Thesis (Ph.D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Aral, Mustafa; Committee Member: Guan, Jiabao; Committee Member: Kim, Seong-Hee; Committee Member: Roberts, Philip; Committee Member: Uzer, Turgay.

It is common knowledge that water is one of the basic needs for human beings. However, the consumption of contaminated water can lead to waterborne diseases and fatalities. It is, therefore imperative to constantly monitor the quality of potable water. There are numerous technologies used for water quality monitoring. These technologies are relatively effective however these tests are expensive and complex to use, which then require experienced technicians to operate them. Other tests are not rapid, making consumers of water susceptible to waterborne diseases. In this study, dye-doped, surface functionalized silica nanoparticles (SiNPs) and surface-functionalized magnetic nanocomposites (MNCs) were proposed as materials that can be applied in order to reduce the time taken to get results as well as to make the processes less complex and portable. The aim of this study was to synthesize and characterize surface functionalized dye-doped SiNPs and surface functionalized MNCs for detection and preconcentration of in water. Additionally, proof of concept had to be shown using the synthesized materials. SiNPs were the materials of choice due to their easily functionalized surfaces and their strong optical properties. SiNPs are photostable and they do not leach in solution due to the inert nature of the silica matrix in aqueous media. MNCs were chosen as materials of choice for preconcentration of E. coli in water because they are easy to synthesize and they can be applied in various biological applications due to their functional groups. SiNPs were synthesized using the water-in-oil microemulsion. The SiNPs were further functionalized with amine and carboxyl groups and avidin. Thereafter, they were bioconjugated with biotinylated anti-E. coli antibodies. The pure and surface functionalized SiNPs were characterized using ATR-FTIR spectroscopy, FE-SEM, HR-TEM, Zeta Sizer, UV-vis spectroscopy and spectrofluorometry. The application of the dye—doped surface functionalized SiNPs in E. coli detection was characterized using the fluorescence plate reader. The SiNPs were spherical and uniform in size. They increased in size as they were being functionalized, ranging from 21.20 nm to 75.06 nm. The SiNPs were successfully functionalized with amine and carboxyl groups as well as with avidin and antibodies. Two methods were investigated for carboxyl group attachment (direct and indirect attachment) and the direct attachment method yielded the best results with a surface charge of -31.9 mV compared to -23.3 mV of the indirect method. The dye loading was found to be 1% after particle synthesis. The optical properties of the Ru(Bpy) dye were enhanced 3 fold when they were encapsulated in the Si matrix. The SiNPs were binding to the E. coli cells and enabled detection. MNCs were synthesized through in-situ polymerization. The MNCs were characterized using ATR-FTIR spectroscopy, SEM, TEM and XRD. The MNCs were successfully functionalized with carboxyl groups. The increase in size of the nanocomposites as seen in SEM images proved that the Fe3O4 was successfully encapsulated in the polymer matrix. The MNCs were proven to be magnetic by a simple magnetism test whereby they were separated in an aqueous solution using an external magnetic field. The antibody-labelled MNCs were binding to the E. coli cells as shown in TEM images. E. coli cells were removed from water at varying concentrations of 1x106 CFU/mL to 1x109 CFU/mL at 10 mL volumes. This study has demonstrated that dye-doped SiNPs amplify the signal of E. coli cells using fluorescence. The study has also demonstrated that the MNCs can be applied in sample preconcentration and enrichment for E. coli detection. However, further studies should investigate and optimize the combination of the two techniques in a point of use device for water quality testing of 100 mL-samples as per the requirement of the SANS 241 standard. / Civil and Chemical Engineering / M. Tech. (Chemical Engineering)

