title: Evaluating leachate recirculation with cellulase addition to enhance waste biostabilisation and landfill gas production.
abstract: The effect of leachate recirculation with cellulase augmentation on municipal solid waste (MSW) biostabilisation and landfill gas production was investigated using batch bioreactors to determine the optimal conditions of moisture content, temperature and nutrients. Experimentation was thereafter scaled-up in 7L bioreactors. Three conditions were tested including (1) leachate recirculation only, (2) leachate recirculation with enzyme augmentation and (3) no leachate recirculation (control). Cumulative biogas production of the batch tests indicated that there was little difference between the leachate and control test conditions, producing on average 0.043m(3)biogaskg(-1) waste. However the addition of cellulase at 15×10(6)Utonne(-1) waste doubled the biogas production (0.074m(3)biogaskg(-1) waste). Similar trend was observed with the bioreactors. Cellulase addition also resulted in the highest COD reduction in both the waste and the leachate samples (47% and 42% COD reduction, respectively). In both cases, the quantity of biogas produced was closer to the lower value of theoretical and data-based biogas prediction indicators (0.05-0.4m(3)biogaskg(-1) waste). This was likely due to a high concentration of heavy metals present in the leachate, in particular Cr and Mn, which are known to be toxic to methanogens. The cost-benefit analysis (CBA) based on the settings of the study (cellulase concentration of 15×10(6)Utonne(-1) waste) showed that leachate bioaugmentation using cellulase is economically viable, with a net benefit of approximately €12.1million on a 5Mt mixed waste landfill.
authors.affiliation: School of Water, Energy and Environment, Cranfield University, MK43 0AL, United Kingdom; Centre for Research in Environmental, Coastal and Hydrological Engineering (CRECHE), School of Engineering, University of KwaZulu-Natal, Howard College Campus, Durban 4041, South Africa.
authors.forename: R R
authors.initials: RR
authors.lastname: Frank
authors.affiliation: Viridor Waste management Ltd, Viridor House, Priory Bridge Road, Taunton, Somerset TA1 1AP, United Kingdom.
authors.forename: S
authors.initials: S
authors.lastname: Davies
authors.affiliation: School of Water, Energy and Environment, Cranfield University, MK43 0AL, United Kingdom.
authors.forename: S T
authors.initials: ST
authors.lastname: Wagland
authors.affiliation: School of Water, Energy and Environment, Cranfield University, MK43 0AL, United Kingdom.
authors.forename: R
authors.initials: R
authors.lastname: Villa
authors.affiliation: Centre for Research in Environmental, Coastal and Hydrological Engineering (CRECHE), School of Engineering, University of KwaZulu-Natal, Howard College Campus, Durban 4041, South Africa.
authors.forename: C
authors.initials: C
authors.lastname: Trois
authors.affiliation: School of Water, Energy and Environment, Cranfield University, MK43 0AL, United Kingdom; Centre for Research in Environmental, Coastal and Hydrological Engineering (CRECHE), School of Engineering, University of KwaZulu-Natal, Howard College Campus, Durban 4041, South Africa. Electronic address: f.coulon@cranfield.ac.uk.
authors.forename: F
authors.initials: F
authors.lastname: Coulon
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D001673:Biodegradation, Environmental; D019149:Bioreactors; D002480:Cellulase; D003362:Cost-Benefit Analysis; D012037:Refuse Disposal / Q000379:methods*; D062611:Solid Waste; D064091:Waste Disposal Facilities; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D062611:Solid Waste; D014874:Water Pollutants, Chemical; D002480:Cellulase
keywords: Enzyme augmentation; Landfill bioreactor; Leachate circulation; Waste biostabilisation