Evaluation of anaerobic co-digestion of dairy manure with food wastes via bio-methane potential assay and CSTR reactor

Yulin Ye, Carlos Zamalloa, Hongjian Lin, Mi Yan, David Schmidt, Bo Hu

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

The introduction of food wastes into anaerobic digestion (AD) brings a promising scenario of increasing feedstock availability and overall energy production from AD. This study evaluated the biodegradability and methane potential from co-digestion of two typical food wastes, kitchen waste and chicken fat, with dairy manure. For single substrate, the bio-methane potential assays showed that kitchen waste had the highest methane yield of 352 L-CH4kg–1-VS added, 92% more than dairy manure alone. Chicken fat at the same Volatile Solid (VS) level (2 g L–1) inhibited bio-methane production. Addition of kitchen waste and chicken fat to a VS percentage of up to 40% improved overall methane yield by 44% and 34%, respectively. Synergistic effect was observed when either combining two or three substrates as AD feedstock, possibly as a result of increased biodegradability of organic materials in chicken fat and kitchen waste compared with dairy manure. Addition of chicken fat improved methane yield more than kitchen waste. However, addition of chicken fat VS over 0.8 g L–1should be cautiously done because it may cause reactor failure due to decrease in pH. The maximum methane yield was 425 L-CH4kg–1-VS, achieved at a VS ratio of 2:2:1 for kitchen waste, chicken fat, and dairy manure. Results from batch AD experiment demonstrated that supplementing dairy manure to chicken fat and/or kitchen waste improved alkalinity of substrate due to the inclusion of more titratable bases in dairy manure, and therefore stabilized the methanogenesis and substantially improved biogas yield. A mixture of substrates of kitchen waste, chicken fat, and dairy manure at a ratio of 1:1:3 was fed to a continuously stirred tank reactor operated at organic loading rates of 3.28, 6.55, and 2.18 g-COD L–1-day (hydraulic retention time of 20, 10, and 30 days, respectively) under mesophilic condition, and methane production rate reached 0.65, 0.95, and 0.34 L-CH4L–1-reactor-day.

Original languageEnglish (US)
Pages (from-to)217-227
Number of pages11
JournalJournal of Environmental Science and Health - Part B Pesticides, Food Contaminants, and Agricultural Wastes
Volume50
Issue number3
DOIs
StatePublished - Mar 4 2015

Keywords

  • Co-digestion
  • bio-methane potential (BMP)
  • chicken fat
  • food waste
  • kitchen waste
  • synergistic effect

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