Effects of hydraulic retention time on the process performance and microbial community structure of an anaerobic single-stage semi-pilot scale reactor for the treatment of food waste. (August 2020)

• Record Type: Journal Article
• Authors: Pramanik, Sagor Kumar; Suja, Fatihah Binti; Pramanik, Biplob Kumar
• Is Part Of: International biodeterioration & biodegradation. Volume 152(2020)
• Publication Date: 2020-08
• Subjects: Mesophilic anaerobic digestion -- Food waste -- High-throughput 16S rRNA gene sequencing -- Microbial community dynamics; Biodegradation -- Periodicals; Bioremediation -- Periodicals; Biodegradation -- Periodicals; Biodégradation -- Périodiques; Biorestauration -- Périodiques; Electronic journals; 620.11223
• DOI: 10.1016/j.ibiod.2020.104999
• Languages: English
• ISSNs: 0964-8305

Abstract

Abstract: The performance of a single-stage semi-pilot scale reactor in anaerobically digesting food waste was examined and its microbial community composition investigated using high-throughput 16S rRNA gene sequencing. Highest biogas yield (1.01 L/g VSadded ), highest removal efficiency for chemical oxygen demand (COD) (95.84%) and volatile solid (VS) (92.7%) were achieved during 124-day HRT. When the hydraulic retention time (HRT) reduced from 124 days to 62 days, ammonia and volatile fatty acids (VFA) concentration in the reactor gradually increased while pH, biogas yield, removal efficiency for VS and COD decreased gradually. This was likely due to the accumulation of volatile fatty acid (VFA), which resulted in scum accumulating in the reactor. The abundance of acid-producing bacteria resulted in the accumulation of VFA in the reactor, which is a critical factor that could explain process failure. Hydrogenotrophic methanogenesis was the main pathway for producing methane from hydrogen and carbon dioxide during the 124-day HRT. The decline in hydrogenotrophic methanogens at 62-day HRT inhibited the decomposition of VFA and accelerated the transfer of the amino acid degradation pathway, which further enhanced VFA accumulation. However, the dominant methanogens failed to degrade the excessive acetate at 41-day HRT. This metabolic discrepancy ultimately led to process deterioration. Highlights: Stability and performance of the AD were significantly affected by different HRTs. Microbial community was investigated by 454 pyrosequencing technique. A significant microbial shift was observed during decreased HRT operations. Proliferation of acid-producing bacteria resulted volatile fatty acid accumulation.