The purpose of this study was to evaluate the performance of alum alone, alum in conjunction with a polymeric coagulant aid, and a primary coagulant polymer in the coagulation-flocculation-sedimentation portion of a water treatment process and to study the implications of the results with respect to future use in direct filtration. The performance of the coagulant, coagulant aid, and primary coagulant polymer was evaluated by altering the flocculation and sedimentation retention times in the pretreatIDEnt process chain. Among the water quality parameters monitored were turbidity, pH, total alkalinity, total hardness, and total solids. A brief literature review for direct filtration and coagulation-flocculation theory was also conducted. The results of this investigation indicated that reduced retention times in the pretreatment process chain treated the selected raw waters sufficiently to enable consideration of direct filtration a viable treatment alternative. Analysis of data obtained indicated the use of polyelectrolyte as a primary coagulant or coagulant aid produced a pinpoint floc which is essential to successful utilization of direct filtration and that the floc formed settled more rapidly than floc from use of aluminum sulfate alone. The use of a polyelectrolyte as a primary coagulant or coagulant aid also reduced the chemical dosages required to provide appropriate turbidity removals. / Master of Science

The disposal of water treatment residual has received little attention due to a lack of regulation, funding, and concern about their environmental impacts. Many treatment plants discharge alum residual directly into nearby water courses or dewater them for landfilling. If suitable land is available, land application of residual is cost effective and has the potential for negligible effects on the environment and may prove to be a long-term solution to the disposal problem. This research project investigated the effects of land application of alum residual on crops or vegetation grown on fine loamy Slagle soil (<i>siliceous, thermic aquic hapludults</i>). Prior research identified the reduction in plant available P as a potential concern. During summer months. many water treatment plants also add powdered activated carbon (PAC) during the treatment process to prevent taste and odor problems. The PAC ultimately ends up in the residual and alters its chemical characteristics. The effects of land-applied PAC residual on plant growth was also investigated. Fescue (<i>festuca arundinacae</i>) yields decreased with increased residual addition. Lime addition did not Significantly effect fescue yield. Reductions in plant yield were attributed to a reduction in plant available phosphorus (P) in soils receiving higher residual loadings. Supplemental fertilization was able to overcome the P availability problem. The presence of manganese in the residual did not adversely affect plant yields. Likewise, incorporation of spent PAC into the residual did not reduce yields. / Master of Science

This research evaluated natural organic matter (NOM) dissolved-solid phase separation resulting from alum coagulation under the following sourcewater conditions: pH, initial NOM concentration, initial turbidity, and temperature. The solid phase was partitioned into two operationally defined size fractions; colloidal matter was defined as organic carbon (OC) retained by a 30 kilodalton ultrafiltration membrane, and particulate matter was defined as OC retained by a 1μm glass-fiber filter. Coagulation pH had a considerable impact on residual OC colloid formation, signified by more colloids formed as a function of alum dose at pH 6.8 as compared to pH 5.8. Initial NOM concentration strongly influenced the alum dose range over which OC colloid formation occurred and was found to be a proportional relationship. The presence of bentonite clay (used as the initial turbidity source) somewhat affected OC colloid formation by exerting some amount of coagulant demand, signified by decreasing OC colloid formation with increasing initial turbidity. Coagulation temperature had a considerable impact on particulate matter formation, as there was an increase in the dose at which particle formation first occurred at 4 ºC when compared to 25 ºC. Phase separation of OC from dissolved to colloidal matter was very similar at both 4 ºC and 25 ºC. The ability for low doses of polymers to replace a large portion of alum in order to further aggregate colloids during flocculation was unsuccessfully investigated. OC phase separation resulting from alum and iron sulfate coagulation was compared on a molar coagulant metal basis. The amount of residual OC associated with colloidal matter was similar, while the critical coagulant dose at which particulate matter formed was shifted to a much higher dose for iron. / Master of Science

