The growth of the heterotrophic plate count in distribution system, causing deterioration of drinking water quality, is called biological re-growth or after-growth. There are many methods to solve above problems such as disinfecting and washing in pipeline. Among them, to lower the concentration of assimilable organic carbon(AOC) in drinking water under a certain level is showed the best control method for inhibiting the growth of microorganisms. AOC is showed as an item of the organic amounts by using microorganisms. The samples of water after disinfecting is took into bacterial of P17 and NOX. Then we measure the growth number counts of two kind of bacterial in their plate to transfer and obtain the concentration of AOC. In this study we investigate the variation of AOC in a tradition water treatment plant and its distribution system by using the results of sampling and analysis of the related items of water quality. Results showed the proportional of AOC-P17 was highest in contains of AOC. The removal of AOC during processes of water treatment was effectively found. But the pre-chlorination caused the increase of AOC level in water let the concentration of AOC be detected over 50£gg acetate-C/L in treated water and the distribution system. AOC level decreased with the increasing distance of distribution system. For the well relation with drinking water quality and treatment units, we should control the biological stability to obtain a good water quality of treated water. Finally we analysis 13 items of water quality by using AutoNet(6.03) with AOC to do the prediction model work. After data simulation and training analysis, three models of AOC prediction (denoted as WTP, Distribution system and WTP& Distribution system) were obtained. The comparisons of three models in inner and outer verification showed good correlation results as well.

In the process of traditional water treatment, the humic acid and fulvic acid can be oxidized by chlorination; besides, it also produces small molecular organic compounds at the same time. Coagulation, flocculation, and sedimentation can reduce the concentration of the Assimilable Organic Carbon (AOC) significantly. An example of Ping-Ding water treatment plant was performed with sampling twelve times monthly from December 2008 to November 2009, the strong influence of chlorine, and coagulation, flocculation on the AOC can be observed. Comparing to the removal efficiency of water process in Ping-Ding water treatment plant, the AOC presented much stably in the distribution systems. We observed the data on the mean concentration of monthly sampling related to the operation unit in the water treatment plant. The Total Organic Carbon (TOC), and the Dissolved Organic Carbon (DOC) had the same trend with AOC in the water treatment process; it showed that TOC, and DOC had well relation to AOC in Ping-Ding water treatment plant. However, scrutinizing single monthly sampling, we found that the concentration of AOC did not fix out with the concentration of TOC and DOC at the same time. Therefore, results indicate that the AOC is mainly related to the smaller organic molecules of the TOC. In the series of sampling, we divided the influence of climate factor into the dry season and the pour season. The research discussed the five analysis items in the final results and discussion¡GTOC, DOC, UV254, UV254/DOC, and AOC. Basically, the concentration of the five analysis items on the pour season is higher than the dry season; it indicates that the raw water¡¦s concentration of organic carbon in Ping-Ding water treatment plant is higher during raining days. This can express the high concentration of the UV254, UV254/DOC, and AOC in water treatment plant in our work.

<p>The river Göta Älv reaches between Vänern and Gothenburg and is the main raw water source for Gothenburg that supplies about 700 000 people with water. To protect and maintain a high water quality, continuously samples and water analyses are made throughout the river. In 1998 a protection area was founded between surte and Lärjeholm where the raw water intake is. This was made to increase the awareness of the importance to protect the water. However, there is a lot of contribution of untreated stormwater to Göta Älv within the protection area.</p><p>Göteborg Water and Sewage Works commissioned this thesis where two areas, Tagene industrial area and Kärra residential area, with untreated stormwater outlets within the protection area are studied. The areas have been divided according to surface composition with different rates of pollutant contribution. Then the stormwater flow and the contribution of pollutants was simulated with the model SEWSYS. The future aim is that the model will be able to simulate the contribution of pollutants for a variety of rains, for the whole protection area.