Enhanced anaerobic co-digestion of waste activated sludge and food waste by sulfidated microscale zerovalent iron: Insights in direct interspecies electron transfer mechanism

Enhanced Methane Generation from Anaerobic Tridigestion of Organic Solid Wastes by Direct Interspecies Electron Transfer Stimulation

“…The time of the methane peak observed in group A1−A5 was earlier than the control group; this may be because the addition of magnetite to the AD system could accelerate the biodegradation of the mixed organic materials in the cosubstrate. Chen et al 5 also found that the CH 4 yield peak appeared earlier and the peak value was higher with the addition of zero-valent iron, compared with the control. The maximum values of daily methane yield in groups A1, A2, A3, A4, and A5 were 58.95, 65.42, 71.33, 67.52, and 70.78 mL/gVS, respectively, which were higher than that in the control group.…”

“…It was reported that interspecies H 2 transfer could promote the efficient growth of Chloroflexi. 5 The abundance of Chloroflexi in A3 and A5 groups was 15.13 and 19.57%, which were lower than that of the control. This may be because magnetite promoted the DIET pathway that did not depend on H 2 as the electron carrier, compared with the control group.…”

“…3 However, the performance of the AD treatment process, regarding methane production and process stability, can be easily limited by the accumulation of volatile fatty acids (VFAs) and long start-up period, 4 which is mainly caused by the low efficiency of electron transfer between acidogenic and methanogenic bacteria. 5 Different methods including optimizing the operational conditions, pretreatment of the substrate, and codigestion with other supporting materials have been reported in previous literature works to improve the perform-ance of the AD system. 6,7 Nevertheless, the implementation of these processes, especially in large-scale AD reactors, can result in increased capital and operational costs of the AD system, offsetting the benefits provided by increased methane production.…”

Improvement of Direct Interspecies Electron Transfer via Adding Conductive Materials in Anaerobic Digestion: Mechanisms, Performances, and Challenges

“…Currently, there are few studies on the influence of adding conductive materials to anaerobic digestion system on sludge dewatering ( Nguyen et al, 2021 ). Obviously, addition of conductive materials significantly increases the amount of biosolids ( Chen S. et al, 2020 ; Yuan et al, 2021 ), which increases the cost of solid waste transportation and treatment in the later stage. Recycling and reuse of conductive materials may be an effective strategy, but the complex technical operation and high investment cannot be ignored.…”

Labile carbon feedstocks trigger a priming effect in anaerobic digestion: An insight into microbial mechanisms

“…To address the global energy crises and environmental pollution, anaerobic digestion (AD) is one of the promising technologies for organic waste degradation and renewable energy recovery in the form of biogas (Lin et al, 2017;Ning et al, 2019b). Recently, AD fed multifeedstocks has been increasingly found to show advanced performance compared to AD fed mono-feedstock, because multi-feedstocks cause "synergistic effects" that improve nutrient balance and buffering capacity and dilute potentially toxic chemicals (Chen et al, 2020;Ning et al, 2019b;Zhang et al, 2021). The AD fed only kitchen wastes easily causes a rise of hydrogen partial pressure, probably lacks buffering capacity (De Vrieze et al, 2013), and thus inhibits the syntrophic interaction between acetogens and methanogens, but AD co-fed kitchen wastes and activated sludge improves direct interspecies electron transfer and nutrient balance, and thus enhances methanogenesis (Li et al, 2020).…”