Upcycling the anaerobic digestion streams in a bioeconomy approach: A review

Abstract: 

Gaseous and liquid anaerobic digestion (AD) streams, currently are at best used for electricity and heat production or simply spreading at the fields, respectively. However, electricity and heat are economically produced from other renewables and advanced fertilizers are needed to avoid leaching and boost nutrients capture. Hence, AD seeks new opportunities to support circular bioeconomy. The overall objective of this review is to present state-of-the-art resource recovery routes for upcycling the AD streams to reduce carbon footprint and formulate alternative products to increase sustainability. Technical barriers and integrated systems to upcycle AD streams through biological means are presented. New technologies and methods to capture CH4, CO2 and nutrients from the digested residual resources are presented, as a) methanotrophs cultivation to be used as feed ingredients; b) CO2 conversion and micro-nutrients capturing from microalgae to be valorized for a wide range of applications (e.g. biofuels, food and feed, fertilizers, bioactive compounds); c) CO2 transformation to biodegradable plastics precursors (e.g. Polybutylene succinate, Polyhydroxyalkanoate); d) digestate valorization for biochar production to support efficient agricultural usage. Moreover, the environmental factors and life cycle assessment perspectives of the novel biorefinery routes are revised highlighting the need for regionalized models or assessments that can reveal the most sustainable routes based on local conditions and requirements. Despite AD poses some positive characteristics related to environmental benefit and emissions reduction, the present wo

Author(s): 
Panagiotis Tsapekos
Benyamin Khoshnevisan
Merlin Alvarado-Morales
Xinyu Zhu
Junting Pan
Hailin Tian
Irini Angelidaki
Keywords: 
Residual resources upcycling
Circular economy
Biogas
Digestate
Added value molecules
Article Source: 
Renewable and Sustainable Energy Reviews Volume 151, November 2021, 111635
Category: 
Basic Biology
Economics
Seaweed composition