Analysis of auto-purification response of the Apies River, Gauteng, South Africa, to treated wastewater effluent

The assimilative capacity of water bodies is an important factor in the integrated management of  surface water resources. The current study examined the auto-recovery processes of the Apies River from wastewater discharged into it from a municipal wastewater treatment facility, using a series of equations, including the modified Streeter-Phelps equation. Field data obtained include dissolved oxygen (DO), temperature, stream velocity, depth, and width. Water samples were also obtained at 10 sampling stations for the determination of biochemical oxygen demand (BOD) using standard methods. It was observed that the DO and BOD level (5.59 mg/L and 8.5 mg/L respectively) of the effluent from the wastewater treatment facility indicated better water quality than the Apies River background DO level (5.42 mg/L) and BOD level (13 mg/L). Also, at 270 m downstream of the effluent discharge point, another effluent stream (Skinnerspruit) adversely impacted on the Apies River with DO and BOD levels of 6.5 mg/L and 9.0 mg/L, respectively, compared to the Apies River background values of 6.81 mg/L and 8.0 mg/L, respectively. The stream, however, recovered well from both the background and imposed pollution sources as it had a computed positive auto-recovery factor of 1.74. Furthermore, the measured DO deficit was plotted against predicted DO deficit. The plot revealed a close match between the measured and predicted DO deficit, indicating that the model could be used for predicting DO deficit along other segments of the river. To further improve on the natural  auto-recovery processes of the Apies River, it was recommended that flow along the Skinnerspruit should be enhanced by clearing the observed aquatic plants growing within the channel. Also,  suspected pollution activities taking place further upstream on the Apies River should be investigated and appropriately addressed.Keywords: de-oxygenation; re-aeration; auto-purification; dissolved oxygen; biochemical oxygen  demand; strea

Recommendations for dealing with waste contaminated with Ebola virus: a Hazard Analysis of Critical Control Points approach

Objective To assess, within communities experiencing Ebola virus outbreaks, the risks associated with the disposal of human waste and to generate recommendations for mitigating such risks. Methods A team with expertise in the Hazard Analysis of Critical Control Points framework identified waste products from the care of individuals with Ebola virus disease and constructed, tested and confirmed flow diagrams showing the creation of such products. After listing potential hazards associated with each step in each flow diagram, the team conducted a hazard analysis, determined critical control points and made recommendations to mitigate the transmission risks at each control point. Findings The collection, transportation, cleaning and shared use of blood-soiled fomites and the shared use of latrines contaminated with blood or bloodied faeces appeared to be associated with particularly high levels of risk of Ebola virus transmission. More moderate levels of risk were associated with the collection and transportation of material contaminated with bodily fluids other than blood, shared use of latrines soiled with such fluids, the cleaning and shared use of fomites soiled with such fluids, and the contamination of the environment during the collection and transportation of blood-contaminated waste. Conclusion The risk of the waste-related transmission of Ebola virus could be reduced by the use of full personal protective equipment, appropriate hand hygiene and an appropriate disinfectant after careful cleaning. Use of the Hazard Analysis of Critical Control Points framework could facilitate rapid responses to outbreaks of emerging infectious disease

Sustainable Living in Africa: Case of Water, Sanitation, Air Pollution and Energy

The study reviewed developmental challenges confronting African countries with specific reference to the availability of potable water, sanitation, energy, water and ambient air. It showed the conflict between the need to exploit environmental capital in order to keep up with the pace of human development activities and the need to utilize resources sustainably. Hitherto, the cost of this development has been at the expense of public health and cleaner environment. The outcome demonstrates the need for a change of approach in the way and manner that environmental resources are exploited for developmental purposes. Two concepts for addressing these problems were discussed. These are the “soft path” approach and the trialog model. The former places high priority on the proper use and management of existing infrastructure or resources rather than acquisition or exploitation of more infrastructure or resources. The latter concept addresses the principle of resource governance through the application of an understanding of the complex relationship between the main stakeholders—government, science, and society. Case studies on the practicality of these concepts were also highlighted and discussed

Hydrological Responses to Land Use/Cover Changes in the Olifants Basin, South Africa

This paper discusses the hydrological impacts of land use changes on the Olifants Basin in South Africa using the Soil and Water Assessment Tool (SWAT). A three-phase land use scenario (2000, 2007 and 2013) employing the “fix-changing” method was used to simulate the hydrology of the Olifants Basin. Changes in land uses were related to different hydrological responses through a multi-regression analysis to quantify the effects of land use changes. Results reveal that from 2000 to 2013, a 31.6% decrease in rangeland with concomitant increases in agriculture lands (20.1%), urban areas (10.5%) and forest (0.7%) led to a 46.97% increase in surface runoff generation. Further, urbanization was revealed as the strongest contributor to increases in surface runoff generation, water yield and evapotranspiration (ET). ET was found to be a key water availability determinant as it has a high negative impact on surface runoff and water yield. Urbanization and agriculture were the most essential environmental factors influencing water resources of the basin with ET playing a dominant role. The output of the paper provides a simplistic approach of evaluating the impacts of land use changes on water resources. The tools and methods used are relevant for policy directions on water resources planning and adaptation of strategies

Experimental Investigation on the Effect of Elevated Temperature on Compressive Strength of Concrete Containing Waste Glass Powder

