A full-scale study of mixing and foaming in egg-shaped anaerobic digesters

Antifoam, dilution and trace element addition as foaming control strategies in mesophilic anaerobic digestion of sugar beet pulp

“…Foaming appears to have a complex set of causes including biological, feedstock-related and operational factors. Biological factors include the presence of excessive numbers of filamentous bacteria (such as Gordonia and Microthrix) (Ganidi et al, 2011;Lienen et al, 2014;Subramanian and Pagilla, 2014;Subramanian et al, 2015;He et al, 2017); or of foaming bacteria (Nocardia and Desulfotomaculum) (Kougias et al, 2014a). Feedstock issues include substrate type or composition (Kougias et al, 2013a(Kougias et al, , 2014bLienen et al, 2014;Subramanian and Pagilla, 2014;Moeller and Görsch, 2015;Moeller et al, 2015bMoeller et al, , 2016Lindorfer and Demmig, 2016); particle size and fibre content (Moeller et al, 2016;Van Weelden et al, 2016); and the presence of surface active agents such as oils and grease (Subramanian and Pagilla, 2014) or fulvic acid (Pognani et al, 2017).…”

“…Feedstock issues include substrate type or composition (Kougias et al, 2013a(Kougias et al, , 2014bLienen et al, 2014;Subramanian and Pagilla, 2014;Moeller and Görsch, 2015;Moeller et al, 2015bMoeller et al, , 2016Lindorfer and Demmig, 2016); particle size and fibre content (Moeller et al, 2016;Van Weelden et al, 2016); and the presence of surface active agents such as oils and grease (Subramanian and Pagilla, 2014) or fulvic acid (Pognani et al, 2017). Process or operational factors may include high organic loading rate (overloading) or inconsistent feed to the digester (Ganidi et al, 2011;Kougias et al, 2013aKougias et al, , 2013bKougias et al, , 2014bKougias et al, , 2014cKougias et al, , 2015bMoeller and Görsch, 2015;Moeller et al, 2012aMoeller et al, , 2015aMoeller et al, , 2015bSuhartini et al, 2014); digester configuration (Ganidi et al, 2009) or mixing intensity and pattern (Subramanian and Pagilla, 2014;Kougias et al, 2014b;Subramanian et al, 2015); temperature changes (Siebels and Long, 2013;Kougias et al, 2014b;Moeller and Görsch, 2015;Lindorfer and Demmig, 2016;Moestedt et al, 2017); and abrupt degassing or viscosity changes (Moeller et al, 2012b(Moeller et al, , 2015bLindorfer and Demmig, 2016).…”

Thermal and ultrasound foam control in biotechnology: a mini-review

“…There are two methods of using chemical agents for foam control: 1) They are applied before foam production to control foaming (antifoaming agents), or they are applied to the solution after the production of foam in order to control foaming (defoamers) [4,16]. They are also used extensively in biotechnology, such as cell culturing and microbial fermentation [17,18], bioprocess industries [19], biogas production [20], and anaerobic digesters [21]. However, the antifoam agents' biological effects are poorly understood because of a wide range of molecular structures and insufficient data about their composition [22].…”

Pathways to Water Sector Decarbonization, Carbon Capture and Utilization

“…Uniform substrate conditions in the digester are desired, but excessive mixing leads to foaming issues which can impact operations and hence biogas production (Pagilla et al, 1997). It was later demonstrated that in most high-rate anaerobic digesters, excessive mixing is highly likely and can cause foaming issues which impact digestion and biogas production (Subramanian & Pagilla, 2015a;Subramanian et al, 2015b). The natural mixing due to biogas production and sludge recirculation through the sludge heating loop are sufficient to maintain homogeneity in the digester and process performance.…”