M.Sc. (Zoology) / National water quality monitoring in South Africa has in the past mainly focused on measuring physical and chemical variables. However, it is increasingly realised that measuring physical and chemical variables on their own cannot provide an accurate account of the general "health" of an aquatic ecosystem. Biological communities, on the other hand, are accurate indicators of overall environmental conditions. Water quality management must, therefore, rely on comparative data for both chemical composition and biological effects. In fact, it appears as if biological monitoring (biomonitoring) is worldwide becoming a primary tool in assessing environmental condition and verifying compliance with effluent discharge. This study classified different biomonitoring approaches and techniques under bioassessment (referring to the field oriented biomonitoring protocols which make use of biotic indices to assess water quality); bioassays (toxicity tests which is usually laboratory-based); behavioural bioassays (including aspects such as early warning systems, and preference and avoidance studies); bacteriological studies (the monitoring of certain microbes to allow the detection of faecal contamination); measurement of bioaccumulation (referring to the methods by which the uptake and retention of chemicals in the body of an organism can be monitored); and fish pathology (fish health studies dealing with the causes, processes and effects of disease). Habitat assessment and evaluation was identified as an essential part of any biosurvey. There can be little uncertainty about the mutual dependence of habitat quality, biological health and chemical characteristics of water in the environment. Relative habitat condition, as the principal determinant of attainable biological potential, should set the context for interpreting the results of a biosurvey and can be used as a general predictor of biological condition. Chemistry can further help to explain and characterise certain impacts. The Crocodile River, Eastern Transvaal, was selected for conducting a case study. The SASS2 rapid bioassessment protocol, as well as a habitat quality index (Hal) was used during five consecutive biosurveys. From the results obtained in this study, it appears as if biomonitoring can be used to good effect in overall environmental assessment. The SASS2 index appeared to be both a robust and sensitive indicator of environmental condition. Application of the SASS2 technique on a regional or even national basis should be feasible with regard to simplicity and practicality. It is also cheaper and less labour intensive than comprehensive chemical monitoring. However, bioassessments should not replace but rather compliment chemical and physical monitoring.

Indiana University-Purdue University Indianapolis (IUPUI) / Numerical models are important tools for simulating processes within complex natural systems, such as hydrodynamics and water quality processes within a water body. From decision makers’ perspectives, such models also serve as useful tools for predicting the impacts of water quality problems or develop early warning systems. However, accuracy of a numerical model developed for a specific site is dependent on multiple model parameters and variables whose values are attained via calibration processes and/or expert knowledge. Real time variations in the actual aquatic system at a site necessitate continuous monitoring of the system so that model parameters and variables are regularly updated to reflect accurate conditions. Multiple sources of observations can help adjust the model better by providing benefits of individual monitoring technology within the model updating process. For example, remote sensing data provide a spatially dense dataset of model variables at the surface of a water body, while in-situ monitoring technologies can provide data at multiple depths and at more frequent time intervals than remote sensing technologies. This research aims to present an overview of an integrated modeling and data assimilation framework that combines three-dimensional numerical model with multiple sources of observations to simulate water column temperature in a eutrophic reservoir in central Indiana. A variational data assimilation approach is investigated for incorporating spatially continuous remote sensing observations and spatially discrete in-situ observations to change initial conditions of the numerical model. This research addresses the challenge of improving the model performance by combining water temperature from multi-spectral remote sensing analysis and in-situ measurements. Results of the approach on a eutrophic reservoir in Central Indiana show that with four images of multi-spectral remote sensing data assimilated, the model results oscillate more from the in-situ measurements during the data assimilation period. For validation, the data assimilation has negative impacts on the root mean square error. According to quantitative analysis, more significant water temperature stratification leads to larger deviations. Sampling depth differences for remote sensing technology, in-situ measurements and model output are considered as possible error source.