</p><p>SEWSYS (Sewer System) is built in MATLAB/Simulink and consists of three modules, a stormwater module, a sanitary wastewater module and a treatment plant module. This project only includes the stormwater module. The model simulates the stormwater flow and the pollutants total phosphorous, total nitrogen, copper, zinc, lead, cadmium and polycyclic aromatic hydrocarbons (PAH). Samples and analysis for the two areas has been carried out for another thesis work during the same period. The results from those analyses have been used for the model settings for the areas.</p><p>Simulations have been performed to adjust the model and evaluate its ability to describe the stormwater flow and the pollutant contribution within the areas. The amount of stormwater and the runoff are well simulated by the model. However, the measured and analysed data has not been enough to get reliable simulations over the pollutant contribution. Further development of the model is necessary. Generally the model simulates lower values compared to measured values, especially in the industrial area. For a more general understanding over how SEWSYS works for the two areas, simulations were carried out on a yearly basis. Those simulations have been compared with general data for stormwater pollutants. Even though the results from the simulations have shown lower values than the measured values, the model shows clearly that the contribution of pollutants from the industrial site is greater than the contribution from the residential site.</p> / <p>Göta Älv sträcker sig från Vänern ner till Göteborg och är Göteborgs huvudsakliga råvattentäkt som försörjer ca 700 000 personer med vatten dagligen. För att säkra råvattenkvaliteten görs kontinuerliga provtagningar utmed älven. Dessutom beslutade Länsstyrelsen 1998 om ett skyddsområde med skyddsföreskrifter för avrinningsområdet mellan Surte i norr till vattenintaget vid Lärjeholm i söder. Ett mål med skyddsområdet är att det ska öka medvetenheten hos boende och de som är verksamma inom området om behovet att värna om vårt vatten. Dock leds det på flera ställen ut orenat dagvatten till älven inom skyddsområdet.</p><p>Examensarbetet är ett uppdrag av Göteborgs Va-verk där två områden med orenade dagvattenutsläpp till Göta Älv studeras, Tagene industriområde samt Kärra bostadsområde. Dessa områden har karterats och dagvattenflödet samt föroreningsbelastningen från dagvattnet har simulerats med modellen SEWSYS. Målet på lång sikt är att modellen ska kunna användas för att simulera föroreningsbelastningen vid olika regn för hela skyddsområdet.</p><p>Modellen SEWSYS (Sewer System) är uppbyggd i MATLAB/Simulink och bygger på tre moduler, en dagvattenmodul, en spillvattenmodul och en reningsverksmodul. För detta projekt har endast delen för dagvatten använts. Modellen simulerar dagvattenflödet och behandlar föroreningarna totalfosfor, totalkväve, koppar, zink, bly, kadmium samt polycykliska aromatiska kolväten (PAH). I ett examensarbete parallellt med detta har provtagning och analyser av föroreningar för de båda områdena ägt rum och dessa värden ligger till grund för inställningen av modellen.</p><p>Simuleringar har utförts för att anpassa modellen samt utvärdera dess förmåga att beskriva dagvattenflödet och föroreningsbelastningen inom de aktuella områdena. Simuleringarna visar att avrinningen och dagvattenflödet simuleras bra av modellen. Det har dock visat sig att de gjorda mätningarna inte har varit tillräckliga som underlag för att få en tillförlitlig beskrivning av föroreningsbelastningen och vidare utveckling är nödvändig. Detta gäller särskilt i industriområdet där modellen generellt simulerar för låga föroreningsmängder. För en mer allmän uppfattning av SEWSYS modellen för de två områdena, har även simuleringar på årsbasis utförts och jämförts med schablonhalter för dagvattenföroreningar. Trots att simuleringsvärdena har legat lägre än de uppmätta värdena på föroreningsmängderna har det gått att visa att industriområdet bidrar till högre föroreningsbelastning än bostadsområdet på recipienten Göta Älv.</p>

