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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Cleaning materials containing copper and zinc.
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ijerph-11-02569-f004: Cleaning materials containing copper and zinc.

Mentions: The concentrations of copper (Cu) from all the study towns were very high, and above the DWAF guideline values (Table 1). The Cu concentrations were in the range 263.68 to 626.00 mg/kg d. m. The Musina municipality had the highest concentration of Cu. The reason for the high Cu concentrations could have been caused probable by the corrosion of the water supply pipes, whose composition includes copper. This was supported by the study of Tjandraatmadja et al. [26] who found that about 46% of the copper in sewage sludge came from the water supply connected to the household pipes in Melbourne, Australia. Musina also has abandoned copper mines and the leachate from these could have got into the raw water used for the supply of the town [27]. Our research results were comparable to the findings of Morrison et al. [2] in which they found Cu values in the range of 245 to 441 mg/kg d. m. and EPA [17] survey which found Cu in the range of 115 to 2,580 mg/kg d. m. An explanation for the high levels of Cu in sludge may be the use of brass (contains copper and zinc) and copper scrubbers as abrasives in general cleaning in household kitchens and the washing of pots (Figure 4).


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)

Cleaning materials containing copper and zinc.
© Copyright Policy
Related In: Results  -  Collection

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

ijerph-11-02569-f004: Cleaning materials containing copper and zinc.
Mentions: The concentrations of copper (Cu) from all the study towns were very high, and above the DWAF guideline values (Table 1). The Cu concentrations were in the range 263.68 to 626.00 mg/kg d. m. The Musina municipality had the highest concentration of Cu. The reason for the high Cu concentrations could have been caused probable by the corrosion of the water supply pipes, whose composition includes copper. This was supported by the study of Tjandraatmadja et al. [26] who found that about 46% of the copper in sewage sludge came from the water supply connected to the household pipes in Melbourne, Australia. Musina also has abandoned copper mines and the leachate from these could have got into the raw water used for the supply of the town [27]. Our research results were comparable to the findings of Morrison et al. [2] in which they found Cu values in the range of 245 to 441 mg/kg d. m. and EPA [17] survey which found Cu in the range of 115 to 2,580 mg/kg d. m. An explanation for the high levels of Cu in sludge may be the use of brass (contains copper and zinc) and copper scrubbers as abrasives in general cleaning in household kitchens and the washing of pots (Figure 4).

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