Modern streamflow measuring equipment, water quality sampling techniques and a better understanding of pollutant washoff are continuously being developed as today's society is in critical need of improving water management, minimizing developmental impacts and preventing environmental hazards. In particular, the study of the spatial, temporal and volumetric characteristics of annual pollutant loading caused by variations in precipitation, land use and other anthropogenic factors is of great significance due to their relation to future global water demands. The research presented here falls in three parts. In the first part of the dissertation, an acoustical Doppler velocity profiler installed in a submerged concrete channel is proposed to continually measure the annual fluctuation in streamflow levels down to dry channel conditions. The tailwater influenced, intermittent streamflow conditions for the City of Kissimmee, Florida were selected for the evaluation of this approach under a 3-year study from 2006 to 2008. The performance of these concrete channels were systematically evaluated by comparisons with established field measurement techniques over various stream configurations and flow conditions. The second part of this research investigates the dynamics of flood wave detection with respect to enabling an automatic water quality sampler to start collecting samples. The main focus was on the accurate detection of flood waves in the absence of rainfall and the presence of fluctuating baseflows and stream stages. In the 3-year study, it was shown that a dual parameter trigger, utilizing independent measuring equipment, resulted in accurate flood wave detection with minimal false triggering of the autosampler. In addition, an incremental or percent deviation from a moving average of stage or flow proved to be a more consistent indicator for the presence of a flood wave. In the third part of this work, the frequency of water quality sampling and the associated level of detail for sampling of rainfall events were investigated with respect to accurately depicting annual pollutant loads. It was found that the seasonal variations in baseflow pollutant loads are not accurately represented by current 4-quarter grab sampling. Also, significant pollutant loading within rainfall events may not be captured by only performing grab sampling during baseflow conditions. In addition, although increased pollutant concentrations were observed within the initial 30 minutes of the flood wave, their actual loadings did not represent a significant impact on the annual pollutant loads. A biweekly grab sampling frequency was found to be adequate in many cases to depict the annual pollutant loads, but depending upon the targeted constituent and particular streamflow condition, rainfall event sampling might also be necessary. The results of this research complemented with other studies will promote better understanding of intermittent streamflows, accurate flood wave detection, and assessment of annual pollutant loads to our nation's waterbodies.

Thesis (MScEng (Civil Engineering))--Stellenbosch University, 2008. / In recent years, concern about the water quality in the Berg River received a fair degree of attention, particularly with the imminent construction of the Berg Water Project (BWP). Particular concerns have been expressed about the water quality with respect to total dissolved salts (TDS) at Misverstand Dam. In previous studies (Fourie and Görgens, 1977) it was identified that the saline water was mostly generated in the lower portion of the Berg River Catchment (Matjies, Moorreesburg and Sandspruit Rivers) and that the abstraction of acceptable quality water higher up in the Berg River could possibly result in salinity problems at Misverstand Dam. Contrary to expectation, these studies also showed that for the most saline catchments, a winter peak in TDS concentrations also existed. To help address these concerns, a Water Research Commission (WRC) project was initiated in 2003 in which the newly-developed salinity module of the daily Agricultural Catchment Research Unit (ACRU) agrohydrological model, known as ACRUSalinity, would be configured for the Berg River Catchment. This model had