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Cette étude cible les questions relatives aux systèmes aqueux de fines particules près ou sous le micron qui sont importantes et nombreuses en environnement avec les résidus anthropiques et en particulier avec les matériaux anthropogéniques des sédiments de rivières et des lacs. Le but principal visé était de démontrer l'importance d'utiliser un surfactant comme agent pour améliorer la séparation colloïdale en milieu aqueux. Dans cette technique les surfactants altèrent la charge de surface des particules qui vont dicter le comportement et la destination des phases respectives du système par les floculations ou suspensions. À cause de leur masse extrêmement petite, l'effet de gravité est atténué et joue un rôle plus voilé avec le temps. Pour des études de caractérisation de tels systèmes, en environnement, où les difficultés tiennent à la présence des fines sous microniques et aux mélanges polyphasés, ces systèmes répondent mal à l'application des méthodes conventionnelles habituellement utilisées de séparation comme la séparation magnétique en milieu sec ou humide, la séparation électroacoustique et la séparation par liqueurs denses. Les paramètres fondamentaux du potentiel zêta déterminent l'état et les conditions pour une suspension ou pour une floculation. La mobilité des particules solides peut être mesurée par une technique acoustique ESA qui permet de calculer les valeurs du potentiel zêta. Cette détermination implique l'intégration des mesures de la distribution granulométrique, du poids spécifique et les considérations des paramètres chimiques du système soit le pH, la température et la conductivité. Nos résultats indiquent, comme l'hypothèse originale le supposait, que les minéraux naturels ont la même polarité de surface et des intensités de charges comparables aux composés anthropiques pour une composition chimique et structure atomique similaire. Les résultats confirment également que pour un système polyphasé, le signe de polarité et l'intensité du zêta initial sont la résultante de la sommation des valeurs de zêta des phases constituantes. L'équation suivante se vérifie: ζ (zeta) mV pour la system = Σζа X Cа + ζb X Cb +....... Plusieurs systèmes artificiels ont été étudiés et les données initiales du système mesuré servent de guides pour trouver les conditions qui permettront d'induire la floculation et le fractionnement en systèmes moins polyphasés et plus simples facilitant ainsi une caractérisation. Les essais et la détermination des paramètres influençant la séparation colloïdale par un surfactant ont été mises au point initialement sur un sédiment de lac comprenant des particules de sulfures de 2 à 3 µm. La présence de grains de sulfures dans le sédiment original n'avait pas été détectée par diffraction de rayons X mais suite au fractionnement et a une concentration résultant plus élevée dans les couches fractionnées, des sulfures pouvaient être identifier. Cette technique a d'ailleurs été utilisée pour caractériser le fractionnement en couches dans lesquelles on retrouve une forte variation dans la concentration des phases constituantes incluant les sulfures. Le fractionnement résultant est de qualité suffisante pour que cette technique soit considérée dans une remédiation environnementale, en particulier pour les résidus miniers où le potentiel de d'acidité excède la capacité de neutralisation engendrant une problématique de drainage minier acide (DMA). Initialement le projet a étudié et caractérisé des mélanges simples de suspension de minéraux suivis d'un ajout progressif des phases du système. pour éventuellement simuler un système naturel contaminé. Une comparaison des similitudes et des différences des systèmes artificiels et naturels sert de base aux conclusions. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Potentiel zêta, Minéraux naturels, Surfactant, Sulfures, Décontamination, Double couche électrique, Séparation colloïdale.

