97 research outputs found
An integrated approach to waste and energy minimization in the wine industry : a knowledge-based decision methodology
No full textThesis (PhD)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: The importance of waste management is growing rapidly for several reasons. These
reasons include the escalating cost of wastewater treatment and cleaning chemicals, an
emerging trend of onerous regulatory regime regarding e uent disposal from governments,
rising public awareness on the adverse e ects of industrial waste as well as drastic reduc-
tion in water resources in the winegrowing regions. In addition, owing to the large energy
demand for refrigeration purposes for high quality wine production and rapidly increasing
energy costs, the challenges of energy management in the wine industry were also inves-
tigated.
In order to address these challenges adequately, the solutions were derived via the
integration of two disciplines: environmental science (waste and energy management)
and computer science (applications of arti cial intelligence). Therefore, the ndings re-
ported from this study seek to advance knowledge through the construction of decision
support systems for waste and energy management in circumstances where conventional
mathematical formalisms are inadequate. In that sense, the dissertation constitutes in-
terdisciplinary research on the application of integrated arti cial intelligence technologies
(expert systems and fuzzy logic) in designing and developing decision tools for waste and
energy management in the wine industry.
The dissertation rst presents the domain of interest, where the scope and breadth of
the problems it addresses are clearly de ned. Critical examination of the domain data-
bases revealed that data, information, and knowledge for waste and energy management
in the wine industry are generally incomplete and lack structure overall. Owing to these
characteristics, a hybrid system approach was proposed for the development of decision
support systems based on fuzzy logic. The integrated decision support systems were de-
veloped based on an object-oriented architecture. This approach facilitated the
exible
design required for waste and energy management-related complex problem-solving.
To illustrate the applicability of the o -line decision tools developed, several case stud-
ies mirroring on actual industrial practices were considered. These systems were found to
be robust and yielded results that were in accordance with actual industrial practices inthe wine industry. Furthermore, they provided intelligent suggestions in scenarios where
there was minimal information, and under certain instances they o ered feasible sugges-
tions in circumstances where a human novice could have problems in making the right
decisions.AFRIKAANSE OPSOMMING: Die belangrikheid van afvalbestuur neem om verskeie redes vinnig toe. Die redes sluit
in die eskalerende koste van afvalwaterbehandeling en skoonmaakmiddels, streng regula-
toriese vereistes van regeringskant met betrekking tot die verwydering van uitvloeisels,
toenemende openbare bewustheid van die nadelinge e ekte van nywerheidsafval, sowel
as die drastiese afname in waterbronne in wynproduserende omgewings. Daarby, a.g.v.
die groot energieverbruik wat deur die verkoeling van hokwaliteitwyn vereis word en die
snelgroeiende energiekoste, is die uitdagings van energiebestuur in die wynbedryf ook on-
dersoek.
Ten einde die uitdagings die hoof te kon bied, is oplossings gevind deur die integrasie
van twee disciplines: omgewingswetenskap (afval- en energiebestuur) en rekenaarweten-
skap (toepassings van kunsmatige intelligensie). Gevolglik is daar deur die bevindinge
van die studie gepoog om kennis te bevorder deur die konstruksie van besluitnemingson-
dersteuningstelsels vir afval- en energiebestuur onder omstandighede waar konvensionele
wiskundige algoritmes ontoereikend sou wees. In die opsig verteenwoordig die proefskrif
interdissiplinre navorsing in die toepassing van gentegreerde kunsmatige intelligensieteg-
nologie (kundige stelsels en wasige logika) in die ontwerp en ontwikkeling van besluitne-
mingshulpmiddels vir afval- en energiebestuur in die wynindustrie.
Die proefskrif baken eers die probleemgebied af, waarna die bestek en omvang van die
probleme waarop die werk gemik is duidelik gede nieer word. Kritiese ondersoek van
die databasisse in die domein het getoon dat die data, informasie en kennis oor afval- en
energiebestuur in die wynbedryf in die algemeen onvolledig en gebrekkig gestruktureer is.
