Effect of Activated Sludge Preservation on Its Adsorption Capacity in Treatment of Wastewater

Adsorption by activated sludge which plays a significant role in substrate removal has received a lot of recognition. A number of studies have been conducted into understanding this mechanism. However, the impact of activated sludge preservation on the adsorption capacity test results has not been documented. Live activated sludge is usually preserved after sampling to maintain the original sludge characteristics in order not to alter its adsorption capacity. Preservation of the sludge is relevant when the sludge has to be transported over long distances before adsorption experiments can be conducted. This paper seeks to present the effects of preservation of activated sludge on its adsorption capacity. The preservation methods considered were pre-aeration and cold-storage of the sludge. Sludge samples were pre-aerated for periods of 4 and 24 hours at room temperature and some were stored at 4?C for 6 hours. Adsorption batch experiments were then carried out on both fresh and preserved activated sludge samples. Glucose was used as an external substrate in these experiments. The results revealed a difference between the adsorption capacity of the fresh and preserved sludge samples. Sludge pre-aeration increased the adsorption capacity of the sludge. There was however, no significant difference in the adsorption capacities for 4h and 24h pre-aerated sludge samples. Adsorption capacity of the 6h cold-stored activated sludge was poor compared to that of the fresh sludge. Keywords: Activated sludge, Activated sludge preservation, Adsorption capacity, Glucos

Integration of Non-Motorized Transportation to Rosslyn and Ga-Rankuwa Corridor of Tshwane, South Africa

The requirements of sustainable transportation system are safety, affordability, accessibility and convenience. A sustainable transportation system connects various transport modes to enhance efficient movement. It is environmentally friendly and economical. The non-motorized transportation (NMT) may offer safe, efficient, economical and sustainable movements required if integrated with the transportation system. Walking begins and ends trips taken by public and private transportation means. The origin and destination of a journey cannot be completed except NMT is employed. However, NMT as a mode of transportation is yet to be adequately utilized to achieve sustainable transportation in the city of Tshwane. The main aim of this research is to determine the optimal transportation means by integrating NMT into the journey between Ga-Rankuwa and Rosslyn. The travel pattern obtained from trip studies of BMW staff between Rosslyn and Ga-Rankuwa was studied and juxtaposed with the integrated transport plan (ITP) and municipal housing survey (MHS) of Tshwane. A linear programming method called simplex technique was utilized for the determination of trip duration and trip cost from the origin-destination study results. The movement records of the BMW staff was optimized. A sensitivity analysis was conducted on the model and the results were evaluated. The result showed that taxi was the most patronized mode of transportation by the BMW staff between Rosslyn and Ga-Rankuwa corridors. The result also showed that the average trip cost of BMW workers from home to office is R18.47. Integration of cycling as a mode of transportation for short distance trips created 3 more trip patterns. When cycling was integrated to the rail transportation, 36% of the transportation cost was reduced. This work also showed that the subsisting trip method may still be used by less than 45% of the BMW staff while more than 55% of the staff may utilize the integration of cycling and train from home to office and vice versa. This research recommends that similar investigation should be done to other routes of economic importance in the City of Tshwane in order to encourage the integration of cycling into transportation from one place to another.

Ameliorating Traffic Congestion and Impact on Climate Change with Park and Ride Transport

Traffic congestion occur as more vehicles ply the road and result in reduced travel speed, increased travel time, unnecessary queuing, obstruction on travel path and impediment to traffic flow. Thirteen per cent of greenhouse gases (GHG) emitted are caused by the transportation system which continues to grow. Fume emanating from vehicles contributes greatly to the emission of GHG. Park and Ride was investigated within the Central Business District (CBD) of Tshwane with a view to improving the traffic congestion and reducing the effects of GHG on the climate. Traffic counts and questionnaires distribution were done on the major access routes to the CBD. The quantities of carbon dioxide (CO2) emitted by traffic and that would be reduced when park and ride system is implemented in the City of Tshwane Metropolitan Municipality (CTMM) were determined. Results of traffic volume counts showed high dependence of more than 70% of people on passenger cars as the mode of transit within the study area. It also revealed that almost 89% of the interviewed population are delayed by traffic, on their way to the work place in the morning. Fifty-four per cent of the people interviewed showed readiness to utilize the park and ride facility if their safety and security would be guaranteed. Furthermore the study showed that 96.2% of CO2 emitted could be reduced by the implementation of the park and ride system on the A Re Yeng BRT and also in the major cities of Tshwane

