Worldwide Research Progress and Trend in Sludge Treatment and Disposal: A Bibliometric Analysis

As a byproduct of sewage treatment in wastewater treatmentplants,sludge has dual attributes with pollution and resource, and its researchis important to ecological environment and energy security. Therefore,it is of great significance to analyze and summarize the developmentof research in the field of sludge treatment and disposal. Based ona bibliometric analysis, this paper analyzed the worldwide researchprocess and trend of sludge treatment and disposal among 49,300 researcharticles and reviews from 1975 to 2021, which were divided into sixtime periods for a more detailed analysis. In this analysis, countries,institutions, authors, and keywords were discussed respectively throughvisual maps. The United States (before 2007-2011) and China(after 2007-2011) were the countries that published the mostpapers, and cooperation between China and other countries became morefrequent after 2007-2011. Research institutions and authorsfrom developed countries and China accounted for the largest proportion.As the main research objects, activated sludge and sewage sludge appearedmost frequently in keywords analysis. In terms of the overall trend,sludge treatment and disposal gradually developed from harmless treatmentand reduction of sludge to the control of emerging pollutants, recyclingof sludge and multidisciplinary research. The analysis of cited authors(W. W. Eckenfelder, M. Henze, and Y. Liu) reflected the recognitionof worldwide researchers. The top 10 cited journals were classifiedas Q1 and Q2 according to journal citation reports, and they werefavored by researchers.