This study examines the effect of elevated temperature on the strength of concrete containing glass powder (GWP) as Ordinary Portland cement replacement. The cement was partially replaced by 0, 15, 18, 21, 24, 27 and 30 % of GWP and samples were prepared at constant water-binder ratio of 0.5. The cube samples after curing in water for 90 days were exposed to 60, 150, 300 and 500°C temperatures increased at a heating rate of 10°C/min. Compressive strength values were measured on unheated samples and after air-cooling period of the heated samples. Scanning electron microscope (SEM) was carried out on selected samples to examine alterations in the matrix and interface. The results indicate a decrease in the compressive strength with increasing temperature, and significant alteration was observed in the concrete matrix and interface from the SEM analyses. However, the results indicate that concrete samples containing 21% GWP exhibit higher strength compared to control

Simulation of Sediment Yield in a Semi-Arid River Basin under Changing Land Use: An Integrated Approach of Hydrologic Modelling and Principal Component Analysis

Intensified human activities over the past decades have culminated in the prevalence of dire environmental consequences of sediment yield resulting mainly from land use changes. Understanding the role that land use changes play in the dynamics of sediment yield would greatly enhance decision-making processes related to land use and water resources management. In this study, we investigated the impacts of land use and cover changes on sediment yield dynamics through an integrated approach of hydrologic modelling and principal component analysis (PCA). A three-phase land use scenario (2000, 2007 and 2013) employing the “fix-changing” method was used to simulate the sediment yield of the Olifants Basin. Contributions in the changes in individual land uses to sediment yield were assessed using the component and pattern matrixes of PCA. Our results indicate that sediment yield dynamics in the study area is significantly attributed to the changes in agriculture, urban and forested lands. Changes in agriculture and urban lands were directly proportional to sediment yield dynamics of the Olifants Basin. On the contrary, forested areas had a negative relationship with sediment yield indicating less sediment yield from these areas. The output of this research work provides a simplistic approach of evaluating the impacts of land use changes on sediment yield. The tools and methods used are relevant for policy directions on land and water resources planning and management

Data-Based Mechanistic Modeling of Flow-Concentration Dynamics of Non-Point Source Pollution: A Case of Upper Vaal Water Management Area

This study aimed at applying the Data Based Mechanistic (DBM) modelling approach to develop a simple, parsimonious and discernable Flow-Concentration (F-C) model that can be partitioned into the various identifiable pathways associated with the pollutant at the catchment scale. An attempt was made to model the occurrence of acid mine drainage (AMD) in the Vaal River by using an indicator water quality parameter (sulphate concentration). The optimal Instrumental Variable (IV) methods of identifying and estimating discrete and continuous-time transfer function models as implemented in the CAPTAIN MATLAB® Toolbox were applied to the time series data in order to identify the appropriate model. A discernable F-C model was developed of three parallel pathways: the “quick-route” depletion pathway with a residence time months; a “slow-route” build-up pathway with a residence time months and a direct term component pathway regressed in 9 months. The resulting model showed that it is possible to use the DBM modelling approach to address the problem of representing the potential lag between polluting activity and its effect as well as provide more salient information about the system dynamics. This kind of information (i.e. the residence times and the advective time delays in the system) could prove useful for the catchment managers in making informed decisions including laying out remediation measures. Keywords: Flow-Concentration Modelling, Non-Point Source Pollution, Data Based Mechanistic Modelling, Transfer Function models, Water Quality, Flow Pathway

A Quantitative Groundwater Resource Management under Uncertainty Using a Retrospective Optimization Framework

Water resources are a major concern for any socio-economic development. As the quality of many surface fresh water sources increasingly deteriorate, more pressure is being imparted into groundwater aquifers. Since groundwater and the aquifers that host it are inherently vulnerable to anthropogenic impacts, there is a need for sustainable pumping strategies. However, groundwater resource management is challenging due to the heterogeneous nature of aquifer systems. Aquifer hydrogeology is highly uncertain, and thus it is imperative that this uncertainty is accounted for when managing groundwater resource pumping. This, therefore, underscores the need for an efficient optimization tool which can sustainably manage the resource under uncertainty conditions. In this paper, we apply a procedure which is new within the context of groundwater resource management—the Retrospective Optimization Approximation (ROA) method. This method is capable of designing sustainable groundwater pumping strategies for aquifers which are characterized by uncertainty arising due to scarcity of input data. ROA framework solves and evaluates a sequence of optimization sub-problems in an increasing number of realizations. We used k-means clustering sampling technique for the realizations selection. The methodology is demonstrated through application to an hypothetical example. The optimization problem was solved and analyzed using “Active Set” algorithm implemented under MATLAB environment. The results indicate that the ROA sampling based method is a promising approach for optimizing groundwater pumping rates under conditions of hydrogeological uncertainty

Improving the Bearing Strength of Sandy Loam Soil Compressed Earth Block Bricks Using Sugercane Bagasse Ash

The need for affordable and sustainable alternative construction materials to cement in developing countries cannot be underemphasized. Compressed Earth Bricks have gained acceptability as an affordable and sustainable construction material. There is however a need to boost its bearing capacity. Previous research show that Sugarcane Bagasse Ash as a soil stabilizer has yielded positive results. However, there is limited research on its effect on the mechanical property of Compressed Earth Brick. This current research investigated the effect of adding 3%, 5%, 8% and 10% Sugarcane Bagasse Ash on the compressive strength of compressed earth brick. The result showed improvement in its compressive strength by 65% with the addition of 10% Sugarcane Bagasse Ash