Abstract:
Effluent from municipal wastewater has recently been one of the major sources of pollution in the
environment. This study quantified the selected heavy metals (HM) ((lead (Pb), chromium (Cr),
cadmium (Cd), arsenic (As) and mercury (Hg)) and antibiotics (amoxicillin, erythromycin,
bactrim, tetracycline, gentamicin and ciprofloxacin) as contaminants of emerging concern (CECs)
in effluent and receiving water bodies in Mzuzu City in the wet and the dry seasons. The samples
(n = 208) were collected from the 3 waste stabilization ponds (WSPs), 3 water bodies and analyzed
using Atomic Absorption Spectrophotometer for HM and High-Performance Liquid
Chromatography for antibiotics. Statistical analysis was done using IBM SPSS version 20 and R
statistical software tools. Detection of the selected heavy metals ranged from 51.85 to 85.19 % and
antibiotics ranged from 14.81 to 96.3 %. The mean concentrations of heavy metals in the wet
season and the dry season were (Pb: 0.34±0.08 mg/L; and Cr: 0.12±0.05 mg/L) and (Pb: 0.03±0.02
mg/L, Cr: 0.01±0.01 mg/L and Cd: 0.004±0.0001 mg/L), respectively. The mean concentration of
antibiotics ranged from below the detectable limit to 51.4±1.26 µg/L in the wet season and
0.13±0.01 µg/L to 158.58±65.85 µg/L in the dry season. There were significant seasonal variations
(p < 0.05) in the occurrence, distribution and sources of HM and antibiotics in both seasons. Major
antibiotics and heavy metals sources in the aquatic environment were the anthropogenic activities
and effluent from WSPs. Mineralization and temperature affected the distribution of antibiotics
and heavy metals in the study area. The removal of HM from WSPs in both seasons ranged from
-17.95 to 100 % while antibiotics removal ranged from -1837.6 to 100 %. The results showed that
WSPs are conducive to removing HM more than antibiotics. Proper treatment and disposal of
waste and wastewater in the environment is key in reducing the occurrence of HM and CECs in
the environment thereby protecting human and aquatic life.
