Kevin Harding | University of the Witwatersrand (original) (raw)

Papers by Kevin Harding

Research paper thumbnail of Quantification of water usage at a South African platinum processing plant

Water SA, Apr 7, 2015

The mining industry utilises 3% of the total water withdrawn in South Africa and is one of the in... more The mining industry utilises 3% of the total water withdrawn in South Africa and is one of the industries responsible for the deterioration of water quality in South Africa. Mine water requirements can be reduced with correct implementation and/ or improvement of current mine water management strategies. Any reduction in mine water requirements will reduce the demand on current water resources and hence the impact on water quality. The direct water footprint for 2 concentrators, a smelter and a tailings dam of a platinum processing plant were calculated using the Water Footprint Network assessment method. This includes the sum of the blue-, green-and grey-water footprints. Water footprints of chemicals used during flotation were excluded from the scope of the investigation. Water used in change houses and offices was included. The water footprint calculated from June 2012 until May 2013 was 201 m 3 /kg PGM (platinum group metals). The first concentrator had a water footprint of 76 m 3 /kg PGM, while the second had a water footprint of 110 m 3 /kg PGM. Overall, the total grey-water footprint made the largest contribution, accounting for 73%, the blue-water footprint was the second largest (27%), and there was no green-water footprint.

Research paper thumbnail of A lifecycle-based evaluation of greenhouse gas emissions from the plastics industry in South Africa

South African Journal of Science, Jan 31, 2023

Increased production rates of plastic and limited disposal methods have fed concerns regarding en... more Increased production rates of plastic and limited disposal methods have fed concerns regarding environmental degradation. Whilst most of the focus is on plastic litter and marine pollution, greenhouse gas emissions of plastic over its value chains are also of interest and non-trivial at the global scale. To quantify the global warming potential of the local plastics industry, a lifecycle-based carbon footprint is presented encompassing activities such as resource extraction, polymer production and conversion, recycling, and disposal stages. The South African plastics sector is estimated to have emitted 15.8 Mt CO 2 eq in 2015, with the granulate production stage bearing the highest environmental load. The consumption of fossil fuel based electricity and the burning of plastic waste also contribute notably to the overall emissions. Additionally, the recycling process in 2015 saved approximately 1.4 Mt of greenhouse gas emissions. Significance: • Research has typically focused on the environmental impacts of the end-of-life stage of plastics, namely disposal and recycling. Despite growing concern, the global warming potential of the local plastics sector across its value chain has not been investigated. • Greenhouse gas emissions arising from the South African plastic sector are non-trivial and are estimated to total 15.8 Mt CO 2 eq in 2015. • Amongst the lifecycle stages, the resin production process had the highest contribution in South Africa due to the country's coal-based monomer production process.

Research paper thumbnail of Comparative life-cycle assessment of maize cobs, maize stover and wheat stalks for the production of electricity through gasification vs traditional coal power electricity in South Africa

Cleaner Environmental Systems, 2021

Currently, coal is the most widely used feedstock for electricity generation, including South Afr... more Currently, coal is the most widely used feedstock for electricity generation, including South Africa with a 77% dependence. However, coal-fired power stations also result in adverse environmental impacts, including air, water and soil pollution. The conversion of biomass, such as maize cobs and other agricultural residues, to electricity, could play a vital role in reducing the dependency on coal power in South Africa as well as reducing these environmental impacts. However, there are very few environmental impact studies in the country to address the production or preparation phase of energy feedstocks for electricity production. This study used life-cycle assessment (LCA) to evaluate the environmental burdens associated with the production of maize and wheat, and the extraction of residue (maize cobs, maize stover or wheat stalks) for producing electricity through gasification and compared these to coal-fired electricity production. The results showed that the main areas of concern for electricity production from biomass were from gasification and transport, contributing roughly 47% each to fossil fuel depletion, just over 46% each towards climate change, 44% and 40% towards particulate matter formation, and 32.8% and 33.2% towards land occupation, respectively. The impacts associated with wheat stalks and maize stover production were higher than those of the maize cobs system. Agricultural land occupation results for the production of 1 kg of maize cobs, maize stover and wheat straw were 4.83 Â 10 À7 , 4.76 Â 10 À7 and 2.38 Â 10 À6 m 2 , respectively, in one year, with similar trends for the other impact categories as well. The most significant impacts of using coal-fired methods of electricity generation were fossil fuel depletion, ozone depletion, natural land transformation, urban land occupation and climate change, with these burdens being over 90% higher than from the gasification of maize cobs. To improve the environmental performance of the biomass energy sector, improvements in agricultural practices should be implemented, including further research on fertilization, water use, agricultural practices, land transformation, biomass conversion technologies, and transportation.

Research paper thumbnail of Environmental performance of extended activated sludge and sequential batch reactor using life cycle assessment

Cleaner Environmental Systems, 2021

Although several studies have been published on the application of life cycle assessment (LCA) on... more Although several studies have been published on the application of life cycle assessment (LCA) on wastewater treatment plants (WWTP), few have been reported from developing countries. In this study, the environmental impacts of a sequential batch reactor (SBR) and extended activated sludge process (EASP) treatment technologies were evaluated and analysed using LCA. SimaPro® 9.1.1.1 software was used, together with the ecoinvent 3.6 database, and the ReCiPe midpoint (H) methodology. A functional unit of 1 m 3 of treated wastewater was used. Normalised results showed that freshwater eutrophication, freshwater ecotoxicity, and human toxicity were the key impact categories. EASP indicated the highest impact result on all evaluated impact categories. Electricity consumption was the main contributor to freshwater ecotoxicity and human toxicity impact categories. Residual phosphorus in the effluent stream was the dominant contributor to freshwater eutrophication. Primary treatment had the highest environmental burden of EASP, due to raw wastewater pumping. Secondary treatment had the highest environmental burden on SBR due to aeration. SBR was the preferable option as it scored less on all the key impact categories evaluated. The coal-based South African electricity mix was found to be highly influential on both the EASP and SBR.

