A bibliometric review of sludge dewatering research from 1993 to 2022

The process of wastewater treatment generates significant volumes of sludge, typically characterized by high water content. The practice of sludge dewatering plays a crucial role in reducing the volume of sludge and consequently, the associated costs of subsequent treatment, transportation, and disposal. This paper provides an exhaustive and impartial summary of research trends in sludge dewatering, spanning the period from 1993 to 2022. The bibliometric data utilized in this study were sourced from the Web of Science Core Collection database. Over 30 y, 5,836 papers have been published on sludge dewatering, witnessing a rapid growth trend in the number of published papers. The highest contributions in terms of the number of papers were made by authors hailing from China, followed by authors from the USA, Canada, Australia, and Japan. An analysis of keywords indicated that anaerobic digestion was the most frequently used. Three prominent research hotspots emerged: the impact of extracellular polymeric substances on sludge dewatering; the role of thermal hydrolysis in enhancing sludge anaerobic digestion; and the dual aspects of hydrothermal carbonization and heavy metals recovery in the context of sludge reuse and disposal.