Trace Elements in Anaerobic Biotechnologies
The use of trace elements to promote biogas production features prominently on the agenda for many biogas-producing companies. However, the application of the technique is often characterized by trial-and-error methodology due to the ambiguous and scarce basic knowledge on the impact of trace elements in anaerobic biotechnologies under different process conditions. This book describes and defines the broad landscape in the research area of trace elements in anaerobic biotechnologies, from the level of advanced chemistry and single microbial cells, through to engineering and bioreactor technology and to the fate of trace elements in the environment.
The book results from the EU COST Action on ‘The ecological roles of trace metals in anaerobic biotechnologies’. Trace elements in anaerobic biotechnologies is a critical, exceptionally complex and technical challenge. The challenging chemistry underpinning the availability of trace elements for biological uptake is very poorly understood, despite the importance of trace elements for successful anaerobic operations across the bioeconomy. This book discusses and places a common understanding of this challenge, with a strong focus on technological tools and solutions. The group of contributors brings together chemists with engineers, biologists, environmental scientists and mathematical modellers, as well as industry representatives, to show an up-to-date vision of the fate of trace elements on anaerobic biotechnologies.
ISBN: 9781789060218 (Paperback)
ISBN: 9781789060225 (eBook)
Chapter 7: Re-use of digestate and recovery techniques
Ana P. Mucha, Savic Dragisa, Ishai Dror, Mirco Garuti, Eric D. van Hullebusch, Sabina Kolbl Repinc, Jakub Muňoz, Santiago Rodriguez-Perez, Blaz Stres, Sergej Usťak, C. M. R. Almeida, 2019. "Re-use of digestate and recovery techniques", Trace Elements in Anaerobic Biotechnologies, Fernando G. Fermoso, Eric van Hullebusch, Gavin Collins, Jimmy Roussel, Ana Paula Mucha, Giovanni Esposito
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Biogas plants receive inputs of different sources of carbon, nutrients, metals and other pollutants from large areas that result in a digestate that is a very complex and concentrated matrix. How to redistribute all these components without causing imbalances in the receiving environments is one of the main questions that arises regarding the reuse of digestate. The main end destinations of digestate within the EU are agriculture, landfill and incineration, in addition to open-mine land reclamation. There are European and country specific end destinations of digestate that have been recently reviewed and made publicly available in an EU commission report. In terms of agricultural application, digestate is seen as a valuable source of carbon and nutrients, but its application is conditioned by disposal limits for nitrogen, phosphorous and metals. Here, we discuss the need for redesign of the process of digestate manipulation in order to increase its value as fertiliser, through addition of compounds, different solid/liquid phases separation or additional treatments. Potential recovery techniques are also discussed. Phytoremediation, the use of plants to uptake metals from different substrates, can be used not only to remove trace metals from the digestate but also for the recovery of metals from plant biomass or their reintroduction into the biodigester. In addition, a combination of landfill with phytoremediation can be a good alternative for the recovery of degraded soils, or for the reclamation of polluted soil for landscape recovery. Another option can be the use of digestate to produce biochar to be applied in agriculture, a technique that increases carbon content in soils while decreasing trace metal bioavailability. Finally, we discuss the new opportunities that are arising for the use of digestate, including microalgae biomass production and bioenergy.