previously been configured and calibrated for the Mkhomazi Catchment (Teweldebrhan, 2003) which exhibited relatively low streamflow TDS concentrations (100 mg/l) and it was deemed necessary to ascertain whether comparable TDS values could be simulated in the Berg River Catchment, where TDS concentration could rise to well above 1 000 mg/l in certain tributaries. In this project, ACRUSalinity was configured for the Berg River Catchment on a distributed basis, aiming to capture the spatial distribution of rainfall and geophysical characteristics which inherently exist in a catchment as expansive as the Berg. Initial application of the "Beta version" of ACRUSalinity to the Berg River Catchment revealed that it failed to produce simulated TDS values which were representative of the observed data. It became evident that the model required both additional salinity-related functions and modifications of existing functions. After the implementation of these algorithm changes the correspondence of simulated and observed TDS concentrations improved markedly. Verification of the ACRUSalinity simulated flows and calibration of the salinity-related parameters was based on the values of predefined objective functions. Reasonably representative flows could be obtained provided that the catchment discretisation and driver rainfall selection process were adequate. Salinity related parameters were determined purely on an iterative basis, although a priori estimation of these parameters was possible. Preliminary interdependency tests of these parameters revealed that the final calibrated set of salinity-related parameters was probably not unique and that some a priori decision making would be required when selecting the most realistic set of parameters. Quantification of the potential effect of the Berg River Dam on the TDS concentrations at Misverstand Dam was achieved as follows: the ACRUSalinity model was verified for flow and calibrated for TDS at available and reliable flow gauging stations. This was then followed by a long-term simulation run which yielded daily TDS time series for comparison, on an exceedance basis, with the observed record. Since the concern about the possible deterioration of water quality at Misverstand Dam was only a winter concern (May to September), comparisons were only drawn over this period. The flow-routing option in ACRUSalinity was not activated and a 1:1 daily comparison of flows and TDS concentrations, based on values of the objective function, was thus not possible. Results from this study showed that even with a daily model, the exceedance percentages of the TDS concentrations after the construction of the Berg River Dam were comparable with the exceedance percentages obtained from the original monthly modelling study (DWAF, 1993). In this study, however, it was possible to capture the increasing TDS concentration which was evident over winter months in the observed data record for the Matjies River and Sandspruit River catchments. The testing of the model’s effectiveness in the evaluation of engineering options was accomplished as follows: several options for ameliorating the possible deterioration of water quality at Misverstand Dam were defined, based on its practicality and cost of implementation. For example, the Withoogte water treatment works abstracts water from Misverstand Dam for supply to the West Coast region when water quality is acceptable (i.e. a TDS lower than 450 mg/l). It was proposed that to minimise the effect of periods when no abstraction from Misverstand could occur due to unacceptable water quality, a second reservoir at the treatment works should be lined and used to provide bridging storage for water from Misverstand Dam when the water quality was acceptable. The calibrated ACRUSalinity model was then modified to reflect the physical attributes of this engineering scenario of interest to produce sets of flow and TDS time series which could be further analysed to determine assurance of supply, in terms of predetermined TDS concentration thresholds in Misverstand Dam. Using this particular engineering option, the analysis revealed that a 300 mg/l TDS upper-limit at Misverstand was too stringent and that 450 mg/l was probably more realistic.

