scholarly journals Assessing the clogging and permeability of degrading packed bed reactors

Water SA ◽  
2018 ◽  
Vol 44 (1 January) ◽  
Author(s):  
Anthin Botes ◽  
Chris James ◽  
Craig M Sheridan
Keyword(s):  
South Africa ◽  
Water Treatment ◽  
Mine Drainage ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Small Scale ◽  
Mining Sector ◽  
Wood Shavings ◽  
Chicken Litter ◽  
The Impact

In South Africa, the need for water treatment is increasing, especially in the mining sector. As active water treatment technologies are expensive, the mining sector has an increasing need for passive water treatment technology, with low maintenance and operating costs, yet efficient water treatment ability. Literature on passive water treatment suggests that these systems only offer a narrow range of treatment capabilities. Therefore, hybrid water treatment systems could be a solution to low-cost water treatment in South Africa. The degrading packed bed reactor (DPBR) is one of the units comprising the hybrid treatment group. The DPBR’s main action is to convert sulfates into sulfides and alkalinity, since this reduces the impact on the environment by increasing the pH and reducing the salinity. In this study, 6 small-scale DPBRs were constructed. Each was classified according to its unique organic source (manure, straw, vegetable food processing waste, wood shavings, chicken litter and a combined sample with layers of all the carbon sources). Synthetic acid mine drainage (AMD) was fed through the 6 bioreactors for a period of 3 months. Permeabilities, leachate samples and effective void volumes were measured from the DPBRs. From the experiments conducted, it was found that the manure and combination bioreactors (with equal layers of manure, straw, compost, wood shavings and chicken litter) had the lowest overall permeabilities, with straw and compost having the highest permeabilities. Linked to this, the experiments showed that the manure and combination bioreactors had the largest decreases in effective porosity with straw and compost having the least. Hydraulically, the combination bioreactor performed the best by incorporating the best attributes from each carbon source. Wood shavings preformed almost as well. Chicken litter clogged within 18 days after the initiation of the experiment and thus was the least effective substrate.

Investigation Of The Impact Of Networking Among Tenants In The Seda Limpopo Jewellery Incubator In South Africa

2014 ◽  
Vol 1 (1) ◽  
pp. 23-26
Author(s):  
Forbes Chiromo ◽  
Goodwell Muyengwa ◽  
Joseph Makuvaza
Keyword(s):  
South Africa ◽  
Limpopo Province ◽  
Raw Material ◽  
Small Scale ◽  
Metal Fabrication ◽  
The Government ◽  
Set Up ◽  
Training Programmes ◽  
The Impact ◽  
Structured Questionnaire

AbstractThis study investigates the extent to which tenants in a jewellery incubator in the Limpopo Province of South Africa network. Since 1994 SEDA has set up more than 31 incubation centres in furniture making, construction, chemicals, jewellery, ICT, metal fabrication, agriculture and small scale mining. This study was done through a survey conducted on tenants in the SEDA Limpopo Jewellery Incubator (SLJI). Information was obtained through a structured questionnaire. The study revealed how tenants benefit from networking around exhibitions and collective purchasing of raw material. Through the Incubator institutional mechanisms, the study explains how tenants share expertise, experiences, technology and resources. Unfortunately the tenants do not initiate the own networking programmes. They lose out on benefits associated with collective effort in other areas such as advertisements, lobbying the government for industrial stands, organising an newsletter, hiring of consultants, and organising joint training programmes. Lastly the study identified opportunities that the tenants could collectively exploit in order strengthen and sustain their businesses.

scholarly journals Impacts of literacy rate and human development indices on agricultural production in South Africa

2013 ◽  
Vol 59 (No. 11) ◽  
pp. 531-536
Author(s):  
S. Leshoro ◽  
T.L.A. Leshoro
Keyword(s):  
South Africa ◽  
Human Development ◽  
Agricultural Production ◽  
Agricultural Sector ◽  
Labour Force ◽  
Small Scale ◽  
Literacy Rate ◽  
Distributed Lag ◽  
Long Run ◽  
The Impact

Agriculture is an important sector in South Africa, and the impact that education and human development would have made in this sector via non-white small scale farming was limited through biased policies of the apartheid era. Due to apartheid laws, South Africa found itself with high levels of unskilled labour force. This study seeks to find the impacts of literacy rate and human development indices on agricultural production using Auto Regressive Distributed Lag (ARDL) Bounds Test approach to co-integration. A long run relationship among the variables, agricultural production (agriculture GDP), literacy rate and human development indices were found. Literacy rate has a positively significant effect on agricultural production in the long run while Human Development Index has a positive and significant impact in the short run. This indicates that the apartheid regime fell short in recognizing the positive effect of education in the agricultural sector by denying a descent education to the majority of non-whites which were farm labourers or small scale farmers. This study provides some policy recommendations.  

scholarly journals Ecological-hydrogeological history of the development of the coal industry in the Western Donbas under the influence of a complex of technogenic factors