Research paper thumbnail of Fatty methyl esters in algal biodiesel

Research paper thumbnail of Generic flowsheeting approach to generating first estimate material and energy balance data for Life Cycle Assessment (LCA) of Penicillin V production

Sustainable Production and Consumption, Jul 1, 2018

Establishment of the key contributors to the environmental burden of a bioprocess at the early de... more Establishment of the key contributors to the environmental burden of a bioprocess at the early design stage provides opportunity to inform the holistic optimization of the process. Here, the production of penicillin V sodium salt by Penicillium chrysogenum is analyzed in terms of material and energy flows and associated energy burdens, assessed through life-cycle analysis, to inform the approach to minimize the environmental impact of key bioprocesses. The material and energy flows are estimated using a generic model (CeBER Bioprocess Modeller), developed and implemented in MS-Excel for early stage estimation of material and energy balance calculations of large-scale microbial bioprocesses. Using these outputs, lifecycle assessment (LCA) is used to estimate environmental impacts associated with producing penicillin V product. Three scenarios for production are considered. It was shown that even with a 55% error in inputs to the CeBER Bioprocess Modeller, using this to determine material and energy balance data and then calculating a full LCA, a final difference in LCA scores of only 5% was obtained. Further key findings in the study showed that electrical and agricultural inputs were the dominant contributors to LCA impacts. Poor separation efficiencies in downstream processing result in high operating volumes and large recycle flows within a process. This, in turn, increased electrical and steam requirements of the process, increasing abiotic depletion and greenhouse gas emissions. The approach provides insight into key process steps in which optimization may reduce environmental costs most significantly.

Research paper thumbnail of Teaching Tips: Effectiveness of Additional Voluntary Consultations

Chemical engineering education, Jul 7, 2017

Research paper thumbnail of Generic flow sheet model for early inventory estimates of industrial microbial processes. I. Flowsheet development, microbial growth and product formation

South African Journal of Chemical Engineering, Dec 1, 2016

Early stage process analysis to maximize economic feasibility and minimize environmental burden i... more Early stage process analysis to maximize economic feasibility and minimize environmental burden is critically important for process flow sheet selection and optimization. This is equally true for bioprocesses. For many systems, including bioprocess systems, the desired material and energy balance data are not available at an early stage of design. The CeBER Bioprocess Modeller (Centre for Bioprocess Engineering Research at the University of Cape Town, Department of Chemical Engineering) has been developed to provide estimates of these material and energy balance data, as well as calculate equipment volumes and utility needs. The model allows for aerobic or anaerobic, intra-or extracellular product formation or biomass growth in a continuous or batch process for various bioproducts produced from a selection of microorganisms using a range of raw materials. Using simple inputs, and default values drawn, the model is suitable for engineers and scientists alike. The model also incorporates the option to select for sterilization and to specify the downstream processing train. In the bioreactor, the model takes into account aeration, agitation, reaction, biomass maintenance, yield, post microbial growth cooling and growth rate calculations, amongst others. This paper presents the model framework for the microbial growth and product formation stages.

Research paper thumbnail of Generic flowsheet model for early inventory estimates of industrial microbial processes. II. Downstream processing

South African Journal of Chemical Engineering, Dec 1, 2016

To ensure optimal process flowsheet selection it is valuable to conduct environmental and economi... more To ensure optimal process flowsheet selection it is valuable to conduct environmental and economic comparisons at an early stage of technology selection and process design. However, the data that is needed to perform these studies are not available at this stage of process development. This is also true for bioprocess systems. To overcome the lack of data, the CeBER (Centre for Bioprocess Engineering Research, University of Cape Town) Bioprocess Modeller was developed to provide material and energy values for industrial microbial processes. This paper presents the downstream processing portion of this flowsheet. The model allows for solideliquid separation, cell disruption, concentration and formulation units as required. The model allows section of appropriate downstream processing units include, amongst others, centrifugation, filtration, precipitation and freeze-drying. At each downstream processing stage, non-reacting and reacting chemicals can be added. The model provides both a material inventory as well as the calculation of the energy input required and waste heat generated. Additionally, the model includes a database of values (including constants, operating conditions and others), drawn from various industrial norms and academic sources. Should specific information not be known, the model selects the most appropriate values based on other decisions made through the model.

Research paper thumbnail of Assessing the availability of life cycle assessments in Austria

International Journal of Life Cycle Assessment, Aug 28, 2018

Purpose This study aims to present the availability of studies that are related to life cycle ass... more Purpose This study aims to present the availability of studies that are related to life cycle assessments (LCA) in Austria since 2000. This study also includes a review of available water and carbon footprint studies along with an analysis of the Global Reporting Initiative (GRI) database pertaining to Austria. The review seeks to explore potential research gaps and to identify needs for similar studies in the country while quantifying the number of available studies that are available to the general public or as background information in other LCA studies. Methods Online searches using Google, Google Scholar, Scopus, and ScienceDirect were conducted using various keywords to find LCA studies. Keywords included: life cycle assessment, LCA, and Austria, as well as water and carbon footprinting. Results were limited to English language studies. Results and discussion A total of 15 studies that pertain directly to LCAs in Austria were found. In addition, four reports for water footprinting and six reports for carbon footprinting were found, and 77 GRI reports. The majority of the LCA studies were only accessible by way of restricted journals. Conclusions The majority of the studies focused on the energy and manufacturing sectors. This was expected, due to exports that make up a large portion of the Austrian economy. Nevertheless, LCA research appeared to be driven by academic sources, rather than industry. Therefore, most of the studies were limited to paid subscriptions and thus were not easily accessible by the general public.

Research paper thumbnail of Review: the availability of life-cycle studies in Sweden

International Journal of Life Cycle Assessment, Jul 20, 2018

Purpose An online review was conducted on the availability of life-cycle assessment (LCA), water,... more Purpose An online review was conducted on the availability of life-cycle assessment (LCA), water, and carbon footprinting studies in Sweden. The main purpose was to quantify the number of available studies, which may be of general interest to nonspecialists or as background data for LCA practitioners. Additionally, results from the Global Reporting Initiative (GRI) reports were also included. Methods The study used online searches conducted in Google and Google Scholar to obtain the publically available reports. Additionally, searches in ScienceDirect, Scopus, and Wiley were performed to obtain other peer-reviewed academic papers. Only English language results were included. Results and discussion LCAs and carbon footprinting studies were the most commonly conducted studies (13 LCA and 12 carbon footprinting studies), whereas water footprinting reports, while still largely available, were fewer in number. A number of GRI reports were also available with the majority of studies conducted for the financial services and real estate sectors. Several studies were in the form of university theses, while companies and research organizations conducted the remainder of research projects. Conclusions While several life-cycle assessments, carbon, and water footprinting studies were accessible via Google searches, given the interest in LCA in the country, e.g., the LCM2013 conference in Gothenburg and The Swedish Life Cycle Centre, more studies were expected.