Over the last decade in North America, an increasing number of microbiological drinking water regulations have been used to manage groundwater resources that are potentially influenced by surface water. Regulations such as the Ontario Ministry of Environment Regulation 505, which requires at least a 60 day groundwater travel time between surface waters and drinking water wells, have been created with limited understanding of subsurface pathogen transport processes. Groundwater Under Direct Influence studies (GUDI or GWUDI in USA) are conducted to assess the need to treat well water at an extraction point. Currently, there is a lack of knowledge regarding factors that affect the transport of pathogens through porous media at the surface water-groundwater interface. Such information is required to supply sufficient quantities of drinking water in a cost effective and safe manner. <br /><br /> Factors that affect pathogen transport through porous media include: properties of the pathogen (i. e. surface charge, size, and morphology), properties of the granular media (i. e. mineralogy, size, texture, angularity) and properties of the water (i. e. pH, ionic strength and content, and natural organic matter). This study examines the effects of ionic strength, grain size and influent virus concentrations on pathogen transport in porous media. Fourteen column tests were conducted using the bacteriophage MS2 and 1. 5 µm microspheres; two commonly used non-pathogenic surrogates representative of human viruses and bacteria, respectively. Two size distributions of crushed silica sand, with median grain diameters of 0. 7 and 0. 34 mm, and two ionic strengths of 8 and 95 mmol/L were used. A 2² partial factorial design was used with a minimum of two replicates of each combination of the parameters. <br /><br /> The results show that complete breakthrough of both viruses and microspheres occurred in medium sand at low ionic strength. It was found that increasing ionic strength by Ca²⁺ addition precluded breakthrough of MS2 in both the medium and fine sands. This represents a greater than 8 log reduction in peak effluent concentration and essentially complete attenuation. <br /><br /> In fine sand, with low ionic strength water, a 5 log reduction in peak MS2 concentrations was observed. In the same sand at high ionic strength, no MS2 broke through the column, corresponding to a greater than 8 log removal. Since complete attenuation occurred in both grain sizes at high ionic strength, the effect of higher ionic strength in the fine sand was indistinguishable from the effect observed from raising the ionic strength in the medium sand. <br /><br /> In contrast to the viruses, microsphere transport was essentially unaffected by increasing ionic strength under the conditions investigated. A 1 log reduction in peak concentration was observed in the high ionic strength water in the medium sand. In spite of this, grain size had a profound effect on the attenuation of microspheres. There was no evidence of microsphere breakthrough in any of the fine sand columns at the low or high ionic strengths, yielding a greater than 5 log reduction in microsphere concentration associated with grain size alone. The effect of varying virus concentration was also investigated. It was found that varying the concentration of viruses between 10⁵ and 10⁷ pfu/ml had no discernable effect on their observed transport characteristics; normalised peak breakthrough concentration, percent attenuation and retardation relative to a bromide tracer. <br /><br /> Based on the results from this Thesis, in a riverbank filtration environment, there is reason to expect that, at comparable water qualities and in similar porous media, multiple logarithmic reductions of viruses and bacteria would occur over the much longer (than column length) flowpaths associated with RBF. There is also reason to expect this attenuation capability to vary based on riverbank grain size and water chemistry.

The purpose of the study is to find a suitable method for removal of iron and manganese considering local economic and environmental aspects. El Salvador is situated in Central America with a coast line towards the Pacific Ocean. The country borders Guatemala and Honduras. Aguilares is a town situated in the department of San Salvador, with a population of approximately 33,000 people. Currently, the population is provided with water for about two hours per day, since it is the highest capacity of the existing wells. During these two hours many households fill a small tank with water to use for the remainder of the day. The water is not safe to use for oral consumption because of the levels of bacteria and other contamination. One of the wells, situated in the community of Florída is not in use at this date because of the high levels of Iron and Manganese in the ground water which cannot be removed with the present technique.Ground water is naturally pure from bacteria at a depth of 30 m or more, however solved metals may occur and if the levels are too high the water is unsuitable to drink. The recommended maximum levels by WHO (2008) [1] for Iron and Manganese are 2 mg/l and 0.5 mg/l respectively.Literature and field studies led to the following results; Iron and manganese can be removed by precipitation followed by separation. Precipitation is achieved by aeration, oxygenation or chemical oxidation and separation is achieved by filtration or sedimentation.The different methods all have advantages and disadvantages. However the conclusion reached in this report is that aeration and filtration should be used in the case of Florída. What equipment and construction that should be used depends on economic and resource factors as well as water requirements, which is up to the council of Aguilares to deliberate.