A.g.v. di eienskappe, is 'n hibriede stelselbeandering voorgestel vir die ontwikkeling van
besluitnemingstelsels gegrond op wasige logika. Die gentegreerde besluitnemingsonders-
teuningstelsels is ontwikkel op 'n objek-georinteerde argitektuur. Die benadering het die
daarstelling van 'n buigsame ontwerp wat benodig word vir komplekse probleemoplossing
in afval- en energiebestuur vergemaklik.
Om die toepaslikheid van die a
ynige besluitnemingshulpmiddels wat ontwerp is, te
illustreer, is verskeie gevallestudies wat werklike industrile praktyk uitbeeld beskou. Diestelsels was robuust en het resultate gelewer wat in ooreenstemming was met werklike
industrile praktyke in die wynnywerheid. Die kundige stelsels het verder intelligente
voorstelle gemaak in scenarios waar daar minimale informasie beskikbaar was, en onder
sekere omstandighede het hulle realistiese oplossings voorgestel waar 'n onkundige persoon
probleme sou gehad he tom die regte besluite te kon neem.Doctora
Simulated environmental risk estimation of engineered nanomaterials: A case of cosmetics in Johannesburg City
No full text This paper attempts to quantify the potential risks posed by engineered nanomaterials (ENMs) to the aquatic and terrestrial ecosystems from cosmetic-based nanoproducts. The predicted environmental concentrations (PEC) were modelled for the silver (nAg) and titanium dioxide (nTiO2) nanoparticles embedded in cosmetic nanoproducts. The Johannesburg Metropolitan City (JHB City), in South Africa, was used as the reference study area. A mathematical model was applied to compute the quantities of ENMs flows from the cosmetic nanoproducts into the JHB City aquatic and terrestrial ecosystems. The risk quotient (RQ) of the nanoscale materials were evaluated as a ratio of PEC to the predicted no effect concentrations (PNEC). RQ values showed wide variance due to factors like; the quantities of ENMs, the fate and pathways of ENMs in the aquatic and terrestrial ecosystems, efficiency of the wastewater treatment plants (WWTP) as well as the economic and demographic data for South Africa and Switzerland. For the aquatic environment, the PEC values of nAg ranged from 2.80 × 10−3 to 6.19 × 10−1 μg L−1 whereas for nTiO2 the values ranged from 2.7 0 × 10−3 to 2.70 × 10−1 μg L−1 under the realistic dilution factor of 1 with the WWTP functioning at high removal efficiency regime. The RQ values in the aquatic ecosystems were mostly >1, indicating the potential risk of both nAg and nTiO2 but <<<1 in the terrestrial ecosystems. Our results provide the first quantification of ENMs potential risk into the environment Johannesburg City in a developing country’s natural and technical settings. </jats:p
Nanotechnology risk assessment from a waste management perspective: Are the current tools adequate?