Research paper thumbnail of Environmental analysis of plastic production processes: Comparing petroleum-based polypropylene and polyethylene with biologically-based poly-β-hydroxybutyric acid using life cycle analysis

Journal of Biotechnology, May 31, 2007

Polymers based on olefins have wide commercial applicability. However, they are made from non-ren... more Polymers based on olefins have wide commercial applicability. However, they are made from non-renewable resources and are characterised by difficulty in disposal where recycle and re-use is not feasible. Poly-␤-hydroxybutyric acid (PHB) provides one example of a polymer made from renewable resources. Before motivating its widespread use, the advantages of a renewable polymer must be weighed against the environmental aspects of its production. Previous studies relating the environmental impacts of petroleum-based and bio-plastics have centred on the impact categories of global warming and fossil fuel depletion. Cradle-to-grave studies report equivalent or reduced global warming impacts, in comparison to equivalent polyolefin processes. This stems from a perceived CO 2 neutral status of the renewable resource. Indeed, no previous work has reported the results of a life cycle assessment (LCA) giving the environmental impacts in all major categories. This study investigates a cradle-to-gate LCA of PHB production taking into account net CO 2 generation and all major impact categories. It compares the findings with similar studies of polypropylene (PP) and polyethylene (PE). It is found that, in all of the life cycle categories, PHB is superior to PP. Energy requirements are slightly lower than previously observed and significantly lower than those for polyolefin production. PE impacts are lower than PHB values in acidification and eutrophication.

Research paper thumbnail of Lignocellulosic bioethanol production from grasses pre-treated with acid mine drainage: Modeling and comparison of SHF and SSF

Bioresource Technology Reports, Sep 1, 2019

Acid mine drainage (AMD) was used for the pre-treatment of indigenous South African grass (Eragro... more Acid mine drainage (AMD) was used for the pre-treatment of indigenous South African grass (Eragrostis curvula), and compared to H 2 SO 4 (1 wt%) pre-treatment. The optimal pre-treatment duration were investigated and found to be 1 day for H 2 SO 4 and 3 days for AMD pre-treatment. The optimal biomass solid loadings were found to be 20 wt% for both pre-treatment methods. Additionally, enzymatic hydrolysis and fermentation to produce ethanol were investigated for both separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF). In both SHF and SSF, the H 2 SO 4 pre-treatment obtained higher concentrations of glucose/ethanol compared to AMD pre-treatment. The concentration of glucose/ethanol obtained using AMD pre-treatment was 70-80% of that achieved using H 2 SO 4 pre-treatment. Empirical equations modeling the glucose/ethanol concentration in all processes were determined using a least squares method. Concentrations predicted by the models were found to have a high correlation (r 2 = 0.87-0.99) to concentrations determined experimentally.

Research paper thumbnail of Evaluation of a combined lignocellulosic / waste water bio-refinery for the simultaneous production of valuable biochemical products and the remediation of acid mine drainage

Biofuels, Bioproducts and Biorefining, Apr 23, 2018

The additional costs required for the pre-treatment of lignocellulosic bio-mass prior to enzymati... more The additional costs required for the pre-treatment of lignocellulosic bio-mass prior to enzymatic hydrolysis have limited the commercial implementation of lignocellulosic biochemical production. The use of acidic mine drainage (AMD) water as an acid source for lignocellulosic pre-treatment has recently been investigated. Large quantities of AMD in South Africa suggest that AMD can be obtained cheaply, thus reducing the cost and increasing the potential of lignocellulosic bio-chemicals. Acidic mine drainage could undergo further remediation using sulfate-reducing bacteria (SRB) so that the water is suitable for release. The feasibility of such a system could be greatly improved if this process were to be incorporated within a bio-refinery, such that all fractions of the bio-mass are used to produce multiple products. This paper investigates such a bio-refinery system, and evaluates the different options based on the bio-refinery complexity profile (BCP). Due to the abundance of grass in the regions where AMD is generated, this was found to be the most suitable feedstock. The most feasible bio-refinery option was found to produce ethanol through fermentation of C6 sugars, although it is recommended that further investigation be conducted into additional high-value bio-chemicals from the C6 sugar platform. C5 sugars released in pre-treatment could be used as a substrate by SRB for AMD remediation. Gasification and direct combustion of lignin had similar BCPs and thus further investigation is required to determine the preferred path. Similarly, further investigation is required for the best processing route for distillery silage.

Research paper thumbnail of The availability of life-cycle assessment, water footprinting, and carbon footprinting studies in Brazil

International Journal of Life Cycle Assessment, Jun 11, 2018

Purpose This study aimed to determine the availability of environmental life cycle assessment (LC... more Purpose This study aimed to determine the availability of environmental life cycle assessment (LCA), water footprinting, and carbon footprinting data in Brazil. In particular, the study is targeted at showing what LCA-related studies are accessible to nonspecialists residing in Brazil as well as LCA specialists interested in accessing Brazilian LCA-related studies. Methods Online searches for LCA documents were performed using publicly available search engines such as Google and Google Scholar, as well as academic databases containing peer-reviewed journal articles such as Scopus, ScienceDirect, and Springer. The searches were conducted utilizing the keywords BLife Cycle Assessment,^Bcarbon footprint,^Bwater footprint,^and BBrazil.R esults and discussion A total of 73 published documents on LCA studies conducted between 2000 and 2016 could be found. Of these, 59 were only available in restricted access journals requiring some form of paid subscriptions. Most of these documents originated from academic institutions. For the majority of the studies, the exact region in which the study was carried out was not specified. Only twelve carbon and water footprinting studies were found. However, it was known that several other studies were available but were not found in these searches unless more specific years, authors, and/or products were included in the search terms. Conclusions It was observed that LCA studies were more established in the energy and agricultural sectors, an expected result given that all LCA studies would rely on energy as a background process, as well as the increasing energy demand due to increasing population and industrial activities in Brazil. Furthermore, it was observed that most LCA studies in the energy sector concentrated on the conversion of biomass, mainly sugarcane and soybean, to biofuels; thereby, establishing a strong link between the energy and agricultural sectors. The results showed that LCA is an emerging quantitative assessment technique in Brazil, especially in the energy and agricultural sectors. While there were over 70 studies found, it is not clear how many of these could be transferable into an LCI database or be used in other studies, due to the exact inputs used.

