Enhanced methane production using pretreated sludge in MEC-AD system: Performance, microbial activity, and implications at different applied voltages. (12th December 2022)

• Record Type: Journal Article
• Authors: Joicy, Anna; Seo, Hwijin; Lee, Myoung-Eun; Kim, Dong-Hoon; Cho, Si Kyung; Ahn, Yongtae
• Is Part Of: International journal of hydrogen energy. Volume 47:Number 96(2022)
• Page Start: 40731
• Page End: 40741
• Publication Date: 2022-12-12
• Subjects: Waste activated sludge -- Pretreatment -- Applied voltage -- DIET -- Methane yield; AD Anaerobic digestion -- ADS Anaerobic digestion sludge -- AP Alkaline pretreatment -- ATP Alkaline-thermal pretreatment -- bDIET biological direct interspecies electron transfer -- CP Combined pretreatment -- DIET Direct interspecies electron transfer -- EAM Electro active microorganisms -- eDIET electrode-mediated direct interspecies electron transfer -- EEB Exoelectrogenic bacteria -- EMA Electrotrophic methanogenic archaea -- IIET Indirect interspecies electron transfer -- MEC-AD Microbial electrolysis cell assisted anaerobic digestion -- WAS Waste activated sludge; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2022.07.154
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: Although various pretreatment methods are employed to promote sludge hydrolysis and thereby promoting methane production in the subsequent microbial electrolysis cell assisted anaerobic digestion (MEC-AD) system, the questions arise are, "which pretreatment method on waste activated sludge (WAS) maximises the sludge hydrolysis and what is the optimal applied voltage on anaerobic digestion (AD) to stimulates the direct interspecies electron transfer (DIET) performance and thereby accelerating the methane production fed with pretreated WAS?" was still unanswered. Herein, firstly, a series of pretreatment methods to hydrolyse and mineralise the organic matter of WAS was performed to evaluate solubilization efficiency and thereafter, the influence of different applied voltages (0.3 V, 0.6 V, and 0.9 V) on coupled MEC-AD reactors fed with pretreated WAS was investigated to apprehend the DIET promotion for methane production. The results indicated that in MEC-AD reactors, the methane yield increased by 27.2%, 44.8%, and 37.3% when the applied voltages were 0.3 V, 0.6 V, and 0.9 V, respectively. Therefore, the alkaline-thermal pretreatment (ATP) enhanced the sludge hydrolysis in WAS, followed by an applied voltage of 0.6 V in the MEC-AD reactor fed with pretreated WAS, enhanced methane production under DIET stimulation induced by the increased abundance of electroactive microorganisms (EAM) and the advanced electron transfer. Besides, the energy balance estimation validates that with an applied voltage of 0.6 V in MEC-AD could achieve higher net energy input. Highlights: ATP method disintegrated the WAS flocs and released organic matter effectively. Polarized electrodes in MEC-AD reactors promote DIET by enriching EAMs. Enhanced methane production was achieved on MEC-AD with an applied voltage of 0.6 V. Further increase in applied voltage of 0.9 V, showed negative effect in methanogenesis.