Cyanobacterial Incident Management Frameworks (CIMFs) for application by drinking water suppliers

Cyanobacteria are commonly found in freshwater systems that are the source waters for the production of drinking water. This is of special importance to the drinking water suppliers as several genera of cyanobacteria can produce cyanotoxins that can affect human health. The possibility that drinking water can be a cyanobacterial-exposure route has resulted in the development of Cyanobacterial Incident Frameworks (CIMFs) that will guide water treatment managers to deal pro-actively with cyanobacteria and their associated toxins in source water by using a step-by-step alert levels framework to ensure provision of safe drinking water. In this paper two CIMF models are described, namely a CIMF model using cyanobacteria identification and enumeration as a primary trigger; and a CIMF model using chlorophyll a as primary trigger. These frameworks are based on the same principle, but differ in minor actions taken, especially at the lower alert levels. It is envisaged that the developed CIMFs would be the platform on which to evaluate the capacity to manage a cyanobacterial incident. Based on the requirements stipulated in the CIMFs and their assessment, the drinking water treatment works (DWTW) would then develop and implement their customised CIMFs.Keywords: cyanobacteria, Cyanobacterial Incident Management Framework (CIMF), drinking water, drinking water treatment works (DWTW), alert level

A methodology for undertaking freshwater fish chemical contaminant surveys for human health risk assessment

Thesis (M.Sc.)--Potchefstroom University for Christian Higher Education, 2001.In South Africa the pollution of freshwater aquatic systems can be linked to point source discharges (waste water treatment works and industrial effluents) and diffuse surface runoff (agricultural, mining and urban). As a result of these anthropogenic activities, innocent people as well as other life forms may be exposed to harmful contaminants, which may be released without adequate consideration of human health and the environmental effects. Studies have shown that when people are exposed to surface water contaminants through contact recreation, drinking water and the consumption of contaminated food their health may be affected. Although the consumption of fish is generally beneficial to people (good source of protein, vitamins, omega fatty acids and basic minerals) consumers of fish are potentially at risk as fish have the potential to bioaccumulate contaminants from the aquatic environment that pose carcinogenic, genotoxic and non-carcinogenic health risks to them. As a result of the potential health risk associated with the consumption of chemical contaminated non-commercially caught fish, the United States of America Environmental Protection Agency (US EPA) has developed a series of four guiding documents for issuing fish consumption advisories. The fish consumption advisories are designed to reduce the risk to fish consumers by providing information that would lead to the voluntarily restriction of fish consumption to levels that pose limited, if any risk. A review of the published literature revealed that several surveys were undertaken in South Africa to investigate chemical contaminants in freshwater fish. Most of these studies were aimed at contributing to the assessment of the health of the aquatic ecosystem under investigation as they focused on species and tissue differences in contaminant bioaccumulation as well as the spatial and temporal variation in contaminant concentrations. The health risks to humans when consuming contaminated fish are seldom addressed. Furthermore, no standard methodology as for example suggested by the US EPA was followed by the different investigations. This shortcoming limits comparison of data from different studies and prevents accurate determination of risk based fish consumption limits for humans. To address this limitation the general objective of this dissertation is to develop a generic methodology that would give guidance in the undertaking offish contaminant surveys to provide information regarding the possible health risk if the fish are consumed by recreational and subsistence fisherman. Furthermore, the methodology would also give guidance to surveys investigating the chemical contamination offish for ecosystem health assessment programmes. The fundamentals of the methodology are based on catchment information (possible anthropogenic activities that can result in chemical pollution), socio-demographic information of consumers of freshwater fish in the catchment, bioaccumulation potential and health risks of analytes, sound sampling design, risk assessment procedures and performing monitoring at different scales and depth. The methodology identifies ten major steps, namely: (i) selection of scale and depth of survey, (ii) assessment of the waterbody catchment, (iii) monitoring system design, (iv) field collection, (v) laboratory sample processing and analysis, (vi) analysis of and reporting of results, (vii) risk assessment, (viii) risk management, (ix) risk communication and (x) evaluation and review of the programme which are discussed to provide guidance to governmental authorities at national or provincial level and project managers. The basic requirements of each step are highlighted as limited resources (financial, infrastructure and skilled personnel) in South Africa would limit the possibility of undertaking detailed assessments as undertaken by the United States of America Environmental Protection Agency (US EPA). Nevertheless, by applying the proposed methodology, sound comparable assessments, based on risk assessment methodology, can be made regarding the human health risk associated with the consumption of freshwater fish in South Africa. The study on the Vaal River Barrage Reservoir and the Klip River indicated that there is potential metal health risks (mainly nickel related) associated with the daily consumption of fish from this system. The finding of this study therefore supports the viewpoint that by monitoring the chemical contaminant levels in freshwater fish and applying a risk-based approach valuable information regarding the possible health risk to the consumers of fish (especially to recreational and subsistence fisherman) can be obtained. These surveys also identify areas in the aquatic system where aquatic life and especially fish have unacceptable chemical contaminant levels due to anthropogenic activities in the catchment. This information can thus be used in catchment management programmes and thereby contribute to the management of the catchments in South Africa. From the foregoing it is evident that by following and implementing the methodology proposed in this dissertation a major contribution would be made towards the protection of the consumers of freshwater fish as well as to the protection the of freshwater aquatic environment. These studies are therefore essential for achieving the ultimate goal of ensuring that the fish populations are fit for present and future human consumption. As the Department of Water Affairs and Forestry is the custodian of freshwater systems in South Africa, the monitoring of chemical contaminant levels in fish according to the proposed methodology should be implemented and managed by the Department in collaboration with other governmental organisations and the Catchment Management Agencies.Master