Research paper thumbnail of A discussion on the availability of life-cycle assessment studies in New Zealand

International Journal of Life Cycle Assessment, Jun 8, 2018

Purpose In order to understand the environmental impacts of various products, processes, or servi... more Purpose In order to understand the environmental impacts of various products, processes, or services, it should be possible to obtain life-cycle assessment (LCA) reports quickly and easily without having to delve into restricted access or hidden databases. The aim of this study is to assess the availability of environmental LCAs, water footprinting, and carbon footprinting studies conducted in New Zealand. Methods To review the quantitative availability of life-cycle assessment studies for New Zealand, simple online searches were performed using the Google and Google Scholar search engines. Additionally, ScienceDirect and Scopus were used to determine the availability of other peer-reviewed LCA-related reports. Results and discussion For the period under review, 20 documents were publicly available. Additionally, other searches conducted via ScienceDirect, Scopus and Google Scholar yielded a further 15 restricted documents. The results included data carbon-and water footprinting studies. The number of LCAs and carbon footprinting reports both exceeded those of water footprinting. Conclusions Over 35 studies were available through Internet searches. This number excludes wool which had six results (Scopus only) and many more through Google. These were not included due to possible repetition and miscounting of results.

Research paper thumbnail of Review: life-cycle assessment, water footprinting, and carbon footprinting in Portugal

International Journal of Life Cycle Assessment, Jun 4, 2018

Purpose A review of readily available quantitative environmental data was conducted in order to d... more Purpose A review of readily available quantitative environmental data was conducted in order to determine the state of sustainability reporting and identify possible future research areas in Portugal. Methods Internet searches of articles written in English and published between 2001 and 2015 were conducted using the keywords Blife-cycle assessment,^BLCA,^Bwater footprint,^Bcarbon footprint,^and BPortugal.^Additionally, reports from the Global Reporting Initiative (2015 only) were included in the search. Results and discussion It was found that 79% of reports found were published in the period 2011-2015. Several reports were found for the forestry, paper and pulp, food and beverage, energy and electricity, waste management, and automotive industries, while no reports were found for the textile, footwear and clothing, and base metal and mineral industries. As such, these are industries on which future studies might focus. No reports found were published by governmental organizations, although it is thought that expanding the search to include Portuguese language results would yields more results. The majority (68%) of companies reporting to the GRI adhered to the relevant guidelines. Conclusions A total of 72 reports were found (41 LCAs, water-or carbon footprints, and 31 GRI reports). It is unclear if there are other reports that may be restricted to Bhidden^datasets or company specific archives. The aim of this report was to highlight those that were available to a non-specialist or international audiences trying to gain a greater understanding of the LCA space in Portugal.

Research paper thumbnail of Feasibility assessment of the production of bioethanol from lignocellulosic biomass pretreated with acid mine drainage (AMD)

Renewable Energy, Sep 1, 2020

A techno-economic evaluation of a lignocellulosic bioethanol facility that uses acid mine drainag... more A techno-economic evaluation of a lignocellulosic bioethanol facility that uses acid mine drainage for the pre-treatment of weeping love grass (Eragrostis curvula) was performed. Both separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) reactor configurations were evaluated. Results were compared to an evaluation of the same process with biomass pre-treated with dilute H 2 SO 4. Capital and operating costs were estimated and a simple economic evaluation was conducted. It was found that all scenarios made a loss except for biomass pre-treated with H 2 SO 4 in the SHF reactor configuration, although the high capital cost resulted in a payback period of 80.7 years, which is unfeasible. SHF was found to produce more ethanol at a lower capital cost than SSF, indicating that it is more economically feasible. Incorporating the remediation of AMD into a simultaneous process could help improve process economics. It is thus recommended that a techno-economic evaluation be conducted on a process that produces bioethanol through SHF and simultaneously remediates AMD.

Research paper thumbnail of Eco-efficiency assessment of pork production through life-cycle assessment and product system value in South Africa

E3S Web of Conferences

The consumption of pork as a source of animal protein has increased worldwide, especially in deve... more The consumption of pork as a source of animal protein has increased worldwide, especially in developing countries such as South Africa. The increase in pork demand is putting pressure on the natural environment, and the costs of production are increasing. This study sought to determine what is the eco-efficiency of pork production in a South African context. It also was meant to determine which processes in the value chain have low eco-efficiencies. Lastly, it sought to find what strategies could be recommended to improve overall eco-efficiency. Eco-efficiency was assessed by following the requirements of the International Standards Organisation ISO 14045 standard, which requires that the Life cycle assessment (LCA) method and product system value be combined. The environmental life cycle costing (LCC) method was used to determine the product system value (Value Added) of pork production. The functional unit was 1 kg of pork carcass, specifically from the cradle to the abattoir gate...

Research paper thumbnail of Extraction of Essential Oils from Lavandula × intermedia ‘Margaret Roberts’ Using Steam Distillation, Hydrodistillation, and Cellulase-Assisted Hydrodistillation: Experimentation and Cost Analysis

Plants

Lavender oil is an important essential oil with many applications. The purpose of this study was ... more Lavender oil is an important essential oil with many applications. The purpose of this study was to compare different methods of essential oil extraction to determine which method would be the most effective and profitable for commercial-scale production from Lavandula × intermedia (‘Margret Roberts’) flowers and leaves. The lavender from this variety flowers year-round, providing an extended production season compared to some other lavender varieties. Steam distillation, hydrodistillation, and cellulase-assisted hydrodistillation were used to extract oil. The average extraction times for steam distillation, hydrodistillation, and cellulase-assisted hydrodistillation were 57-, 51-, and 49 min, respectively, and the average energy consumption was 15.0-, 13.4-, and 30.8 kJ/g, respectively. Cellulase-assisted hydrodistillation produced the best quality oils, with a lower camphor content and a sweeter, more pleasant smell, while steam-distilled oils had the highest camphor content, as w...

