In a semi-arid country like South Africa, the availability and quality of water has always played an important part in determining not only where people can live, but also their quality of life. The supply of water is also becoming a restriction to the socio-economic development of the country, in terms of both the quality and quantity of what is available. Thus different monitoring techniques should be put in place to help inform the process of conserving this precious commodity and to improve the quality of what is already available. Water quality monitoring has traditionally been by the means of physico-chemical analysis; this has more recently been augmented with the use of biomonitoring techniques. However, since the biota commonly used to indicate aquatic conditions are not always present in wetlands; this study tested the use of diatoms as bio-indicators in wetlands. Diatom samples were collected from thirteen wetlands in the Western Cape Province, and cells from these communities were enumerated and diatom ?based indices were calculated using version 3.1 of OMNIDIA. These indices were useful for indicating water quality conditions when compared to the measured physico-chemical parameters. In addition, most diatom species found were common to those found in riverine environments, making the transfer of ecological optima possible. The objective of the study was to provide a preliminary diatom-based index for wetlands, however, given the relatively small study area and the strong bias towards coastal wetlands it was deemed inadvisable to construct such an index, instead several indices are recommended for interim use until further research that more comprehensively covers wetlands in South Africa has been conducted. It is thus the recommendation of this study that more data is collected for comparison to other wetlands and that in the interim, indices such as SPI be applied for routine biomonitoring of these environments. / Thesis (M.Sc. (Botany))--North-West University, Potchefstroom Campus, 2010.

Thesis (M.Env.Sc.-Res.)--University of Wollongong, 2007. / Typescript. Includes bibliographical references: leaf 99-104.

The focus of this project was to investigate the use of interdigitated electrodes (IDEs) as impedimetric ion-selective chemical sensors for the determination of several important analytes found within a freshwater aquarium. The overall aim of this research was to work towards a prototype sensing device that could eventually be developed into a commercial product for sale to aquarium owners. Polyvinyl chloride and sol-gels containing commercially-available ionophores for four aquarium-significant ions (NH4+, NO2-, NO3- and pH) were prepared and investigated for use within polymeric ion-selective membranes. Three separate IDE transducers were produced using either photolithography or screen-printing microfabrication techniques. A sinusoidal voltage was applied to the IDEs and an LCR meter was used to measure changes in the conductance and capacitance of the ion-selective membrane layer deposited over the electrode digits. Each ionophore, when tested within potentiometric ion-selective electrodes (ISEs), was found to be suitable for further investigation within IDE devices. Sol-gels were investigated as a potential membrane material for a coated wire electrode; however, poor response characteristics were observed. An IDE sensor fabricated in-house using lift-off photolithography and spin-coated with a polymeric membrane was found to produce non-selective responses caused by changes in the conductivity of the test solution. IDE devices with reduced geometric parameters were purchased and coated with a selective polymeric membrane. When the membrane was spin-coated, non-selective responses were observed; therefore, drop-coating of the membrane material was investigated. This initially resulted in an unacceptably long response time; however, this effect was reduced by decreasing the membrane solution viscosity prior to drop-coating. A fully-screen printed carbon IDE device was fabricated by incorporating the ionophore into a support matrix based on a commercial dielectric paste. Matrix interferences to the sensor response were reduced by printing ‘build-up’ layers over the sensing area prior to the ion-selective membrane. Two novel routes for monitoring the water quality of an aquarium, using IDE sensors fabricated by either photolithography or screen-printing, have been demonstrated. Due to the commercial aspect of this project, it is important to consider the final cost of producing these sensors. Both of the techniques used to produce ion-selective sensors require further experimentation to optimise the sensor response, prior to integration within a multi-analyte sensing prototype.

Although water is incredibly abundant on Earth, only 2.5 % of the water reserve is freshwater, and one third of the world’s population lacks safe drinking water. Water quality monitoring (WQM) is thus a crucial asset to safeguard this invaluable resource. Gaining popularity in the 1960s, WQM has since evolved from a lab-based, labour-intensive program to an increasingly automated operation. Today, autonomous sensors automatically assess water quality, albeit with surpassed technology, complex procedures, and expensive equipment. This thesis presents a next-generation, IoT-based WQM system, capable of unparalleled high-frequency data collection at a fraction of the cost of present-day solutions, that operates via The Thing Network’s public LoRaWAN connectivity. The system is validated through a lightweight prototype buoy, which is deployed on a 14-days-long campaign in the lakes of Stockholm. The study concludes that (i) The Things Network is a promising backbone for monitoring applications in the smart city, with an estimated current 57 % coverage of Stockholm; (ii) IoT devices can harvest sufficient solar energy to deliver 30–60 messages/h all year round even at high latitudes; (iii) IoT-based WQM has the potential for unprecedented resolution, energy-efficiency, and cost-effectiveness compared to traditional industrial-grade, cellular-based systems. / Även om vatten är otroligt rikligt på jorden, är bara 2,5 % av vattenreserven sötvatten, och en tredjedel av världens befolkning saknar säkert dricksvatten. Water quality monitoring (WQM) är således en avgörande tillgång för att skydda denna ovärderliga resurs. WQM blev allt populärare på 1960-talet och har sedan dess utvecklats från ett labbaserat, arbetskrävande program till en alltmer automatiserad verksamhet. Idag bedömer autonoma sensorer automatiskt vattenkvaliteten, om än med överträffad teknik, komplexa förfaranden och dyr utrustning. Denna avhandling presenterar ett nästa generations, IoT-baserade WQM-system, som kan möta högfrekvent datainsamling utan motstycke till en bråkdel av kostnaden för dagens lösningar, som fungerar via The Things Network offentliga LoRaWAN-anslutning. Systemet valideras genom en lätt prototypboj, som används på en 14 dagar lång kampanj i Stockholms sjöar. Studien drar slutsatsen att (i) The Things Network är en lovande ryggrad för övervakning av applikationer i den smart city, med en uppskattningsvis 57 % täckning av Stockholm; (ii) IoT-enheter kan skörda tillräckligt med solenergi för att leverera 30-60 meddelanden/timme året runt även på höga breddgrader; (iii) IoT-baserat WQM har potential för oöverträffad upplösning, energieffektivitet och kostnadseffektivitet jämfört med traditionella, industriella, cellbaserade system.

