Thesis(Ph.D. Agriculture (Soil Science)) -- University of Limpopo, 2020 / Due to high incidents of drought in the semi-arid regions of Limpopo Province, South Africa, the potential feasibility of using treated wastewater for irrigating vegetable crops had been researched and developed under the best practices of Natuurboerdery farming system. The investigation aimed at the development of soil and plant health management strategies for crops irrigated with treated wastewater that could ameliorate the ever-increasing demand for fresh irrigation water in the Province. Seven specific objectives, reduced to three overall objectives under Natuurboedery farming system were intended to investigate (1) the chemical and biological quality of treated wastewater used in irrigation with respect to disposal points and sampling period, (2) the responses of soil physico-chemical properties, heavy metal distribution and biological-soil-health indicators to irrigation with treated wastewater under field conditions and (3) the partitioning of cations and heavy metals in root, stem and leaf tissues of onion, tomato and a selected weed plant irrigated with treated wastewater. In each objective, unless otherwise stated, treatment effects were described at the probability level of 5%. In Objective 1, relative to the borehole water, treated wastewater had lower concentration of Ca, Mg, K, Na, Cl, HCO3 - , SO4 - , Zn, Cr and Pb, with temporal and spatial tendencies in accumulation of certain elements. In contrast, the treated wastewater had higher loads of pathogenic microbes that included bacteria (Escherichia coli, Salmonella spp., Shigella spp. and Vibrio spp.), protozoa (Entamoeba histolytica) and two helminths (Schistosoma mansoni; Ascaris lumbricoides), with temporal and spatial tendencies. In Objective 2, Al and Cr tended to be high in deeper soil layers (60-100 cm), whereas most essential nutrient elements and essential heavy metals (Cu, Fe, Mn, Ni, Zn, As, Cr and Pb) were contained in the upper soil levels (0-40 cm). The upper soil levels were also characterised by having substantial attributes of root health, namely, soil organic carbon, active carbon and potentially mineralisable nitrogen. In Objective 3, root, stem and leaf tissues of horseweed (Conyza canadensis L.), onion (Allium cepa L.) and tomato (Solanum lycopersicum L.) plants had different accumulation abilities for different metals, except for As. Contrary to the expectation, the onion bulb contained less test cations and heavy metals. In conclusion, in terms of chemical component at the time of sampling, as depicted from the water and soil samples, the treated wastewater was suitable for irrigation. However, in terms of pathogenic microbes, the treated wastewater was not suitable for irrigating crops intended for human consumption due to significantly higher loads than the permissible standards. Amongst all observed challenges, the reduction of pathogenic microbes should be given priority since it contravened existing national and international standards for using treated wastewater for in irrigation of crops intended for human consumption. / National Research Foundation (NRF)

Fresh water scarcity is an alarming issue for communities across the globe. The development of water recycling and reuse technologies has become crucial in expanding the limited water resources. Reverse osmosis (RO) is among the key processes that can treat wastewater to meet potable water reuse standards. Despite the advancements in RO membrane technologies, many challenges persist regarding the operation and maintenance of RO membranes, such as membrane fouling. Extensive research investigations have focused on developing RO membrane modifications to combat the decreased performance due to fouling. Polyethylenimine (PEI) is a promising polymer used for enhancing the anti-fouling properties of thin film composite (TFC) RO membranes. PEI, a positively charged polymer with high charge density, is commonly grafted on TFC RO membrane surfaces to produce smoother, more hydrophilic membranes to minimize fouling. However, little research is available on the optimal PEI placement within the composite RO membrane layers for enhancing antifouling properties. The current study aimed to investigate whether alternative positions within the membrane layers could yield better anti-fouling performance compared to incorporation PEI on the membrane surface. Unmodified (i.e., control) and PEI-modified TFC RO membranes were fabricated in the laboratory. The PEI-modified membranes were produced in two variations with regards to the position of PEI in the composite membrane layer. The first variation, named PEI-1, involved immersing the polysulfone (Psf) support layer of the membrane in an aqueous PEI solution, before the active polyamide (PA) layer was formed. The second variation, named PEI-2, consisted of immersing the fully formed TFC RO membrane in an aqueous PEI solution to incorporate