The river Göta Älv reaches between Vänern and Gothenburg and is the main raw water source for Gothenburg that supplies about 700 000 people with water. To protect and maintain a high water quality, continuously samples and water analyses are made throughout the river. In 1998 a protection area was founded between surte and Lärjeholm where the raw water intake is. This was made to increase the awareness of the importance to protect the water. However, there is a lot of contribution of untreated stormwater to Göta Älv within the protection area. Göteborg Water and Sewage Works commissioned this thesis where two areas, Tagene industrial area and Kärra residential area, with untreated stormwater outlets within the protection area are studied. The areas have been divided according to surface composition with different rates of pollutant contribution. Then the stormwater flow and the contribution of pollutants was simulated with the model SEWSYS. The future aim is that the model will be able to simulate the contribution of pollutants for a variety of rains, for the whole protection area. SEWSYS (Sewer System) is built in MATLAB/Simulink and consists of three modules, a stormwater module, a sanitary wastewater module and a treatment plant module. This project only includes the stormwater module. The model simulates the stormwater flow and the pollutants total phosphorous, total nitrogen, copper, zinc, lead, cadmium and polycyclic aromatic hydrocarbons (PAH). Samples and analysis for the two areas has been carried out for another thesis work during the same period. The results from those analyses have been used for the model settings for the areas. Simulations have been performed to adjust the model and evaluate its ability to describe the stormwater flow and the pollutant contribution within the areas. The amount of stormwater and the runoff are well simulated by the model. However, the measured and analysed data has not been enough to get reliable simulations over the pollutant contribution. Further development of the model is necessary. Generally the model simulates lower values compared to measured values, especially in the industrial area. For a more general understanding over how SEWSYS works for the two areas, simulations were carried out on a yearly basis. Those simulations have been compared with general data for stormwater pollutants. Even though the results from the simulations have shown lower values than the measured values, the model shows clearly that the contribution of pollutants from the industrial site is greater than the contribution from the residential site. / Göta Älv sträcker sig från Vänern ner till Göteborg och är Göteborgs huvudsakliga råvattentäkt som försörjer ca 700 000 personer med vatten dagligen. För att säkra råvattenkvaliteten görs kontinuerliga provtagningar utmed älven. Dessutom beslutade Länsstyrelsen 1998 om ett skyddsområde med skyddsföreskrifter för avrinningsområdet mellan Surte i norr till vattenintaget vid Lärjeholm i söder. Ett mål med skyddsområdet är att det ska öka medvetenheten hos boende och de som är verksamma inom området om behovet att värna om vårt vatten. Dock leds det på flera ställen ut orenat dagvatten till älven inom skyddsområdet. Examensarbetet är ett uppdrag av Göteborgs Va-verk där två områden med orenade dagvattenutsläpp till Göta Älv studeras, Tagene industriområde samt Kärra bostadsområde. Dessa områden har karterats och dagvattenflödet samt föroreningsbelastningen från dagvattnet har simulerats med modellen SEWSYS. Målet på lång sikt är att modellen ska kunna användas för att simulera föroreningsbelastningen vid olika regn för hela skyddsområdet. Modellen SEWSYS (Sewer System) är uppbyggd i MATLAB/Simulink och bygger på tre moduler, en dagvattenmodul, en spillvattenmodul och en reningsverksmodul. För detta projekt har endast delen för dagvatten använts. Modellen simulerar dagvattenflödet och behandlar föroreningarna totalfosfor, totalkväve, koppar, zink, bly, kadmium samt polycykliska aromatiska kolväten (PAH). I ett examensarbete parallellt med detta har provtagning och analyser av föroreningar för de båda områdena ägt rum och dessa värden ligger till grund för inställningen av modellen. Simuleringar har utförts för att anpassa modellen samt utvärdera dess förmåga att beskriva dagvattenflödet och föroreningsbelastningen inom de aktuella områdena. Simuleringarna visar att avrinningen och dagvattenflödet simuleras bra av modellen. Det har dock visat sig att de gjorda mätningarna inte har varit tillräckliga som underlag för att få en tillförlitlig beskrivning av föroreningsbelastningen och vidare utveckling är nödvändig. Detta gäller särskilt i industriområdet där modellen generellt simulerar för låga föroreningsmängder. För en mer allmän uppfattning av SEWSYS modellen för de två områdena, har även simuleringar på årsbasis utförts och jämförts med schablonhalter för dagvattenföroreningar. Trots att simuleringsvärdena har legat lägre än de uppmätta värdena på föroreningsmängderna har det gått att visa att industriområdet bidrar till högre föroreningsbelastning än bostadsområdet på recipienten Göta Älv.

