Abstract
Wastewater treatment generates a huge amount of sewage sludge, which is a source of environmental pollution. Among the alternatives for the management of this waste, industrial composting stands out as one of the most relevant. The objective of this study was to analyze the bacterial population linked to this process and to determine its effectiveness for the reduction, and even elimination, of microorganisms and pathogens present in these organic wastes. For this purpose, the bacteriome and the fecal bacteria contamination of samples from different sewage sludge industrial composting facilities were evaluated. In addition, fecal bacteria indicators and pathogens, such as Salmonella, were isolated from samples collected at key stages of the process and characterized for antibiotic resistance to macrolide, β-lactam, quinolone, and aminoglycoside families. 16S rRNA phylogeny data revealed that the process clearly evolved toward a prevalence of Firmicutes and Actinobacteria phyla, removing the fecal load. Moreover, antibiotic-resistant microorganisms present in the raw materials were reduced, since these were isolated only in the bio-oxidative phase. Therefore, industrial composting of sewage sludge results in a bio-safe final product suitable for use in a variety of applications.
Highlights
The accelerated appearance of antibiotic resistance has become a global health problem (Abadi et al, 2019; Mobarki et al, 2019)
These parameters inform about the correct evolution of the process and included moisture, organic matter, temperature, pH, electrical conductivity, C/N ratio, and bulk density (BD)
The organic matter reduced around 30–50% when the maturation phase was reached due to the mineralization
Summary
The accelerated appearance of antibiotic resistance has become a global health problem (Abadi et al, 2019; Mobarki et al, 2019). It is estimated that by 2050 there will be 10 million deaths as a result of this problem (He et al, 2020). The situation is aggravated by the spread caused by the continuous generation of waste of anthropogenic origin (Karkman et al, 2018) These include, among others, sewage sludge, which contains heavy metals, organic compounds, pathogens (Lamastra et al, 2018), and traces of antibiotics that promote the emergence of antibiotic-resistant bacteria (ARGs) (Sun et al, 2019; Urra et al, 2019). A good management of these biosolids is crucial to avoiding the environmental and sanitary threats derived of the application of improperly treated sewage sludge (Kacprzak et al, 2017)
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