PEI on the surface of the active PA layer. The PEI used in the study for membrane modification had branched configuration with molecular weight of 1200 g/mole. The laboratory-scale TFC RO membranes produced herein were characterized and tested for water flux, salt rejection, and fouling behavior. The water flux and salt rejection, commonly referred to as permselectivity, of all the membranes produced were evaluated in a crossflow filtration unit. On the other hand, the fouling tests were conducted in a dead-end membrane filtration unit because of operational limitations of the crossflow unit. The PEI-1 membrane produced a water flux of 18.7 LMH (L/m2hr) and a stable salt rejection of 82.1%. The PEI-2 membrane resulted in a water flux of 22.4 LMH and a salt rejection of 85.2%. These results indicate that incorporating PEI on the membrane PA active surface layer achieved better permselectivity compared to PEI-1, which is the membrane with PEI incorporated inside the structure (i.e., incorporated on the Psf support layer). However, both PEI-modified membranes exhibited lower permselectivity performance compared to the unmodified control membrane, which produced a water flux of 23.9 LMH and salt rejection of 88.2%. To test fouling of the unmodified and PEI modified RO membranes, bovine serum albumin (BSA) was chosen as a model foulant based on preliminary investigations conducted herein to compare BSA to sodium alginate. After the foulant was introduced in the feed, the unmodified membrane exhibited a 31.8% total fouling ratio, the decrease in flux from the foulant solution compared to running clean DI water. However, a 90.7% flux recovery ratio was achieved when a final DI water rinse was performed. The PEI-1 membrane had a 39.7% total fouling ratio and a 81.6% flux recovery ratio after rinsing with DI water. The PEI-2 membrane showed a 43.1% total fouling ratio as a result of BSA fouling and a 94% flux recovery ratio when rinsed with DI water at the end of the fouling test. Water contact angle (WCA) analysis confirmed that the PEI-2 membrane had the most hydrophilic surface (WCA 25.1°) compared to the control membrane (WCA 52.9°). The higher hydrophilicity of PEI-2 aligns with its higher flux recovery results, which indicated reduced membrane fouling. Furthermore, the PEI-2 membrane had a drastically lower WCA than those reported in the literature for PEI-modified membranes, which ranged from (63° – 80°). In conclusion, the increased flux recovery and surface hydrophilicity of the PEI-2 membrane indicated that the best anti-fouling performance would likely be obtained when PEI is grafted onto the surface of the active PA membrane surface. Future research is warranted to optimize the PEI-2 membrane by exploring the effect of PEI concentration, molecular weight, and structural configuration (i.e., branched versus linear), on anti-fouling performance of the membranes.

Thesis (MSc)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Large volumes of wastewater are generated annually during the grape harvest season from various processing and cleaning operations at wineries, distilleries and other wine-related industries. South African regulatory bodies dictate that wastewater should have a pH of 5.5 to 7.5 and a chemical oxygen demand (COD) lower than 75 mg/L. However, winery wastewater has a typical pH of 4 to 5 and a COD varying between 2 000 and 12 000 mg/L. Urban wineries channel the wastewater to local sewage treatment facilities and are often heavily fined for exceeding governmental requirements. Rural wineries usually have little or no treatment operations for their wastewater and it is often irrigated onto crops, which may result in environmental pollution and contamination of underground water resources. Various criteria are important in choosing a wastewater treatment system, such as an ecofriendly process that is flexible to withstand various concentration loads and characteristics, requiring low capital and operating costs, minimal personal attention and do not require too much land. In this study, a large variation in COD, pH and chemical composition of the winery wastewater was observed that could be related to varying factors such as the harvest load, operational procedures and grape variety. Wastewater from destemming and pressing operations contained higher concentrations of glucose, fructose and malic acid, which originated from the grape berries. The fermentable sugars (glucose and fructose) contributed to almost half of the COD with a smaller contribution from ethanol and acetic acid. The low pH can be ascribed to relative high concentrations of organic acids in the wastewater. The efficacy of biological treatment systems depends strongly on the ability of microorganisms to form biofilm communities that are able to degrade the organic compounds in the wastewater. Preliminary identification of microorganisms that naturally occur in winery wastewater indicated the presence