The recently developed technique of diffusive gradients in thin films (DGT) for speciation measurement of analytes in the environment was further developed through the development of series of new binding phases including poly(acrylamide-co-acrylic acid) copolymer hydrogel (PAM-PAA), poly(acrylamidoglycolic acid-co-acrylamide) (PAAGA-PAM) hydrogel, the Whatman P81 cellulose phosphate ion exchange membrane (P81) and a liquid binding phase of poly(4-styrenesulfonate) (PSS). A new diffusion layer, cellulose dialysis membrane, was also employed for the liquid binding phase DGT. PAM-PAA copolymer hydrogel was prepared by the controlled hydrolysis of polyacrylamide (PAM) in an alkaline solution of 10% sodium hydroxide. The capacity of the copolymer hydrogel to bind various metal ions was tested under a range of uptake conditions. Ions such as Cu2+ and Cd2+ were bound more strongly to the copolymer hydrogel than the competing ions such as Na+, K+, Ca2+ and Mg2+. Metals bound to the copolymer hydrogel can be efficiently eluted in 2 M HNO3 solution (>94%). Application of this new binding material to DGT technique was validated in a synthetic lake water (Windermere, Lake District, UK) with a recovery of 99.0% for Cu2+. PAAGA-PAM hydrogel was prepared by copolymerising 2-acrylamidoglycolic acid with acrylamide. The metal ion binding properties of the hydrogel were characterised for Cu2+, Cd2+ and competing ions under various experimental conditions. The hydrogel was shown to bind Cu2+ and Cd2+ strongly under non-competitive binding conditions, with binding capacities of 5.3 and 5.1 micromol cm-2, respectively. The binding capacity of each metal decreased, under competitive binding conditions (with a range of metal ions present at 17.8 mN), to 1.3 and 0.17 micromol cm-2, respectively, indicating a strong selective binding towards Cu2+. The metal ions were readily recovered (>94%) by eluting with 2 M HNO3. Finally, the copolymer hydrogel was tested as a binding phase with the DGT technique. A linear mass vs. time relationship was observed for Cu2+ in Windermere water with a recovery of close to 100%. The use of a commercially available solid ion exchange membrane (P81) as the binding phase in DGT analysis was demonstrated. P81 is a strong cation exchange membrane. Its performance characteristics as a new binding phase in DGT measurement of Cu2+ and Cd2+ were systematically investigated. Several advantages over the conventional ion exchange resin-embedded hydrogel based binding phases used in DGT were observed. These include: simple preparation, ease of handling, and reusability. The binding phase preferentially binds to transition metal ions rather than competing ions. Within the optimum pH range (pH 4.0 - 9.0), the maximum non-competitive binding capacities of the membrane for Cu2+ and Cd2+ were 3.22 and 3.07 micromol cm-2, respectively. The suitability of the new membrane-based binding phase for DGT applications was validated experimentally. The results demonstrated excellent agreement with theoretically predicted trends. The reusability of this binding phase was also investigated. Application of a liquid binding phase and a dialysis membrane diffusive layer were proposed for the first time. The binding phase was a 0.020 M solution of poly(4-styrenesulfonate) (PSS) polyelectrolyte using a specially designed DGT device. The binding properties of Cd2+, Cu2+, and a range of alkali and alkaline earth metal ions to the PSS solution were characterised. The PSS behaved like a cation exchanger with preferential binding to Cd2+ (6.0 micromole ml-1, log K = 9.0) and Cu2+ (2.5 micromole ml-1, log K = 8.1) under competitive binding conditions. The DGT devices were successfully validated for Cd2+ and Cu2+ in Windermere water. The speciation performance of the solid and liquid binding phases developed in this study was investigated in solutions containing ethylenediaminetetraacetic acid disodium salt (EDTA), humic acid (HA), glucose (GL), dodecylbenzenesulfonic acid (DBS) and tannic acid (TA) with Cu2+ and Cd2+. The ratios of labile metals over total metals were at good agreement with calculated theoretical values using Stability Constants Database. The results indicated that the DGT-labile concentration measured by DGT with these binding phases is essentially free metal ion concentration in the sample. All newly developed DGT binding phases were successfully applied for environmental speciation. The field deployments were carried out in both freshwater and salt-water test sites.

