Applications of Up-Flow Anaerobic Sludge Blanket (UASB) and Characteristics of Its Microbial Community: A Review of Bibliometric Trend and Recent Findings.

Maria Cristina Collivignarelli,Vincenzo Torretta,Ioannis A Katsoyiannis,Alessandro Abbà,Marco Carnevale Miino,Elena Cristina Rada,Francesca Maria Caccamo,Silvia Calatroni

doi:10.3390/ijerph181910326

Abstract

The interest in research on up-flow anaerobic sludge blanket (UASB) reactors is growing. The meta-analysis of bibliometric data highlighted the growing interest in four diverse topics: (i) energy recovery production; (ii) combination with other treatments; (iii) the study of processes for the removal of specific pollutants and, (iv) characterization of microbial community and granular sludge composition. In particular, the papers published in the first 6 months of 2021 on this process were selected and critically reviewed to highlight and discuss the results, the gaps in the literature and possible ideas for future research. Although the state of research on UASB is to be considered advanced, there are still several points that will be developed in future research such as the consolidation of the results obtained on a semi-industrial or real scale, the use of real matrices instead of synthetic ones and a more in-depth study of the effect of substances such as antibiotics on the microbiota and microbiome of UASB granular biomass. To date, few and conflicting data about the environmental footprint of UASB are available and therefore other studies on this topic are strongly suggested.

Highlights

The up-flow anaerobic sludge blanket (UASB) systems were first proposed in the 1970s and, recently, the interest in using this technology has grown [1]
The meta-analysis of bibliometric data highlighted the change in main aspects of research and the current hot topics: (i) energy production; (ii) combination with other treatments; (iii) the study of processes for the removal of specific pollutants and, (iv) characterization of microbial community and granular sludge composition
Several applications of UASB in more complex treatment lines are reported in the literature

Summary

Introduction

The up-flow anaerobic sludge blanket (UASB) systems were first proposed in the 1970s and, recently, the interest in using this technology has grown [1]. In the UASB process, the biomass is not of the flock type but of granular consistency due to a phenomenon in which microorganisms formed granular groups with a more compact structure, a higher dimension, higher density and higher settling capacity than in the conventional active sludge (CAS) [2]. The inoculation of biomass already granulated proved to be an effective method to reduce the start-up phase [6]. Other drawbacks of this technology include the difficulty associated with the operation of the three-phases separation, the possible sludge washout and foam formation [7,8,9,10]

Objectives

Methods

Results

Discussion

Conclusion