched PPB cultures in an outdoor flat plate photobioreactor treating poultry-processing wastewater. Attached growth had lower VFA removal efficiencies (95 ± 2.7 vs 84 ± 6.4 %) due to light limitations and low substrate diffusion rates. Nevertheless, similar overall treatment performances and productivities were achieved (16 ± 2.2 and 18 ± 2.4 gCOD·m^-2·d^-1 for attached and suspended) at loading rates of 1.2-1.5 gCOD·L^-1·d^-1. Biofilms had higher quality than suspended biomass, with lower ash contents (6.9(0.6)% vs 57(16)%) and higher PPB abundances (0.45-0.67 vs 0.30-0.45). The biofilm (20-50 % of the total biomass) might be used as feed and the suspended fraction as fertiliser, improving the economics of the process. Semi-continuous PPB growth outdoors as biofilm is technically feasible, obtaining a superior product without jeopardising performance.

Keywords: Biofilm; PPB; Resource recovery; Single-cell protein; Wastewater.

MeSH terms

Bacteria
Biofilms
Biomass
Bioreactors
Photobioreactors*
Proteobacteria
Wastewater*

Substances

Wastewater