Research paper thumbnail of Quantification of water usage at a South African platinum processing plant

Water SA, Apr 7, 2015

The mining industry utilises 3% of the total water withdrawn in South Africa and is one of the in... more The mining industry utilises 3% of the total water withdrawn in South Africa and is one of the industries responsible for the deterioration of water quality in South Africa. Mine water requirements can be reduced with correct implementation and/ or improvement of current mine water management strategies. Any reduction in mine water requirements will reduce the demand on current water resources and hence the impact on water quality. The direct water footprint for 2 concentrators, a smelter and a tailings dam of a platinum processing plant were calculated using the Water Footprint Network assessment method. This includes the sum of the blue-, green-and grey-water footprints. Water footprints of chemicals used during flotation were excluded from the scope of the investigation. Water used in change houses and offices was included. The water footprint calculated from June 2012 until May 2013 was 201 m 3 /kg PGM (platinum group metals). The first concentrator had a water footprint of 76 m 3 /kg PGM, while the second had a water footprint of 110 m 3 /kg PGM. Overall, the total grey-water footprint made the largest contribution, accounting for 73%, the blue-water footprint was the second largest (27%), and there was no green-water footprint.

Research paper thumbnail of A lifecycle-based evaluation of greenhouse gas emissions from the plastics industry in South Africa

South African Journal of Science, Jan 31, 2023

Increased production rates of plastic and limited disposal methods have fed concerns regarding en... more Increased production rates of plastic and limited disposal methods have fed concerns regarding environmental degradation. Whilst most of the focus is on plastic litter and marine pollution, greenhouse gas emissions of plastic over its value chains are also of interest and non-trivial at the global scale. To quantify the global warming potential of the local plastics industry, a lifecycle-based carbon footprint is presented encompassing activities such as resource extraction, polymer production and conversion, recycling, and disposal stages. The South African plastics sector is estimated to have emitted 15.8 Mt CO 2 eq in 2015, with the granulate production stage bearing the highest environmental load. The consumption of fossil fuel based electricity and the burning of plastic waste also contribute notably to the overall emissions. Additionally, the recycling process in 2015 saved approximately 1.4 Mt of greenhouse gas emissions. Significance: • Research has typically focused on the environmental impacts of the end-of-life stage of plastics, namely disposal and recycling. Despite growing concern, the global warming potential of the local plastics sector across its value chain has not been investigated. • Greenhouse gas emissions arising from the South African plastic sector are non-trivial and are estimated to total 15.8 Mt CO 2 eq in 2015. • Amongst the lifecycle stages, the resin production process had the highest contribution in South Africa due to the country's coal-based monomer production process.

Research paper thumbnail of Comparative life-cycle assessment of maize cobs, maize stover and wheat stalks for the production of electricity through gasification vs traditional coal power electricity in South Africa

Cleaner Environmental Systems, 2021

Currently, coal is the most widely used feedstock for electricity generation, including South Afr... more Currently, coal is the most widely used feedstock for electricity generation, including South Africa with a 77% dependence. However, coal-fired power stations also result in adverse environmental impacts, including air, water and soil pollution. The conversion of biomass, such as maize cobs and other agricultural residues, to electricity, could play a vital role in reducing the dependency on coal power in South Africa as well as reducing these environmental impacts. However, there are very few environmental impact studies in the country to address the production or preparation phase of energy feedstocks for electricity production. This study used life-cycle assessment (LCA) to evaluate the environmental burdens associated with the production of maize and wheat, and the extraction of residue (maize cobs, maize stover or wheat stalks) for producing electricity through gasification and compared these to coal-fired electricity production. The results showed that the main areas of concern for electricity production from biomass were from gasification and transport, contributing roughly 47% each to fossil fuel depletion, just over 46% each towards climate change, 44% and 40% towards particulate matter formation, and 32.8% and 33.2% towards land occupation, respectively. The impacts associated with wheat stalks and maize stover production were higher than those of the maize cobs system. Agricultural land occupation results for the production of 1 kg of maize cobs, maize stover and wheat straw were 4.83 Â 10 À7 , 4.76 Â 10 À7 and 2.38 Â 10 À6 m 2 , respectively, in one year, with similar trends for the other impact categories as well. The most significant impacts of using coal-fired methods of electricity generation were fossil fuel depletion, ozone depletion, natural land transformation, urban land occupation and climate change, with these burdens being over 90% higher than from the gasification of maize cobs. To improve the environmental performance of the biomass energy sector, improvements in agricultural practices should be implemented, including further research on fertilization, water use, agricultural practices, land transformation, biomass conversion technologies, and transportation.

Research paper thumbnail of Environmental performance of extended activated sludge and sequential batch reactor using life cycle assessment

Cleaner Environmental Systems, 2021

Although several studies have been published on the application of life cycle assessment (LCA) on... more Although several studies have been published on the application of life cycle assessment (LCA) on wastewater treatment plants (WWTP), few have been reported from developing countries. In this study, the environmental impacts of a sequential batch reactor (SBR) and extended activated sludge process (EASP) treatment technologies were evaluated and analysed using LCA. SimaPro® 9.1.1.1 software was used, together with the ecoinvent 3.6 database, and the ReCiPe midpoint (H) methodology. A functional unit of 1 m 3 of treated wastewater was used. Normalised results showed that freshwater eutrophication, freshwater ecotoxicity, and human toxicity were the key impact categories. EASP indicated the highest impact result on all evaluated impact categories. Electricity consumption was the main contributor to freshwater ecotoxicity and human toxicity impact categories. Residual phosphorus in the effluent stream was the dominant contributor to freshwater eutrophication. Primary treatment had the highest environmental burden of EASP, due to raw wastewater pumping. Secondary treatment had the highest environmental burden on SBR due to aeration. SBR was the preferable option as it scored less on all the key impact categories evaluated. The coal-based South African electricity mix was found to be highly influential on both the EASP and SBR.