Assessing the genotoxic potential of wastewater effluents from three wastewater treatment plants in South Africa

Wastewater treatment plants are mainly monitored for quality in terms of their biological oxygen demand and microbiological constituents as stipulated in the specific discharge permit. Wastewater influents and effluents were taken from three WWTPs in South Africa over the summer and winter seasons. Previous toxicity tests such as the Vibrio fischeri bioluminescence assay and the Selenastrum capricornutum algal growth inhibition test have shown that the effluents displayed acute toxicity. To further investigate the quality of the effluent, the genotoxic potential was determined using the SOS Chromosome and UMU Chromosome test. The SOS Chromotest demonstrated induction factor values of above 1.5 for influents during both seasons indicating that the influents were genotoxic (p < 0.05). Effluents discharged during winter and summer also had induction factors greater than 1.5 (p < 0.05). A range of induction factors was detected with the UMU-Chromotest for influents and effluents (1.98 ± 0.38 and 2.40 ± 0.51, respectively). Findings show point sources in the area can lead to influents and effluents that are potentially genotoxic. Designing a monitoring programme that encompasses testing of both the regulatory determinants with additional specialized tests can provide a more holistic view of wastewater quality and the efficiency of WWTP to reduce the discharge of hazards. HIGHLIGHTS Wastewater treatment plants are unable to remove genotoxic compounds present in effluents.; Wastewater treatment plants are poorly maintained and have failing infrastructure, consequently the discharge of untreated effluents into the environment.; Wastewater treatment plant managers should look at alternative methods of testing other than conventional methods in order to provide a holistic water quality.; The UMU-C test and the SOS Chromotest are relatively easy assays that can be used to determine.; Seasonal differences of the presence of genotoxic compounds in effluents can be seen.

A baseline study on the prevalence of microplastics in South African drinking water: from source to distribution

Due to the worldwide increasing prevalence of microplastics in the aquatic environment, this study aimed to perform a screening of the source and drinking water of South Africa’s largest bulk drinking water supplier to determine the extent to which microplastics occur in the water. Source water samples, samples immediately after treatment, and samples in the distribution network (Johannesburg, Mabopane, Garankua and Pelindaba) were analysed. Microplastics concentrations in the source water ranged from 0.24 to 1.47 particles/L, immediately after treatment from 0.56 to 0.9 particles/L, and in the distribution network from 0.26 to 0.88 particles/L. Most of the microplastics found in the water were classified as ‘fragments’ and a few as ‘fibres’. The control sample (indicating contamination during sample preparation and analysis) showed 0.34 particles/L, which was higher than some of the samples taken, indicating very low microplastics concentrations in these samples. Little evidence was found that the drinking water treatment processes reduced the number of microplastics from the source to the final treated water. No evidence could be found that the pipes in the distribution network contribute to microplastics in the tap water. The most frequently found polymer in the samples was rubber. Based on mass, however, as a function of particle size and polymer density, ethylene-vinyl-acetate (a polymer commonly used as foam in sporting equipment and flip-flops) comprised 54% of the microplastics and polyethylene (standard and chlorinated) 25%

