Phthalates removal efficiency in different wastewater treatment technology in the Eastern Cape, South Africa

Abstract

The removal capacity of different wastewater treatment plant (WWTP) technologies adopted in rural areas for phthalate was investigated in the Eastern Cape, South Africa. Wastewater samples collected from three selected WWTPs which use activated sludge (AS), trickling filter (TF), and oxidation pond (OP) technology were extracted using the solid-phase extraction method followed by gas chromatography-mass spectrometry (GC-MS) analysis. The six selected phthalate esters (PAEs) dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), di(2-ethyl hexyl) phthalate (DEHP), and di-n-octyl phthalate (DOP) were detected in all the samples collected from the WWTPs. DBP was the most abundant compound in the influent, effluent, and sludge samples with a maximum detection of 2497 μgL, 24.2 μgL, and 1249 μg/g dW, respectively, followed by DEHP and BBP. There was a relatively high removal capacity achieved by AS in Alice, TF in Berlin, and OP in Bedford with a removal efficiency that varied between 77 and 99%, 76 and 98%, and 61 and 98%, respectively. A high significant correlation of PAE removal with total suspended solids (TSS) and turbidity suggests that the removal performance proceeded more through adsorption on settling particles and sludge than on biodegradation. However, the concentrations of PAEs detected in the final effluent and sludge samples exceeded acceptable levels allowed internationally for a safe aquatic environment. AS may have exhibited a more stable and better performance across the different seasons; however, pollution source control still deserves a special attention to prevent the risk posed by these micropollutants.

Heavy Metals in Wastewater and Sewage Sludge from Selected Municipal Treatment Plants in Eastern Cape Province, South Africa

“…Composite samples of influent, effluent and river water were collected into 2 L polyethene bottles previously washed with nitric acid and well rinsed with distilled water. The samples were collected in a continuous sweeping motion extending the mouth of the bottle to the run-off discharge and were preserved with a few drops of concentrated HNO 3 (adjusted to~pH 2.0) [44,46,48].…”

“…Their removal efficiencies were linked to their high capacities to remove the suspended particles onto which most of these contaminants were adsorbed, hence increasing concentrations in the sewage sludge when settled. Another reason given for such reduction is volatilization of the lighter congeners during aeration and sludge dehydration [48,114,115].…”

Photodegradation Pathways of Typical Phthalic Acid Esters Under UV, UV/TiO2, and UV-Vis/Bi2WO6 Systems

“…There was a maximum detection of 2,497 µg/L dibutyl phthalate (DBP) in the influent of a wastewater treatment plant in Africa. Different treatment processes had different removal effects, and DBP was shown to tend to accumulate in the sludge, exceeding acceptable levels for a safe aquatic environment (Salaudeen et al, 2018). Noura (Al-Jandal et al, 2018) revealed significant levels of phthalates in seawater (2.1-4.6 µg/L) and sediment (2.1-15.7 mg/kg dry wt) samples.…”

Assessment of Environmental Pollution and Human Exposure to Pesticides by Wastewater Analysis in a Seven-Year Study in Athens, Greece

“…In this work the frequency of detection was 52% and mean concentrations reached 225 ng/L. In general, it is detected at various concentrations in untreated wastewater from relatively low (0.3 ng/L) to high (50 µg/L) values depending on the specific area [76,77]. The application of dimethyl phosphate as an insect repellent is currently limited and the found concentrations are probably due to its use as a plasticizer.…”