Research paper thumbnail of Fatty methyl esters in algal biodiesel

Research paper thumbnail of Generic flowsheeting approach to generating first estimate material and energy balance data for Life Cycle Assessment (LCA) of Penicillin V production

Sustainable Production and Consumption, Jul 1, 2018

Establishment of the key contributors to the environmental burden of a bioprocess at the early de... more Establishment of the key contributors to the environmental burden of a bioprocess at the early design stage provides opportunity to inform the holistic optimization of the process. Here, the production of penicillin V sodium salt by Penicillium chrysogenum is analyzed in terms of material and energy flows and associated energy burdens, assessed through life-cycle analysis, to inform the approach to minimize the environmental impact of key bioprocesses. The material and energy flows are estimated using a generic model (CeBER Bioprocess Modeller), developed and implemented in MS-Excel for early stage estimation of material and energy balance calculations of large-scale microbial bioprocesses. Using these outputs, lifecycle assessment (LCA) is used to estimate environmental impacts associated with producing penicillin V product. Three scenarios for production are considered. It was shown that even with a 55% error in inputs to the CeBER Bioprocess Modeller, using this to determine material and energy balance data and then calculating a full LCA, a final difference in LCA scores of only 5% was obtained. Further key findings in the study showed that electrical and agricultural inputs were the dominant contributors to LCA impacts. Poor separation efficiencies in downstream processing result in high operating volumes and large recycle flows within a process. This, in turn, increased electrical and steam requirements of the process, increasing abiotic depletion and greenhouse gas emissions. The approach provides insight into key process steps in which optimization may reduce environmental costs most significantly.

Research paper thumbnail of Teaching Tips: Effectiveness of Additional Voluntary Consultations

Chemical engineering education, Jul 7, 2017

Research paper thumbnail of Generic flow sheet model for early inventory estimates of industrial microbial processes. I. Flowsheet development, microbial growth and product formation

South African Journal of Chemical Engineering, Dec 1, 2016

Early stage process analysis to maximize economic feasibility and minimize environmental burden i... more Early stage process analysis to maximize economic feasibility and minimize environmental burden is critically important for process flow sheet selection and optimization. This is equally true for bioprocesses. For many systems, including bioprocess systems, the desired material and energy balance data are not available at an early stage of design. The CeBER Bioprocess Modeller (Centre for Bioprocess Engineering Research at the University of Cape Town, Department of Chemical Engineering) has been developed to provide estimates of these material and energy balance data, as well as calculate equipment volumes and utility needs. The model allows for aerobic or anaerobic, intra-or extracellular product formation or biomass growth in a continuous or batch process for various bioproducts produced from a selection of microorganisms using a range of raw materials. Using simple inputs, and default values drawn, the model is suitable for engineers and scientists alike. The model also incorporates the option to select for sterilization and to specify the downstream processing train. In the bioreactor, the model takes into account aeration, agitation, reaction, biomass maintenance, yield, post microbial growth cooling and growth rate calculations, amongst others. This paper presents the model framework for the microbial growth and product formation stages.

Research paper thumbnail of Generic flowsheet model for early inventory estimates of industrial microbial processes. II. Downstream processing

South African Journal of Chemical Engineering, Dec 1, 2016

To ensure optimal process flowsheet selection it is valuable to conduct environmental and economi... more To ensure optimal process flowsheet selection it is valuable to conduct environmental and economic comparisons at an early stage of technology selection and process design. However, the data that is needed to perform these studies are not available at this stage of process development. This is also true for bioprocess systems. To overcome the lack of data, the CeBER (Centre for Bioprocess Engineering Research, University of Cape Town) Bioprocess Modeller was developed to provide material and energy values for industrial microbial processes. This paper presents the downstream processing portion of this flowsheet. The model allows for solideliquid separation, cell disruption, concentration and formulation units as required. The model allows section of appropriate downstream processing units include, amongst others, centrifugation, filtration, precipitation and freeze-drying. At each downstream processing stage, non-reacting and reacting chemicals can be added. The model provides both a material inventory as well as the calculation of the energy input required and waste heat generated. Additionally, the model includes a database of values (including constants, operating conditions and others), drawn from various industrial norms and academic sources. Should specific information not be known, the model selects the most appropriate values based on other decisions made through the model.

Research paper thumbnail of Assessing the availability of life cycle assessments in Austria

International Journal of Life Cycle Assessment, Aug 28, 2018

Purpose This study aims to present the availability of studies that are related to life cycle ass... more Purpose This study aims to present the availability of studies that are related to life cycle assessments (LCA) in Austria since 2000. This study also includes a review of available water and carbon footprint studies along with an analysis of the Global Reporting Initiative (GRI) database pertaining to Austria. The review seeks to explore potential research gaps and to identify needs for similar studies in the country while quantifying the number of available studies that are available to the general public or as background information in other LCA studies. Methods Online searches using Google, Google Scholar, Scopus, and ScienceDirect were conducted using various keywords to find LCA studies. Keywords included: life cycle assessment, LCA, and Austria, as well as water and carbon footprinting. Results were limited to English language studies. Results and discussion A total of 15 studies that pertain directly to LCAs in Austria were found. In addition, four reports for water footprinting and six reports for carbon footprinting were found, and 77 GRI reports. The majority of the LCA studies were only accessible by way of restricted journals. Conclusions The majority of the studies focused on the energy and manufacturing sectors. This was expected, due to exports that make up a large portion of the Austrian economy. Nevertheless, LCA research appeared to be driven by academic sources, rather than industry. Therefore, most of the studies were limited to paid subscriptions and thus were not easily accessible by the general public.

Research paper thumbnail of Review: the availability of life-cycle studies in Sweden

International Journal of Life Cycle Assessment, Jul 20, 2018

Purpose An online review was conducted on the availability of life-cycle assessment (LCA), water,... more Purpose An online review was conducted on the availability of life-cycle assessment (LCA), water, and carbon footprinting studies in Sweden. The main purpose was to quantify the number of available studies, which may be of general interest to nonspecialists or as background data for LCA practitioners. Additionally, results from the Global Reporting Initiative (GRI) reports were also included. Methods The study used online searches conducted in Google and Google Scholar to obtain the publically available reports. Additionally, searches in ScienceDirect, Scopus, and Wiley were performed to obtain other peer-reviewed academic papers. Only English language results were included. Results and discussion LCAs and carbon footprinting studies were the most commonly conducted studies (13 LCA and 12 carbon footprinting studies), whereas water footprinting reports, while still largely available, were fewer in number. A number of GRI reports were also available with the majority of studies conducted for the financial services and real estate sectors. Several studies were in the form of university theses, while companies and research organizations conducted the remainder of research projects. Conclusions While several life-cycle assessments, carbon, and water footprinting studies were accessible via Google searches, given the interest in LCA in the country, e.g., the LCM2013 conference in Gothenburg and The Swedish Life Cycle Centre, more studies were expected.