of various bacterial and yeast species that could be effective in the biological treatment of the wastewater. When evaluated as pure cultures under aerobic conditions, some of the yeast isolates effectively reduced the COD of a synthetic wastewater, whereas the bacterial isolates were ineffective. The most effective yeast isolates were identified as Pichia rhodanensis, Kloeckera apiculata, Candida krusei and Saccharomyces cerevisiae. Our search for cost-effective biological treatment systems led to the evaluation of a Rotating Biological Contactor (RBC) for the treatment of winery wastewater. The RBC was evaluated on a laboratory scale with 10% (v/v) diluted grape juice and inoculated with a mixed microbial community isolated from winery wastewater. The results showed a reduction in the COD that improved with an extended retention time. Evaluation of the RBC on-site at a local winery during the harvest season resulted on average in a 41% decrease in COD and an increase of 0,75 pH units. RFLP analysis of the biofilm communities within the RBC confirmed a population shift in both the bacterial and fungal species during the evaluation period. The most dominant yeast isolates were identified with 18S rDNA sequencing as Saccharomyces cerevisiae, Candida intermedia, Hanseniaspora uvarum and Pichia membranifaciens. All these species are naturally associated with grapes and/or water and with the exception of Hanseniaspora uvarum, they are able to form either simple or elaborate pseudohyphae. / AFRIKAANSE OPSOMMING: Groot hoeveelhede afloopwater word jaarliks gedurende die druiwe-oestyd deur verskeie prosessering- en skoonmaakoperasies deur wynkelders, distilleer- en ander wynverwante industrieë gegenereer. Suid-Afrikaanse beheerliggame vereis dat afloopwater ‘n pH van 5.5 tot 7.5 en ‘n chemiese suurstofbehoefte (COD) van minder as 75 mg/l moet hê. Kelderafloopwater het egter gewoonlik ‘n pH van 4 tot 5 en ‘n COD van 2 000 tot 12 000 mg/L. Stedelike wynkelders voer die afloopwater na ń plaaslike rioolsuiweringsaanleg wat dikwels tot swaar boetes vir oortreding van die wetlike vereistes lei. Plattelandse wynkelders het gewoonlik min of geen behandelingsprosesse vir hul afloopwater nie en gebruik die water dikwels vir gewasbesproeiing, wat tot omgewingsbesoedeling en kontaminasie van ondergrondse waterbronne kan lei. Verskeie kriteria is belangrik in die keuse van ‘n waterbehandelingstelsel, byvoorbeeld ‘n omgewingsvriendelike proses wat verskillende konsentrasieladings en samestellings kan hanteer, ‘n lae kapitaal- en bedryfskoste en minimale persoonlike aandag vereis en min ruimte benodig. Hierdie studie het getoon dat kelderafloopwater ‘n groot variasie in COD, pH en chemiese samestelling het wat met wisselende faktore soos die oeslading, operasionele prosesse en selfs die druifkultivar verband kan hou. Afloopwater van ontstingeling- en parsoperasies het hoër konsentrasies glukose, fruktose en appelsuur wat van die druiwekorrels afkomstig is. Die fermenteerbare suikers (glukose en fruktose) dra tot amper 50% van die COD by, met ‘n kleiner bydrae deur etanol en asynsuur. Die lae pH kan grootliks aan organiese sure in die afloopwater toegeskryf word. Die effektiwiteit van biologiese behandelingstelsels steun sterk op die vermoë van mikroorganismes om biofilmgemeenskappe te vorm wat die organiese verbindings in die afloopwater kan afbreek. Voorlopige identifikasie van mikro-organismes wat natuurlik in wynafloopwater voorkom, het die teenwoordigheid van verskeie bakteriese en gisspesies aangedui. Evaluering van hierdie isolate onder aërobiese toestande het getoon dat sommige van die gis-isolate die COD van ‘n sintetiese afloopwater effektief kon verlaag, terwyl die bakteriese isolate oneffektief was. Die mees effektiewe gis-isolate is as Pichia rhodanensis, Kloeckera apiculata, Candida krusei en Saccharomyces cerevisiae geïdentifiseer. Ons soektog na ‘n koste-effektiewe biologiese behandelingsisteem het tot die evaluering van ‘n ‘Rotating Biological Contactor’ (RBC) vir die behandeling van afloopwater gelei. Die RBC is op laboratoriumskaal met 10% (v/v) verdunde druiwesap geëvalueer en met ‘n gemengde mikrobiese gemeenskap wat uit afloopwater geïsoleer is, innokuleer. Die resultate het ‘n verlaging in die COD getoon wat met ‘n langer retensietyd verbeter het. Evaluering van die RBC by ‘n plaaslike wynkelder gedurende die oesseisoen het gemiddeld ‘n verlaging van 41% in die COD en ‘n verhoging van 0,75 pH eenhede getoon. RPLP analise van die biofilmgemeenskappe in die RBC het ‘n bevolkingsverskuiwing in beide die bakteriese en swamspesies aangetoon. Die mees dominante gisspesies is met 18S rDNA volgordebepaling as Saccharomyces cerevisiae, Candida intermedia, Hanseniaspora uvarum en Pichia membranifaciens geïdentifiseer. Al hierdie spesies word gewoonlik met druiwe en/of water geassosieer en is, met die uitsondering van Hanseniaspora uvarum, in staat om òf eenvoudige òf komplekse pseudohife te vorm.

