HEJun-guo,YINShi-min,ZHAOMei-hua,et al.Effect of Particle Size of Iron Conducting Media on Anaerobic Digestion Efficiency of Excess Sludge[J].China Water & Wastewater,2022,38(7):11-18.
Effect of Particle Size of Iron Conducting Media on Anaerobic Digestion Efficiency of Excess Sludge
China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU]
volume:
第38卷
Number:
第7期
Page:
11-18
Column:
Date of publication:
2022-04-01
- Keywords:
- excess sludge; anaerobic digestion; conducting medium; zero-valent iron (ZVI); magnetite; particle size
- Abstract:
- Anaerobic digestion of excess sludge has some problems such as long cycle time and low efficiency. Iron conducting media are capable of improving anaerobic digestion efficiency by promoting interspecific electron transfer. Therefore, the effects of two conducting media [zero-valent iron (ZVI) powder and magnetite] with different particle sizes on anaerobic digestion efficiency of excess sludge were investigated. The change of particle size of ZVI and magnetite had a great influence on sludge anaerobic digestion efficiency, and the two conducting media promoted anaerobic digestion in different ways. Magnetite promoted hydrolysis and acidification process and provided more methanogenic substrates. However, ZVI accelerated the consumption of hydrolytic acidification products, thus promoting methanogenesis. Profile of biogas yield was an increasing trend with the decrease of particle size of ZVI and magnetite. When the particle size was 400 mesh, the biogas yield reached 457.8 mL/gVSS and 447.6 mL/gVSS, respectively, which were 16.8% and 14.2% higher than that of the blank group, and the methane contents were 5.7% and 4.4% higher than that of the blank group, respectively. The organic degradation rate increased obviously, which was beneficial to sludge reduction. In addition, the conductivity of sludge supernatant in ZVI group and magnetite group was significantly higher than that in the blank group, which was conducive to the improvement of electron transfer efficiency among microbial populations. SEM analysis of sludge surface showed that the agglomeration of ZVI and magnetite with microorganisms was close, which directly improved the efficiency of direct interspecific electron transfer. The high-throughput sequencing results indicated that ZVI and magnetite promoted the diversity of microbial community. Firmicutes was enriched in the magnetite group, which promoted the hydrolysis and acidification process. In the ZVI group, the relative abundance of Methanosaeta increased with the decrease of ZVI particle size, which promoted the methane production in methanogenic stage.
Last Update:
2022-04-01