Impact of Organic Loading Rate on Psychrophilic Anaerobic Digestion of Solid Dairy Manure

Noori M. Cata Saady and Daniel I. Massé
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Noori M. Cata Saady: Dairy and Swine Research and Development Center, Agriculture and Agri-Food Canada, Sherbrooke, QC J1M 0C8, Canada
Daniel I. Massé: Dairy and Swine Research and Development Center, Agriculture and Agri-Food Canada, Sherbrooke, QC J1M 0C8, Canada

Energies, 2015, vol. 8, issue 3, 1-18

Abstract: Increasing the feed total solids to anaerobic digester improves the process economics and decreases the volume of liquid effluent from current wet anaerobic digestion. The objective of this study was to develop a novel psychrophilic (20 °C) anaerobic digestion technology of undiluted cow feces (total solids of 11%–16%). Two sets of duplicate laboratory-scale sequence batch bioreactors have been operated at organic loading rates (OLR) of 6.0 to 8.0 g total chemical oxygen demand (TCOD) kg ?1 inoculum day ?1 (d ?1 ) during 210 days. The results demonstrated that the process is feasible at treatment cycle length (TCL) of 21 days; however, the quality of cow feces rather than the OLR had a direct influence on the specific methane yield (SMY). The SMY ranged between 124.5 ± 1.4 and 227.9 ± 4.8 normalized liter (NL) CH 4 kg ?1 volatile solids (VS) fed d ?1 . Substrate-to-inoculum mass ratio (SIR) was 0.63 ± 0.05, 0.90 ± 0.09, and 1.06 ± 0.07 at OLR of 6.0, 7.0, and 8.0 g TCOD kg ?1 inoculum d ?1 , respectively. No volatile fatty acids (VFAs) accumulation has been observed which indicated that hydrolysis was the rate limiting step and VFAs have been consumed immediately. Bioreactors performance consistency in terms of the level of SMYs, VFAs concentrations at end of the TCL, pH stability and volatile solids reduction indicates a stable and reproducible process during the entire operation.

Keywords: psychrophilic; dry anaerobic digestion; high-solids content; cow manure (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2015
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Citations: View citations in EconPapers (4)

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