M. Tech., (Faculty of Applied and Computer Science), Vaal University of Technology / There is huge concern in the mining and industries to manage wastewater prior to discharge into the environment. It is generally cheaper and cost reducing for industries to treat its own wastewater before discharging to the local authority sewer. Dense Media Separation (DMS) Powders Company produces milled and atoms ferro-silicon by pyro-metallurgical process. DMS Powders uses municipal water for all processes taking place in the plants. The water used during the processes of milled and atom ferrosilicon powder is discharged into the environment without being treated. By treating this process wastewater before discharging will result in reducing the water consumption by recycling and the penalty costs for polluting the environment. The primary objective of this study is to find suitable method for treatment of DMS Powders’ process water using selected membrane processes. Membrane processes are better choice compared to traditional physical/chemical treatment processes, due to their advantages of approving water quality, no phase change, no chemical addition and simple operation. Two commercial membranes namely; NF-, and SW30HR are used in the treatment of DMS Powders process water. These membranes were purchased from (Dow/Filmtec) Manufacturing Company (Pty) situated in South Africa. Membranes were characterised by Scanning Electron Microscopy (SEM), Thermo Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA) and Fourie Transform Infrared (FTIR) instruments. For synthetic water three membranes (NF- , NF90, and SW30HR) are investigated for the study. The fluxibility indicated that NF- membrane has higher flux compared to NF90 and SW30HR membranes. All the three membranes were very good in terms of rejection on single salts. Fouling was studied on DMS Powders process water. Concentration polarization was formed on NF- and SW30HR membranes investigations on selected membranes conclude that NF- membrane will be the suitable membrane for treatment of DMS Powders process water because of its high fluxibility and rejection. Discharged effluent of DMS Powders could comply with the legislature and environmental pollution could be minimised. The study revealed that fouling does occur during treatment of process water. SW30HR showed that M9 Plant had more fouling for M9 samples than other Plants (M8A and M8B). It was because of higher concentrations in suspended solids.or M8A, M8B and M9 process water.

Submitted in fulfillment for the requirements of the degree of Master of Engineering, Department of Chemical Engineering, Durban University of Technology, KwaZulu-Natal, South Africa, 2016. / A large fraction of the world's population, around 1.1 billion people, do not have access to acceptable sources of water. In South Africa there is a growing pressure on the available freshwater resources. New sources of freshwater supply are becoming increasingly scarce, expensive or politically controversial. This has led to large scale interest in the application of water reclamation and reuse of domestic, mining and industrial wastewater as an alternative water supply sources. This is becoming critical to sustain development and economic growth in the Southern African region. This research aims at providing both social and scientific information on the importance of greywater reuse and recycling as an alternate source to aid water demand management under South African conditions. The approach to this research work was divided into two main thrusts: the first was to gain an understanding of the public attitudes towards the idea of reusing greywater that is usually perceived as wastewater which pose health concerns. The second was to provide an understanding of typical greywater quality in a peri-urban community in Durban, South Africa as well as investigate the suitability of a horizontal roughing filtration system in reducing pollutant strength of contaminants found in greywater for non-potable reuse applications. In order to achieve the central aim of this research study, the following objectives were considered: • Investigation of public perception and attitudes towards the reuse of greywater. • Determination of greywater quality in a peri-urban community in Durban South Africa. • Investigation of the performance of a horizontal roughing filtration system for the treatment of greywater collected from a peri-urban community in Durban, South Africa. It was important to have an understanding of public perception and attitudes towards the reuse of greywater because of the fact that the success of any reuse application depends on the acceptance of the public. The methodological approach for this aspect of the research work involved administering of structured questionnaires to residents within the community through field visits. The questionnaire addressed issues related to attitudes towards the reuse of greywater, perceived advantages related to the reuse of greywater and concerns related to public health issues regarding the reuse of greywater. The successful implementation of any greywater treatment process depends largely on its characteristics in terms of the pollutant strength. The methodological approach for this aspect of the research work involved physico- chemical characterization of the greywater collected from different sources within the households in the peri-urban community. Greywater samples were collected from the kitchen, shower and laundry within each of the households. This aspect of the research work was undertaken to gain an understanding of greywater