Limits...
Assessment of heavy metals in municipal sewage sludge: a case study of Limpopo province, South Africa.

Shamuyarira KK, Gumbo JR - Int J Environ Res Public Health (2014)

Bottom Line: The concentrations of silver found were low, but significant, in the range 0.22 to 21.93 mg/kg dry mass.The highest concentration of silver was found in Louis Trichardt town with a concentration of 21.93 ± 0.38 mg/kg dry mass while the lowest was Thohoyandou with a concentration of 6.13 ± 0.12 mg/kg dry mass.The result showed that silver was indeed present in the wastewater sewage sludge and at present there is no DWAF guideline standard.

View Article: PubMed Central - PubMed

Affiliation: Department of Hydrology and Water Resources, University of Venda, P/Bag x5050, Thohoyandou 0950, South Africa.

ABSTRACT
Heavy metals in high concentrations can cause health and environmental damage. Nanosilver is an emerging heavy metal which has a bright future of use in many applications. Here we report on the levels of silver and other heavy metals in municipal sewage sludge. Five towns in Limpopo province of South Africa were selected and the sludge from their wastewater treatment plants (WWTPs) was collected and analysed. The acid digested sewage sludge samples were analysed using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) methods. The concentrations of silver found were low, but significant, in the range 0.22 to 21.93 mg/kg dry mass. The highest concentration of silver was found in Louis Trichardt town with a concentration of 21.93 ± 0.38 mg/kg dry mass while the lowest was Thohoyandou with a concentration of 6.13 ± 0.12 mg/kg dry mass. A control sludge sample from a pit latrine had trace levels of silver at 0.22 ± 0.01 mg/kg dry mass. The result showed that silver was indeed present in the wastewater sewage sludge and at present there is no DWAF guideline standard. The average Cd concentration was 3.10 mg/kg dry mass for Polokwane municipality. Polokwane and Louis Trichardt municipalities exhibited high levels of Pb, in excess DWAF guidelines, in sludge at 102.83 and 171.87 mg/kg respectfully. In all the WWTPs the zinc and copper concentrations were in excess of DWAF guidelines. The presence of heavy metals in the sewage sludge in excess of DWAF guidelines presents environmental hazards should the sludge be applied as a soil ameliorant.

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Population with flush toilet connected to sewage system for each town [14].
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ijerph-11-02569-f003: Population with flush toilet connected to sewage system for each town [14].

Mentions: The towns of Louis Trichardt and Tzaneen had the highest Ag concentrations of 21.93 ± 0.38 mg/kg d. m. and 13.40 ± 0.46 mg/kg d. m., respectively, while the lowest was Thohoyandou with a concentration of 6.13 ± 0.12 mg/kg d. m. of silver (Figure 2). This suggests that residents in Louis Trichardt probably use more of the silver-containing cosmetics than the rest of the towns. The pit latrine sample had trace silver concentration of 0.22 ± 0.01 mg/kg d. m. and was the lowest since households using pit latrines do not usually dispose their wastewater into the pit latrine. Instead, they pour their bathwater and laundry water usually on compost or water the trees [20]. The result of 6.89 ± 0.11 mg/kg d. m. observed in Polokwane is unexpected, as it has a larger population than the other towns. The populations of Polokwane, Louis Trichardt, Thohoyandou, Musina and Tzaneen according to Stats SA [14], are shown in Figure 3.


Assessment of heavy metals in municipal sewage sludge: a case study of Limpopo province, South Africa.

Shamuyarira KK, Gumbo JR - Int J Environ Res Public Health (2014)

Population with flush toilet connected to sewage system for each town [14].
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3986993&req=5

ijerph-11-02569-f003: Population with flush toilet connected to sewage system for each town [14].
Mentions: The towns of Louis Trichardt and Tzaneen had the highest Ag concentrations of 21.93 ± 0.38 mg/kg d. m. and 13.40 ± 0.46 mg/kg d. m., respectively, while the lowest was Thohoyandou with a concentration of 6.13 ± 0.12 mg/kg d. m. of silver (Figure 2). This suggests that residents in Louis Trichardt probably use more of the silver-containing cosmetics than the rest of the towns. The pit latrine sample had trace silver concentration of 0.22 ± 0.01 mg/kg d. m. and was the lowest since households using pit latrines do not usually dispose their wastewater into the pit latrine. Instead, they pour their bathwater and laundry water usually on compost or water the trees [20]. The result of 6.89 ± 0.11 mg/kg d. m. observed in Polokwane is unexpected, as it has a larger population than the other towns. The populations of Polokwane, Louis Trichardt, Thohoyandou, Musina and Tzaneen according to Stats SA [14], are shown in Figure 3.

Bottom Line: The concentrations of silver found were low, but significant, in the range 0.22 to 21.93 mg/kg dry mass.The highest concentration of silver was found in Louis Trichardt town with a concentration of 21.93 ± 0.38 mg/kg dry mass while the lowest was Thohoyandou with a concentration of 6.13 ± 0.12 mg/kg dry mass.The result showed that silver was indeed present in the wastewater sewage sludge and at present there is no DWAF guideline standard.

View Article: PubMed Central - PubMed

Affiliation: Department of Hydrology and Water Resources, University of Venda, P/Bag x5050, Thohoyandou 0950, South Africa.

ABSTRACT
Heavy metals in high concentrations can cause health and environmental damage. Nanosilver is an emerging heavy metal which has a bright future of use in many applications. Here we report on the levels of silver and other heavy metals in municipal sewage sludge. Five towns in Limpopo province of South Africa were selected and the sludge from their wastewater treatment plants (WWTPs) was collected and analysed. The acid digested sewage sludge samples were analysed using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) methods. The concentrations of silver found were low, but significant, in the range 0.22 to 21.93 mg/kg dry mass. The highest concentration of silver was found in Louis Trichardt town with a concentration of 21.93 ± 0.38 mg/kg dry mass while the lowest was Thohoyandou with a concentration of 6.13 ± 0.12 mg/kg dry mass. A control sludge sample from a pit latrine had trace levels of silver at 0.22 ± 0.01 mg/kg dry mass. The result showed that silver was indeed present in the wastewater sewage sludge and at present there is no DWAF guideline standard. The average Cd concentration was 3.10 mg/kg dry mass for Polokwane municipality. Polokwane and Louis Trichardt municipalities exhibited high levels of Pb, in excess DWAF guidelines, in sludge at 102.83 and 171.87 mg/kg respectfully. In all the WWTPs the zinc and copper concentrations were in excess of DWAF guidelines. The presence of heavy metals in the sewage sludge in excess of DWAF guidelines presents environmental hazards should the sludge be applied as a soil ameliorant.

Show MeSH
Related in: MedlinePlus