2018 ◽  
Vol 27 (1) ◽  
pp. 156-161
Author(s):  
G. P. Yevgrashkina ◽  
V. K. Marchenko ◽  
I. O. Tkachenko ◽  
O. I. Korol ◽  
A. V. Masenko
Keyword(s):  
Mathematical Models ◽  
Ground Water ◽  
Mine Drainage ◽  
Coal Industry ◽  
Coal Extraction ◽  
Small Scale ◽  
Scientific Publications ◽  
Hydrogeological Conditions ◽  
The Impact ◽  
Tailing Ponds

The Western Donbas is a mining-manufacturing region of Ukraine with a potential for increasing coal extraction in the following years. The operation of mines is followed by intense water drainage of highly mineralized ground water which accumulates in tailing ponds, which were built in the ravines without barriers screening the water-containing rocks. The problem of rational usage and protection from contamination and exhaustion of all types of water sources available for practical usage is relevant for the studied region, and all around the world. The development of a fundamental scientific solution to this problem was started in 1986, when a constantly operating mathematical model (COMM) of the changes in hydrogeological conditions of the Western Donbas was developed. The authors were the Pavlohrad Geological-Survey Expedition (PGSE), the Dnipropetrovsk Affiliate of the Institute of Mineral Resources (DAIMR) and the Department of Geology and Hydrogeology of O. Honchar Dnipropetrovsk National University. It is a regional, multi-functional, constantly improved hydrogeological project limited in space but without a time limit. The COMM of the Western Donbas, along with the most obvious advantages, has one disadvantage. In spite of its small scale (1:100000) , it provides only a general characteristic of technogenic changes in the ground water regime of the territory and cannot constitute a single scientific basis for developing nature-protection hydrogeologic measures. Therefore,it has been supplemented with mathematical models of the territories adjacent to the local objects of technogenic impact on the ground water. This includes tailing ponds, tailing dams, mining dumps and mine drainage. The first three types of technogenic objects have already been sufficiently studied and described in scientific publications (Eugrashkina , 2011 ; Eugrashkina , 2012; Eugrashkina , 2013; Eugrashkina, 2013). This paper focuses on the mathematical models, changes in hydrogeological conditions under the impact of the fourth factor mine drainage. The first three factors contaminate ground water, the fourth causes decreases in the operational reserves as a result of flow of the fresh water from the upper horizons to the productive dried-out layer.

scholarly journals Treatment of AMD using a combination of saw dust, bentonite clay and phosphate in the removal of turbid materials and toxic metals

2021 ◽  
Author(s):  
I. O. Ntwampe
Keyword(s):  
South Africa ◽  
Particle Size ◽  
Removal Efficiency ◽  
Toxic Metals ◽  
Laboratory Experiments ◽  
Mine Drainage ◽  
Bentonite Clay ◽  
Small Scale ◽  
Saw Dust ◽  
Natural Organic Compounds

Abstract Acid mine drainage collected from the western decant in South Africa was treated in a series of small-scale laboratory experiments. 200 mL of the sample was poured into five 500 mL glass beakers using flocculants formed by mixing size-optimized 1.5 g of bentonite clay with 3.5 g saw dust and 1.0 g of Na3PO4 in triplicates (experiment A). Four similar sets of control experiments were conducted using the same amount of bentonite clay and saw dust with varying Na3PO4, contents in AMD treatment; the rationale being to determine the efficiency of Na3PO4 (experiments B, C and D). The results show that conductivity has an influence in the removal of the turbid materials. The removal efficiency of toxic metals using a flocculant containing 220 μm bentonite clay particle size and 0.012 or 0.25 M of Na3PO4 is higher than 96% when compared to that of the samples dosed with a flocculant containing 0.05 M Na3PO4, which is less than 91%. The flocculent also showed optimal removal efficiency of both turbid materials and toxic metals, i.e. removal efficiency within a range 96.5–99.3%. The flocculants containing 0.025 M Na3PO4 showed optimal removal efficiency of turbidity, colour, toxic metals and natural organic compounds.

The impact of innovation on agribusiness competitiveness: the mediating role of technology transfer and productivity

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Patient Rambe ◽  
Peter Khaola
Keyword(s):  
South Africa ◽  
Technology Transfer ◽  
Emerging Economies ◽  
Structural Equation ◽  
Small Scale ◽  
Content Type ◽  
Innovation And Technology ◽  
Agricultural Business ◽  
The Impact ◽  
Productivity And Competitiveness

