Thematic and Geographical Trend in Scientific Research Applied in Municipal Wastewater Treatment Plants: an Overview

Municipal wastewater treatment plants (MWWTPs) are considered essential to protect human health and aquatic systems. However, several studies in the scientific field have identified adverse environmental effects in these treatment units that involve challenges in the water industry. Therefore, this work has the following objectives: (1) to understand the global context in which MWWTPs operate and (2) to determine the thematic and geographic trend in scientific research. Through the "Publish or Perish" software, scientific articles indexed in the Scopus and Google Scholar databases during the period 2000 to 2020 were obtained. Specific terms were used: "Municipal Wastewater Treatment Plants"; "Municipal Wastewater Treatment Plants," so that all terms must be contained in the title of the document. Categorization was defined according to key concepts considered as adverse effects indicated in the literature and that involve common problems in the water industry at the municipal level. As a result, 1844 documents (papers, reviews, books, book chapters, citations, letters, theses, and conference papers) were retrieved and subjected to a process of refinement (discrimination) where only articles, chapters, conference papers, and reviews were considered. Finally, 800 articles were selected for further content analysis, identifying seven categories and 30 subcategories. The category of "Emerging contaminants" was the most relevant within the research topics, and the category with the least available research was "Air quality." The articles were also analyzed by economic region, identifying Asia with the largest number of studies on various topics. In conclusion, future research should be oriented towards management, energy, and air quality issues, because they are subjects of little research involving process efficiency, energy savings, and impacts on the quality of life.