Fluoride naturally occurs in some ground and surface waters at high concentrations all around the world. Due to increasing health concerns about over-exposure to fluoride in drinking water, the United States Environmental Protection Agency (USEPA) has begun to review fluoride as a drinking water contaminant. Should the USEPA decide to lower the fluoride maximum contaminant limit (MCL), many water systems in addition to those already struggling to meet the fluoride MCL will require defluoridation as part of their drinking water treatment process. Alum coagulation was investigated as a defluoridation treatment strategy in this research project. Surface and blended (ground/surface) drinking water sources with high fluoride concentrations pose a unique challenge to defluoridation by alum coagulation because of the presence of both natural organic matter (NOM) and fluoride. Defluoridation of synthetic and natural waters using jar tests elucidated interactions of fluoride, NOM, and aluminum during alum coagulation. Alum coagulation was able to remove 80% of fluoride from natural waters with a 500 mg/L alum dose; however, 50% fluoride removal was observed to be possible with an alum dose of 150-170 mg/L. The optimum pH for fluoride removal in synthetic and natural waters was observed to be approximately 6.5 and was found to be an important factor in determining the overall performance of alum coagulation. The presence of fluoride during alum coagulation was found to reduce the removal of three low molecular weight (LMW) organics, acting as surrogates for NOM, to different extents depending on their functionality. The presence of LMW organic acids in synthetic waters did not impact the removal of fluoride; however, increasing NOM concentrations in the natural waters likely accounted for decreasing fluoride removals observed in the natural waters. Additional jar tests with natural waters revealed that pH adjustment was unnecessary for defluoridation of high pH and high alkalinity waters and that an enhanced precipitation effect occurred at low alum doses when no pH adjustment was made during alum coagulation. The enhanced precipitation effect caused comparable or enhanced removals of fluoride and NOM to be observed despite system pH values being higher than the optimal defluoridation pH of 6.5. Lower aluminum residuals were also observed as part of the enhanced precipitation effect, suggesting that when precipitation begins under high pH conditions, fluoride interference does not occur and therefore promotes more precipitate formation with greater available surface area for adsorption. However, as precipitation occurs, pH drops, and fluoride increasingly interacts with the aluminum precipitate resulting in greater overall fluoride removals. / text

