Search

Fe4O3 has shown great potential as an enhancer of batch anaerobic digestion performance. In this study, the effect of two types of Fe3O4 additive utilization strategies (magnetic separation recycling strategy and replenishment without recycling strategy) on semi-continuous anaerobic co-digestion of sludge and corn straw were investigated. A maximum methane yield of 163.88 ± 12.18 mL/g·VS·d was obtained at the dosage of 10 g/kg Fe3O4 with magnetic separation recycling strategy compared to the control without the addition of Fe3O4. As compared to the replenishment strategy, the recycling strategy improved specific daily methane yields by 38.45% and 45.75% for Fe3O4 addition amounts of 5 g/kg and 10 g/kg, respectively. The results show that the recycling of Fe3O4 additives can further optimize the composition of VFAs. Although the total VFAs were not elevated, the proportion of acetic acid increased and the proportion of propionic acid as well as butyric acid decreased. The present research supports the magnetic recycling of Fe3O4 as a new strategy to solve the problem of additive loss in semi-continuous anaerobic digestion process. [ABSTRACT FROM AUTHOR]

Food waste represents a valuable resource potential for the production of advanced biofuels, including biomethane. This study systematically assessed the impact of salt on biomethane production from different components of food waste. The highest biomethane yields of 258.89 ± 10.96, 337.52 ± 16.36, and 448.49 ± 23.375 mL/g volatile solids (equivalent to biodegradability indexes of 75.75%, 88.92% and 92.66%) were achieved from cellulose-rich, starch-rich and protein-rich components, respectively, at a salt concentration of 3 g NaCl/L. The biomethane yield was improved by 9.69–31.24% with low-concentration salt compared with no salt addition, but it was inhibited by high salinity. Inhibition induced by high salinity (15 g NaCl/L) on biomethane production followed the order of protein (15.50%) < starch (28.03%) < cellulose (42.92%). Co-digestion of different components effectively mitigated the inhibitory effect of salt on biomethane production. Microbial community analysis revealed that archaea were significantly affected by high salinity. With a high concentration of salt (15 g/L), acetoclastic methanogens (Methanosatea) predominated in the digestion of starch-rich components, whilst hydrogenotrophic methanogens (Methaonmassiliicoccus and Methanobacterium) predominated in the digestion of cellulose-rich and protein-rich components. Additionally, some salt-tolerant microorganisms (SC103 , Thermovirga and Methanosarcina) were selectively enriched at high salinity. [Display omitted] • Maximum CH 4 yield was 448.5 mL/g VS from protein-rich components at 3 g/L NaCl. • Lowest salt inhibition threshold (5 g NaCl/L) was observed in starch-rich digestion. • Fermentative bacteria were more resistant to salinity compared to methanogens. • Acetoclastic Methanosatea was dominant under high-salinity starch-rich digestion. [ABSTRACT FROM AUTHOR]

• Effects of different recycled magnetic additives on the AD was investigated. • Methane production increased by 79.81% with addition of recycled Fe 3 O 4. • The predominant aceticlastic pathway was consolidated with recycled Fe 3 O 4. • Recycled Fe 3 O 4 enriched more Methanosarcina that broadened the methanogenic pathway. The addition of magnetic additives has been found to enhance the anaerobic co-digestion of sludge and straw. Due to strong magnetic properties, these additives can be easily separated from the digestate, allowing for recycling during the continuous anaerobic digestion process. This study aimed to investigate the impact of different recycled magnetic additives (specifically, magnetic biochar and Fe 3 O 4) on the anaerobic co-digestion of sewage sludge with corn straw. The results showed that the addition of recycled Fe 3 O 4 with an initial amount of 10 g/kg resulted in the highest cumulative methane yield of 295.70 mL/g VS added , which increased by 79.81% as compared to the control. The results suggest that magnetic biochar with higher carbon content exerts a more noticeable impact on shortening the digestion lag phase time, as indicated by kinetic analysis. With the addition of recycled Fe 3 O 4 , the Methanosaeta and Methanosarcina enhanced significantly. Especially Methanosarcina , which was increased from 3.85% to 6.28%, resulting in a 2.43% increase. Furthermore, the predominant aceticlastic pathway of digestion process was consolidated, and the enriched Methanosarcina broadened the pathways of methanogenesis. This research provides a potential utilization strategy of recycling Fe 3 O 4 for accelerating the anaerobic degradation of urban and rural areas solid waste. [ABSTRACT FROM AUTHOR]

[Display omitted] • Methane production were improved with addition of biochar, magnetic biochar and Fe 3 O 4. • The cumulative methane yield was increased by 60.47% with 5 g/kg of Fe 3 O 4. • The direct interspecies electron transfer (DIET) was enhanced by Fe 3 O 4. • The strategy of recycling Fe 3 O 4 additive has the best economic benefit. The co-digestion of corn straw and sewage sludge with different additives (biochar, magnetic biochar, Fe 3 O 4) were investigated. The highest cumulative methane yield of 245.15 mL/g VS added was obtained with the Fe 3 O 4 addition ratio of 5 g/kg, which was 60.47% higher than that of the control run (without additives). The lag phase time was shortened from 5.46 to 3.82 days with a biochar dosage of 5 g/kg. The performance of Fe 3 O 4 on methane production from the co-digestion process was better than that of the biochar and magnetic biochar. The direct interspecies electron transfer (DIET) was enhanced with regard to the increased concentration of acetic acid and decreased concentration of propionic acid. Microbial community analysis showed that the Geobacter and Methanosarcina were selectively enriched on the surface of Fe 3 O 4 , promoting the DIET and acetoclastic methanogenesis pathway. The cost-benefit analysis proved that the strategy of recycling Fe 3 O 4 additive has the best economic benefit. [ABSTRACT FROM AUTHOR]