No full text The burgeoning nanotechnology industry is rapidly generating new forms of waste streams generically referred herein as nanowastes. However, little is known about the fate and behavior of these waste streams and their impacts thereof in different ecological systems despite their increasingly widespread dispersion into the environment through production, distribution, handling, and nanomaterials (NMs) incorporation into bulk products processes. In this paper, risk assessment of nanotechnology from a waste management perspective was examined to elucidate potential new forms of challenges nanowastes may likely pose to the current legislative and waste management systems. This was through the identification of several knowledge gaps that merit urgent attention in order to increase our collective understanding of managing nanowastes safely, responsibly, and sustainably. The paper presents the identified gaps and consequently proposes a qualitative risk assessment of nanowastes to address some of the current challenges. The applicability of the proposed model is illustrated through several examples. In addition, the first nanowastes classification protocol presented in this article show that a given nanomaterial may result in generating nanowaste streams of different forms with variant hazard levels ranging from benign to extremely being hazardous waste streams — a dramatic phenomenon from the conventional waste streams due to macroscale chemicals. The study shows that it is in the early days to draw broad generic classification of different nanowastes, and each stream may require their risk profile be assessed on a case-by-case basis. We conclude by presenting several recommendations on what needs to be done in dealing with nanowastes as means of avoiding unintended long-term consequences of nanotechnology. </jats:p
Comment on “Risk Assessments Show Engineered Nanomaterials To Be of Low Environmental Concern”
No full textEcological risk modelling of antiretroviral drugs in the aquatic environment
No full textDissertation (MSc (Applied Science) Water Utilisation)--University of Pretoria, 2022.The success of antiretroviral therapy (ART) programme's on the management of the Human Immunodeficiency Virus/ Acquired Immunodeficiency Syndrome (HIV/AIDS) in the Sub-Saharan African (SSA) region has inadvertently led to the release of antiretroviral drugs (ARVs) into the environment. This study aimed to model the quantities and risks of ARVs in aquatic environments. Herein, the ecological risks of first regime (efavirenz (EFV), lamivudine (3TC), nevirapine (NVP), zidovudine (AZT) and tenofovir (TDF)), and second regime ARVs (lopinavir (LPV), atazanavir (ATV), ritonavir (RTV), didanosine (DDI) and dolutegravir (DTG)) were investigated. ARV releases and quantification into the aquatic environment were based on Eswatini as a study case country using the material flow analysis (MFA) approach. Quantities of ARVs into the environment were estimated for all ten drugs using the input model parameters, viz.: (number of people living with HIV (PLWHIV), number of people on ARVs, drug dosages, treatment adherence and drug excretion rate). The predicted environmental concentrations (PEC) were then compared to the predicted no effect concentrations (PNEC) to estimate the possible risk (by deriving the risk quotient (RQ). Owing to the dearth of ecotoxicological data for ARVs, Ecological Structure Activity Relationships (ECOSAR) was used to derive the toxicity of each drug for three species: daphnia, algae, and fish. Results indicated quantities of ARVs were three-fold higher in surface water relative to wastewater. For example, in 2017, EFV was 5 671 and 1 853 kg in surface water and wastewater, respectively. Higher flows of ARVs in surface waters were associated with a lack of sanitation services for most Eswatini population, and low wastewater treatment plant (WWTP) performance. Results further showed wide variability of PECs in surface water (0.08–73.2 μg/L) and wastewater (0.02 – 23.1 μg/L). Of the ten ARVs, the risk of DTG was unquantifiable due to a lack of ecotoxicity data even when using the ECOSAR approach. Only DDI had RQs 10) to all three taxa. Further, NVP and AZT presented moderate risk (1 < RQ < 10) to algae, and 3TC and TDF posed minimal risk (RQ < 1) to daphnia. No risk for the ARVs was estimated in wastewater except for TDF due to the lack of their bacterial toxicity data. Results herein make it possible for the first time to quantify the potential environmental risks of ARVs using a modelling approach. The model can be extended to other SSA countries given their limited capabilities to detect and quantify ARVs risks in the environment using costly analytical techniques. Furthermore, the results suggest lack of sanitation services and high HIV/AIDs prevalence in SSA with concomitant high concentrations of ARVs in the environment potentially may trigger antiretroviral drug resistance, with possible negative implications to the ART programme.Chemical EngineeringMSc (Applied Science) Water UtilisationUnrestricte
Mixture effects of metallic nanoparticles, and organic contaminant on Daphnia magna in aqueous media.
No full textDissertation (MSc (Chemical Engineering))- -University of Pretoria, 2022.Engineered nanoparticles (ENPs) including silver (n-Ag) and zinc oxide (n-ZnO) are among rapidly increasing contaminants of emerging concern (CECs) globally. Moreover, pesticides (e.g. atrazine (ATZ)) owing to their extensive application are present in variant ecological systems like ground and surface waters, with unintended threats to aquatic life forms. Further, increasing presence of different classes of CECs and persistent organic pollutants (POPs) has led to their co-existence as mixtures in the environmental systems; but with unknown toxicological outcomes to organisms at different biological levels of organization. Herein, freshwater crustacean Daphnia magna was used as a model organism to assess the biological effects of individual ENPs, their binary mixtures with or without ATZ, and ternary mixtures with ATZ. The organisms were exposed to variant concentrations of ENPs and ATZ in ISO medium (standard freshwater), and immobilization was investigated as the endpoint.