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-06-02T16:53:40Z No. of bitstreams: 1 469858 Texto Completo.pdf: 7135001 bytes, checksum: 232fdeb10ae43ec70dca9941fb5b3828 (MD5) / Made available in DSpace on 2015-06-02T16:53:41Z (GMT). No. of bitstreams: 1 469858 Texto Completo.pdf: 7135001 bytes, checksum: 232fdeb10ae43ec70dca9941fb5b3828 (MD5) Previous issue date: 2015-03-24 / Ternary alloys of III-V semiconductor materials, in particular Ga1-xInxSb, are ideal candidates for substrates because of the possibility to define the lattice constant as a function of concentration of the third element, indium, enabling the adjustment of the lattice parameter in accordance to the subsequent epitaxial layer. Therefore, the mono-crystallinity of the epitaxial layer is favored and the tensions at the interface layer/substrate are reduced, allowing to numerous possibilities and applications. Aluminum (Al) is considered an isoelectric dopant for Ga and In, meaning that it does not change the number of charge carriers, but increases the mobility in GaSb crystals. When Al is added to the Ga1-xInxSb ternary alloy, it can have influence over native defects passivating and/or compensating them. To understand the influence of Al on the distribution of indium (In) in ternary alloys of Ga1-xInxSb, pure and doped Ga0,8In0,2Sb crystals were obtained with approximately 1020 atoms/cm3 of Al using a vertical Bridgman system.Analysis by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), particle induced X-ray emission (PIXE) and particle induced gamma ray emission (PIGE) were used for the structural and compositional characterization of the crystals. The obtained crystals of Ga0,8In0,2Sb, doped with aluminum or not, exhibited segregation of the third element, however, for Ga0,8In0,2Sb:Al crystals the segregation decreased. The crystals of Ga0,8In0,2Sb:Al presented a good structural homogeneity when compared to the undoped alloy, and they were free from cracks and micro cracks. All of the obtained crystals presented precipitates, twins and grains with different concentrations of In. In the crystals doped with aluminum, single regions were observed in the solidification direction, which can be associated to a more uniform distribution of indium.The small compositional variation observed in the crystals, in radial direction, and measured by PIXE, may be related to the solid-liquid interface?s quasi-equilibrium behavior. The results indicated that aluminum has influenced the indium distribution in the crystals, in the solidification direction, and the electrical properties imply that the aluminum may have contributed to the generation of accepter defects such as GaSb, InSb e AlSb, wherein the number of charge carriers increased in the doped crystals. The possibility of complex defects generation such as (VGaGaSb), (VGaInSb) e (VGaAlSb) cannot be excluded, since the charge mobility in the doped crystals decreased. / Ligas tern?rias de materiais semicondutores III-V, nomeadamente Ga1-xInxSb, s?o candidatas ideais para substratos, pois a possiblidade de se definir a constante de rede em fun??o da concentra??o do terceiro elemento, o ?ndio, possibilita o ajuste do par?metro de rede de acordo com a camada epitaxial subsequente. Desta forma, a monocristalinidade da camada epitaxial ? favorecida e as tens?es na interface camada/substrato s?o diminu?das, introduzindo in?meras possibilidades e aplica??es. O alum?nio (Al) ? considerado um dopante isoel?trico do Ga e do In, isto ?, n?o altera o n?mero de portadores de carga, mas aumenta a mobilidade em lingotes de GaSb. Ao ser adicionando na liga tern?ria Ga1-xInxSb, pode influenciar passivando e/ou compensando os defeitos nativos. Para compreender a influ?ncia do Al na distribui??o do ?ndio (In) em ligas tern?ria de Ga1-xInxSb, foram obtidos lingotes de Gao,8In0,2Sb puros e dopados com aproximadamente 1020 ?tomos/cm3 de Al em um sistema Bridgman vertical.An?lises por microscopia eletr?nica de varredura (MEV), espectroscopia por dispers?o de energia (EDS), difra??o de raios X (XRD), emiss?o de raios X induzida por part?culas (PIXE) e emiss?o de raios gama induzida por part?culas (PIGE) foram utilizadas para a caracteriza??o estrutural e composicional dos lingotes. Os lingotes de Ga0,8In0,2Sb obtidos, dopados ou n?o com alum?nio, apresentaram segrega??o do terceiro elemento, por?m, para os lingotes Ga0,8In0,2Sb:Al a segrega??o foi menor. Os lingotes de Ga0,8In0,2Sb:Al apresentaram uma boa homogeneidade estrutural, livres de fissuras e micro trincas, quando comparados ? liga n?o dopada. Todos os lingotes obtidos apresentam forma??o de precipitados, maclas e gr?os com diferentes concentra??es de In. Nos lingotes dopados com alum?nio foram observadas regi?es com pequena quantidade de gr?os na dire??o da solidifica??o, que podem ser atribu?das a uma distribui??o do ?ndio mais uniforme. A pequena varia??o composicional observada nos lingotes, no sentido radial, mensurada por PIXE, pode ser atribu?da ao comportamento pr?ximo ao equil?brio da interface s?lido-liquido.Os resultados obtidos sugerem a influ?ncia do alum?nio na distribui??o de ?ndio nos lingotes, na dire??o da solidifica??o, ao mesmo tempo que as propriedades el?tricas sugerem que o alum?nio possa ter contribu?do para a gera??o de defeitos aceitadores como GaSb, InSb e AlSb, sendo que o n?mero de portadores de carga aumentou nos lingotes dopados. N?o se exclui a possibilidade da gera??o de defeitos complexos como (VGaGaSb), (VGaInSb) e (VGaAlSb), uma vez que a mobilidade das cargas nos lingotes dopados diminuiu.