Even though the necessity of water quality monitoring systems is increasing, and though mobile watery quality monitoring systems using the combination of automatic measuring devices and autonomous vehicles is becoming available, research on effective deployment of such systems is not studied well. The locations or paths to take the measurement are one of the most important design factors to maximize the performance of water quality monitoring systems, and they needs to be optimized to maximize the monitoring performance. To solve these optimization problems, multi-objective genetic algorithms were proposed and developed. The proposed optimization procedures were applied to hypothetical circular lakes and Lake Pontchartrain in order to obtain optimal monitoring locations, straight monitoring paths, and higher-order monitoring paths under various conditions. Also, the effect of various parameters such as the speed of a monitoring vessel, the weights of possible scenarios, and etc. are investigated. The optimization models found optimal solutions efficiently while reflecting various effects of complex physical settings. The results from the optimizations show that distribution of possible source locations is an important factor that affects optimal solutions greatly. In a closed water body, wind is major forcing that determines hydrodynamics and contaminant transport, and it affects optimal solutions as well. Straight monitoring lines do not perform very well due to their incapability to cover the irregular boundaries of water bodies. Higher-order optimal monitoring paths overcome this difficulty and perform well up to a comparable level of a few stationary monitoring locations even under realistic and transient conditions.

A piscicultura vem crescendo ao longo dos anos impulsionada pelo aumento da população mundial. A demanda crescente de alimentos faz com que seja necessário o aprimoramento constante das técnicas de manejo, aumentando a produção e diminuindo os custos, tornando a atividade sustentável. Neste contexto, a adesão de recursos tecnológicos que auxiliem no manejo e controle dos viveiros é muito importante. O monitoramento da qualidade da água também é essencial na piscicultura, pois determinadas variáveis, como por exemplo a temperatura, tem relação direta com o metabolismo dos peixes, influenciando na quantidade de ração ingerida pelos mesmos. A aquisição de ração representa até 79% dos custos de produção, tornando-se vital a obtenção da máxima conversão alimentar. Após levantamento realizado com um grupo de piscicultores da região Oeste do Paraná, visando investigar se estes levam em consideração a qualidade da água em seus viveiros como forma de otimizar o manejo, e se os mesmos utilizam recursos tecnológicos em seu processo produtivo, constatou-se que a maioria não leva em consideração a qualidade da água em seu processo produtivo, assim como também não fazem uso de recursos tecnológicos para auxiliar no manejo. Os resultados deste levantamento motivaram o desenvolvimento de um sistema de monitoramento da qualidade da água através de uma boia sensorial autônoma, interligada a um software de apoio ao manejo e gestão dos viveiros produtivos. A fim de testar o sistema e verificar o seu potencial econômico, realizou-se um experimento durante 26 semanas, envolvendo dois grupos de quinze tilápias distribuídas aleatoriamente em dois tanques, um dotado do sistema de monitoramento, e outro não. O processo de arraçoamento foi baseado em tabelas utilizadas pelos piscicultores entrevistados no levantamento, sendo o arraçoamento no tanque dotado do sistema de monitoramento calculado com base na temperatura e peso dos animais, enquanto que no outro tanque o cálculo levou em consideração apenas o peso das tilápias. Durante o experimento, foram registrados o peso médio, a quantidade de ração ingerida, e o comprimento padrão, os quais foram analisados por meio de estatística descritiva, teste de normalidade de Anderson-Darling e teste t de Student para comparação de médias de amostras independentes. Também foi obtido o valor da conversão alimentar, que foi calculado mediante a divisão da quantidade de ração consumida por cada grupo de tilápias pelo ganho de peso adquirido pelos mesmos. Como resultado, observou-se que a conversão alimentar no tanque monitorado foi maior em relação ao tanque não monitorado, acarretando uma economia no consumo de ração por quilo (Kg) de tilápia produzida durante o período experimental. Observou-se também que não houve diferença significativa entre os pesos médios e os comprimentos padrão das tilápias dos dois tanques ao final do experimento. A boia sensorial e os softwares interligados a ela se mostraram eficazes durante todo o experimento, mostrando-se aptos a serem instalados em viveiros produtivos reais. Estes resultados evidenciaram a viabilidade econômica do sistema de monitoramento proposto, tornando-se uma excelente alternativa para o aumento da renda na piscicultura. / Fish farming has been growing over the years driven by increasing world population. The increasing demand of food production makes it necessary to constantly improve management techniques, increasing production and reducing costs, making the activity sustainable. In this context, the adhesion of technological resources that assist in the management and control of nurseries is very important. The monitoring of water quality is also essential in fish farming, since certain variables, such as temperature, are directly related to the fish metabolism, influencing the amount of feed consumed by them. The acquisition of ration represents up to 79% of the production costs, making it vital to obtain maximum feed conversion. After a survey, that was carried out with a group of fish farmers from the western region of Paraná to investigate whether they consider the quality of water in their nurseries to optimize management, and if they use technological resources in their production process, it was verified that most do not consider the quality of water in their production process, nor do they make use of technological resources to aid in their management. The results of this survey motivated the development of a water quality monitoring system through an autonomous sensorial buoy, linked to a software to support the management of productive nurseries. To test the system and to verify its economic potential, an experiment was carried out for 26 weeks, involving two groups of fifteen tilapias distributed randomly in two tanks, one endowed with the monitoring system, and another not. The process of feeding was based on feeding tables used by the fish farmers interviewed in the survey, with the feeding in the tank with the monitoring system calculated based on the temperature and weight of the animals, while in the other tank the calculation considered only the weight of tilapias. During the experiment, mean weight, amount of feed intake, and standard length were recorded, which were analyzed by means of descriptive statistics, Anderson-Darling normality test and Student's t-test for comparison of independent sample means. The value of feed conversion was also obtained, which was calculated by dividing the amount of feed consumed by each tilapia group by the weight gain acquired by them. As a result, it was observed that the feed conversion in the monitored tank was higher in relation to the unmonitored tank, resulting in a saving of the ration consumption per kilogram (kg) of tilapia produced during the experimental period. It was also observed that there was no significant difference between the average weights and the standard tilapia lengths of the two tanks at the end of the experiment. The sensory buoy and the software connected to it proved to be effective throughout the experiment, showing that they could be installed in real productive nurseries. These results evidenced the economic viability of the proposed monitoring system, making it an excellent alternative for increasing income in fish farming.