Disinfectants, such as chlorine, are widely used in water treatment plants to ensure the safety and quality of drinking water. However, these disinfectants easily react with some natural or man-made organic compounds in raw water and form disinfection by-products (DBPs). For example, halogenated acetic acid (HAAs) and trihalomethanes (THMs) are two main components of DBPs. These DBPs contained in drinking water will increase the risk of cancer in human body. Therefore, researches on halogenated acetic acid¡¦s potential of causing cancer have increased currently. Organic acids are usually the reactants which proceed in chlorination reaction into products of disinfection by-products in water treatment plant. The purpose of this study is to investigate adsorption characteristics in solution by using tests of kinetics and equilibrium adsorptions and kinetic model evaluations of selected fulvic acids (FA) extracted from raw water. Therefore, we use commercial single-walled carbon nanotube (SWCNT) for the adsorbents, and calculate thermodynamic parameters (£GG, £GS and £GH) in order to further understand the adsorption mechanism of CNTs. The maximum adsorbed amounts of FA onto SWCNTs was calculated by the Langmuir model at 25¢J, reaching 61.88mg / g which were much higher than that onto commercially available granular activated carbon (10.69 mg/g). The adsorption capacity of FA onto CNTs increased with decreasing outer diameter of CNTs (dp), molecular weight of FA, trmperature and pH value in all texts. In the condition of constant temperature 25¢J, we analyzed HAAFP after the test of equilibrium adsorption and that the removal efficiency of HAAFP could reach 40.76%. The best selection in kinetic models evaluation, fitting models such as Modified Freundlich equation, Pseudo-1st-order equation and Pesudo-2nd-oder equation, is Modified Freundlch equation model. In addition, intraparticle diffusion equation model was fitted well and showed adsorption process was controlled by pore diffusion. We calculated the activation energy of carbon nanotube adsorption of FA and found that film diffusion was the main factor for controlling reaction rate. According to results of thermodynamic parameters indicated that the adsorption was spontaneously and an exothermic reaction. It is obvious that the adsorption capacity as well as the reaction rate of CNTs are superior to that of granular activated carbon in raw water. These results suggest that CNTs possess highly potential applications in environmental protection. In the future, if we can combine nanotube technology with disinfection technology and apply such technique on the end of processing unit for design of either the domestic treatment facilities or small simple water treatment in drinking water. Thus it will enhance the new treatment technology of drinking water and the safety of the public health. Another possibility will be to promote the opportunity of marketing development in drinking water.

Since the demand for fresh potable water increases every year, it is important to have future water demand strategies in place. People expect a secure, high quality, water supply and the water supply industry is governed by increasingly stringent water quality guidelines and legislation. The Cape Metropolitan Area (CMA) faces the challenge of an increasing demand for fresh water in excess of the existing supply. The City is responsible for the planning and development of the local water supply resources as well as managing the water demand in the CMA and to supplement the water supply to the City of Cape Town from local sources. The ‘Voëlvlei Augmentation Scheme’ was identified as one of the options to augment the water supply to the CMA. This option would involve pumping winter water from the Berg River via a pipeline to the Voëlvlei water treatment plant (WTP). The Voëlvlei WTP was designed to treat water from the adjacent Voëlvlei Dam. This Voëlvlei WTP raw water has a higher turbidity and a lower colour in comparison to the Berg River water. The plant’s treatment conditions were optimized to remove this high turbidity. The Voëlvlei WTP raw water also contains a relatively high manganese concentration and coagulation therefore occurs at a high pH with ferric sulphate to remove the manganese during the initial stages of the water treatment process. As the quality of the Berg River water is different to that of the Voëlvlei WTP raw water, it might not be possible to treat the Berg River water at the Voëlvlei WTP using the plants current treatment parameters. The Berg River water could possibly be blended with the Voëlvlei WTP raw water before treatment at the WTP. If the Berg River water, or its blends, could not be treated at the Voëlvlei WTP using the plants current treatment parameters, then this water would have to be pre-treated before entering the plant. Various forms of pre-treatment could be used, e.g., conventional water treatment using either aluminium or ferric sulphate as primary coagulants or ion-exchange water treatment using the MIEX® resin or even a combination of both. The main objective of this study was to determine a treatment strategy for the Berg River water at the Voëlvlei WTP. It is therefore