Toward the Transition of Agricultural Anaerobic Digesters into Multiproduct Biorefineries

Abstract

Anaerobic digestion allows for the proper management of agro-waste, including manure. Currently, more than 18,000 anaerobic digestion plants are under operation in EU, 80% of which are employed in the rural context. Tariff schemes for power generation from biogas produced during anaerobic digestion of agricultural feedstocks in Germany, Italy and Austria are coming to an end and new approaches are needed to exploit the existing infrastructures. Digesters in the rural context can be implemented and modified to be transformed into sustainable multi-feedstock and multi-purpose biorefineries for the production of energy, nutrients, proteins, bio-chemicals such as carboxylic acids, polyesters and proteins. This paper describes how the transition of agricultural anaerobic digesters into multi-products biorefineries can be achieved and what are the potential benefits originating from the application of a pilot scale platform able to treat cow manure and other crop residues while producing volatile fatty acids, polyhydroxyalkanoates, microbial protein material, hydrogen, methane and a concentrated liquid stream rich in nitrogen, potassium and phosphorus.

Production of short-chain fatty acids (SCFAs) as chemicals or substrates for microbes to obtain biochemicals

“…Several economically sustainable techniques are available. A variety of demonstration plants has been established during the last years, and thus the establishment of industrial processes seems to be possible in the near future [ 131 – 136 ].…”

Unlocking the Full Potential: New Frontiers in Anaerobic Digestion (AD) Processes

“…Validation of two theoretically derived equations for predicting pH in CO 2 biomethanisation [14] X X X Toward the transition of agricultural anaerobic digesters into multiproduct biorefineries [15] X X X…”

“…As an approach with the explicit goal of making the best possible use of one unit of biomass, the concept of the biorefinery has evolved in the last decades; its main feature is to process biomass through different schemes operated widely in parallel, thus supplying a multitude of valuable outputs. Bolzonella et al [15] present a biorefinery pilot plant based on AD that was designed to supply a set of products, namely, energy products (hydrogen, methane), chemicals (short chain volatile fatty acids, polyhydroxyalkanoates), and other materials (nutrients for agriculture, microbial proteins for food or animal feed applications). In such a biorefinery, AD becomes one integrated element of a larger system, as it is complemented by other processes (mechanical, chemical, or biological).…”

Valorización de subproductos agroindustriales mediante la aplicación de tecnología de membrana / valorization of agroindustrial by-products through the application of membrane technology

“…Both studies reported lower TAN recovery efficiencies of the removed TAN (55.3% and 54.45%,respectively). Therefore, it can be stated that more studies on nutrient recovery in digestates are necessary, since results may vary due to different feedstock characterizations for co-digestion (Bolzonella et al, 2023;Xie et al, 2018). In particular, it would be particularly relevant for agro-industrial waste that, due to their seasonality or their composition, there is no easy way to recycle them alone, such as apple pomace.…”