quality from different sources within and between households. In order to achieve the third objective of this research work, a pilot plant horizontal roughing filtration system was designed and fabricated for the treatment of greywater. The system consisted of three compartments containing different sizes of gravel that served as the filter media. This was done in order to investigate the effect of varying filter media size on the performance of the horizontal roughing filtration system in treating greywater. The system had an adjustable manual valve used in varying the filtration rate. The impact of varying filtration rate on the performance of the horizontal roughing filtration system in treating greywater was also investigated. The main findings of this research were: • From the survey conducted, the percentage of the public willing to accept the reuse of greywater within the community was far higher than the percentage opposing its reuse. Concerns have often been expressed by the public that the reuse of greywater could pose possible adverse effects to public health. However, in this pilot study it was found that a higher percentage of respondents (>60%) disagree that the reuse of greywater could negatively impact on public health compared to less than 20% of the respondents that agree. An interesting finding of this study was that a greater percentage of the respondents were willing to have a dual water distribution system installed in their current place of residence. • The physico-chemical characterization of greywater from different sources within the households investigated indicated that, the quality of greywater varies considerably between all sources and from household to household. None of the households investigated produced the same quality of greywater. It was also found that greywater generated from the kitchen contains the most significant pollutants in terms of the physico-chemical parameters considered in this study compared to the other sources within the household. • The pilot plant horizontal roughing filtration system demonstrated its suitability for the treatment of greywater for non-potable reuse applications. It was observed that 90% turbidity and 63% Chemical Oxygen Demand reduction was achieved over the entire duration of operation of the horizontal roughing filter. It was also observed that the removal efficiency was significantly higher in the compartment with the smallest filter media size and the removal efficiency was significantly higher at lower filtration rates. It is therefore concluded from the investigation conducted in this research that the role of the public is a vital component in the development and implementation of any reuse system / application. It was found that there was a relatively high level of acceptance for the reuse of greywater among the respondents within the community where the study was conducted. The greywater characteristics results obtained from this investigation indicated the necessity of treatment prior to disposal in the environment. Also, a low BOD5/COD ratio of 0.24, which is significantly lower than 0.5, is an indication that the greywater generated from the community cannot be easily treated using biological treatment processes and/or technologies. The pilot horizontal roughing filtration system used for the treatment of greywater in this study demonstrated its suitability for the treatment of greywater for non-potable reuse applications such as irrigation, toilet flushing and washing activities. / M

Les procédés d'osmose inverse (OI) permettent la production d'eau recyclée de très haute qualité grâce à l'élimination de contaminants organiques et inorganiques et de micro-organismes. Le suivi du bon fonctionnement de ce procédé est nécessaire pour valider la rétention des virus pathogènes afin de protéger la santé des usagers. La présence de minéraux et matières organiques dans les effluents rend inévitable le colmatage des membranes lors de leur fonctionnement et diminue ainsi leur performance. Afin d'éviter et d'éliminer ces colmatages, les stations de traitements des eaux utilisent des produits chimiques. Ces derniers vont modifier les performances globales des membranes en polyamide comme par exemple la diminution de la perméabilité à l'eau, et plus particulièrement les performances de rétention des virus, or l'ensemble de ces perturbations n'est que très peu compris et donc peu maitrisé. L'abattement des virus par l'OI sur des membranes intègres ou modifiées (ex : colmatage) ont donc été déterminés en mesurant la rétention d'un virus modèle de type phage MS2 et de substituts comme les sels (mesurés par conductivité), la rhodamine-WT (R-WT) ou les sulfates. La conductivité est, en effet, la technique de contrôle standard dans les stations de traitement des eaux (échelle industrielle).Le premier objectif de ce travail est d'évaluer l'utilisation d'un autre paramètre, les matières organiques dissoutes (DOM) comme nouveau substitut de virus et de déterminer l'impact du dysfonctionnement des procédés d'OI sur l'abattement des DOM et des sels à l'échelle industrielle. Les DOM peuvent en effet également être utilisées comme indicateur de qualité des eaux en fonction de leurs compositions et de leurs concentrations. L'abattement des DOM est donc testé comme nouvelle technique de surveillance afin de distinguer les fuites des changements de performance des membranes. Il est conclu que les DOM peuvent être utilisées comme nouvelle technique de contrôle. De plus, une variation de l'abattement des DOM peut aider à identifier des fuites de manière plus robuste que par l'abattement