Research paper thumbnail of Environmental analysis of plastic production processes: Comparing petroleum-based polypropylene and polyethylene with biologically-based poly-β-hydroxybutyric acid using life cycle analysis

Journal of Biotechnology, May 31, 2007

Polymers based on olefins have wide commercial applicability. However, they are made from non-ren... more Polymers based on olefins have wide commercial applicability. However, they are made from non-renewable resources and are characterised by difficulty in disposal where recycle and re-use is not feasible. Poly-␤-hydroxybutyric acid (PHB) provides one example of a polymer made from renewable resources. Before motivating its widespread use, the advantages of a renewable polymer must be weighed against the environmental aspects of its production. Previous studies relating the environmental impacts of petroleum-based and bio-plastics have centred on the impact categories of global warming and fossil fuel depletion. Cradle-to-grave studies report equivalent or reduced global warming impacts, in comparison to equivalent polyolefin processes. This stems from a perceived CO 2 neutral status of the renewable resource. Indeed, no previous work has reported the results of a life cycle assessment (LCA) giving the environmental impacts in all major categories. This study investigates a cradle-to-gate LCA of PHB production taking into account net CO 2 generation and all major impact categories. It compares the findings with similar studies of polypropylene (PP) and polyethylene (PE). It is found that, in all of the life cycle categories, PHB is superior to PP. Energy requirements are slightly lower than previously observed and significantly lower than those for polyolefin production. PE impacts are lower than PHB values in acidification and eutrophication.

Research paper thumbnail of Lignocellulosic bioethanol production from grasses pre-treated with acid mine drainage: Modeling and comparison of SHF and SSF

Bioresource Technology Reports, Sep 1, 2019

Acid mine drainage (AMD) was used for the pre-treatment of indigenous South African grass (Eragro... more Acid mine drainage (AMD) was used for the pre-treatment of indigenous South African grass (Eragrostis curvula), and compared to H 2 SO 4 (1 wt%) pre-treatment. The optimal pre-treatment duration were investigated and found to be 1 day for H 2 SO 4 and 3 days for AMD pre-treatment. The optimal biomass solid loadings were found to be 20 wt% for both pre-treatment methods. Additionally, enzymatic hydrolysis and fermentation to produce ethanol were investigated for both separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF). In both SHF and SSF, the H 2 SO 4 pre-treatment obtained higher concentrations of glucose/ethanol compared to AMD pre-treatment. The concentration of glucose/ethanol obtained using AMD pre-treatment was 70-80% of that achieved using H 2 SO 4 pre-treatment. Empirical equations modeling the glucose/ethanol concentration in all processes were determined using a least squares method. Concentrations predicted by the models were found to have a high correlation (r 2 = 0.87-0.99) to concentrations determined experimentally.

Research paper thumbnail of Evaluation of a combined lignocellulosic / waste water bio-refinery for the simultaneous production of valuable biochemical products and the remediation of acid mine drainage

Biofuels, Bioproducts and Biorefining, Apr 23, 2018

The additional costs required for the pre-treatment of lignocellulosic bio-mass prior to enzymati... more The additional costs required for the pre-treatment of lignocellulosic bio-mass prior to enzymatic hydrolysis have limited the commercial implementation of lignocellulosic biochemical production. The use of acidic mine drainage (AMD) water as an acid source for lignocellulosic pre-treatment has recently been investigated. Large quantities of AMD in South Africa suggest that AMD can be obtained cheaply, thus reducing the cost and increasing the potential of lignocellulosic bio-chemicals. Acidic mine drainage could undergo further remediation using sulfate-reducing bacteria (SRB) so that the water is suitable for release. The feasibility of such a system could be greatly improved if this process were to be incorporated within a bio-refinery, such that all fractions of the bio-mass are used to produce multiple products. This paper investigates such a bio-refinery system, and evaluates the different options based on the bio-refinery complexity profile (BCP). Due to the abundance of grass in the regions where AMD is generated, this was found to be the most suitable feedstock. The most feasible bio-refinery option was found to produce ethanol through fermentation of C6 sugars, although it is recommended that further investigation be conducted into additional high-value bio-chemicals from the C6 sugar platform. C5 sugars released in pre-treatment could be used as a substrate by SRB for AMD remediation. Gasification and direct combustion of lignin had similar BCPs and thus further investigation is required to determine the preferred path. Similarly, further investigation is required for the best processing route for distillery silage.

Research paper thumbnail of The availability of life-cycle assessment, water footprinting, and carbon footprinting studies in Brazil

International Journal of Life Cycle Assessment, Jun 11, 2018

Purpose This study aimed to determine the availability of environmental life cycle assessment (LC... more Purpose This study aimed to determine the availability of environmental life cycle assessment (LCA), water footprinting, and carbon footprinting data in Brazil. In particular, the study is targeted at showing what LCA-related studies are accessible to nonspecialists residing in Brazil as well as LCA specialists interested in accessing Brazilian LCA-related studies. Methods Online searches for LCA documents were performed using publicly available search engines such as Google and Google Scholar, as well as academic databases containing peer-reviewed journal articles such as Scopus, ScienceDirect, and Springer. The searches were conducted utilizing the keywords BLife Cycle Assessment,^Bcarbon footprint,^Bwater footprint,^and BBrazil.R esults and discussion A total of 73 published documents on LCA studies conducted between 2000 and 2016 could be found. Of these, 59 were only available in restricted access journals requiring some form of paid subscriptions. Most of these documents originated from academic institutions. For the majority of the studies, the exact region in which the study was carried out was not specified. Only twelve carbon and water footprinting studies were found. However, it was known that several other studies were available but were not found in these searches unless more specific years, authors, and/or products were included in the search terms. Conclusions It was observed that LCA studies were more established in the energy and agricultural sectors, an expected result given that all LCA studies would rely on energy as a background process, as well as the increasing energy demand due to increasing population and industrial activities in Brazil. Furthermore, it was observed that most LCA studies in the energy sector concentrated on the conversion of biomass, mainly sugarcane and soybean, to biofuels; thereby, establishing a strong link between the energy and agricultural sectors. The results showed that LCA is an emerging quantitative assessment technique in Brazil, especially in the energy and agricultural sectors. While there were over 70 studies found, it is not clear how many of these could be transferable into an LCI database or be used in other studies, due to the exact inputs used.

