Application of a constructed wetland for the removal of antibiotic residue, antibiotic-resistant bacteria, and antibiotic-resistance genes from pharmaceutically contaminated wastewater

Abstract

The significant increases in abundance of pharmaceuticals, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs) in the environment have drawn attention over public health. The presence of these contaminants in wastewaters is well-documented as a factor contributing to the decreased potency of antibiotics used in healthcare. These types of contaminants can be removed from wastewater using a number of techniques, including phytoremediation, which has demonstrated effectiveness. The removal of these contaminants by various aquatic plants has been explored, and the results are promising. The aim of this research was first, to analyze antibiotic resistance patterns of bacteria isolated from hospital wastewater effluent, which is a consequence of antibiotics occurrence in wastewater. Second, to investigate the removal of some selected antibiotics from synthetic wastewater in constructed wetland (CW) planted with Cyperus alternifolius, Canna indica, and one planted with both of these plant species, as well as the influence of antibiotics on microbial density and community in CW. Hospital wastewater samples were collected from the Benjamin Mkapa Hospital in Dodoma, Tanzania, where the hospital's wastewater is treated in a horizontal subsurface flow CW planted with Typha latifolia before being discharged into the environment. The results of hospital wastewater analysis showed that bacteria isolated from treated hospital wastewater were resistant to tested antibiotics and harbored antibiotics resistance genes. These findings demonstrate that CW can disseminate ARB and ARGs despite hospital wastewater treatment, which poses a risk to the public's health. In the pilot CW, the system planted with a single plant species (Cyperus alternifolius) outperformed those planted with mixed plant species or Canna indica alone in the removal of tested antibiotics from wastewater. This is supported by the observation of higher bacteria abundance in CW with Cyperus altenifolius than Canna indica, while the difference was not significant (p > 0.05). The findings of this investigation revealed that although there is a general decline in bacteria abundance, there is no significant change (p > 0.05) due to antibiotic presence in wastewater. It is concluded that, despite variations in performance, the plants studied play a significant role in pharmaceuticals remediation from wastewater