Anaerobic digestion of purple phototrophic bacteria - The release step of the partition-release-recover concept

Tim Hülsen; Yang Lu; Iván Rodríguez; Yolanda Segura; Fernando Martínez; Daniel Puyol; Damien J Batstone

doi:10.1016/j.biortech.2020.123125

Anaerobic digestion of purple phototrophic bacteria - The release step of the partition-release-recover concept

Bioresour Technol. 2020 Jun:306:123125. doi: 10.1016/j.biortech.2020.123125. Epub 2020 Mar 6.

Authors

Tim Hülsen¹, Yang Lu², Iván Rodríguez³, Yolanda Segura³, Fernando Martínez³, Daniel Puyol³, Damien J Batstone⁴

Affiliations

¹ Advanced Water Management Centre, Gehrmann Building, The University of Queensland, Brisbane, Queensland 4072, Australia; CRC for Water Sensitive Cities, PO Box 8000, Clayton, Victoria 3800, Australia. Electronic address: t.huelsen@awmc.uq.edu.au.
² Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore.
³ Group of Chemical and Environmental Engineering (GIQA), University Rey Juan Carlos, C/Tulipán, s/n, 28933 Móstoles, Madrid, Spain.
⁴ Advanced Water Management Centre, Gehrmann Building, The University of Queensland, Brisbane, Queensland 4072, Australia; CRC for Water Sensitive Cities, PO Box 8000, Clayton, Victoria 3800, Australia.

PMID: 32197190
DOI: 10.1016/j.biortech.2020.123125

Abstract

Purple phototrophic bacteria (PPB) have been proposed as a high-growth, assimilative option for wastewater treatment. The original partition-release-recover concept proposal requires their near complete digestion and release (and subsequent recovery) of energy and nutrients in an anaerobic digester. While the growth (partition) step has been extensively assessed, no work has been done on their anaerobic digestion characteristics (release). Continuous mesophilic (20d) and thermophilic (10d) digestion could achieve around 55% volatile solids degradation (VSD), with 35% (mesophilic) and 20% (thermophilic) nitrogen solubilisation. Post digestion (with/without pretreatment) could increase the VSD to 70% and nitrogen solubilisation to 43%. A number of pretreatment options were tested, with high temperature and sonication being relatively effective, and chemical treatment, and temperature phased digestion being relatively ineffective vs controls. Overall, anaerobic digestion of PPB results in substantial residual particulate material, with an increased nitrogen content, and avenues to effectively utilise this residue should be identified.

Keywords: Anaerobic digestion; Biological methane production; Nutrient recovery; Purple phototrophic bacteria.