| 1. |
- Amdany, Robert, et al.
(author)
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Investigating the temporal trends in PAH, PCB and OCP concentrations in Hartbeespoort Dam, South Africa, using semipermeable membrane devices (SPMDs)
- 2014
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In: Water S.A.. - : South African Water Research Commission. - 0378-4738 .- 1816-7950. ; 40:3, s. 425-436
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Journal article (peer-reviewed)abstract
- The seasonal variability of persistent organic pollutants in Hartbeespoort Dam, South Africa, was investigated using semipermeable membrane devices (SPMDs) as passive samplers. Freely dissolved waterborne polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were sampled to investigate seasonal changes in their concentrations. Exposure of the passive samplers was done for 14 days at the same sampling site in each of the four seasons of the year, in 2011. The SPMD-derived analyte amounts enabled the calculation of time-weighted averages of free dissolved waterborne levels of the contaminants. Concentrations ranged from 30.0 ng.l(-1) to 51.5 ng.l(-1) for PAHs, 38 pg l(-1) to 150 pg.l(-1) for PCBs, 9.2 to 10.4 ng.l(-1) for HCHs and 0.3 to 0.8 ng.l(-1) for DDTs, respectively. It was also noted that the winter season generally exhibited higher contaminant concentrations for most compounds studied, which likely reflects the seasonality of their atmospheric deposition. An attempt was also made to identify possible sources of PAH contaminants in the dam by examining PAH ratios. These diagnostic ratios were inclined towards pyrogenic sources of pollution, except for the winter season where both pyrogenic and petrogenic sources likely contribute to the contamination pattern.
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| 2. |
- Andersson, Lotta, et al.
(author)
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Use of participatory scenario modelling as platforms in stakeholder dialogues
- 2008
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In: Water S.A.. - 0378-4738 .- 1816-7950. ; 34:4, s. 439-447
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Journal article (peer-reviewed)abstract
- A participatory methodology, based on dialogues between stakeholders and experts has been developed and tested in the drainage area to Kaggebo Bay in the Baltic Sea. This study is focused on the EU Water Framework Directive, with emphasis on reduction of eutrophication. The drainage area is included in the WFD administrative area of the Motala Strom River basin. A similar approach is now applied in a recently initiated project in the Thukela River basin, with focus on impacts of climate change on water resources. The methodology is based on the idea that a catchment model serves as a platform for the establishment of a common view of present conditions and the causes behind these conditions. In the following steps, this is followed by model-assisted agreement on environmental goals (i.e. what do we want the future to look like?) and local agreement on a remedy or mitigation plans in order to reduce environmental impact (e. g. eutrophication); alternatively to adapt to conditions that cannot be determined by local actions (e. g. climate change). By involving stakeholder groups in this model-supported stepwise process, it is ensured that all stakeholder groups involved have a high degree of confidence in the presented model results, and thereby enable various actors involved to share a common view, regarding both present conditions, goals and the way to reach these goals. Although this is a process that is time-(and cost-) consuming, it is hypothesised that the use of this methodology is two-pronged: it increases the willingness to carry out remedies or necessary adaptations to a changing environment, and it increases the level of understanding between the various groups and therefore ameliorates the potential for future conflicts. Compared to traditional use of model results in environmental decision-making, the experts role is transformed from a one-way communication of final results to assistance in the various steps of the participatory process.
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| 3. |
- Eriksson, Eva, 1973-, et al.
(author)
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Household chemicals and personal care products as sources for xenobiotic organic compounds in grey wastewater
- 2003
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In: Water S.A.. - : Academy of Science of South Africa. - 0378-4738 .- 1816-7950. ; 29:2, s. 135-146
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Journal article (peer-reviewed)abstract
- Despite contributing 75% of the total wastewater flow to domestic sewers, little is currently known concerning the detailed production patterns and characteristics of grey wastewater. In this study, an inventory of the consumption of household chemicals including a diary survey of water-consuming activities was carried out over seven consecutive days in a block of flats. In total 290 parameters in 92 household chemicals were registered in the inventory in which 30 out of 38 tenants participated. The study was accompanied by quantitative analyses of selected parameters and a screening for organic components in grey wastewater. More than 190 individual components were identified by GC-MS. Identified substances were grouped into eight substance classes based on their application and their concentrations were semi-quantitatively assessed. Several fragrances like citronellol, hexyl cinnamic aldehyde and menthol as well as some preservatives, e.g. citric acid and triclosan, were identified. The measurements also showed that unwanted and unexpected compounds like drugs and pesticides could be present, as well as chemicals not directly deriving from household chemicals or personal care products, e.g. flame-retardants. The inventory provided detailed information about the consumption of various types of household chemicals, but no information on compound concentrations could be assessed due to the limited data in the list of contents of the household chemicals. It was shown that tracking of potentially toxic compounds used in households was possible.
