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Kinetics and Energy Yield in Anaerobic Digestion: Effects of Substrate Composition and Fundamental Operating Conditions

cris.virtual.author-orcid0000-0003-0810-8086
cris.virtual.author-orcid0000-0001-6128-0315
cris.virtualsource.author-orcid90398b3a-5dd4-4557-a041-509a3389a7fb
cris.virtualsource.author-orcidab187d78-3916-499a-a077-9e8a0069cf71
dc.abstract.enThis review relates the kinetics of anaerobic digestion (AD) to energy outcomes, including typical ranges of methane yields and volumetric methane productivities (down to hourly g L−1 h−1 scales relevant for industrial plants). It further translates these relationships into practical control principles that support stable, high methane productivity. Evidence spans substrate selection and co-digestion with emphasis on carbon/nitrogen (C/N) balance, pretreatment strategies, and reactor operation, linking process constraints with operating parameters to identify interventions that raise performance while limiting inhibition. Improving substrate accessibility is the primary step: pretreatment and co-digestion shift limitation beyond hydrolysis and allow safe increases in organic loading. Typical mesophilic operation involves hydraulic retention times of about 10–40 days for food waste and 20–60 days for different types of livestock manure and slowly degradable energy crops, with stable performance achieved when the solids retention time (SRT) is maintained longer than the hydraulic retention time (HRT). Stability is further governed by sustaining a low hydrogen partial pressure through hydrogenotrophic methanogenesis. Temperature and pH define practicable operating ranges; meanwhile, mixing should minimise diffusion resistance without damaging biomass structure. Early-warning indicators—volatile fatty acids (VFAs)/alkalinity, the propionate/acetate ratio, specific methanogenic activity, methane (CH4)% and gas flow—enable timely adjustment of loading, retention, buffering, mixing intensity and micronutrient supply (Ni, Co, Fe, Mo). In practice, robust operation is generally associated with VFA/alkalinity ratios below about 0.3 and CH4 contents typically in the range of 50–70% (v/v) in biogas. The review consolidates typical feedstock characteristics and biochemical methane potential (BMP) ranges, as well as outlines common reactor types with their advantages and limitations, linking operational choices to energy yield in combined heat and power (CHP) and biomethane pathways. Reported pretreatment effects span approximately 20–100% higher methane yields; for example, 18–37% increases after mechanical size reduction, around 20–30% gains at 120–121 °C for thermal treatments, and in some cases nearly a two-fold increase for more severe thermal or combined methods. Priorities are set for adaptive control, micronutrient management, biomass-retention strategies, and standardised monitoring, providing a coherent route from kinetic understanding to dependable energy performance and explaining how substrate composition, pretreatment, operating parameters, and kinetic constraints jointly determine methane and energy yield, with particular emphasis on early-warning indicators.
dc.affiliationWydział Inżynierii Środowiska i Inżynierii Mechanicznej
dc.affiliation.instituteKatedra Inżynierii Biosystemów
dc.affiliation.instituteKatedra Inżynierii Wodnej i Sanitarnej
dc.contributor.authorPilarski, Krzysztof
dc.contributor.authorPilarska, Agnieszka
dc.date.access2025-12-01
dc.date.accessioned2025-12-01T14:00:02Z
dc.date.available2025-12-01T14:00:02Z
dc.date.copyright2025-11-28
dc.date.issued2025
dc.description.accesstimeat_publication
dc.description.bibliographyil., bibliogr.
dc.description.financepublication_nocost
dc.description.financecost0,00
dc.description.if3,2
dc.description.number23
dc.description.points140
dc.description.versionfinal_published
dc.description.volume18
dc.identifier.doi10.3390/en18236262
dc.identifier.issn1996-1073
dc.identifier.urihttps://sciencerep.up.poznan.pl/handle/item/6167
dc.identifier.weblinkhttps://www.scilit.com/publications/6a1009b0eb6f422fa3bb6af845747d0c
dc.languageen
dc.pbn.affiliationenvironmental engineering, mining and energy
dc.pbn.affiliationmechanical engineering
dc.relation.ispartofEnergies
dc.relation.pagesart. 6262
dc.rightsCC-BY
dc.sciencecloudnosend
dc.share.typeOPEN_JOURNAL
dc.subject.enanaerobic digestion
dc.subject.enkinetics
dc.subject.enenergy yield
dc.subject.enpretreatment
dc.subject.enorganic loading rate
dc.subject.enhydraulic retention time
dc.subject.enspecific methanogenic activity
dc.subtypeReviewArticle
dc.titleKinetics and Energy Yield in Anaerobic Digestion: Effects of Substrate Composition and Fundamental Operating Conditions
dc.typeJournalArticle
dspace.entity.typePublication