important to determine if the Berg River water could be treated at the Voëlvlei WTP using the current treatment regime. Also, if the Berg River water should be blended with the Voëlvlei WTP raw water, this study would determine which blend would be the most suited for treatment at the Voëlvlei WTP. If the Berg River water could not be treated directly at the Voëlvlei WTP, a pre-treatment strategy for this water should be determined. The cost of pretreatment of the Berg River water as compared to the cost of direct treatment at the Voëlvlei WTP should also be evaluated. In order to determine the best treatment strategy for the Berg River water at the Voëlvlei WTP, it was important to sample the Berg River water and the Voelvlei WTP raw water at regular intervals over a period of at least a year to determine its quality and the impact of seasonal changes. Various laboratory physical (e.g., turbidity) and chemical (e.g., total alkalinity) analyses were conducted on the Berg River water and Voëlvlei WTP raw water to determine its quality. The experimental procedure focused mainly on the Jar test which simulates the coagulation, flocculation and sedimentation processes at the Voëlvlei WTP. Jar tests were conducted on the Berg River water and the Voëlvlei WTP raw water using ferric sulphate and aluminium sulphate as coagulants to determine the optimum pH and optimum coagulant dosage concentration for each coagulant. The Berg River water was also blended with the Voëlvlei WTP raw water in three different proportions and Jar tests were conducted on these blends using ferric sulphate as the coagulant at a coagulation pH of 5.0 and a Fe3+ dosage of 5.0 mg/L. Jar tests were also conducted on these blends with the Voëlvlei WTP treatment parameters using ferric sulphate as the coagulant at a coagulation pH of 9.2 and a Fe3+ dosage of 3.5 mg/L. The analytical results showed a similar pattern for the characterization of the Berg River water and the Voëlvlei WTP raw water. The iron and aluminium concentrations were consistently low during the summer months with significant increases during the winter months. There were no significant seasonal impact on the UV absorbance and colour. The Jar test results of the Voëlvlei WTP raw water and the Berg River water with ferric sulphate as the coagulant showed an optimum Fe3+dosage of 3.0 to 4.0 mg/L and 4.0 to 6.0 mg/L, respectively, with an optimum coagulation pH range of 6.6 to 9.5 and 5.0 to 10.0, respectively. The Jar test results of the Voëlvlei WTP raw water and the Berg River water with aluminium sulphate as the coagulant showed an optimum Al3+ dosage of 2.5 to 3.0 mg/L and 4.0 to 5.0 mg/L, respectively, with an optimum coagulation pH of 6.0 to 7.0 and 6.0, respectively. The Jar test results obtained for all 3 blends were similar to each other. The UV absorbance of the treated water was consistently below the operational specification, while the turbidities were inconsistent and did not always comply with the SANS 241:2006 Specification (Class I) for drinking water. The iron of the treated water was also consistently above the specified value of <0.200 mg/L. The Jar tests conducted on all 3 blends, with the Voëlvlei WTP treatment parameters, also yielded similar results. The UV absorbance of the treated water was consistently above the maximum operational specification of 0.100, while the turbidities were also consistently above the SANS 241:2006 Specification of <1 NTU. Both ferric sulphate and aluminium sulphate can be used as coagulants to treat the Berg River water, although ferric sulphate would be the preferred choice due to its wide coagulation pH range and also because of differences in their health effects. The Voëlvlei WTP coagulates at a pH of 9.2 to remove turbidity and any manganese that might be present in the raw water. The manganese would not be removed at the low coagulation pH of aluminium sulphate. The specified treatment parameters, including the Voëlvlei WTP treatment parameters, used in treating the raw water blends were not effective and further investigation and research is necessary to determine its optimum treatment parameters. This study concluded that the Berg River water cannot be effectively treated at the Voëlvlei WTP using the plants treatment parameters, even if it is blended with the Voëlvlei WTP raw water. Therefore, the best treatment strategy for the Berg River water at the Voëlvlei WTP would be pre-treatment of the water before entering the Voëlvlei WTP. Although there are various ways of pre-treating the Berg River water, this study has identified the following possible pre-treatment strategies:<ul><li>pre-treatment with ferric sulphate and lime</li><li> pre-treatment with ferric sulphate and lime in conjunction with MIEX® resin</li><li> pre-treatment with MIEX® resin only</li></ul> Further research and investigation would be necessary to determine the best pretreatment strategy in terms of cost and efficiency. The pre-treated Berg River water would have to pass through the Voëlvlei WTP treatment process (i.e. high coagulation pH) to remove any manganese that might be present in the water. It is recommended that more samples should be taken at various points along the Berg River upstream of the Voëlvlei WTP over a longer period of time to compare the quality of water at these points in the river and also to monitor the effect of various run-off sites. Further research and investigation is necessary to determine the optimum treatment parameters for the Berg River water when blended with the Voëlvlei WTP raw water. Other blending ratios, different to those used in this study, should also be investigated. A more in-depth investigation is also necessary to determine the actual capital and operational costs for the pre-treatment of the Berg River water. / Dissertation (MSc)--University of Pretoria, 2011. / Chemical Engineering / unrestricted