Structural and elastic properties of binary FCC Pt-Rh alloys – a first-principles study

Alloying Pt with Rh significantly enhances the high temperature stress rupture strength and maintains both oxidation and corrosion resistance at elevated temperatures. Such unique property combination renders Pt-Rh alloys mainstay in space technology, glass and chemical industries. However, the exponential increase in the price of Rh in the past few years stirs an industrial concern. As a result, some industries are beginning to search for alternative alloys that can offer similar properties. This study conducted first-principles calculations to generate structural and elasticity data on binary Pt-Rh alloys using both supercell and virtual crystal approximation (VCA) approaches, to serve as a benchmark for new alternative Pt-based alloys

Long-term spatial and temporal microbial community dynamics in a large-scale drinking water distribution system with multiple disinfectant regimes

Long-term spatial-temporal investigations of microbial dynamics in full-scale drinking water distribution systems are scarce. These investigations can reveal the process, infrastructure, and environmental factors that influence the microbial community, offering opportunities to re-think microbial management in drinking water systems. Often, these insights are missed or are unreliable in short-term studies, which are impacted by stochastic variabilities inherent to large full-scale systems. In this two-year study, we investigated the spatial and temporal dynamics of the microbial community in a large, full scale South African drinking water distribution system that uses three successive disinfection strategies (i.e. chlorination, chloramination and hypochlorination). Monthly bulk water samples were collected from the outlet of the treatment plant and from 17 points in the distribution system spanning nearly 150 km and the bacterial community composition was characterised by Illumina MiSeq sequencing of the V4 hypervariable region of the 16S rRNA gene. Like previous studies, Alpha- and Betaproteobacteria dominated the drinking water bacterial communities, with an increase in Betaproteobacteria post-chloramination. In contrast with previous reports, the observed richness, diversity, and evenness of the bacterial communities were higher in the winter months as opposed to the summer months in this study. In addition to temperature effects, the seasonal variations were also likely to be influenced by changes in average water age in the distribution system and corresponding changes in disinfectant residual concentrations. Spatial dynamics of the bacterial communities indicated distance decay, with bacterial communities becoming increasingly dissimilar with increasing distance between sampling locations. These spatial effects dampened the temporal changes in the bulk water community and were the dominant factor when considering the entire distribution system. However, temporal variations were consistently stronger as compared to spatial changes at individual sampling locations and demonstrated seasonality. This study emphasises the need for long-term studies to comprehensively understand the temporal patterns that would otherwise be missed in short-term investigations. Furthermore, systematic long-term investigations are particularly critical towards determining the impact of changes in source water quality, environmental conditions, and process operations on the changes in microbial community composition in the drinking water distribution system.Rand Water, Gauteng, South Africa through the Rand water Chair in Water Microbiology at the University of Pretoria. Sarah Potgieter would also like to acknowledge the National Research Foundation (NRF) for additional funding.http://www.elsevier.com/locate/watres2019-08-01hj2018Microbiology and Plant Patholog

A simplified analytical procedure for simultaneous determination of alkylphenol ethoxylates and brominated flame retardants in fish tissue samples from Vaal River, South Africa.

In this study, the concentration of alkylphenol ethoxylates (APEs) and brominated flame retardants (BFRs) were determined in fish samples, Labeo umbratus and Carp, collected from the Vaal River in South Africa. Ultrasonic-assisted extraction technique was used to extract the organic contaminants from fish samples, and the resulting extract was purified by sulphuric acid lipid removal followed by Strata X-cartridge SPE clean-up. The APEs and BFRs were derivatized using heptafluorobutyric anhydride before analysis with GC-MS. In both types of fish samples, lower oligomers of APEs were more abundant than the higher oligomers, while HBCD, BDE99 and PBB101 were the dominant BFRs. The concentrations of these pollutants ranged from 1.061 ng/g lipids (t-BP) in Labeo umbratus to 11.860 ng/g lipids (HBCD) in Carp