This study optimised methane yield from pig manure (PM) co-digested with banana peel, cabbage and pumpkin residues (BCP). A two-factor response surface methodology was used, with PM fraction and batch digestion time as factors. Blank-corrected biochemical methane potential (BMP) was the main response, with methane volume and energy yield as supporting responses. Design-Expert was used for quadratic modelling, while Python supported model checking and sensitivity analysis. BMP ranged from 191.48 to 468.23 N mL CH₄ g⁻¹ VS. The PM fraction contributed 98.975% of the model sum of squares, compared with 0.855% for digestion time. The absolute maximum occurred at PM0:BCP100 after 60 days, but this was mono-digestion. The highest tested co-digestion BMP was 332.85 N mL CH₄ g⁻¹ VS at PM50:BCP50 after 60 days. At 45 days, the same blend achieved 324.95 N mL CH₄ g⁻¹ VS, retaining 97.6% of the 60-day yield. Feedstock composition affected methane yield more strongly than digestion time. PM50:BCP50 at 45 days is a time-efficient laboratory-scale condition requiring validation in continuous digesters.
Experimental two-factor response surface optimisation of methane yield from pig manure co-digested with banana peel, cabbage and pumpkin waste
Authors
- Olalekan Joseph Ogunniyi Center for Sustainability Engineering and Future Technologies, College of Science, Engineering and Technology, University of South Africa, Florida, 1709, and Department of Industrial and Engineering Management, College of Science, Engineering and Technology, University of South Africa, Florida, 1709, South Africa. https://orcid.org/0000-0002-1327-3484
- Charles Mbohwa Center for Sustainability Engineering and Future Technologies, College of Science, Engineering and Technology, University of South Africa, Florida, 1709, and Department of Industrial and Engineering Management, College of Science, Engineering and Technology, University of South Africa, Florida, 1709, South Africa. https://orcid.org/0000-0002-8268-5984
- Peter Onu Department of Industrial and Engineering Management, College of Science, Engineering and Technology, University of South Africa, Florida, 1709, South Africa. https://orcid.org/0000-0001-9114-1068
- Steadyman Chikumba Department of Industrial and Engineering Management, College of Science, Engineering and Technology, University of South Africa, Florida, 1709, South Africa. https://orcid.org/0000-0003-4908-4076
- Humbulani Simon Phuluwa Department of Industrial and Engineering Management, College of Science, Engineering and Technology, University of South Africa, Florida, 1709, South Africa. https://orcid.org/0009-0008-4399-5155