Evaluation of the physicochemical characterization of ENPs was carried out to establish plausible link between their properties, and the observed biological outcomes. Aggregation of n-Ag increased with exposure time; whereas that of n-ZnO significantly decreased over time. For the binary mixtures, results revealed irrespective of ENPs type, aggregation size increased in the presence of ATZ due to hetero-aggregation between the compounds. Results of the ternary mixtures indicated aggregation size was four-fold relative to those of ENPs binary mixtures. Dissolution of individual n-Ag and n-ZnO increased and decreased over exposure period of 48 h, respectively. The presence of ATZ enhanced the dissolution of ENPs in the binary mixtures. However, in the ternary system a reduction of the dissolution of both ENPs in the presence of ATZ was observed.
Studies on the toxicity of individual contaminants based on median effective concentration (EC50) values in decreasing order were n-Ag > n-ZnO > ATZ, largely attributed to high dissolution of n-Ag in the exposure medium. For binary mixtures with n-Ag, higher toxicity was apparent, relative to other mixture systems (binary or ternary). For ternary mixtures, no toxicological outcomes were observed irrespective of the exposure concentrations. These findings demonstrated that the toxic silver ions were the primary driver of toxicity towards D. magna. Moreover, co-existence of both nanoscale and macroscale may lead to the chemical transformation of CECs in the exposure medium with marked reduction of individual contaminants toxic effects.Water Research Commission (WRC)Department of Water and Sanitation (DWS)Chemical EngineeringMsc (Chemical Engineering)Unrestricte
Market dynamics as a driver towards the evolution of research needs : the case of up-flow anaerobic sludge blanket seeding granules
No full textCITATION: Musee, N. & Lorenzen, L. 2013. Market dynamics as a driver towards the evolution of
research needs : the case of up-flow anaerobic sludge
blanket seeding granules, Water SA, 39(1):131-142, doi:http://dx.doi.org/10.4314/wsa.v39i1.13.The original publication is available at http://www.wrc.org.zaMarket dynamics offer positive (incentive) or negative (disincentive) feedback loops that shape the research needs for, or
certain aspects of, a particular technology. Our case study results illustrate how market dynamics have influenced the evolution of research needs in the wastewater treatment sector, with specific emphasis on research on the seeding granules used to
start up-flow anaerobic sludge blanket (UASB) reactors. Because of insufficient data on the actual market demand for seeding
granules for UASB plants, surrogate data, on the number of UASB plants installed internationally from 1970 to 2007, were
used to predict the potential future demand for seeding granules. Secondly, we also determined whether or not such a demand
would provide sufficient economic justification for the installation of one or more plants for manufacturing seeding granules
in South Africa. The direct relationship between the demand for seeding granules and increased numbers of UASB plants
was based on the premise that the start-up of each plant required a seeding inoculum before effluent could be treated. Three
methods were used to obtain the data used in this study, namely: a literature survey, a questionnaire survey, and interviews
with people having expert knowledge of wastewater treatment technologies. Our findings suggest that the UASB technology
has largely been marginalised in the wastewater treatment market because of the introduction of competing technologies,
and due to high initial capital costs. As a result, South African market demand for the seeding granules is likely to be very
small or non-existent, because the number of new UASB plants installed per year is likely to decrease in future. Secondly, our
research suggests that market dynamics, political contexts and technologies will continue to change, exerting an increasing
downward influence on the UASB technology over time.Publisher's versio
Effects of Two Antiretroviral Drugs on the Crustacean Daphnia magna in River Water