The task of providing clean drinking water is made more demanding since pollutants have the ability to percolate into the groundwater. Because of the limited budget for drinking water monitoring and the high cost of drinking water contaminant analysis, it is of the highest importance to only analyze relevant contaminants. The aim of this study is thus to develop a monitoring tool that is adapted according to the specific industrial activities and land uses in a water catchment area to simplify and target relevant pollutants in raw water. This will also minimize the costs and increase the effectiveness of the groundwater monitoring. First we conducted a scientific data literature search to empirically enquire the answers to the following questions: (1) Can a so called basic analytical parameter package be designed with appurtenant addition packages? (2) What environmentally hazardous industries are present in the water catchment area of the water source Harplinge-Dettan? (3) How can it be assured that a parameter package is complete, and that not new or forbidden substances are being used and which are not being identified? We further mapped out the surrounding industries in the area of Harplinge-Dettan as well as the agricultural purposes of the land. From here we designed a basic analytical parameter package, which essentially is a list of possible parameters that can be found in a water catchment area. These parameters are recurrent pollutants that can be found in any catchment area. Additionally, we designed several additional packages which are specific to the surrounding industries for that water catchment area. Subsequently, the parameters here are outliers found in the basic analytical parameter package. This means that these are non-recurring pollutants that can only be linked to a specific source (i.e. trikloretylen can be linked to dry cleaning facilities, but no other activity in the area).

The task of the diploma thesis ‚‚Adjustment of the pumping station and delivery pipeline of the raw water to location of JETE for considered building up of new nuclear sources‘‘ is to figure out a capability of the pumping station Hněvkovice to draw a sufficient capacity of a raw water to the Temelín nuclear power plant. In case of necessity, it designs useful adjustment of a pumping station and deliver pipeline for increasing the raw water delivery rate.

Water is the most essential resource for life. In cases where drinking water is processed from surface water it is important to ensure the raw water is of good quality, and is suitable for processing through the water treatment plant. The drinking water for Västerås is sourced from Västeråsfjärden, in the western side of Lake Mälaren. The city itself is home to marinas, ports, a wastewater treatment plant, the Svartån outlet, sewage pumping stations and stormwater outlets. Because of the negative effects these activities have on surface water quality, Mälarenergi AB is interested in relocating the raw water intake point to Granfjärden, 10 km east of Västeråsfjärden. At Granfjärden the intake point would be less exposed to the activities in Västerås, and could be placed at a greater depth, resulting in better water quality. In this Master’s thesis the water quality and the pollution risks at Västeråsfjärden and Granfjärden sites are compared. Existing water quality data were compared, and pollution risks were investigated in two ways. Firstly potential risks in the catchment area were identified through compiling previously reported information and map analysis. Secondly, possible accident scenarios from shipping were identified. Following this, SMHI simulated the accident scenarios and their estimated effects on the two sites were then assessed.   This research shows that the water quality difference between sites is small but key differences exist in the levels of organic matter, color, transparency and temperature, making the Granfjärden location preferable. Potential problems associated with the low oxygen levels found during the end of summer at Granfjärden may be addressed by temporarily raising the intake point. It should be noted however that this temporary solution may increase the exposure to pollution. In conclusion, accident scenario simulations showed the potential concentration of pollutants at both sites is low, with effluents diluted at least 1000 times. Prevailing southwesterly and westerly winds occuring at both intake points generate a clockwise circulation in Västeråsfjärden.  