Comparative Analysis of Organic Waste Valorization in Agro-Industrial Sectors

Thesis Abstract

This study addresses the escalating challenge of organic waste generated across agro-industrial sectors and the underutilization of valorization opportunities that exacerbate environmental, economic, and social costs. The central aim is to conduct a comparative analysis of organic waste valorization potentials across crop processing, livestock production, and agro-enterprise value chains to identify optimal pathways, synergies, and barriers. Specific objectives include (i) characterizing the composition and quantity of organic waste streams in three representative agro-industrial subsectors, (ii) evaluating technical feasibility and energy- and nutrient-recovery performance of selected valorization routes (anaerobic digestion, composting, and biochar production), (iii) assessing economic viability and lifecycle environmental impacts of each pathway, and (iv) developing a decision-support framework to guide sector-specific valorization investments. Theoretical underpinning combines the Resource-Based View to elucidate internal capabilities enabling valorization, and the Circular Economy theory to frame systemic waste-to-resource transitions, with supplementary use of the Technological Innovation Systems lens to interpret diffusion dynamics. The study adopts a mixed-methods research design integrating cross-sectional quantitative assessment with qualitative insights. The population encompasses agro-industrial facilities within the maize milling, dairy processing, and fruit canning sub-sectors in a mid-sized agricultural region. A stratified random sample of 60 facilities (20 per subsector) will be selected. Quantitative data will be collected through structured waste audit surveys, production records, and performance metrics, alongside laboratory analyses of waste samples. Laboratory experiments will determine biochemical methane potential (BMP) for anaerobic digestion, compost maturity indicators (C/N ratio, cation exchange capacity, respiration activity), and biochar properties (surface area, porosity, nutrient content) following standardized ASTM/ISO methods. Qualitative input will be gathered via semi-structured interviews with 36 stakeholders (12 per subsector) including plant managers, process engineers, and policy officers to capture perceived barriers, enabling conditions, and governance mechanisms. Data analysis will integrate quantitative and qualitative strands. Descriptive statistics and inferential analyses will compare performance indicators across subsectors using ANOVA, with post hoc Tukey tests to identify significant differences in methane yield, compost maturity, and biochar adsorption capacity. Regression analyses will model the relationship between feedstock characteristics, process parameters, and valorization performance metrics. Life cycle assessment (LCA) will be conducted following ISO 14044 to compare cradle-to-grave environmental impacts of the valorization routes, complemented by tech-economic analysis (net present value, internal rate of return, and payback period) to evaluate economic viability. A thematic analysis approach will be employed for interview transcripts, ensuring triangulation with quantitative findings. The study will synthesize results into a cross-sector comparison highlighting technical feasibility, economic attractiveness, environmental benefits, and policy-enabling conditions. Expected findings anticipate that anaerobic digestion will yield the highest energy recovery potential in dairy and fruit-processing streams, whereas composting will perform best for crop-processing residues, with biochar offering notable soil amendment benefits in peri-urban agro-enterprises. Economic analyses are expected to reveal variability in viability contingent on scale, gate fees, and access to incentives, while LCA results will show trade-offs between greenhouse gas mitigation and energy consumption across pathways. The research is anticipated to reveal sector-specific barriers such as feedstock heterogeneity, pre-treatment requirements, regulatory constraints, and market demand for end products, as well as enabling conditions including institutional coordination, access to financial instruments, and technical training. The study contributes to knowledge by providing a comparative, evidence-based framework for selecting organic waste valorization pathways across agro-industrial sectors, integrating technical, economic, and environmental dimensions within a coherent decision-support model. It advances the understanding of how sectoral characteristics influence valorization potential and offers practical guidance for policymakers, industry practitioners, and researchers on designing targeted interventions, investment incentives, and scalable pilot projects. The main conclusion posits that an optimized, sector-tailored mix of anaerobic digestion, composting, and biochar production can maximize resource recovery and minimize environmental footprints, contingent on improved feedstock management, robust quality control, and supportive regulatory and financial environments. Recommendations include establishing standardized waste characterization protocols, developing sector-specific valorization standards for end-products, creating revolving funds or feed-in tariffs to improve investment returns, and prioritizing capacity-building programs to enhance system integration and technology diffusion across agro-industrial value chains.