A piscicultura vem crescendo ao longo dos anos impulsionada pelo aumento da população mundial. A demanda crescente de alimentos faz com que seja necessário o aprimoramento constante das técnicas de manejo, aumentando a produção e diminuindo os custos, tornando a atividade sustentável. Neste contexto, a adesão de recursos tecnológicos que auxiliem no manejo e controle dos viveiros é muito importante. O monitoramento da qualidade da água também é essencial na piscicultura, pois determinadas variáveis, como por exemplo a temperatura, tem relação direta com o metabolismo dos peixes, influenciando na quantidade de ração ingerida pelos mesmos. A aquisição de ração representa até 79% dos custos de produção, tornando-se vital a obtenção da máxima conversão alimentar. Após levantamento realizado com um grupo de piscicultores da região Oeste do Paraná, visando investigar se estes levam em consideração a qualidade da água em seus viveiros como forma de otimizar o manejo, e se os mesmos utilizam recursos tecnológicos em seu processo produtivo, constatou-se que a maioria não leva em consideração a qualidade da água em seu processo produtivo, assim como também não fazem uso de recursos tecnológicos para auxiliar no manejo. Os resultados deste levantamento motivaram o desenvolvimento de um sistema de monitoramento da qualidade da água através de uma boia sensorial autônoma, interligada a um software de apoio ao manejo e gestão dos viveiros produtivos. A fim de testar o sistema e verificar o seu potencial econômico, realizou-se um experimento durante 26 semanas, envolvendo dois grupos de quinze tilápias distribuídas aleatoriamente em dois tanques, um dotado do sistema de monitoramento, e outro não. O processo de arraçoamento foi baseado em tabelas utilizadas pelos piscicultores entrevistados no levantamento, sendo o arraçoamento no tanque dotado do sistema de monitoramento calculado com base na temperatura e peso dos animais, enquanto que no outro tanque o cálculo levou em consideração apenas o peso das tilápias. Durante o experimento, foram registrados o peso médio, a quantidade de ração ingerida, e o comprimento padrão, os quais foram analisados por meio de estatística descritiva, teste de normalidade de Anderson-Darling e teste t de Student para comparação de médias de amostras independentes. Também foi obtido o valor da conversão alimentar, que foi calculado mediante a divisão da quantidade de ração consumida por cada grupo de tilápias pelo ganho de peso adquirido pelos mesmos. Como resultado, observou-se que a conversão alimentar no tanque monitorado foi maior em relação ao tanque não monitorado, acarretando uma economia no consumo de ração por quilo (Kg) de tilápia produzida durante o período experimental. Observou-se também que não houve diferença significativa entre os pesos médios e os comprimentos padrão das tilápias dos dois tanques ao final do experimento. A boia sensorial e os softwares interligados a ela se mostraram eficazes durante todo o experimento, mostrando-se aptos a serem instalados em viveiros produtivos reais. Estes resultados evidenciaram a viabilidade econômica do sistema de monitoramento proposto, tornando-se uma excelente alternativa para o aumento da renda na piscicultura. / Fish farming has been growing over the years driven by increasing world population. The increasing demand of food production makes it necessary to constantly improve management techniques, increasing production and reducing costs, making the activity sustainable. In this context, the adhesion of technological resources that assist in the management and control of nurseries is very important. The monitoring of water quality is also essential in fish farming, since certain variables, such as temperature, are directly related to the fish metabolism, influencing the amount of feed consumed by them. The acquisition of ration represents up to 79% of the production costs, making it vital to obtain maximum feed conversion. After a survey, that was carried out with a group of fish farmers from the western region of Paraná to investigate whether they consider the quality of water in their nurseries to optimize management, and if they use technological resources in their production process, it was verified that most do not consider the quality of water in their production process, nor do they make use of technological resources to aid in their management. The results of this survey motivated the development of a water quality monitoring system through an autonomous sensorial buoy, linked to a software to support the management of productive nurseries. To test the system and to verify its economic potential, an experiment was carried out for 26 weeks, involving two groups of fifteen tilapias distributed randomly in two tanks, one endowed with the monitoring system, and another not. The process of feeding was based on feeding tables used by the fish farmers interviewed in the survey, with the feeding in the tank with the monitoring system calculated based on the temperature and weight of the animals, while in the other tank the calculation considered only the weight of tilapias. During the experiment, mean weight, amount of feed intake, and standard length were recorded, which were analyzed by means of descriptive statistics, Anderson-Darling normality test and Student's t-test for comparison of independent sample means. The value of feed conversion was also obtained, which was calculated by dividing the amount of feed consumed by each tilapia group by the weight gain acquired by them. As a result, it was observed that the feed conversion in the monitored tank was higher in relation to the unmonitored tank, resulting in a saving of the ration consumption per kilogram (kg) of tilapia produced during the experimental period. It was also observed that there was no significant difference between the average weights and the standard tilapia lengths of the two tanks at the end of the experiment. The sensory buoy and the software connected to it proved to be effective throughout the experiment, showing that they could be installed in real productive nurseries. These results evidenced the economic viability of the proposed monitoring system, making it an excellent alternative for increasing income in fish farming.