Biofilm carriers and their application in wastewater treatment: A review

Biofilm technology, recognized as an efficient and stable approach for wastewater treatment, fundamentally relies on suitable carriers to support microbial attachment and growth. The characteristics of these carriers profoundly influence the morphological structure, metabolic activity, and overall pollutant degradation efficiency of biofilms. This article systematically reviews recent research progress on biofilm carriers and proposes a five-category classification system comprising inorganic carriers, organic inert and reactive carriers, fiber-based carriers, naturally degradable carriers, and novel functionalized carriers. By analyzing the performance and application scenarios of various carrier types, their advantages in terms of economic viability and environmental friendliness are demonstrated. Furthermore, strategies for surface modification and composite material synthesis to further enhance biofilm performance are discussed. This review aims to provide theoretical guidance for the development of efficient, energy-saving, and sustainable wastewater treatment processes and to offer practical references for technology selection and engineering applications in relevant enterprises.