title: Long-term thermophilic mono-digestion of rendering wastes and co-digestion with potato pulp.
abstract: In this study, mono-digestion of rendering wastes and co-digestion of rendering wastes with potato pulp were studied for the first time in continuous stirred tank reactor (CSTR) experiments at 55°C. Rendering wastes have high protein and lipid contents and are considered good substrates for methane production. However, accumulation of digestion intermediate products viz., volatile fatty acids (VFAs), long chain fatty acids (LCFAs) and ammonia nitrogen (NH4-N and/or free NH3) can cause process imbalance during the digestion. Mono-digestion of rendering wastes at an organic loading rate (OLR) of 1.5 kg volatile solids (VS)/m(3)d and hydraulic retention time (HRT) of 50 d was unstable and resulted in methane yields of 450 dm(3)/kg VS(fed). On the other hand, co-digestion of rendering wastes with potato pulp (60% wet weight, WW) at the same OLR and HRT improved the process stability and increased methane yields (500-680 dm(3)/kg VS(fed)). Thus, it can be concluded that co-digestion of rendering wastes with potato pulp could improve the process stability and methane yields from these difficult to treat industrial waste materials.
authors.affiliation: University of Jyväskylä, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland. Electronic address: suvi.bayr@jyu.fi.
authors.forename: S
authors.initials: S
authors.lastname: Bayr
authors.affiliation: University of Jyväskylä, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Ojanperä
authors.affiliation: University of Jyväskylä, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland.
authors.forename: P
authors.initials: P
authors.lastname: Kaparaju
authors.affiliation: University of Jyväskylä, Department of Biological and Environmental Science, P.O. Box 35, FI-40014 University of Jyväskylä, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Rintala
mesh_terms: D000003:Abattoirs; D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D019149:Bioreactors; D007220:Industrial Waste / Q000032:analysis*; D008697:Methane / Q000378:metabolism*; D011198:Solanum tuberosum / Q000737:chemistry*
chemical_list: D007220:Industrial Waste; D008697:Methane
keywords: Anaerobic digestion; Biogas; Co-digestion; Potato pulp; Rendering waste; Thermophilic