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| 4. |
- Eriksson, Eva, 1973-, et al.
(author)
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Organic matter and heavy metals in grey-water sludge
- 2010
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In: Water S.A.. - : Academy of Science of South Africa. - 0378-4738 .- 1816-7950. ; 36:1, s. 139-142
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Journal article (peer-reviewed)abstract
- Grey-water intended for non-potable reuse is being intensively studied, but little attention has been given to the associated solid fraction, the grey-water sludge. In this study grey-water sludge originating from bathroom grey-water has been screened with respect to organic matter; particles; short-chain fatty alcohols and acids; selected metals and basic parameters as well as characterization of the organic matter content by oxygen utilization rate (OUR). The grey-water sludge contains metal loads comparable to Danish sewage sludge, and it exceeds the Danish quality criteria for spreading on agricultural land for cadmium and nickel. If dewatered and managed as soil it would be classified as ‘Class 3; polluted soil’ with respect to cadmium, copper and nickel. The OUR results indicate that the grey-water biological sludge contains an equivalent amount of readily degradable organic matter compared to municipal activated sludge. But it contains 35% more readily, and 90% more slowly, hydrolysable organic matter than municipal sludge.
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| 5. |
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| 6. |
- Hey, Gerly, et al.
(author)
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Removal of pharmaceuticals in WWTP effluents by ozone and hydrogen peroxide
- 2014
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In: Water S.A.. - : Academy of Science of South Africa. - 1816-7950 .- 0378-4738. ; 40:1, s. 165-173
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Journal article (peer-reviewed)abstract
- Ozonation to achieve removal of pharmaceuticals from wastewater effluents, with pH values in the upper and lower regions of the typical range for Swedish wastewater, was investigated. The main aim was to study the effects of varying pH values (6.0 and 8.0), and if small additions of H2O2 prior to ozone treatment could improve the removal and lower the reaction time. The effluents studied differed in their chemical characteristics, particularly in terms of alkalinity (65.3-427 mg center dot l(-1) HCO3-), COD (18.2-41.8 mg center dot l(-1)), DOC (6.9-12.5 mg center dot l(-1)), ammonium content (0.02-3.6 mg center dot l(-1)) and specific UV absorbance (1.78-2.76 l center dot mg(-1)center dot m(-1)). As expected, lower ozone decomposition rates were observed in the effluents at pH 6.0 compared to pH 8.0. When pH 8.0 effluents were ozonated, a higher degree of pharmaceutical removal occurred in the effluent with low specific UV absorbance. For pH 6.0 effluents, the removal of pharmaceuticals was most efficient in the effluent with the lowest organic content. The addition of H2O2 had no significant effect on the quantitative removal of pharmaceuticals but enhanced the ozone decomposition rate. Thus, H2O2 addition increased the reaction rate. In practice, this will mean that the reactor volume needed for the ozonation of wastewater effluents can be reduced.
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| 7. |
- Hey, T., et al.
(author)
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Evaluating 5 and 8 pH-point titrations for measuring VFA in full-scale primary sludge hydrolysate
- 2013
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In: Water S.A.. - : Academy of Science of South Africa. - 1816-7950 .- 0378-4738. ; 39:1, s. 17-22
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Journal article (peer-reviewed)abstract
- An evaluation of 5 and 8 pH-point titrimetric methods for determining volatile fatty acids (VFAs) was conducted, and the results were compared for tap water and primary treated wastewater at the laboratory scale. These techniques were then applied to full-scale primary sludge hydrolysate, and the results were compared with those obtained via gas chromatography. The comparison showed that the VFA concentrations measured with the two titration methods were higher than those obtained via gas chromatography, differing by 9 and 13 mg COD.l(-1) for the hydrolysate and by 5 and 6 mg COD.l(-1) for the ordinary primary settler effluent. No improvement in the accuracy of VFA concentration measurement was obtained from applying the 8 pH-point titration method instead of the 5 point method. The 5 pH-point method was successfully applied to determine VFA in full-scale primary sludge hydrolysate and was shown to be equally efficient to the methods that are routinely-used for this purpose.
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| 8. |
- Ismail, M, et al.