Over the last decade in North America, an increasing number of microbiological drinking water regulations have been used to manage groundwater resources that are potentially influenced by surface water. Regulations such as the Ontario Ministry of Environment Regulation 505, which requires at least a 60 day groundwater travel time between surface waters and drinking water wells, have been created with limited understanding of subsurface pathogen transport processes. Groundwater Under Direct Influence studies (GUDI or GWUDI in USA) are conducted to assess the need to treat well water at an extraction point. Currently, there is a lack of knowledge regarding factors that affect the transport of pathogens through porous media at the surface water-groundwater interface. Such information is required to supply sufficient quantities of drinking water in a cost effective and safe manner. <br /><br /> Factors that affect pathogen transport through porous media include: properties of the pathogen (i. e. surface charge, size, and morphology), properties of the granular media (i. e. mineralogy, size, texture, angularity) and properties of the water (i. e. pH, ionic strength and content, and natural organic matter). This study examines the effects of ionic strength, grain size and influent virus concentrations on pathogen transport in porous media. Fourteen column tests were conducted using the bacteriophage MS2 and 1. 5 µm microspheres; two commonly used non-pathogenic surrogates representative of human viruses and bacteria, respectively. Two size distributions of crushed silica sand, with median grain diameters of 0. 7 and 0. 34 mm, and two ionic strengths of 8 and 95 mmol/L were used. A 2² partial factorial design was used with a minimum of two replicates of each combination of the parameters. <br /><br /> The results show that complete breakthrough of both viruses and microspheres occurred in medium sand at low ionic strength. It was found that increasing ionic strength by Ca²⁺ addition precluded breakthrough of MS2 in both the medium and fine sands. This represents a greater than 8 log reduction in peak effluent concentration and essentially complete attenuation. <br /><br /> In fine sand, with low ionic strength water, a 5 log reduction in peak MS2 concentrations was observed. In the same sand at high ionic strength, no MS2 broke through the column, corresponding to a greater than 8 log removal. Since complete attenuation occurred in both grain sizes at high ionic strength, the effect of higher ionic strength in the fine sand was indistinguishable from the effect observed from raising the ionic strength in the medium sand. <br /><br /> In contrast to the viruses, microsphere transport was essentially unaffected by increasing ionic strength under the conditions investigated. A 1 log reduction in peak concentration was observed in the high ionic strength water in the medium sand. In spite of this, grain size had a profound effect on the attenuation of microspheres. There was no evidence of microsphere breakthrough in any of the fine sand columns at the low or high ionic strengths, yielding a greater than 5 log reduction in microsphere concentration associated with grain size alone. The effect of varying virus concentration was also investigated. It was found that varying the concentration of viruses between 10⁵ and 10⁷ pfu/ml had no discernable effect on their observed transport characteristics; normalised peak breakthrough concentration, percent attenuation and retardation relative to a bromide tracer. <br /><br /> Based on the results from this Thesis, in a riverbank filtration environment, there is reason to expect that, at comparable water qualities and in similar porous media, multiple logarithmic reductions of viruses and bacteria would occur over the much longer (than column length) flowpaths associated with RBF. There is also reason to expect this attenuation capability to vary based on riverbank grain size and water chemistry.

No description available.

No description available.

Extreme rainfall in raw water resource is greatly caused by climate change in Taiwan now. When typhoons are occurred, the turbidity in raw water is caused a high concentration frequently. In Taiwan the raw water, used by water treatment plants, comes from majorly river water. Most water treatment plants use chlorine disinfection; the disinfection process also produced excess disinfection by-products when raw water contains high turbidity and organic matter. In recent years, membrane method is widely being applied in water purification, but shortcomings were the higher price and not longer life. The purpose of this study is to investigate the treatment efficiency of turbidity, TOC, AOC, THMs and THMFP by using cheap nonwoven and biofilter (denoted as This System). In this study we used the base weight of 35 g/m2 nonwoven in filtration experiments for turbidity removal. Experimental results show turbidity removal by this system was nearly 90% when inlet turbidity is under moderate condition. The turbidity of treated water in effluent is all below 2 NTU that is compliance with national drinking water quality standards. Turbidity removal was about 90% using nonwoven with 21 pieces. Removal of organic matter is about 39% using biofilter when influent was in the low concentration of TOC. The removal rate is about 77% when the high TOC concentration in influent. In removal of TOC, TOC removal of raw water (I) was about 26.41%. The concentration of TOC was reduced from1169.9 £gg/L to 856.9£gg/L. The TOC removal of raw water (¢º) was about 19.65%. The concentration of TOC was reduced from 680.8£gg/L to 521£gg/L. The TOC removal of raw water (¢») was about 48.78%. The concentration of TOC was reduced from 1819 £gg/L to 936.5£gg/L. In removal of AOC, the removal rate of raw water (I) was about 50.83%. The concentration of AOC was from 59.51 £gg acetate-C/L to 28.42 £gg acetate-C/L). The removal of raw water (¢º) was about 50.97%. The concentration of AOC was from 73.08 £gg acetate-C/L to 35.8 £gg acetate-C/L. The removal of raw water (¢») was about 65.07%. The concentration of AOC was from 226.60 £gg acetate-C/L to 81.19 £gg acetate-C/L. The suggested limit level of AOC in treated water is 50£gg acetate-C/L Longer empty bed contact time of biofilter should enable the concentration below 50 £gg acetate-C/L. Removal of AOC increased with increased the empty bed contact time of biofilter . In removal of THMs and THMFP (denoted as precursors), the raw water (I) : THMs removal was about 50.22%. The concentration of THMs was reduced from 34.64 £gg/L to 17.56 £gg/L. The raw water (¢º): THMFP removal was about 46.83%. The concentration of THMs was reduced from 34.18 £gg/L to 18.27 £gg/L. The raw water (¢»): THMFP removal was about 51.81%. The concentration of THMFP was reduced from 81.49 £gg/L to 39.25 £gg/L. They were all lower than national standard of drinking water (THMs 80 £gg/L). Thus, this system can effectively remove turbidity, TOC, THMs and THMs precursors in raw water.

