Mahato P, Rajagopal R, Goyette B, Adhikary S. Low-temperature anaerobic digestion of chicken manure at high organic and nitrogen loads - strategies for controlling short chain fatty acids.
BIORESOURCE TECHNOLOGY 2022;
351:127049. [PMID:
35331887 DOI:
10.1016/j.biortech.2022.127049]
[Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/17/2022] [Accepted: 03/18/2022] [Indexed: 06/14/2023]
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.
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