With rising populations and expanding industries, the need for effective and affordable wastewater treatment is increasing. Trickling filter technology stands out as a strong, flexible option, especially as green solution and energy saving. It has been a cornerstone of wastewater treatment for nearly a century, offering a robust and efficient fixed-film bioreactor system for organic matter removal, nitrification, and, in some cases, denitrification. This chapter provides a comprehensive review of the philosophical perspectives and scientific literature surrounding trickling filter technologies. It explores the historical evolution of trickling filters, the theoretical principles underpinning their operation, and the various design advancements that have enhanced their performance. Additionally, the chapter examines the role of trickling filters in modern wastewater management, their sustainability implications, and the ongoing debates regarding their applicability compared to other biological treatment systems. This review aims to offer a holistic understanding of trickling filter technology and its future trajectory in the field of wastewater treatment. The status of trickling filter technology recognized that the experience in terms of dimensioning is essentially based on investigations into mineral media trickling filters operated in temperate climates. However, numerous studies indicate that wastewater temperature has a decisive influence on the treatment performance of trickling filters both carbon elimination and nitrification. This chapter demonstrates the key factors influencing the design of trickling filters, as well as the current state of their development. It also provides a comprehensive review of the philosophical perspectives and existing literature related to trickling filter technologies.