The success of surface water treatment strongly depends on the effectiveness of coagulant performance. Aluminium sulfate (alum), the most widely used coagulant in water treatment plants in Canada, is well known for its poor performance in cold water. Polyaluminium chloride (PACl), a relatively new polymeric aluminium coagulant increasingly being used in water treatment plants, is found to have many advantages over conventional alum. However, PACl hydrolysis reaction is quite complex and its action is not fully understood. In this research, a series of bench-scale jar tests with alum and PACl was conducted. Alum and PACl coagulation flocs were analyzed for the evaluation of coagulant performances at 19C and 5C for the Split Lake water treatment plant. The results of this research indicated that the settling properties of PACl flocs were superior to those of alum flocs, especially at the lower temperature. The average size of PACl flocs was relatively smaller than that of alum flocs. The density of PACl flocs could be higher than that of alum flocs. And the number of settled PACl flocs could be higher than that of settled alum flocs. The effects of temperature on alum flocs and PACl flocs were different. Alum flocs size decreased at 5C. This is most likely due to the existence of monomeric aluminium species in alum aqueous solution. PACl flocs size did not change significantly at the 5C. This may be due to the existence of polymeric aluminium species in PACl aqueous solution. / February 2006

Thesis (Ph. D.)--Institute of Paper Chemistry, 1942. / Includes bibliographical references (p. 83-86).

The success of surface water treatment strongly depends on the effectiveness of coagulant performance. Aluminium sulfate (alum), the most widely used coagulant in water treatment plants in Canada, is well known for its poor performance in cold water. Polyaluminium chloride (PACl), a relatively new polymeric aluminium coagulant increasingly being used in water treatment plants, is found to have many advantages over conventional alum. However, PACl hydrolysis reaction is quite complex and its action is not fully understood. In this research, a series of bench-scale jar tests with alum and PACl was conducted. Alum and PACl coagulation flocs were analyzed for the evaluation of coagulant performances at 19C and 5C for the Split Lake water treatment plant. The results of this research indicated that the settling properties of PACl flocs were superior to those of alum flocs, especially at the lower temperature. The average size of PACl flocs was relatively smaller than that of alum flocs. The density of PACl flocs could be higher than that of alum flocs. And the number of settled PACl flocs could be higher than that of settled alum flocs. The effects of temperature on alum flocs and PACl flocs were different. Alum flocs size decreased at 5C. This is most likely due to the existence of monomeric aluminium species in alum aqueous solution. PACl flocs size did not change significantly at the 5C. This may be due to the existence of polymeric aluminium species in PACl aqueous solution.

The success of surface water treatment strongly depends on the effectiveness of coagulant performance. Aluminium sulfate (alum), the most widely used coagulant in water treatment plants in Canada, is well known for its poor performance in cold water. Polyaluminium chloride (PACl), a relatively new polymeric aluminium coagulant increasingly being used in water treatment plants, is found to have many advantages over conventional alum. However, PACl hydrolysis reaction is quite complex and its action is not fully understood. In this research, a series of bench-scale jar tests with alum and PACl was conducted. Alum and PACl coagulation flocs were analyzed for the evaluation of coagulant performances at 19C and 5C for the Split Lake water treatment plant. The results of this research indicated that the settling properties of PACl flocs were superior to those of alum flocs, especially at the lower temperature. The average size of PACl flocs was relatively smaller than that of alum flocs. The density of PACl flocs could be higher than that of alum flocs. And the number of settled PACl flocs could be higher than that of settled alum flocs. The effects of temperature on alum flocs and PACl flocs were different. Alum flocs size decreased at 5C. This is most likely due to the existence of monomeric aluminium species in alum aqueous solution. PACl flocs size did not change significantly at the 5C. This may be due to the existence of polymeric aluminium species in PACl aqueous solution.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 82-84). Also available via the Internet.