Increased applied voltage in the presence of GAC enhances microbial activity and methane production during anaerobic digestion of food waste

The positive effects of conductive material supplementation on anaerobic digestion have been mainly investigated for single synthetic substrates, while its significance for real and complex organic wastes such as food waste has not been sufficiently investigated. This study investigated the effect of conductive material (biochar and magnetite) and trace metal supplementation on the anaerobic digestion of food waste by means of biochemical methane potential assays. The results indicated that the supplementation of biochar and trace metals improved both total biogas production and methane yields. A biochar dose of 2.0 and 5.0 g/L resulted in 11.2 ± 6.5 and 27.3 ± 9.5% increase in biogas and 8.3 ± 6.8 and 33.2 ± 2.8% increase in methane yield, respectively. Moreover, the same reactors demonstrated high food waste stabilization performance of over 80% chemical oxygen demand removal efficiency. These results indicate that biochar supplementation leads to more enhanced anaerobic digestion operation that could be through increased surface area for microbial growth and/or direct interspecies electron transfer mechanism. In turn, food waste will not only be stabilized but also valorized by anaerobic digestion at higher efficiencies that support sustainable waste management through both environmentally safe disposal and value-added generation.

Download Full-text

Influence of mesophilic and thermophilic conditions on the anaerobic digestion of food waste: Focus on the microbial activity and removal of long chain fatty acids

Waste Management & Research ◽

10.1177/0734242x18801195 ◽

2018 ◽

Vol 36 (11) ◽

pp. 1106-1112 ◽

Cited By ~ 10

Author(s):

Xiaohui Guo ◽

Kang Kang ◽

Gaoyuan Shang ◽

Xiunan Yu ◽

Ling Qiu ◽

...

Keyword(s):

Fatty Acids ◽

Anaerobic Digestion ◽

Microbial Activity ◽

Food Waste ◽

Biogas Production ◽

Organic Loading Rate ◽

Long Chain Fatty Acids ◽

Methanogenic Activity ◽

Long Chain ◽

Chain Fatty Acids

The mesophilic reactor (MR) exhibited advantages in biogas production and performance stability over thermophilic reactor (TR) during the long-term anaerobic digestion (AD) of food waste (FW) with stepwise organic loading rate elevating. It was interesting to explore the mechanism causing the divergences in performances between these two reactors. The microbial activity was compared on day 110 when TR began to deteriorate. The results show that MR had significantly higher specific acetoclastic methanogenic activities (SAMA) and specific propionate and butyrate oxidative activities (SPOA and SBOA) than TR. The SAMA, SPOA and SBOA in TR were only 50.3%, 18.6% and 46.4% of those values in MR, respectively. Remarkably, the specific hydrogenotrophic methanogenic activity of 15.5±2.1, 15.7±4.6 mmol CH4·L−1 original slurry·d−1 in MR and TR was comparative with insignificant difference, which indicates that the microbial activity in TR had been inhibited widely apart from the hydrogenotrophic methanogenesis. Additionally, many particles with the diameters of 1–2 mm were observed to form in MR and identified as complexes of calcium and long chain fatty acids (LCFAs). The formation of calcium crystallization might alleviate the inhibition of LCFAs during AD of FW, which further supports the better performance in MR than TR.

Download Full-text