Research paper thumbnail of A discussion on the availability of life-cycle assessment studies in New Zealand

International Journal of Life Cycle Assessment, Jun 8, 2018

Purpose In order to understand the environmental impacts of various products, processes, or servi... more Purpose In order to understand the environmental impacts of various products, processes, or services, it should be possible to obtain life-cycle assessment (LCA) reports quickly and easily without having to delve into restricted access or hidden databases. The aim of this study is to assess the availability of environmental LCAs, water footprinting, and carbon footprinting studies conducted in New Zealand. Methods To review the quantitative availability of life-cycle assessment studies for New Zealand, simple online searches were performed using the Google and Google Scholar search engines. Additionally, ScienceDirect and Scopus were used to determine the availability of other peer-reviewed LCA-related reports. Results and discussion For the period under review, 20 documents were publicly available. Additionally, other searches conducted via ScienceDirect, Scopus and Google Scholar yielded a further 15 restricted documents. The results included data carbon-and water footprinting studies. The number of LCAs and carbon footprinting reports both exceeded those of water footprinting. Conclusions Over 35 studies were available through Internet searches. This number excludes wool which had six results (Scopus only) and many more through Google. These were not included due to possible repetition and miscounting of results.

Research paper thumbnail of Review: life-cycle assessment, water footprinting, and carbon footprinting in Portugal

International Journal of Life Cycle Assessment, Jun 4, 2018

Purpose A review of readily available quantitative environmental data was conducted in order to d... more Purpose A review of readily available quantitative environmental data was conducted in order to determine the state of sustainability reporting and identify possible future research areas in Portugal. Methods Internet searches of articles written in English and published between 2001 and 2015 were conducted using the keywords Blife-cycle assessment,^BLCA,^Bwater footprint,^Bcarbon footprint,^and BPortugal.^Additionally, reports from the Global Reporting Initiative (2015 only) were included in the search. Results and discussion It was found that 79% of reports found were published in the period 2011-2015. Several reports were found for the forestry, paper and pulp, food and beverage, energy and electricity, waste management, and automotive industries, while no reports were found for the textile, footwear and clothing, and base metal and mineral industries. As such, these are industries on which future studies might focus. No reports found were published by governmental organizations, although it is thought that expanding the search to include Portuguese language results would yields more results. The majority (68%) of companies reporting to the GRI adhered to the relevant guidelines. Conclusions A total of 72 reports were found (41 LCAs, water-or carbon footprints, and 31 GRI reports). It is unclear if there are other reports that may be restricted to Bhidden^datasets or company specific archives. The aim of this report was to highlight those that were available to a non-specialist or international audiences trying to gain a greater understanding of the LCA space in Portugal.

Research paper thumbnail of Feasibility assessment of the production of bioethanol from lignocellulosic biomass pretreated with acid mine drainage (AMD)

Renewable Energy, Sep 1, 2020

A techno-economic evaluation of a lignocellulosic bioethanol facility that uses acid mine drainag... more A techno-economic evaluation of a lignocellulosic bioethanol facility that uses acid mine drainage for the pre-treatment of weeping love grass (Eragrostis curvula) was performed. Both separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) reactor configurations were evaluated. Results were compared to an evaluation of the same process with biomass pre-treated with dilute H 2 SO 4. Capital and operating costs were estimated and a simple economic evaluation was conducted. It was found that all scenarios made a loss except for biomass pre-treated with H 2 SO 4 in the SHF reactor configuration, although the high capital cost resulted in a payback period of 80.7 years, which is unfeasible. SHF was found to produce more ethanol at a lower capital cost than SSF, indicating that it is more economically feasible. Incorporating the remediation of AMD into a simultaneous process could help improve process economics. It is thus recommended that a techno-economic evaluation be conducted on a process that produces bioethanol through SHF and simultaneously remediates AMD.

Research paper thumbnail of Eco-efficiency assessment of pork production through life-cycle assessment and product system value in South Africa

E3S Web of Conferences

The consumption of pork as a source of animal protein has increased worldwide, especially in deve... more The consumption of pork as a source of animal protein has increased worldwide, especially in developing countries such as South Africa. The increase in pork demand is putting pressure on the natural environment, and the costs of production are increasing. This study sought to determine what is the eco-efficiency of pork production in a South African context. It also was meant to determine which processes in the value chain have low eco-efficiencies. Lastly, it sought to find what strategies could be recommended to improve overall eco-efficiency. Eco-efficiency was assessed by following the requirements of the International Standards Organisation ISO 14045 standard, which requires that the Life cycle assessment (LCA) method and product system value be combined. The environmental life cycle costing (LCC) method was used to determine the product system value (Value Added) of pork production. The functional unit was 1 kg of pork carcass, specifically from the cradle to the abattoir gate...

Research paper thumbnail of Extraction of Essential Oils from Lavandula × intermedia ‘Margaret Roberts’ Using Steam Distillation, Hydrodistillation, and Cellulase-Assisted Hydrodistillation: Experimentation and Cost Analysis

Plants

Lavender oil is an important essential oil with many applications. The purpose of this study was ... more Lavender oil is an important essential oil with many applications. The purpose of this study was to compare different methods of essential oil extraction to determine which method would be the most effective and profitable for commercial-scale production from Lavandula × intermedia (‘Margret Roberts’) flowers and leaves. The lavender from this variety flowers year-round, providing an extended production season compared to some other lavender varieties. Steam distillation, hydrodistillation, and cellulase-assisted hydrodistillation were used to extract oil. The average extraction times for steam distillation, hydrodistillation, and cellulase-assisted hydrodistillation were 57-, 51-, and 49 min, respectively, and the average energy consumption was 15.0-, 13.4-, and 30.8 kJ/g, respectively. Cellulase-assisted hydrodistillation produced the best quality oils, with a lower camphor content and a sweeter, more pleasant smell, while steam-distilled oils had the highest camphor content, as w...