Evaluation of a Horizontal Subsurface Constructed Wetland for the Removal of Antibiotics, Antibiotic Resistant Bacteria and Heavy Metals from Hospital Waste Water
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Date
2020-03-03
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Addis Ababa University
Abstract
Wastewater plays an important role in the dissemination of antibiotic resistant bacteria and source for the release of antibiotics and other pollutants to the environment. Human exposure to antibiotics, heavy metals and antibiotic resistant bacteria are among the major public health concerns. Hence, the aim of this study was to evaluate the efficiency of a horizontal subsurface flow (HSSF) constructed wetland in removing antibiotic-resistant bacteria, heavy metals and antibiotic concentration. Samples were taken from Tikur Anbessa Specialized Referral Hospital periodically for five months in 2018 and fed into a constructed wetland in the College of Natural and Computational Sciences Addis Ababa University. Influent and effluent were collected and analyzed for organic matter, nutrients, heavy metals, antibiotics, antibiotic resistant bacteria and other physiochemical parameters. The result of this study showed that removal of BOD and COD did not exhibit significant (p=0.005) difference between the plants T. latifolia, P. karka and their combination against the unvegetated control. Removal of nutrients (N and P) was more (p=0.05) efficient in Typha latifolia and Phragmite karka than the combined plant. The mean concentration of zinc in raw, influent, typha planted cell, typha and phragmites planted cell, control (non-vegetated) and Phragmites planted treatment were 0.283, 0.353, 0.054, 0.112, 0.219 and 0.048mg/l respectively. P. karka showed good removal efficiency for Nickel (73%) and Zinc (86%). The count of bacteria resistant to ciprofloxacin, gentamicin doxycycline and cefotaxime were decreased in all constructed wetland cells compared to resistant bacteria count in the influent. The mean concentration of ciprofloxacin cefotaxime in the influent were 1.23 ppm and 17 ppm and lower removal efficiency observed in all cell for ciprofloxacin and the highest removal efficiency observed the cell planted with typha latifolia and unvegetated control for cefotaxime. Strong positive correlation (r2=0.98, P=0.11) was found between the high cefotaxime concentration in the wastewater and high count of resistant bacteria for cefotaxime in the influent water and the water treated with Typha latifolia, while strong negative correlation in unplanted control and Phragmite karka and the combined plants. It was concluded that the wetland process performance optimization schemes need to include antibiotics and heavy metals for maximum removal efficiency in hospital wastewater treatment.
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Cefotaxime, Ciprofloxacin, Macrophyte, Wastewater