Utility of constructed wetlands for treatment of hospital effluent and antibiotic resistant bacteria in resource limited settings: A case study in Ujjain, India

Abstract

Increasing generation of wastewater and its indiscriminate disposal is detrimental to human and animal health. Resource-limited settings often struggle for efficient wastewater treatment systems owing to lack of funds and operational difficulties. Therefore, alternative treatment systems involving low expenditure and simplistic operations are need of the hour. Constructed wetlands are one such alternative that can efficiently remove variety of pollutants from wastewater. In this study, we have assessed the utility of constructed wetlands for treatment of hospital wastewater in Ujjain. An in-house wetland system was designed and constructed using Typha latifolia and Phragmites karka. Results showed that wetland was efficient for removal of various physico-chemical and biological contaminants, namely, biochemical-oxygen-demand (77.1%), chemical-oxygen-demand (64.9%), turbidity (68.3%), suspended-solids (63%), total-phosphorus (58.7%), nitrate-nitrogen (33%), fecal coliforms (96.8%), and total coliforms (95.6%). Paired t test revealed that removal efficiencies for various parameters were significantly different among Phragmites, Typha, and control cells (p ≤ 0.05). Study also depicted that most of the bacterial isolates in inlet wastewater were selectively resistant to antibiotics (ciprofloxacin and sulphamethaxazole) as well and these isolates were also removed. Precisely, Typha was fairly suitable for antibiotic resistant bacteria removal. Thus, constructed wetlands were found to be one of the suitable options for wastewater treatment in resource-limited settings. PRACTITIONER POINTS: Constructed wetlands are one of the suitable options for wastewater treatment in resource limited settings. These systems involve wetland vegetation, soil, and associated microbial assemblages to improve the water quality. Typha and Phragmites were found to be efficient for treating the hospital wastewater. Experiments showed that antibiotic resistant bacteria may also be removed through constructed wetland systems. Easy operation, cost effectiveness, and efficiency are important attributes.

Keywords: Phragmites; Typha; antibiotic resistant bacteria; constructed wetlands; wastewater.

FIGURE 1

Schematic of the designed constructed wetland (CW)

FIGURE 2

Removal efficiency of constructed wetland cells for physico‐chemical and biological parameters

FIGURE 3

Seasonal variation in the removal efficacy of pollutants by different constructed wetland cells: (a) BOD, (b) COD, (c) turbidity, (d) TSS, (e) TP, (f) NO₃‐N, (g) total coliforms, and (h) fecal coliforms

FIGURE 4

Antibiotic resistance pattern (%) of E. coli isolates for ciprofloxacin (CPF) and sulphamethaxazole (SMX) in influent (raw sewage) and effluents of constructed wetland cells (dotted lines in the graph indicate the antibiotic resistance pattern [%] in the raw sewage)

FIGURE 5

Seasonal variation in antibiotic resistance pattern (%) of E. coli isolates for ciprofloxacin (CPF) (a) and sulphamethaxazole (SMX) (b) in influent (raw sewage) and effluents of constructed wetland cells (dotted lines in the graph indicate the antibiotic resistance pattern [%] in the raw sewage in different seasons)