Effects of Two-Stage Operation on Stability and Efficiency in Co-Digestion of Food Waste and Waste Activated Sludge

Energies

Ruying Li¹  Xinyuan Liu¹  Min Ji¹ 

[1] School of Environmental Science and Engineering, Tianjin University, Tianjin 300350, China;

关键词: two-stage anaerobic digestion;    hydrogen production;    methane production;    food waste;    waste activated sludge;   

DOI  :  10.3390/en12142748

来源: DOAJ

【 摘 要 】

The two-stage anaerobic digestion (AD) technology attracts increasing attention due to its ability to collect both hydrogen and methane. A two-stage AD system feeding with food waste and waste activated sludge was investigated in order to achieve higher energy yield and organics removal. The two-stage process consists of a thermophilic H₂-reactor and a mesophilic CH₄-reactor, achieved the highest hydrogen and methane yields of 76.8 mL/g-VS and 147.6 mL/g-VS at hydraulic retention times (HRTs) of 0.8 d and 6 d, respectively. The co-digestion process in this study required much less external alkalinity to maintain the pH values than sole food waste digestion in the literature. Compared with the single-stage mesophilic methane AD process, the two-stage AD system had better performance on operation stability, biogas and energy yields, organics removal and chemical oxygen demand (COD) conversion at high organic loading rates (OLRs). According to the TA-cloning analysis, the dominant bacteria in H₂-reactor was closely related to Clostridium sp. strain Z6 and species Thermoanaerobacterium thermosaccharolyticum. The dominant methanogens in two-stage and single-stage CH₄-reactor were recognized as acetotrophic methanogens and hydrogenotrophic methanogens, respectively. The presence of the genus Nitrososphaera in the two CH₄-reactors might contribute to the low NH₄⁺-N concentration in digestate and low CO₂ content in biogas.

【 授权许可】

Unknown