No full textAntiretroviral (ARVs) drugs are used to manage the human immunodeficiency virus (HIV) disease and are increasingly being detected in the aquatic environment. However, little is known about their effects on non-target aquatic organisms. Here, Daphnia magna neonates were exposed to Efavirenz (EFV) and Tenofovir (TFV) ARVs at 62.5–1000 µg/L for 48 h in river water. The endpoints assessed were mortality, immobilization, and biochemical biomarkers (catalase (CAT), glutathione S-transferase (GST), and malondialdehyde (MDA)). No mortality was observed over 48 h. Concentration- and time-dependent immobilization was observed for both ARVs only at 250–1000 µg/L after 48 h, with significant immobilization observed for EFV compared to TFV. Results for biochemical responses demonstrated that both ARVs induced significant changes in CAT and GST activities, and MDA levels, with effects higher for EFV compared to TFV. Biochemical responses were indicative of oxidative stress alterations. Hence, both ARVs could potentially be toxic to D. magna
Effects of two antiretroviral drugs on the crustacean Daphnia magna in river water
No full textSUPPLEMENTARY MATERIALS : TABLE S1: Classes and types of individual Food and Drug Administration-approved ARVs for clinical use; TABLE S2: Global measured
environmental concentrations of ARVs in different matrices [3,22,53,81,82]; TABLE S3: Molecular Formula and physico-chemical properties of ARVs; TABLE S4: Physicochemical parameters of freshwater samples collected from Elands River; TABLE S5: Physicochemical properties of ER water during exposure recorded for the controls, lowest and highest exposure concentrations at 0 and 48 h; TABLE S6: Cumulative immobilization of D. magna exposed to variant concentrations of EFV and TFV.Antiretroviral (ARVs) drugs are used to manage the human immunodeficiency virus
(HIV) disease and are increasingly being detected in the aquatic environment. However, little is
known about their effects on non-target aquatic organisms. Here, Daphnia magna neonates were
exposed to Efavirenz (EFV) and Tenofovir (TFV) ARVs at 62.5–1000 g/L for 48 h in river water. The
endpoints assessed were mortality, immobilization, and biochemical biomarkers (catalase (CAT),
glutathione S-transferase (GST), and malondialdehyde (MDA)). No mortality was observed over
48 h. Concentration- and time-dependent immobilization was observed for both ARVs only at
250–1000 g/L after 48 h, with significant immobilization observed for EFV compared to TFV. Results
for biochemical responses demonstrated that both ARVs induced significant changes in CAT and GST
activities, and MDA levels, with effects higher for EFV compared to TFV. Biochemical responses were
indicative of oxidative stress alterations. Hence, both ARVs could potentially be toxic to D. magna.Water Research Commission (WRC) South Africa.https://www.mdpi.com/journal/toxicsam2023Chemical Engineerin
Evaluation of Apical and Molecular Effects of Algae Pseudokirchneriella subcapitata to Cerium Oxide Nanoparticles
No full textCerium oxide engineered nanoparticles (nCeO2) are widely used in various applications and are, also, increasingly being detected in different environmental matrixes. However, their impacts on the aquatic environment remain poorly quantified. Hence, there is a need to investigate their effects on non-target aquatic organisms. Here, we evaluated the cytotoxic and genotoxic effects of <25 nm uncoated-nCeO2 on algae Pseudokirchneriella subcapitata. Apical (growth and chlorophyll a (Chl a) content) and genotoxic effects were investigated at 62.5–1000 µg/L after 72 and 168 h. Results demonstrated that nCeO2 induced significant growth inhibition after 72 h and promotion post 96–168 h. Conversely, nCeO2 induced enhanced Chl a content post 72 h, but no significant changes were observed between nCeO2–exposed and control samples after 168 h. Hence, the results indicate P. subcapitata photosynthetic system recovery ability to nCeO2 effects under chronic-exposure conditions. RAPD-PCR profiles showed the appearance and/or disappearance of normal bands relative to controls; indicative of DNA damage and/or DNA mutation. Unlike cell recovery observed post 96 h, DNA damage persisted over 168 h. Thus, sub-lethal nCeO2-induced toxicological effects may pose a more serious threat to algae than at present anticipated
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