A Unified Theory of Sustainable Operations Research: Integrating Environmental Externalities into Multi-Objective Optimization for Nigerian Industries

Contemporary operations research frameworks applied in Nigerian industrial contexts have largely neglected environmental externalities, treating production, logistics, and supply chain optimization as purely economic problems, despite the growing regulatory and stakeholder pressure to internalize environmental costs into operational decision-making. This dissertation develops a unified theory of sustainable operations research that formally integrates environmental externalities into multi-objective optimization formulations, with original theoretical contributions grounded in empirical applications across Nigerian industrial sectors. A systematic foundation is established by synthesizing literature from environmental economics, multi-objective optimization, life cycle assessment, and corporate sustainability management. Original contributions include: a formal taxonomy of environmental externality types and their mathematical representation within multi-objective programming frameworks; an axiomatic treatment of environmental objective aggregation under value incommensurability; and the development of epsilon-constraint and weighted Chebyshev methods extended to incorporate stochastic environmental impact uncertainty. The theory is instantiated through three complementary empirical applications: multi-objective production planning at a petroleum refinery in Warri with CO2 and effluent emission objectives; sustainable logistics network design for a consumer goods distributor operating across the Northwest zone with carbon footprint minimization; and multi-objective solid waste facility location in Lagos with health impact and equity objectives. Each application generates original Pareto frontier characterizations and trade-off analyses revealing the economic cost of environmental compliance. The dissertation establishes a coherent theoretical basis for sustainable industrial operations research in Nigeria, with broad applicability to emerging economy contexts globally. Keywords: sustainable operations research, environmental externalities, multi-objective optimization, Nigeria, Pareto frontier