des sels. Le deuxième objectif est de déterminer l'effet des défauts membranaires sur les abattements d'un virus modèle (phage MS2) et de quatre substituts (R-WT, DOM, sulfate et sels) à l'échelle de systèmes de laboratoire. Deux systèmes à flux longitudinal est utilisés : une membrane plane et un module à spirale. Dans un premier temps, l'effet du colmatage sur les abattements de ces différents virus et substituts est étudié. Le colmatage organique, créé en utilisant un mélange de matières organiques, a pour effet d'augmenter de plus de 0,1 log les abattements de la R-WT, des sels et des DOM. Cette augmentation générale peut être due au blocage des cavités de la membrane et/ou par la sorption des substituts sur les matières organiques.Le colmatage inorganique, créé en utilisant un mélange de sels, n'a pas d'effet sur le rejet des substituts sauf pour les sels qui montre un comportement différent entre les deux systèmes. Dans le système à membrane plane, la couche inorganique permet d'augmenter le passage des sels à travers la membrane. Par opposition, il n'y a pas d'effet sur leur abattement avec le module à spirale. Cette variation entre les deux systèmes peut être causée par la différence de configuration (module à spirale contre membrane plane). Dans un deuxième temps, l'effet du chlore (modes passif et actif) sur la rétention de ces cinq composés est mesuré. Après un contact de 9000 ppm.h de NaOCl à pH 7, la surface membranaire change chimiquement. La formation de liaison Cl dans la couche en polyamide et la rupture des liaisons NH provoquent l'augmentation de la perméabilité à l'eau et diminuent l'abattement de l'ensemble des substituts. Malgré une forte diminution de 1,2 log de l'abattement en sel, l'abattement minimum du phage MS2 reste de 3 log. / One of the major applications of reverse osmosis (RO) process is the production of high quality recycled water by providing a barrier to remove organic and inorganic contaminants as well as pathogens including viruses. In order to protect public health, validation and monitoring of the RO process integrity are necessary to ensure its correct operation. During operation a certain degree of fouling is inevitable and can reduce RO membrane performance. Thus, chemicals are often used in water treatment plants to prevent or remove the membrane fouling. However, these chemicals can modify the integrity of the polyamide layer on RO membrane overtime. Up-to-date, the impact of membrane's physical change on its virus removal efficiency cause by the chemical use during operation is still not well understood.A minimum virus removal efficiency of intact and impaired (e.g. by fouling) RO membranes can be ascertained by measuring the rejection of MS2 phage and virus surrogates such as salt as measured by conductivity, rhodamine-WT (R-WT) or sulphate. However, conductivity measurement is the only full-scale standard monitoring technique. The removal of dissolved organic matter (DOM), which has been used as an indicator of water quality, can possibly be used for this purpose.The first objective of this work was to assess the suitability of DOM as a virus surrogate and to determine the impact of process failure on salt and DOM rejection in full-scale plants. A change of the conductivity does not necessarily mean that the membrane integrity has been breached. Thus, DOM monitoring has been tested and combined with the conductivity monitoring in order to distinguish between leaks and changes in membrane performances. It was concluded that DOM could be used as new monitoring technique. Moreover, a variation of DOM rejection can help identifying leaks better than just conductivity profiling alone.The second objective was to determine the effect of membrane impairments on the rejection of one model virus (MS2 phage) and four virus surrogates (R-WT, DOM, sulphate and salt) using lab-scale RO set-ups. To this aim, two different cross-flow set-ups were used: a flat-sheet and a single 2.5” spiral-wound module.Firstly, the effects of organic fouling and scaling on the rejection of model virus and virus surrogates were studied separately. Organic fouling was created using a mix of organic foulants. The result of this study showed an increase of the rejection by more than 0.1 log for R-WT, salt and DOM. The general increase of the surrogates' rejection might be due to the blocking of cavities of the polyamide membrane and/or to the sorption of surrogates to the fouling layer, which was observed by different autopsy techniques.Scaling was created using a mix of inorganic salts in order to reconstitute the composition of a RO feed water and avoiding the presence of organic foulants. Scaling was found to have no impact on the rejection of all tested virus surrogates except for salt. Salt rejection showed a change of behaviour between different set-ups: with the 2.5” module set-up the inorganic layer led to a stabilisation of the salt rejection, whereas the salt rejection increased with the flat-sheet set-up. This could be explained by the variations of the systems configuration (i.e. spiral module versus flat-sheet, feed spacer height, etc.).Secondly, the long-term impact of membrane ageing by exposure to chlorine, either active under filtration or passive by soaking, on the rejection of the model virus and four surrogates was studied. After a contact time of 9000 ppm∙h NaOCl at pH 7, the membrane surface chemistry changed. The introduction of chlorine in the membrane chemistry and the breakage of amide bonds caused an increase of the water permeability and a decrease of the model virus and virus surrogates rejection.