With the increases of environmental awareness and attention by the government and audiences, people begin to prosecute the pollution makers instead of tolerance. This study tried to control an air pollution source from a wallpaper plant for the purpose of attenuating odor prosecutes by residents near the plant. This study investigated chemical scrubbing, ozonation followed by GAC (Granular Activated Carbon) adsorption and biotrickling filtration techniques as control methods for eliminating odorous compounds from a waste gas stream emitted from the wallpaper plant. Scrubbing test results indicate that with an oxidative solution of 800 mg/L residual chlorine at pH 7.0 and a reductive solution of 0.2% hydrogen peroxide at pH = 12, around 90% of the VOCs (volatile organic compounds) in the tested gas could be removed. Odor intensities could be reduced from 2,317 (expressed as dilutions to threshold) to 130. Results also indicate that around 85 % of the carbonyl compounds, 41% of the alkenes and 22% of the alkanes in the waste gas could be eliminated. No removal of aromatic and halo-hydrocarbons was observed. It requires around NT$70 for chemicals to treat 1000 m3 of the gas. Ozonation-GAC adsorption tests indicate that with an ozone dosage of 5 ppm in the waste gas and a gas-ozone contact time of 12 s followed by GAC adsorption, around 95% of the VOCs in the tested gas could be removed. Odor intensities were reduced from 2,317 to <55. Around 94 % of the carbonyl compounds, 79% of the alkanes, 76% of halo-hydrocarbons, 41% of the alkenes and 20% of aromatics in the waste gas could be removed. Around NT$ 15,700 for ozone and GAC is required to treat 1000m3 of the gas. Results from biotrickling filtration tests indicate that with the supplementations of nitrogen and phosphorous nutrients to biofilms attached to wood-chip packings, around 83% of the influent VOCs could be biodegraded. Odor intensities could be reduced from 1,737 to <55. Around 61 % of the carbonyl compounds, 67% of the alkanes, 18% of halo-hydrocarbons and 33% of aromatics in the waste gas could be removed. Around NT$ 13 is required to treat 1000m3 of the gas. For an actual application, it is suggested that a process that a combination of chemical scrubbing and ozonation-GAC adsorption may be a proper solution to the control of the odorous emission from the plant. Biotrickling filtration can be best after verifying the performances of the technique by a pilot test.

ABSTRACT The mortalities for aquaculture animals in a newly established pond tend to be high. The phenomenon can be described as the ¡§new pond syndrome¡¨. The main reason for the phenomenon is still unclear. However, it is suspected that the accumulation of ammonia due to insufficient nitrifying bacteria in the system may have been the cause. The purposes of this thesis are to test the theory and to rectify the problem by introducing a nitrifying trickling filtration system using E. amblycephalus as the experimental animal. It was found that the ammonia concentrations did increase to the levels detrimental to the newly hatched fries within 6 days. The LD50 of ammonia to the young fries was determined to be 0.034 ppm in 48 hr. The nitrifying filtration system could reduce the ammonia concentrations substantially and raise the breeding rates for the fries. On two separate trials, one with fish tanks in the laboratory and the other in the ponds of a fish farm, 12.3% and 4.2% of the newly hatched fries were still alive after 34 days, respectively, as compared to 0% and 0.035% for the controls. Meanwhile, a pH value of equal to or greater than 8.6 was detrimental to the fries. Therefore, the low breeding rates for the E. amblycephalus fries may have been caused by the ¡§new pond syndrome¡¨ due to the toxic effects of accumulated ammonia in the early stage of the pond usage. Removal of ammonia with the filtration system could increase the survival rates for the fries.