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

Use of Sustainable Materials in Self-Healing Concrete

Vulnerability to cracks is one of the major flaws of concrete infrastructure. The need to reduce the repair cost of this defect birthed the need for self-healing concrete. The incidence of cracks on concrete structures is a big threat to the stability of bridges, concrete roads, and other concrete infrastructures. This review assessed the use of self-healing technology on concrete using sustainable material as an active method of healing crack. This was done with the view of improving the stability, strength, and sustainability of infrastructure for national growth. The outcome of the review showed three prominent methods used in self-healing technology, which include autogenous healing, encapsulation of polymeric material, and microbial production of calcium-carbonate (biotechnological approaches). The review also revealed that calcium carbonate is a versatile material that can be used in crack healing for the filling of voids and improves the porosity of the concrete. The success of using the autogenous healing method depends on the diameter of the crack induced in the concrete structure. Additionally, this method can operate independently in different conditions regardless of the crack position. Correspondingly, lowering the water-cement ratio improves the autogenous healing process. The use of encapsulation of polymeric material and microbial production of calcium-carbonate methods showed that the presence of water and humidity is a critical factor to be considered. However, biotechnology using microbial action is prone to the production of ammonium ions (NH4+) through ureolytic activity, which results in nitrogen oxide emission into the atmosphere. Congruently, this may affect the durability of the concrete. Based on the uniqueness of this technology, it is recommended for the construction of sustainable infrastructure now and in the foreseeable future

Treatment potential of Typha latifolia in removal of heavy metals from wastewater using constructed wetlands

The objective of the study was to evaluate the phytoremediation potential of the aquatic macrophyte Typha latifolia for removal of cadmium, chromium and lead from synthetic wastewaters in constructed wetlands (CW). Four laboratory scale CW units were set up, each containing granite and soil. Typha latifolia was planted in the 1st unit then intercropped with Vetiveria zizanioides, Phragmites australis and Cyperus latifolius in the 2nd, 3rd and 4th unit respectively. The units were treated to wastewaters of different metal concentrations and metal combinations. Wastewater was sampled at different retention periods. Results showed substantial reduction in metal concentrations. Metals were removed in the order Cr>Cd>Pb with maximum removal efficiencies being 96.36±0.52%, 95.70±1.26% and 80.59±3.58% for Cd, Cr and Pb respectively in the typha only units. The percentage removal of the metals increased with increase in retention time. This study recommends application of Typha latifolia in treatment of industrial and mine wastewater

A study of the influence of coarse aggregate shape characteristics on permanent deformation of asphalt mixes.

Paper presented at the 32nd Annual Southern African Transport Conference 8-11 July 2013 "Transport and Sustainable Infrastructure", CSIR International Convention Centre, Pretoria, South Africa.The effect of aggregate shape properties such as angularity, texture, sphericity, roundness, flat and elongation on the performance of asphalt mixes have not been thoroughly investigated using direct measurement techniques. This is partly because aggregates do not have regular shapes, and it is a daunting task to accurately determine these properties. In this paper, three types of aggregates are used to produce asphalt mixes in order to study the effect of coarse aggregate shape properties on the permanent deformation. A modern three-dimensional (3-D) laser scanning device available at the Council for Scientific and Industrial Research (CSIR) in South Africa was used to directly obtained shape properties of the aggregates. Permanent deformation tests were conducted in the laboratory on three different mixes produced from the aggregates to compare performance. It was found that the three asphalt mixes have different resistance to permanent formation. The aggregates with high surface texture and angularity improve resistance to permanent deformation of the asphalt mix when compared with those with more rounded or spherical shapes.This paper was transferred from the original CD ROM created for this conference. The material was published using Adobe Acrobat 10.1.0 Technology. The original CD ROM was produced by Document Transformation Technologies Postal Address: PO Box 560 Irene 0062 South Africa. Tel.: +27 12 667 2074 Fax: +27 12 667 2766 E-mail: nigel@doctech URL: http://www.doctech.co.zamv201

Assessment of Spatial Variation of Groundwater Quality in a Mining Basin

Assessment of groundwater quality is vital for the sustainable safe use of this inimitable resource. However, describing the overall groundwater quality condition—particularly in a mining basin—is more complicated due to the spatial variability of multiple contaminants and the wide range of indicators found in these areas. This study applies a geographic information system (GIS)-based groundwater quality index (GQI) to assess water quality in a mining basin. The study synthesized nine different water quality parameters available—nitrate, sulphate, chloride, sodium, magnesium, calcium, dissolved mineral solids, potassium, and floride (NO−, SO2−, Cl−, Na+, Mg2+, Ca2+, DMS, 34 K+ and F−)—from 90 boreholes across the basin by indexing them numerically relative to the World Health Organization standards. The study compared data from 2006 and 2011. The produced map indicated a lower GQI of 67 in 2011 compared to 72 in 2006. The maximum GQI of 84.4 calculated using only three parameters (Mg2+, K+ and F−) compared well with the GQI of 84.6 obtained using all nine parameters. A noticeable declining groundwater quality trend was observed in most parts of the basin, especially in the south-western and the northern parts of the basin. The temporal variation between the GQIs for 2006 and 2011 indicated variable groundwater quality (coefficient of variation = 15–30%) in areas around the mining field, and even more variability (coefficient of variation >30%) in the south-western and eastern parts of the basin

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