Field Study on Heavy Metal Removal in a Natural Wetland Receiving Municipal Sewage Discharge

Field Study on Heavy Metal Removal in a Natural Wetland Receiving Municipal Sewage Discharge

C. S. Shibambu J. R. Gumbo W. M. Gitari

Department of Hydrology and Water Resources, University of Venda, South Africa.

Department of Ecology and Resources Management, University of Venda, South Africa.

1 January 2017
| Citation



Constructed and natural wetlands have been used successfully in the treatment and polishing of municipal wastewater all over the world, including in South Africa. Here we report on the heavy metal removal in a natural wetland that is receiving municipal sewage discharge, Limpopo province, South Africa. The natural wetland is located downstream of Makhado oxidation ponds and is dominated by the reed plant Phragmites australis. The changes in the metal variation from discharge of oxidation ponds to middle section and downstream of the natural wetland was analysed for heavy metals by ICP-MS over a 12 month period. The annual rainfall data were obtained from Agricultural Research Council. The following heavy metals: total chromium, zinc, cadmium and lead were effectively reduced during the passage through the wetland, to levels below the Department of Water & Sanitation (DWS) guidelines for waste water discharge. In contrast, the manganese and iron was reduced slightly above the DWS guideline value during the drier season and was higher during the wet season indicating a contribution of soil and water erosion. With copper it was effectively reduced during the wet and dry seasons with the exception in April, June and September when the downstream section was three times higher than the DWS guideline value. Thus the natural wetland was able to reduce considerable the heavy metals in the municipal discharge during its passage in the wetland. This is able to render the water in downstream of the wetland safe for rural communities to use the water for irrigation purposes.


drinking water, heavy metal reduction, natural wetland, phragmites australis rural communities


[1] Pindihama, G.K., Gumbo, J.R. & Oberholster, P.J., Evaluation of a low cost technology to manage algal toxins in rural water supplies. African Journal of Biotechnology, 10(86), pp. 19883–19889, 2011.

[2] Harding, W.R., Thornton, J.A., Steyn, G., Panuska, J. & Morrison, I.R., Hartbeespoort dam Remediation Project (Phase 1). Final Report (Volume 1). Project Number 58/2003. Completed October 2004. Department of Agriculture, Conservation, Environment and Tourism (DACET) of the Provincial Government of North West Province (NWPG), South Africa, p. 166, 2004.

[3] Oberholster, P.J., Botha, A.M., Chamier, J. & de Klerk, A.R., Longitudinal trends in water chemistry and phytoplankton assemblage downstream of the riverview wwtp in the upper olifants river. Ecohydrology & Hydrobiology, 13(1), pp. 41–51, 2013.

[4] Jack, U., Mackintosh, G., Jagals, C. & Van der Merwe, J., Development of a comprehensive monitoring and auditing tool for oxidation ponds systems in the middle vaal and upper orange catchment areas. Water SA, 32(5), pp. 655–660, 2006.

[5] Butler, E., Hung, Y.T., Al Ahmad, M.S., Yeh, R.Y.L., Liu, R.L.H. & Fu, Y.P., Oxidation pond for municipal wastewater treatment. Applied Water Science, pp. 1–21, 2015.

[6] Meiring, P.G.J., Integrating oxidation ponds and biological trickling filters. Proceeding Third Biennial Conference, 1993.

[7] Pescod, M.B., The role and limitations of anaerobic pond systems. Water Science and Technology, 33(7), pp. 11–21, 1996.

[8] van Niekerk, A., Seetal, A., Dama-Fakir, P., Boyd, L. & Gaydon, P., Guideline document: package plants for the treatment of domestic wastewater. Pretoria, South Africa, pp.1–95, 2009.

[9] Ogunfowokan, A.O., Adenuga, A.A., Torto, N. & Okoh, E.K., Heavy metals pollution in a sewage treatment oxidation pond and the receiving stream of the Obafemi Awolowo University, Ile Ife. Nigeria. Environmental Monitoring and Assessment, 143, pp. 25–41, 2008.

[10] Baloyi, C., Gumbo, J.R. & Muzerengi, C., Pollutants in sewage effluent and sludge and their impact on downstream water quality: a case study of Malamulele sewage plant, South Africa. Water Pollution XII, 182, p. 15, 2014.

[11] Kudakwashe K,. Shamuyarira, K.K., & Gumbo, J.R., Assessment of heavy metals in municipal sewage sludge: a case study of limpopo province, South Africa. International Journal of Environmental Research and Public Health, 11(3), pp. 2569–2579, 2014. 

[12] Potgieter, M., The role of wetlands play in water reclamation: Science in Africa, www. sciencein

[13] Vymazal, J., Švehla, J., Kröpfelová, L. & Chrastný, V., Trace metals in phragmites australis and phalaris arundinacea growing in constructed and natural wetlands. Science of the Total Environment, 380(1), pp. 154–162, 2007.

[14] Gazea, B. Adam, K. & Kontopoulos, A., A Review of passive systems for the treatment of acid mine drainage. Mineral Engineering, 9(1), pp. 23–31, 1995.


[16] Sheoran, A.S. & Sheoran, V., Heavy metal removal mechanism of acid mine drainage in wetlands: A critical review. Journal of Minerals Engineering, 19(2), pp. 105–116, 2006.

[17] Omprakash, S., Reduction of heavy metals from waste water by Wetland. International Letters of Natural Sciences, 7, pp. 35–43, 2014.

[18] Matagi, S.V., Swai, D. & Mugabe., R., A review of heavy metal removal mechanisms in wetlands. African Journal of Tropical Hydrobiology and Fisheries, 8(1), pp. 13–25, 1998.

[19] Department of Water Affairs (DWA), Annexure: General and Special Effluent Standards, Government Gazette 18 May 1984 no 9225. Regulation no. 991 18 May 1984.

[20] Chen, M., Tang, Y., Li, X. & Yu, Z., Study on heavy metal removal efficiencies of constructed wetlands with different substrates. Journal of Water Resource and Protection, 1(1), pp. 22–34, 2009.