(author)
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Levels and Potential Health Hazards of Chlorinated Pesticidesin Surface Water Samples of Charsadda Area of Pakistan Using SPME-GC-ECD Technique
- 2021
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In: Water S.A.. - : MDPI. - 0378-4738 .- 1816-7950. ; 13, s. 1-14
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Journal article (peer-reviewed)abstract
- In the present study, we determined the levels of chlorinated pesticide residues in surfacewater samples collected from the Charsadda district (KPK, Pakistan). SPME-GC-ECD with COMBIPAL CTC autosampler was used for extraction and analysis of 20 organochlorine pesticides in thecollected water samples. For maximum efficiency of the SPME procedure, several parameters werestudied, including the extraction and desorption time of the fiber, solution pH, agitation of samples,and stirring speed, etc. This method showed good liner response, with R2 values in the range of0.9887 to 0.9999 for all pesticides. This method also provided good percent recoveries at 1 µg L−1(87.5to 106.0%) and at 2 µg L−1(88.5 to 109.2%). Lower limits of detection for all 20 chlorinated pesticideswere found to be lower than their maximum permissible contamination levels. Approximately 50%of the surface water samples collected from the Charsadda district were found to be contaminatedwith the pesticides γ-BHC, heptachlor, aldrin and dieldrin, with maximum concentrations of 0.023,0.108, 0.014 and 0.013 µg L−1, respectively. For adults and children, the cancer risk from water dueto contamination by various pesticides ranged from 0 to 33.29 × 10−6. The non-carcinogenic riskfrom each pollutant in the water samples of the Charsadda district was found to be in the order ofheptachlor > aldrin > dieldrin > γ-BHC. However, the pesticides α-BHC, β-BHC, heptachlor epoxide,chlordane, endrin, 4,40-DDD, endrin ketone, 4,40-DDT, endosulfan sulfate and methoxychlor werenot detected in any of the surface water samples of investigated in the present study.
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| 9. |
- Matsinhe, Nelson, et al.
(author)
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Water services with independent providers in peri-urban Maputo: Challenges and opportunities for long-term development
- 2008
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In: Water S.A.. - 1816-7950. ; 34:3, s. 411-420
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Journal article (peer-reviewed)abstract
- Water service delivery to most residents of peri-urban areas of greater Maputo depends largely on alternative service providers. mostly in the form of small-scale independent providers (SSIPs). This paper discusses the present and long-term challenges facing SSIPs in supplying quality water of sufficient quantity in peri-Urban Maputo and possible human health risks associated with the consumption of water provided by SSIPs. Extensive water sampling and analyses were conducted to evaluate the physicochemical and bacteriological quality of water provided by independent providers and the associated human health risks. Borehole pumping tests, the results of which were interpreted using the graphical method of Jacob, were used to evaluate the regional aquifer potential, the long-term impacts of its exploitation and the aquifer Vulnerability to external contamination. From the results of bore hole pumping tests it was concluded that the present yields are in average 33% lower than estimated safe yields and that larger than present yields therefore can be exploited. The aquifer Vulnerability to external contamination (e.g. by E. coli and nitrates) is low, mainly because of low hydraulic loads and the existence of a rather thick (10 to 30 m) sandy unsaturated stratum where bacteria die-off and biological denitrification probably Occurs. However, the aquifer vulnerability to sea sea-water intrusion is high. Currently, the health risks posed to Consumers relying on services provided by SSIPs are small; even so, 13 out of 35 controlled boreholes had either total coliform or faecal coli form levels higher than the WHO standard. In the long run SSIPs may face more serious water quality problems due either to over-exploitation of the aquifer system or increased hydraulic loads resulting from increased Population density.
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| 10. |
- Mosimane, Keotshephile, et al.
(author)
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Variability in chemistry of surface and soil waters of an evapotranspiration-dominated flood-pulsed wetland : Solute processing in the okavango delta, Botswana
- 2017
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In: Water S.A.. - : Academy of Science of South Africa. - 1816-7950 .- 0378-4738. ; 43:1, s. 104-115
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Journal article (peer-reviewed)abstract
- Water chemistry is important for the maintenance of wetland structure and function. Interpreting ecological patterns in a wetland system therefore requires an in-depth understanding of the water chemistry of that system. We investigated the spatial distribution of chemical solutes both in soil pore water and surface water, along island-floodplain-channel hydrological gradients in seasonally and permanently inundated habitats between major regions in the Okavango Delta, Botswana. Our results show that major cations (Ca, Na, Mg, and K), dissolved silica (DSi), dissolved boron (B), dissolved organic matter (DOC) and electrical conductivity increased significantly, at p ≤ 0.05, from the inlet of the Delta (the Panhandle) to the distal downstream reaches, suggesting the influence of evapoconcentration. Concentrations of dissolved Fe, Al, Zn, Cu, and Mn significantly decreased, at p ≤ 0.05, from the inflow of the Delta to the distal reaches. Only Na, Mn, Fe, Al, and DOC showed significant differences, at p ≤ 0.05, along the local floodplain-channel hydrological gradients, with higher solute concentrations in the floodplains than the channels. Solute concentrations in soil water exhibited similar distribution patterns to those in surface water, but concentrations were higher in soil water. Based on the results, we hypothesise that floodplain emergent vegetation and the channel-fringing vegetation in the Panhandle (a fault-bounded entry trough to the Delta) and the permanently inundated eco-region together influence the cycling of solutes that enter the Delta through uptake.
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