Acid Rain Purification Technologies for Tailored Mitigation Strategies in Developing Countries

Abstract

Acid rain, caused primarily by SO₂ and NOₓ emissions from fossil fuel combustion, remains a major environmental challenge with significant ecological and human health consequences. This review compares existing control technologies, focusing on efficiency, cost, feasibility, and applicability to developing countries where resources and infrastructure may be limited. For SO₂ mitigation, calcium-based flue gas desulfurization (FGD) is widely applied because it is relatively simple and cost-effective, although its efficiency is somewhat lower than alternative methods. Sodium-based sorbents, by contrast, can achieve higher removal efficiency but are constrained by elevated costs and more complex disposal requirements, which limit large-scale adoption. For NOₓ control, combustion modifications represent low-cost options that can be implemented during the design or operation of boilers, but their effectiveness is limited compared with post-combustion methods. Advanced techniques such as selective catalytic reduction (SCR) provide high removal efficiency and reliability, yet demand substantial investment, sophisticated operation, and continuous maintenance. Considering these trade-offs, developing countries should prioritize technologies that balance cost and performance. A practical pathway involves adopting calcium-based FGD for SO₂ reduction, while integrating hybrid NOₓ reduction strategies that combine low-cost combustion modifications with selective downstream treatment, ensuring both technical feasibility and alignment with local economic conditions.