PurposeThe pre-eminence of innovation and technological transfer in promoting agricultural productivity and competitiveness in developing countries is widely acknowledged. However, the disparate streams of literature on productivity and competitiveness have explored innovation and technology transfer as independent predictors. Consequently, the mechanisms through which innovation and technology transfers jointly affect productivity and competitiveness of small, medium and micro enterprises (SMMEs) in emerging economies remain under-explored in literature. The present study sought to examine the relationships among innovation, technology transfer, productivity and competitiveness of small-scale agricultural businesses (SSABs) in selected regions in South Africa and Zimbabwe, neighbouring countries which have been plagued by food insecurity in recent years.Design/methodology/approachA total of 400 questionnaires were distributed to SSABs owners based in Free State and Mashonaland provinces of South Africa and Zimbabwe, respectively. In total, 268 usable questionnaires (67%) were returned for analysis. Partial least squares structural equation modelling (PLS-SEM) and Process macro (based on SPSS) techniques were used to analyse data.FindingsThe results supported direct significant paths between innovation and technology transfer; technology transfer and productivity; and productivity and competitiveness. Furthermore, the results suggested that technology transfer and productivity consecutively fully mediate the relationship between innovation and competitiveness.Research limitations/implicationsThe use of a survey could not provide sufficient explanations as to why the variable examined related the way they did.Practical implicationsThe study provides useful insights into the significance of considering the dimensions and methods of innovation and technology transfer in agricultural business activities and processes to improve productivity and competitiveness of SSABs.Social implicationsThe study provides some insights into how innovation and technology transfer could be employed by small scale agricultural businesses as critical mechanisms for heightening productivity and competitiveness of these firms to guarantee food security and employment creation for emerging economies.Originality/valueTo the researchers' knowledge, this is one of the pioneer studies to examine the impact of both innovation and technology transfer on productivity and competitiveness of SSABs in two countries in Southern Africa. The study also constitutes a significant contribution to examining serial mediation of technology transfer and productivity of innovation and competitiveness.

scholarly journals Modeling and Design of a Multi-Tubular Packed-Bed Reactor for Methanol Steam Reforming over a Cu/ZnO/Al2O3 Catalyst

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 610 ◽  
Author(s):  
Jimin Zhu ◽  
Samuel Simon Araya ◽  
Xiaoti Cui ◽  
Simon Lennart Sahlin ◽  
Søren Knudsen Kær
Keyword(s):  
Steam Reforming ◽  
Packed Bed ◽  
Methanol Conversion ◽  
Operating Conditions ◽  
Packed Bed Reactor ◽  
Inlet Temperature ◽  
Methanol Steam Reforming ◽  
Shell Side ◽  
Co Concentration ◽  
The Impact

Methanol as a hydrogen carrier can be reformed with steam over Cu/ZnO/Al2O3 catalysts. In this paper a comprehensive pseudo-homogenous model of a multi-tubular packed-bed reformer has been developed to investigate the impact of operating conditions and geometric parameters on its performance. A kinetic Langmuir-Hinshelwood model of the methanol steam reforming process was proposed. In addition to the kinetic model, the pressure drop and the mass and heat transfer phenomena along the reactor were taken into account. This model was verified by a dynamic model in the platform of ASPEN. The diffusion effect inside catalyst particles was also estimated and accounted for by the effectiveness factor. The simulation results showed axial temperature profiles in both tube and shell side with different operating conditions. Moreover, the lower flow rate of liquid fuel and higher inlet temperature of thermal air led to a lower concentration of residual methanol, but also a higher concentration of generated CO from the reformer exit. The choices of operating conditions were limited to ensure a tolerable concentration of methanol and CO in H2-rich gas for feeding into a high temperature polymer electrolyte membrane fuel cell (HT-PEMFC) stack. With fixed catalyst load, the increase of tube number and decrease of tube diameter improved the methanol conversion, but also increased the CO concentration in reformed gas. In addition, increasing the number of baffle plates in the shell side increased the methanol conversion and the CO concentration.

scholarly journals Simulation of Methanol Synthesis in Packed Bed Reactor for Utilization of CO2 from Acid Gas Removal Unit

2018 ◽  
Vol 67 ◽  
pp. 03005
Author(s):  
Bayu Sari Adji ◽  
Yuswan Muharam ◽  
Sutrasno Kartohardjono
Keyword(s):  
Oil And Gas ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Small Scale ◽  
Production Plant ◽  
High Concentration ◽  
Methanol Production ◽  
Acid Gas ◽  
Oil And Gas Fields ◽  
Gas Removal

There are many oil and gas fields in Indonesia which contain high CO2 that need to be treated. The Acid Gas Removal Unit (AGRU) is installed to remove the CO2. The AGRU will release the CO2 gas from the regeneration column. It still contains a high concentration of CO2 (higher than 80%). The accumulation of CO2 emission to the atmosphere will impact the environment. To promote environment-friendly technology, the process can be improved with conversion of CO2 into methanol. It will provide a relatively closed loop of the carbon cycle and as a renewable energy alternative. This study aims to provide packed bed reactor design which can be implemented in the small-scale methanol production plant utilizing high CO2 feed gas. The reactor temperature was varied from 200°C to 250°C and pressure were operated in the range of 40 Bar up to 75 Bar. These variations were used to analyze the effects of methanol production. The simulation results showed that peak methanol production rate was achieved at the temperature around 230°C. As the conclusion, the reactor showed better performance at the higher pressure and higher temperature although the reaction is exothermic including the recycling process can reduce the cost of hydrogen.

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