Critical Evaluation of Emerging Technologies for Microplastic Removal: A Comprehensive Review from Technological, Environmental Perspectives and Economic Performance

Microplastic (MPs) pollution represents a widespread and persistent global challenge arising from both primary MPs intentionally manufactured at microscopic scales and secondary MPs produced through fragmentation of larger plastic debris. Owing to their physicochemical stability, environmental mobility, and strong affinity for co-contaminants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and metals, MPs are widely distributed across aquatic and terrestrial systems, raising concerns for ecosystems and human health. This study presents a systematic and comparative review of MP treatment technologies reported predominantly between 2021 and 2025, with emphasis on aqueous matrices including urban and industrial wastewater as well as natural waters. Seven technology categories are evaluated: adsorption, electrocoagulation, advanced oxidation processes (AOPs, particularly heterogeneous photocatalysis), biological and microbial treatments, ferrate(VI) oxidation, membrane filtration and emerging separation methods, and ecotoxicological assessment of degradation products. Across the reviewed literature, adsorption, electrocoagulation, ferrate-assisted coagulation or flotation, and membrane filtration frequently report high apparent removal efficiencies (≈80-99%). However, true polymer mineralization remains uncommon and is primarily associated with selected AOP configurations or enzyme-mediated pathways, especially those targeting polyethylene terephthalate (PET). The performance of AOPs is constrained by energy demand, catalyst stability and immobilization challenges, scale-up limitations related to light distribution, and uncertainties regarding transformation-product toxicity. Biological treatments and nature-based systems generally function as complementary approaches, contributing mainly to particle retention and partial transformation because of slow kinetics and incomplete mineralization. Importantly, available evidence indicates that while some processes yield effluents with low toxicity, others may generate more bioactive soluble by-products, underscoring the need to couple removal efficiency metrics with standardized toxicity and by-product characterization. Economic reporting remains scarce and largely limited to operating expenditures (OPEX), with electrocoagulation displaying the greatest variability. Overall, effective MP mitigation will likely require integrated treatment trains, pilot-scale validation, and robust techno-economic and life-cycle assessment frameworks to ensure both operational performance and environmental safety.