Municipal solid waste utilisation for green energy in Gauteng province - South Africa : a review

This short paper discusses the potential of utilizing various municipal solids waste streams as feed stock for green energy production. These waste streams includes but not limited to mixed combustible waste, rubber and plastic waste, health care risk waste, organic biodegradable waste, biomass and sewage sludge. Technologies such as anaerobic digestion, gasification and pyrolysis have been reviewed relative to the location and waste stream quantities in the selected sample area. It was discovered that there are environmental, social and economic benefits in waste to energy approach for the waste streams reviewed. The feasibility of implementing such technologies is mainly dependent on the initial capital investment and operational cost of the facility. Other factors include the size of the waste stream, product price and demand

Alkenes - ester polymeric solvents thermodynamic interactions - Part 1

This work focused on the interactions between ester solvents and volatile organic compounds of alkene in nature. Infinite dilution activity coefficients of alkenes in various fatty acid ester solvents were predicted in order to study and thermodynamically understand the nature and effect of the bond interactions involved. Activity coefficients were computed using Microsoft Excel model specifically designed for this purpose. The ester solvent chain length and saturation influenced the solubility of alkene organics. Saturated and longer ester chains gave better absorption performance. Alkenes were found to be more soluble than their alkane counterparts of similar carbon count

The effect of degrading agents and diluents on oil recovery from lithium based waste lubricating grease

In this study, the recovery of base oils from waste lithium based lubricating grease was investigated using a novel combination of thermal degradation in an aqueous caustic solution and solvent extraction. Lubricating grease is an important resource that cannot be disposed of randomly due to the presence of pollutants. In response to economic challenges and environmental protection, there is a growing trend to regenerate and reuse waste lubricant. Waste grease was initially dissolved in a 20 w/w% KOH solution at 80oC while being agitated for a period of 15 min. Two distinct layers were observed after 10 min of settling time. The top layer being of dark brown oil and the bottom layer was a heterogeneous mixture. The two layers were separated by decantation. The bottom layer was cooled to 45oC followed by slow addition of n-hexane while agitating to prevent the settling of solids. Two distinct layers were also formed, the top homogeneous mixture of light brown oil–toluene mixture and the bottom sludge layer. This research has further optimized the process by studying the effect of KOH concentration to enhance flocculation and recovery of oil. Oil recovery increased from 5% to 30%. The recovery also increased with an increase of solvent-togrease ratio up to 1:6. A solvent recovery of 82.6% to 88% by mass was obtained through fractional distillation. The overall oil recovery from waste grease using the combined extraction processes was 75 w/w%

Alkenes - ester polymeric solvents thermodynamic interactions - part 2

This paper is a continuation of our work reported previously [1] on the interaction between ester solvents and alkene volatile organic compounds (VOCs). The interactions were presented inform of infinite dilution activity coefficients. A Microsoft Excel spreadsheet for the modified UNIFAC Dortmund group contribution method [2] was designed and used in computing the required phase equilibrium. The size of the solvent molecule (biodiesel) relative to the VOC molecule influenced the thermodynamic interactions. The degree of ester (biodiesel) bond saturation influenced the ease in which cyclic VOCs interacted with the solvent compared to their straight chain counterparts. The location of branches such as methyl branches in relation to the double-bonded carbons had an impact on the predicted infinite dilution activity coefficients

Tyre derived fuel as an alternative fuel for CI engines

The study presented in this article investigated the potential use of tyre derived fuel-diesel blends as an alternative low cost fuel for compression ignition engines. A short review was conducted on waste tyre pyrolysis technology and its benefits in addressing the waste tyre management while providing an alternative usable fuel for diesel engines. Crude oil obtained from slow pyrolysis of waste tyres was distillated and its respective fractions were characterized and blended with low sulphur diesel fuel for fuelling a stationery truck engine linked to a hydraulic dynamometer. The test results revealed that fuel fraction blends with low sulphur diesel can be used to fuel a conventional compression ignition engine, however special attention is required to manage the exhausts emission due to high concentration of sulphur dioxide. There is no doubt that tyre derived fuel has a potential as future alternative fuel for compression ignition engines

Intermolecular dynamics between aromatic compounds and ester polymeric solvents

This work focused on the interactions that occur between ester solvents and simple aromatic solutes. Solutes were selected from various functional groups in their simplest form, and predictions of activity coefficients at infinite dilution were made using the Modified UNIFAC Dortmund group contribution model. The model computation was set up on a Microsoft Excel spreadsheet specifically designed for this purpose. For polar aromatic solutes, solubility decreased with increase in size of the ester solvent molecule and the opposite was found to be true for non-polar solutes. For all aromatic/ ester solvent interactions there was a decrease in activity coefficients with an increase in the degree of ester unsaturation

