Anaerobic co-digestion of pig manure and algae: Impact of intracellular algal products recovery on co-digestion performance

Abstract

This paper investigates anaerobic co-digestion of pig manure and algae (Scenedesmus sp.) with and without extraction of intracellular algal co-products, with views towards the development of a biorefinery concept for lipid, protein and/or biogas production. Protein and/or lipids were extracted from Scenedesmus sp. using free nitrous acid pre-treatments and solvent-based Soxhlet extraction, respectively. Processing increased algae methane yield between 29% and 37% compared to raw algae (VS basis), but reduced the amount of algae available for digestion. Co-digestion experiments showed a synergy between pig manure and raw algae that increased raw algae methane yield from 0.163 to 0.245 m(3) CH4 kg(-1)VS. No such synergy was observed when algal residues were co-digested with pig manure. Finally, experimental results were used to develop a high-level concept for an integrated biorefinery processing pig manure and onsite cultivated algae, evaluating methane production and co-product recovery per mass of pig manure entering the refinery.

High-value products from macroalgae: the potential uses of the invasive brown seaweed, Sargassum muticum

“…Not only is AD a relatively simple process from an engineering/infrastructure perspective, but it also has the potential to exploit the entire organic carbon content of macroalgae, and can readily tolerate high moisture content, therefore eliminating energy intensive drying (Jard et al 2013;Milledge and Heaven 2014). However, the biomethane potential of S. muticum is low at 0.13 L CH 4 g -1 VS (Jard et al 2013;Soto et al 2015), and considerably below that typical of seaweed at 0.2 L CH 4 g -1 VS (Alvarado- Morales et al 2013;Chen et al 2015) and *30 % of that from common commercially exploited feedstocks (Astals et al 2015;Banks and Zhang 2010;Golueke et al 1957;Nallathambi Gunaseelan 1997;Nguyen et al 2014). This, together with the availability of a variety of other more readily fermentable wastes, may make the collection of S. muticum for AD commercially unattractive.…”

Co-generation of biohydrogen and biomethane through two-stage batch co-fermentation of macro- and micro-algal biomass

“…and waste activated sludge and found that anaerobic co-digestion of varying amounts of sludge with Chlorella increased the biogas yields by 73% -79%, compared to mono-digestion of Chlorella. Astals et al (2015) investigated anaerobic co-digestion of algae Scenedesmus sp. and pig manure.…”

Golden Tides: Problem or Golden Opportunity? The Valorisation of Sargassum from Beach Inundations

“…is low at~0.13 L·CH 4 ·g −1 ·VS [33,34,52], and considerably below that typical of seaweed at 0.2 L·CH 4 ·g −1 ·VS [121,174,175] and~30% of that from common commercially exploited feedstocks [176][177][178][179][180]. There is considerable conjecture about the reasons for the relatively low practical methane yields compared to the theoretical values [33,71,103,120,181], and more research is needed to find the cause of low methane yields and how to overcome them.…”