This causes all effluents from urban activities to reach that intake point, which is the most notable risk associated with this site.  In contrast, the two largest risks for the Granfjärden site are shipping effluents and the microbiological load from individual sewage treatment systems and animal waste. / Vatten är vårt viktigaste livsmedel och en förutsättning för allt liv. I de fall där råvatten för beredning av dricksvatten tas från ytvatten är det ytterst viktigt att säkerställa en bra vattenkvalitet, lämpat för dricksvattenberedning. Västerås stad tar idag sitt råvatten från Västeråsfjärden, i Mälarens västra delar, 3 km från Västerås stad. I staden finns bl.a. småbåtshamnar, oljehamn, avloppsreningsverk, Svartåns utlopp, nödbräddavlopp, avloppspumpstationer och dagvattenutsläpp. Dessa aktiviteter påverkar vattenkvaliteten i fjärden negativt och därför har Mälarenergi AB valt att undersöka möjligheterna att flytta intaget till Granfjärden, 10 km öster om Västeråsfjärden. Där skulle råvattenintaget inte vara lika utsatt för samhällets direkt negativa vattenpåverkan. Intaget kan läggas på ett större djup och där kan vattenkvaliteten vara bättre och mindre riskutsatt. I detta examensarbete har vattenkvaliteten och föroreningsriskerna jämförts mellan fjärdarna. Analysresultat från provtagningar i Granfjärden jämfördes med prover från Västeråsfjärden. Riskerna behandlades i två delar. I den första delen identifierades föroreningsrisker genom att sammanställa material från tidigare projekt samt genom att studera kartor. I den andra delen togs olycksscenarion inom sjöfarten fram. SMHI simulerade dessa scenarion och en bedömning gjordes sedan över hur riskutsatta de båda råvattenintagen är. Trots det stora avståndet från Västerås stad till Granfjärden var skillnaden i vattenkvalitet mellan fjärdarna förvånansvärt liten, men skillnader påvisades för några av de analyserade parametrarna. Granfjärdens bottenvatten hade signifikant lägre halter organiskt material, lägre färgtal och lägre temperatur än det nuvarande råvattenintaget. Däremot förekom lägre syrgashalter i slutet av sommaren än vid råvattenintaget i Västeråsfjärden. Om problem skulle uppstå i dricksvattenberedningen till följd av låga syrgashalter finns möjlighet att byta till ett grundare intag vid samma punkt. Det grundare intaget är dock mer utsatt för risker än det djupare. Samtliga utsläpp från de simulerade olyckorna späddes ut minst 1000 gånger innan de spred sig till råvattenintagen. Båda råvattenintagen är som mest utsatta vid sydvästlig och västlig vind. I Västeråsfjärden ger dessa vindriktningar en medurs strömningsbild i fjärden, vilket innebär att föroreningsutsläpp från staden förs mot råvattenintaget. De största riskerna för råvattenintaget i Granfjärden är utsläpp i farleden och den mikrobiologiska belastningen från enskilda avlopp och djurhållning. I Västeråsfjärden är den största riskfaktorn utsläpp från stadens aktiviteter och verksamheter längs den östra stranden.

FundaÃÃo de Amparo à Pesquisa do Estado do Cearà / This study has as objective to estimate the optimal price, in order to provide information for sustainable use of the Worker Canal in the CearÃ. For estimation of the optimal price was necessary to obtain the parameters of elasticity and marginal cost of provisioning. The price elasticities of demand for irrigation and public supply company were estimated using the method of demand all or nothing, ordinary least squares, instrumental variables and least squares in two stages. The marginal cost was estimatedby the incremental cost. Based on the results we can conclude that the demand for irrigation is more sensitive to price changes than demand for public supply, while irrigators employers and capitalists, are more sensitive towards the families. In calculating the marginal cost was noted that it has a value less than the average cost. In calculating the optimal price, it was found that the higher tariff is brought to the public water supply, and between irrigators, the units capitalist employers should pay an amount greater than the family units / Este estudo tem como objetivo estimar o preÃo Ãtimo, com o intuito de conceder informaÃÃes para o uso sustentÃvel do Canal do Trabalhador, no CearÃ. Para a estimaÃÃo do preÃo Ãtimo, foi necessÃrio obter os parÃmetros de elasticidade e custo marginal de provisionamento. As elasticidades-preÃo da demanda dos irrigantes e da empresa de abastecimento pÃblico foram estimadas utilizando o mÃtodo da demanda tudo ou nada, dos mÃnimos quadrados ordinÃrios, das variÃveis instrumentais e dos mÃnimos quadrados em dois estÃgios. O custo marginal foi estimado pelo mÃtodo do custo marginal de longo prazo convencional. Com base nos resultados obtidos, pode-se concluir que a demanda dos irrigantes à mais sensÃvel Ãs variaÃÃes de preÃo do que a demanda para abastecimento pÃblico, sendo que os irrigantes patronais e capitalistas sÃo mais sensÃveis em relaÃÃo aos familiares. No cÃlculo do custo marginal, observou-se que este possui um valor menor do que o custo mÃdio. No cÃlculo do preÃo Ãtimo, constatou-se que a tarifa maior deveria ser repassada para o abastecimento pÃblico e, entre os irrigantes, as unidades patronais capitalistas deveriam pagar um valor maior que as unidades familiares