Reduction of vehicle exhaust emissions from diesel engines using the whale concept filter

In this work, the effect of using a Whale filter on the overall vehicle exhaust emissions was evaluated. A Whale filter is a South African patented diesel particulate filter designed to operate as a secondary diesel filter for the removal of particulate contaminants up to 0.5 microns in size in the fuel prior to injection. It is believed that removal of contaminants prior to injection may improve the fuel injection efficiency, thereby promoting efficient combustion, and thus resulting in reduced emissions and fuel consumption. Emissions tests were conducted on four different vehicle categories to validate this. All vehicles underwent pre-emissions testing prior to installation of the Whale filter. Each test was conducted for a period of approximately 20 minutes by varying the engine speed. The Applus + Autologic Vehicle Emissions Analyser was used to measure the emissions at each stage, and a similar procedure was followed to measure the emissions after installation of the Whale filter. The results showed a significant average reduction in carbon monoxide CO (35.3%), nitrogen oxides NOx (26.1%) and hydrocarbons HC (34.3%) emissions after the Whale filter was installed in the four vehicles

A comparison of waste lubricating oil treatment techniques

Waste lubricating oil is a resource that cannot be disposed of randomly due to the presence of pollutants. In response to economic problems and environmental protection, there is a growing trend to regenerate and reuse waste lubricants [1]. The recovery techniques discussed in this paper are reprocessing, rerefining and incineration of waste lubricating oil. The major objective of this paper is to analyze and compare the regenerative technologies, thus creating the foundation for government, the private sector and other stakeholders in policy formation and selection of recovery techniques

Foreign Direct Investment and Economic Growth in South Africa: A Vector Error Correction (VEC) Model Approach

The objective of this research study was to examine the influence of foreign direct investment on economic growth in South Africa during the period 1994-2014. Time series annual data on real gross domestic product (GDP) growth, foreign direct investment, and terms of trade were sourced from the South African Reserve Bank (SARB) historical macroeconomic statistics online database. Unit root and cointegration properties of data were analysed using Augmented Dickey-Fuller and Johansen cointegration test techniques, respectively. The Vector Error Correction model was applied to compute long-run and short-run parameters of endogenous variables in the model. Results of the long-run section of the cointegrating equation show that for every 1 percent rise in foreign direct investment, there was a statistically significant rise in growth of gross domestic product by about 0.05 percentage points during the period 1994-2014. Results of the error correction component of the gross domestic product growth equation show that about 62 percent of the deviance from the long-run stability pathway was rectified in the first year after the deviation occurred. Results of the impulse response functions indicate that a one standard deviation in foreign direct investment had a statistically significant and positive effect on future gross domestic product growth after the first year. Keywords: Foreign direct investment (FDI), gross domestic product (GDP) growth, Vector Error Correction (VEC) model DOI: 10.7176/JESD/12-12-01 Publication date:June 30th 202

Infrastructure and Foreign Direct Investment Inflows in South Africa: An Engle-Granger Error Correction Model Approach

The aim of this study was to examine the impacts of infrastructure quality and infrastructure investment on foreign direct investment in South Africa over the period 1970-2015. Time series annual data on foreign direct investment, infrastructure quality, infrastructure investment, financial market development, market size, macroeconomic stability and trade openness indicators were collected from relevant sources. Unit root tests were done using Augmented Dickey-Fuller and Phillips Perron methods, while cointegration was tested using the Johansen cointegration approach. The Engle-Granger error correction model was used to compute long-run and short-run estimates of the model. Results of the first step long-run segment show that trade openness, market size and infrastructure quality had statistically significant and positive impacts on FDI inflows. Macroeconomic stability had a significant and negative impact on FDI inflows, while financial market development and infrastructure investment had insignificant and negative impacts on FDI inflows. In the short run, the error correction term shows that 50.7% of disequilibrium in FDI inflows was corrected within a period of one year. Market size, macroeconomic stability and infrastructure investment had statistically significant and negative impacts on FDI inflows into South Africa over the sample period under review. Infrastructure quality, financial development and trade openness had positive but insignificant impacts on FDI inflows into the country. The estimated model passed all the diagnostic and stability tests. Keywords: Foreign direct investment (FDI) inflows, infrastructure quantity, infrastructure quality, Engle-Granger Error Correction Model DOI: 10.7176/JESD/12-12-02 Publication date:June 30th 202