M. Tech., (Chemical Engineering, Department of Chemical Engineering, Faculty of Engineering and Technology Vaal University of Technology| / The methods used to remove potassium sulphate (K2S04) and other impurities contained within Karbochem finishing plant effluent were investigated. Reverse osmosis was explored for this application. The study was conducted in two steps. The first step focuses mainly on the effluent treatment using BW30 flatsheet as well as BW30-2540 spiral-wound reverse osmosis membranes for the rejection of potassium and sulphate ions. The membranes were supplied by Filmtec. The second step reveals the possible use of potassium sulphate obtained from the brine stream in the fertiliser and fertigation industry by a literature search. Reverse osmosis study was conducted on a laboratory scale unit using flat sheet membranes and also on a pilot plant scale using spiral wound membrane modules. The tests were conducted at a feed pressure of 20 bar(g) with the membrane rejections being 98% and 99.1% on flat sheet membrane, and 96.9% and 99.4% on spiral wound membrane for potassium and sulphates respectively. The results show that both membranes have completely desalinated. Significant reduction in the concentrations of all problematic quality parameters, especially of potassium and the sulphate ions was noted. Granular activated carbon (GAC) bed treatment was recommended for pretreatment of the effluent prior to exposure of the membrane to avoid organic fouling of the membrane. GAC treatment was tested to illustrate its effectiveness to adsorb the COD's. / NRF

A Research Report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering University of Witwatersrand Johannesburg, February 2016 / A growing population, rapid urbanisation, and climate change are increasing the pressure on water supplies. The chances of finding new freshwater sources for urban areas are becoming nearly impossible, implying that existing water supplies must go further to satisfy the basic need of potable water. Water reclamation involves the treatment of wastewater to meet defined water quality standards so that it may be reused. Direct potable reuse refers to the introduction of wastewater, which has been treated to meet specified standards, directly into the potable water supply distribution system. Water reuse has become an attractive alternative since wastewater is constantly being produced by populations, which can be treated for reuse. This study examines the sustainability of water reclamation for potable purposes, through an assessment of the Beaufort West Water Reclamation Plant, which includes interviews with the plant manager and process controllers, as well as a review of the relevant documentation. The study employs the use of economic, environmental and societal indicators as a tool in determining the sustainability of water reclamation. The results of the research show that direct potable reuse may be a sustainable solution to reducing the stress on water resources, although certain aspects of the reclamation process require further development in order to progress toward sustainability. In order to provide a long term solution, water reclamation will have to be implemented in conjunction with other water conservation strategies. / MT2017

A cultura da cana-de-açúcar, pelo alto consumo de água e de nutrientes, além da destinação industrial, apresenta características ideais para o recebimento de efluente de estações de tratamento de esgoto (EETE) sob a forma de irrigação. Esta prática tem como objetivo a reciclagem de nutrientes e de água, o incremento da produtividade e a economia de fertilizantes, de terra arável e de água potável. Apesar das múltiplas vantagens ambientais, não é desprovida de riscos, e este trabalho teve como objetivos avaliar a dinâmica de nutrientes no sistema solo-planta de canavial irrigado com efluente de esgoto tratado em dois ciclos consecutivos da cana-soca e a influência do aporte de nutrientes e outros elementos via efluente sobre a nutrição mineral da canade- açúcar. Foram aplicadas lâminas de irrigação com o esgoto tratado entre 0 (sem irrigação) e 200 % da exigência de água pela cultura, em gotejamento subsuperficial. Foram avaliados os aportes de nutrientes e outros elementos pelo efluente, os efeitos na composição nutricional da planta e da fração trocável do solo e o desempenho quantitativo e qualitativo da cultura. Concluiu-se que o efluente pode fornecer até 163 kg ha-1 de N; 14 kg ha-1 P; 145 kg ha-1 de K; 80 kg ha-1 de Ca; 28 kg ha-1 de Mg; 207 kg ha-1 de S; 0,45 kg ha-1 de B; 0,07 kg ha-1 de Cu; 0,25 kg ha-1 de Fe e 0,18 kg ha-1 de Mn, sendo fonte potencial de nutrientes à cultura da cana-de-açúcar, principalmente N, Ca e S, precisando de complementação mineral de P, K, Mg e micronutrientes. O estado nutricional da cultura, avaliado pela diagnose foliar melhorou para N, Mg, S e Cu no segundo ano avaliado. A folha +1 foi mais sensível às alterações de disponibilidade de nutrientes. A presença de elementos no efluente que podem potencialmente provocar degradação nas propriedades físicas do solo, tal como o sódio, contaminação de águas subterrâneas, como o nitrogênio, ou ainda tóxicos, como