Microbial Insight into a Pilot-Scale Enhanced Two-Stage High-Solid Anaerobic Digestion System Treating Waste Activated Sludge

Abstract

High solid anaerobic digestion (HSAD) is a rapidly developed anaerobic digestion technique for treating municipal sludge, and has been widely used in Europe and Asia. Recently, the enhanced HSAD process with thermal treatment showed its advantages in both methane production and VS reduction. However, the understanding of the microbial community is still poor. This study investigated microbial communities in a pilot enhanced two-stage HSAD system that degraded waste activated sludge at 9% solid content. The system employed process “thermal pre-treatment (TPT) at 70 °C, thermophilic anaerobic digestion (TAD), and mesophilic anaerobic digestion (MAD)”. Hydrogenotrophic methanogens Methanothermobacter spp. dominated the system with relative abundance up to about 100% in both TAD and MAD. Syntrophic acetate oxidation (SAO) bacteria were discovered in TAD, and they converted acetate into H2 and CO2 to support hydrogenotrophic methanogenesis. The microbial composition and conversion route of this system are derived from the high solid content and protein content in raw sludge, as well as the operational conditions. This study could facilitate the understanding of the enhanced HSAD process, and is of academic and industrial importance.

Enhancing Anaerobic Digestion: The Effect of Carbon Conductive Materials

“…Taking into account that the treatment of lignocellulosic biomass under anaerobic conditions will leave unconverted a fraction of the solid material, performing the process under a high solid configuration seems to be the most obvious way for attaining the digestion of this material. These high solid technologies (with solid content material greater than 15%) are gaining great interest because of the advantage of the smaller size of the plant, but also lower heating energy demand, easiness of post-treatment of the digested material and lower liquid production [72,73]. The co-digestion of switchgrass with swine, poultry and dairy manure has shown promising results for the first one with methane yields similar to those obtained for submerged fermentation systems (337 mL CH 4 /g VS) [72].…”

Biochar and Energy Production: Valorizing Swine Manure through Coupling Co-Digestion and Pyrolysis

“…However, the presence of lignocellulosic material in agricultural wastes poses challenges to this process due to the recalcitrant nature of lignin, which can result in lower biogas yields than expected when evaluated in terms of the organic loading rate of the feed, and the need of operating at a higher solid content. This requires novel process configurations as is the case for a high solid content and solid-state digestion [15,16]. The high availability of lignocellulosic biomass, combined with the fact that it does not ethically compete for land dedicated to food production, makes this organic material an ideal candidate for enhancing and optimizing digestion performance.…”

Evaluation of the biomethanation potential of enriched methanogenic cultures on gelatin

“…Anaerobic digestion is a complex microbial metabolic process that can be carried out by different syntrophic organisms. It has been an economically attractive and alternative process for the treatment of different types of industrial wastes (Wu et al 2017;Liu and Liao 2018;Perisin and Sund 2018). Lignocellulosic wastes are widely used as the raw materials for industrial production of organic solvents, organic acids, and biofuel.…”