Low-temperature anaerobic digestion of chicken manure at high organic and nitrogen loads - strategies for controlling short chain fatty acids. (May 2022)

• Record Type: Journal Article
• Authors: Mahato, Prativa; Rajagopal, Rajinikanth; Goyette, Bernard; Adhikary, Suman
• Is Part Of: Bioresource technology. Volume 351(2022)
• Publication Date: 2022-05
• Subjects: Anaerobic Digestion -- Ammonia -- Chicken Manure -- High-Solids -- Short Chain Fatty Acids; Biomass -- Periodicals; Biomass energy -- Periodicals; Bioremediation -- Periodicals; Agricultural wastes -- Periodicals; Factory and trade waste -- Periodicals; Organic wastes -- Periodicals; Bioénergie -- Périodiques; Déchets agricoles -- Périodiques; Déchets industriels -- Périodiques; Déchets organiques -- Périodiques; Déchets (Combustible) -- Périodiques; 662.88
• DOI: 10.1016/j.biortech.2022.127049
• Languages: English
• ISSNs: 0960-8524

Abstract

Graphical abstract: Highlights: Tracking SCFA indicators prevented digester failure at early stage. Acclimatised liquid inoculum and the mode of operation minimized SCFA accumulations. Controlling SCFA/alkalinity ratio ensured digester stability with SMY > 0.6 LCH4 /gVS. Applied protocol can promote adoption of high-solids AD of chicken manure at 20 ± 1°C. Abstract: Objective of this work was to investigate the technical feasibility of low-temperature, closed-loop two-stage (liquid–solid) anaerobic digesters to treat chicken-manure (TS:68%; NH3 :8 g/L) as a sole-feedstock. Effect of pH, temperature, treatment-duration, organic loading rate (OLR) and inoculum-recirculation ratio on short chain fatty acids (SCFA) production was studied. Digesters were operated at 20 ± 1 °C for 282-d over 4 batch-runs (∼70-d/batch) at an OLR of 8.78–4.3 gVS/L/d. Results showed that specific methane yield above 0.6 LCH4 /gVS was feasible with a methane concentration > 60%. SCFA speciation of the entire system was monitored through the liquid-digester. Among SCFA indicators, the ratios of propionic-to-acetic acids, (butyric + valeric)-to-acetic acids, and total SCFA-to-alkalinity were observed within the limit, i.e., below 1.4, 0.3 and 0.8, respectively, indicating high-digester stability. This strategy allowed early detection, diagnosis of process failures in high-solids digester in fed-batch mode, and re-evaluation of operating protocol to enrich performance with economic-benefits.