The Influence of Micro-Oxygen Addition on Desulfurization Performance and Microbial Communities during Waste-Activated Sludge Digestion in a Rusty Scrap Iron-Loaded Anaerobic Digester

Renjun Ruan, Jiashun Cao, Chao Li, Di Zheng and Jingyang Luo
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Renjun Ruan: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China
Jiashun Cao: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China
Chao Li: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China
Di Zheng: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China
Jingyang Luo: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China

Energies, 2017, vol. 10, issue 2, 1-19

Abstract: In this study, micro-oxygen was integrated into a rusty scrap iron (RSI)-loaded anaerobic digester. Under an optimal RSI dosage of 20 g/L, increasing O 2 levels were added stepwise in seven stages in a semi-continuous experiment. Results showed the average methane yield was 306 mL/g COD (chemical oxygen demand), and the hydrogen sulphide (H 2 S) concentration was 1933 ppmv with RSI addition. O 2 addition induced the microbial oxidation of sulphide by stimulating sulfur-oxidizing bacteria and chemical corrosion of iron, which promoted the generation of FeS and Fe 2 S 3 . In the 6th phase of the semi-continuous test, deep desulfurization was achieved without negatively impacting system performance. Average methane yield was 301.1 mL/g COD, and H 2 S concentration was 75 ppmv. Sulfur mass balance was described, with 84.0%, 11.90% and 0.21% of sulfur present in solid, liquid and gaseous phases, respectively. The Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) analysis revealed that RSI addition could enrich the diversity of hydrogenotrophic methanogens and iron-reducing bacteria to benefit methanogenesis and organic mineralization, and impoverish the methanotroph ( Methylocella silvestris ) to reduce the consumption of methane. Micro-oxygen supplementation could enhance the diversity of iron-oxidizing bacteria arising from the improvement of Fe(II) release rate and enrich the sulphur-oxidising bacteria to achieved desulfurization. These results demonstrated that RSI addition in combination with micro-oxygenation represents a promising method for simultaneously controlling biogas H 2 S concentration and improving digestion performance.

Keywords: micro-oxygen; anaerobic digestion; chemical corrosion; average methane yield; sulfur-oxidizing bacteria; desulfurization efficiency; sulfur balance (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2017
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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