Water is an essential part of human life. According to the sustainable development goal (SDG), monitoring water quality is a fundamental goal of the international community. Therefore, there has been research on how the quality of water can be monitored and improved.  Data related to water quality can provide service opportunities such as to inform if the water is suitable for drinking by monitoring the quality of water resources. However, there has been limited research exploring opportunities and challenges of digital water quality monitoring services to fulfill requirements in rural areas, such as clean and safe water for drinking. Some challenges can be due to the geographical location of the area or avoiding certain regions for implementing a service due to political agenda or infrastructure, especially in less developed countries or areas. The lack of exploration of opportunities points to the need to further investigate service opportunities like to inform if the water is suitable for drinking in rural areas. It is crucial to monitor water quality and offer services because bad water quality can lead to health issues or poor yield in agriculture, some of the few consequences. Therefore, in my paper, using the Design Science Research (DSR) approach, I have explored various opportunities and challenges of digital water quality monitoring services in Indian rural areas. The result demonstrates opportunities related to the exploration of digital water quality monitoring services in rural areas and the challenges that need to be overcome in order to realize the opportunities. This overview can inform researchers, designers, and stakeholders to understand new service opportunities and challenges of digital water quality monitoring services in rural areas.

Water quality monitoring is vital in smart city planning for managing water resources. In the smart city, more data is being collected. In terms of data related to water quality, many data sources such as smart sensors attached to water quality monitoring systems have been continuously collecting a significant amount of data. The potential of collected data from these sources holds no value for smart cities, unless it is being used to provide digital services such as information about clean and safe drinking water, swimming, fishing, domestic uses, and water reuse. However, the knowledge on how to utilize water quality data for the benefits of smart cities is limited. So, in this paper, I propose digital water quality monitoring services for smart city residents. I explore this proposition through a design study engaging smart city residents, service designers, and developers of water quality monitoring systems. As a result, a service blueprint is presented to illustrate how such services can be designed to provide water quality information for different activities. The study aims to illustrate how opportunities of water quality monitoring system can be explored for smart cities. The study intends that the results are helpful to designers and researchers in designing and developing digital water quality monitoring services in smart cities.

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The monitoring of pH and free chlorine concentration in drinking water is important for water safety and public health. However, existing laboratory-based analytical methods are laborious, inefficient, and costly. This thesis focuses on the development of an easy-to-use, sensitive, and low-cost drinking water quality monitoring system for pH and free chlorine. An inkjet printing technology with a two-step thermolysis process in air is developed to deposit palladium/palladium oxide (Pd/PdO) films as potentiometric pH sensing electrodes. The redox reaction between PdO and hydronium ions generates the sensor output voltage. A large PdO percentage in the film provides a high sensitivity of ~60 mV/pH. A defect-free Pd/PdO film with small roughness contributes to a fast response and a high stability. When the Pd ink is thermalized in low vacuum, the deposited Pd/PdO film shows a bilayer structure. The residual oxygen in the low vacuum environment assists the decomposition of organic ligands for Pd to form a thin and continuous layer beneath submicron Pd aggregates. The oxidized bilayer film behaves as a temperature sensor with a sensitivity of 0.19% resistance change per °C, which can be used to compensate the sensed pH signals. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is drawn by hand to form a free chlorine sensor. Free chlorine oxidises PEDOT:PSS, whose resistivity increment indicates the free chlorine concentration in the range of 0.5-500 ppm. Also, we simplified an amperometric free chlorine sensor based on amine-modified pencil leads. The simplified sensor is calibration-free, potentiostat-free, and easy-to-use. The pH, temperature, and free chlorine sensors are fabricated on a common substrate and connected to a field-programmable gate array board for data processing and display. The sensing system is user-friendly, cheap, and can accurately monitor real water samples. / Thesis / Doctor of Philosophy (PhD) / Sensitive, easy-to-use, and low-cost pH and free chlorine monitoring systems are important for drinking water safety and public health. In this thesis, we develop an inkjet printing technology to deposit palladium/palladium oxide films for potentiometric pH sensors and resistive temperature sensors. The different electrical and electrochemical properties of the palladium/palladium oxide films are realized by creating different film morphologies using different ink thermolysis atmospheres. The developed pH and temperature sensors are highly sensitive, fast in response, and stable. For free chlorine sensors, a hand drawing process is used to deposit poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), which is an indicator for the free chlorine concentration over a wide range. We also developed a calibration-free free chlorine sensors based on modified pencil leads. Such a free chlorine sensor is integrated with the pH and temperature sensors, and an electronic readout system for accurate on-site drinking water quality monitoring at low cost is demonstrated.