The impact of industries on surface water quality of River Ona and River Alaro in Oluyole Industrial Estate, Ibadan, Nigeria

Samples of water from two rivers (River Ona and River Alaro) in Oluyole Industrial Estate, Ibadan, Nigeria were analysed to evaluate the impact of industrial discharges on the surface water quality. The results obtained indicated that most of the parameters analysed (pH, total hardness, sulphate, chloride, nitrate and dissolved solids) were lower than the World Health Organisation (WHO) maximum permissible limit for drinking water. However, the levels of nitrate, chloride, total phosphorus, total solids and oil and grease were higher in the industrial zones than those found in the upstream of both rivers. These ranged between 3.00 – 8.55, 7.48 – 11.78, 2.14 – 3.57, 260 – 520 mg/l and 381.20 – 430.80 mg/l, respectively. Nitrate and total phosphorus which are essential nutrients for plants were the most accumulated in both rivers. The gross organic pollution indicators monitored (chemical oxygen demand and oil and grease) revealed that River Alaro was more polluted than River Ona. It was established from the results of this study that industrial discharges had negative impact on the surface water qualities of both rivers. Hence, extraction of water from both rivers for domestic and agricultural purposes requires some forms of physical and chemical treatment.Key words: River Ona, River Alaro, industrial discharges, surface water quality

Variation in levels and removal efficiency of heavy and trace metals from wastewater treatment plant effluents in Cape Town and Stellenbosch, South Africa

This study focused on one year monitoring campaign to monitor the occurrence and removal of Endocrine Disruptive Metals (EDMs) and trace metals from selected wastewater treatment plants (WWTPs) in Stellenbosch and Cape Town. Composite water samples were collected from the WWTPs from January 2010 to December 2010 on a quarterly basis and concentrations determined using inductively coupled plasma-mass spectrometry (ICP-MS) after open beaker digestion. A total of 432 water samples consisting of raw, primary effluent, secondary effluent and final effluents were collected and analyzed. The general abundance distribution pattern for metals was Zn > Cu > Pb > Cr > Ni > As > Co > Cd > Hg. The removal efficiency ranged from 1.5% for Hg at Zandvliet WWTP plant during winter to 98.27% for Cu at Athlone WWTP treatment plant during summer. The final effluent concentration for most of the metals were within South African water quality guidelines while As, Hg, Cd and Pb concentration were higher than maximum limits set by the Canadian Council of Ministers of the Environment. Potsdam WWTP showed to be the most effective at heavy metals removal as compared with the other five treatment plants investigated in this study. The effluent metal concentration over time could pose health risk if used for agricultural irrigation.Keywords: Seasonal variation, endocrine disrupting metals, wastewater treatment plants, effluents, coupled plasma-mass spectrometry (ICP-MS), Cape Tow

Poly- and perfluorinated substances in environmental water from the Hartbeespoort and Roodeplaat Dams, South Africa

Concentrations of poly- and perfluorinated substances (PFASs) were determined in Hartbeespoort and Roodeplaat Dams, South Africa. Water samples were collected from the dams in February–March, and May–June, representing southern hemisphere summer and winter seasons, respectively. Solid phase extraction (SPE) was used to extract the analytes from the water samples and liquid chromatography-tandem mass spectrometry (LC-MS/MS) used for analysis. The mean PFAS concentrations detected ranged from 1.38–346.32 ng∙L-1 and 2.31–262.29 ng∙L-1 in the Hartbeespoort Dam and Roodeplaat Dam, respectively. Perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS) and perfluoroheptanoic acid (PFHpA) were the most dominant PFASs detected. The PFAS concentrations detected were higher in summer than in winter, but the difference between seasons was not statistically significant (p = 1). Furthermore, the concentrations of short-chain PFASs were higher than the longer chains. Overall, the PFAS concentrations in the present study are comparable to those reported in other parts of South Africa, and also Ghana, higher than the concentrations reported in Uganda, Singapore, and Vietnam, and lower than those in Germany, Japan and China. The measured concentrations of PFOA and PFOS raise concerns of human exposure to these chemicals since they are above the USEPA advisory limit. This suggests that communities living within the vicinity of the dams are most likely to be exposed to these chemicals

Leachate seepage from landfill: a source of groundwater mercury contamination in South Africa

Mercury has been used for many centuries in the production of consumer products such as thermometers, electrical switches, fluorescent light bulbs, batteries, biocides and pesticides, cosmetics and dental amalgam filling, among others. After use, these mercury-containing consumer products form part of the municipal solid waste (MSW). As a result of an unseparated solid waste collection system, mercury-containing wastes tend to end up in landfills where mercury and other pollutants can leach out of products into landfill leachates. The present study, therefore, was conducted with the aim of determining the total mercury (THg) concentrations in leachate and sediment samples collected from 4 selected landfill sites (3 sites in Gauteng Province – Soshanguve, Hatherly, Onderstepoort and 1 site in Limpopo Province – Thohoyandou). Groundwater samples were collected from the monitoring boreholes at the four selected landfill sites in the summer and winter periods. An acid digestion method was employed for sample preparation and this was followed by analysis using cold vapour atomic absorption spectrophotometry (CVAAS). The concentration range of total mercury in the Thohoyandou leachate, sediment and groundwater samples was 0.12–2.07 μg/L, 0.03–0.48 μg/g and 0.09–2.12 μg/L, respectively. In Soshanguve, the concentration range of total mercury in leachate, sediment and groundwater samples was 0.10–1.20 μg/L, 0.04–0.62 μg/g and nd –1.66 μg/L respectively, Hatherly concentration range was 0.42–1.31 μg/L and 0.06–0.78 μg/g in leachate and sediment, respectively and in Onderstepoort the concentration range was 0.12–2.41 μg/L, 0.03–0.50 μg/g and 0.05–2.44 μg/L, in leachate, sediment and groundwater, respectively. The findings from this study suggest that there is a likelihood of groundwater pollution by mercury from landfill leachate seepage, particularly for landfills that are not lined with a geomembrane.&nbsp