cromo e cobre, exige monitoramento constante da área agrícola que recebe este resíduo. Neste trabalho de curto prazo, estes elementos não representaram problemas. A irrigação com EETE proporcionou aumento do desempenho vegetativo da cultura e um ganho de produtividade na cana-de-açúcar de até 19,84 e 40,47 Mg ha-1, na primeira e na segunda socas, respectivamente. A qualidade industrial da cana-de-açúcar não foi alterada significativamente pela irrigação com EETE. Este trabalho mostrou que a irrigação com EETE é exequível, possui potencial econômico e seria uma solução possível para parte da demanda agrícola de água e dos problemas de poluição dos corpos dágua naturais. / Sugarcane cultivation, due to the high water and nutrients consumption, besides the industrial utilization, has ideal characteristics for receiving sewage treatment plant effluent (STPE) as irrigation. This practice aims to recycle nutrients and water, increasing productivity and decreasing the use of fertilizers, agricultural land and potable water. Despite the many environmental benefits, it has risks, and this study aimed to evaluate the dynamics of nutrients in the soil-sugarcane plant system irrigated with treated sewage effluent in two consecutive sugarcane ratoon cycles and the influence of nutrient and other elements added as effluent on the sugarcane mineral nutrition. Irrigations with treated sewage were applied up to 200% of the crop water requirement by subsurface drip. Nutrient and other elements input by the effluent, its effect on plant nutritional composition, soil exchangeable fraction and the quantitative and qualitative sugarcane performance were evaluated. Effluent can provide up to 163 kg ha-1 N, 14 kg ha-1 P, 145 kg ha-1 K, 80 kg ha-1 Ca, 28 kg ha-1 Mg, 207 kg ha-1 S, 0.45 kg ha-1 B, 0.07 kg ha-1 Cu, 0.25 kg ha-1 Fe and 0.18 kg ha-1 Mn, being a potential source of N, Ca and S, needing additional P, K, Mg and micronutrients fertilization. Sugarcane nutritional status as assessed by foliar analysis was improved for N, Mg, S and Cu in the second ratoon evaluated. Top visible dewlap leaf was more sensitive to changes in the nutrients availability. The presence of elements in the effluent that can potentially cause degradation in soil physical properties, such as sodium, groundwater contamination, such as nitrogen, or toxic substances, such as chromium and copper, requires constant monitoring of the agricultural area that receives this residue. In these short-term experiments there were no such problems. The replacement of crop evapotranspiration by irrigation with STPE provided an increase in vegetative performance and a gain in productivity of the sugarcane by 19.84 and 40.47 Mg ha-1, in the first and in the second ratoon, respectively. Industrial quality of sugarcane was not significantly affected by irrigation with STPE. This study showed that irrigation with STPE is potentially feasible, has economic potential, and would be a possible solution to part of the agricultural water demand and natural water bodies pollution problems

O objetivo deste estudo foi avaliar a qualidade virológica da água de reúso produzida em uma das estações de tratamento de esgoto da cidade de São Paulo. Para tanto, foram coletadas concomitantemente 177 amostras de esgoto tratado (100L) e bruto (15L) e os vírus concentrados utilizando método Viradel-ultracentrifugação. Em seguida as amostras foram tratadas com Vertrel XF e os ácidos nucléicos extraídos para a detecção de adenovírus (HAdV), rotavírus (RV-A), norovírus e vírus da hepatite A (VHA). A detecção por PCR e/ou RT-PCR evidenciou RV-A (G1-G5), VHA e HAdV incluindo os da espécie F tanto no esgoto bruto quanto no tratado, no entanto norovírus não foram detectados em ambos os efluentes. A infectividade de RV-A e HAdV foi avaliada por cultivo celular e os rotavírus RV-A foram também quantificados por reação de imunoperoxidase direta. PCR em tempo real foi padronizada para quantificação de vírus não cultiváveis ou de difícil cultivo como os VHA. Com base nos resultados obtidos foi verificada a ocorrência e a distribuição anual de cada vírus nas águas de reúso. / The aim of the study was to evaluate the virological quality from one Sewage Treatment Plant in the state of São Paulo. From January/2005 to November/2006, 177 samples (15L) of raw sewage were collected at the entrance and another 177 (100L) at the end of treatment, twice a week. Viruses were concentrated by filtration through positively charged microporous filters, followed by ultracentrifugation. Virus concentrates were treated by using Vertrel-XF and the viral genomes extracted for detection of adenovirus (HAdV), rotavirus (RV-A), norovirus and hepatitis A virus (HAV). PCR and RT-PCR revealed RV-A (G1-G5), HAV and HAdV, including the enteric ones (species F) in sewage and treated wastewater samples. Norovirus was not detected in any samples. The infectivity of HAdV and RV-A was assayed by inoculating onto suitable cell line. Immunoperoxidase assay was used to calculate the rotavirus FFU/L in the samples. Real time-PCR was standardized for enumeration of non-cultivable virus. The occurrence and annual distribution of each virus in reuse water were analyzed.