A proposta deste trabalho foi a concepção de um modelo para o dimensionamento otimizado de sistemas para tratamento de água baseados na tecnologia de Ultrafiltração com membranas de fibra-oca pressurizadas. O modelo relaciona o comportamento das membranas com a qualidade da água bruta através de resultados de ensaios em unidade piloto ou de bancada e equações de bloqueio de poros. A validação desta relação foi realizada através da análise dos dados de uma planta piloto operada em dois períodos distintos em regimes de fluxo variando de 60 a 70L/m².h e alimentada com água bruta proveniente de um manancial de superfície. Os resultados apontaram para a predominância do mecanismo de obstrução através da formação de torta e indicaram uma boa aderência das equações do modelo físico à realidade observada. Variáveis econômicas foram incorporadas ao modelo de forma a permitir a otimização através da busca do mínimo custo total de propriedade. Uma análise de sensibilidade demonstrou que os parâmetros de projeto mais impactantes no custo total, quantidade de membranas, duração do ciclo de filtração e duração do ciclo de contralavagem, podem variar seu peso em diferentes regiões do mundo influenciando o dimensionamento. Outras variáveis de projeto como a vazão de ar de limpeza demonstraram ser pouco significantes para a redução do custo total. A otimização do modelo foi realizada através de um algoritmo de busca numérica para as variáveis de duração do ciclo de filtração e quantidade de membranas, os resultados a partir das informações colhidas na planta piloto levaram a um projeto arrojado, porém dentro das recomendações gerais dos fabricantes de membranas. Como conclusão é possível afirmar que o modelo de dimensionamento do projeto é capaz de reduzir os custos totais de uma estação de tratamento de água baseada na tecnologia de ultrafiltração além de demonstrar potencial para a otimização dinâmica de plantas já instaladas. / The goal of this work was the development of an optimal design model for water treatment plants based in the pressurized hollow-fiber ultrafiltration membrane technology. The model uses operational data from pilot plants or bench scale units as input and pore blocking equations to predict the behavior of the membranes. The correlation between the fouling model adopted and the pilot plant results was evaluated using a pilot plant operated in two different time frames with flux rates from 60L/m²h to 70L/m²h and fed with raw water from a lake. The results from this validation have shown that the major fouling mechanism is the cake filtration and the theoretical curves had a good fitting with the operational data. To allow the cost optimization, economic variables were added to the model. A sensitivity analysis demonstrated that the most significant design parameters on the overall cost were the membrane area, the duration of the filtration cycle and the duration of the backwash cycle. According to the analysis, since the costs of the commodities and membranes are different from a region to the other, the optimal system design will also be different. Other design parameters like the membrane aeration rate have shown almost no impact on the total operating cost. The model optimization for the membrane quantity and the filtration cycle duration was based on bi-dimensional discrete numeric algorithm. The results from the optimization using the pilot plant data were compatible with the typical ranges and limits proposed by the membrane manufacturers. The design model proposed was able to reduce the total costs of new plants and demonstrated a good potential for the dynamic optimization of existing plants.

Gram-negative bacterial cells are surrounded by a cell membrane which protects the cell and controls the transport of nutrients and waste products in and out of the cells at a fast rate. This rapid transport of nutrients and wastes through the cell membrane is made possible by channel proteins called porins. Various types of porins present in the cell membrane have specific functions depending on their selectivity towards different nutrients, and channel proteins selective towards water are called aquaporins. These proteins restrict the passage of all entities except water molecules and they provide a fast transport rate of water molecules at 109 molecules/second per channel. The high selectivity of porins has led to their incorporation into synthetic systems, and one example is the addition of porins to separations membranes in order to enhance their performance in terms of selectivity and permeability, in a field called biomimetics. The concept of incorporating aquaporins into synthetic membranes has been studied for the last 10 years in order to enhance the water permeability and selectivity of membranes for water purification; however, there are still limitations such as high costs, difficulties in fabrication of aquaporins, their alignment into synthetic membrane assembly, low stability, and limitations on number of aquaporin molecules that can be introduced into synthetic membranes limit their applicability. In recent years, concurrent with the work on aquaporin-based biomimetic membranes, there has been an increase in the study of synthesizing molecules with similar structure-function relationships of aquaporins. These artificial channels attempt to mimic the high-water permeability and selectivity of aquaporins, while being synthesized using simple chemistry, being solvent compatible, and requiring less space on the membrane surface which helps to incorporate more channels into the membrane assembly. The objectives of this study were to first incorporate aquaporins into synthetic nanofiltration membranes without chemical alteration them to prevent flattening or denaturing of aquaporins; then, the second objective was to install functional groups on aquaporins and align them in the direction of water flow; lastly, the third objective was to synthesize artificial channels in order to overcome the issues with aquaporin stability, alignment, and efficient packing of water channels onto the membrane surface. For the first objective, aquaporins were treated with a polysaccharide, gum Arabic, and incorporated into an amphiphilic polymer, polyvinyl alcohol with alkyl side chains (PVA-alkyl), in order to simulate the natural housing of lipid bilayer for aquaporins and to protect them from denaturing. Long alkyl chains provided the hydrophobic component, while PVA provided the hydrophilic component of the amphiphilic polymer. Membranes modified with aquaporins displayed lower flux declines and higher flux recoveries after reverse flow filtration, along with improved rejection values for both protein and salt solutions as compared to PBI and PBI-PVA-alkyl membranes. However, there was leakage of ions between channels. Therefore, in order to improve the rejection of protons, ions and other impurities, the channels were aligned with the direction of water flow. Functional groups were installed on Aquaporins using site-directed mutagenesis for covalent attachment to the polymer matrix so that the proteins could be immobilized to the membranes and aligned in the direction of the flow. Aquaporin constructs were modified to bear affinity tags or unique amino acids at the N-terminus of the aquaporin molecule, which was used to facilitate directional immobilization. Each aquaporin monomer was modified with a unique amino acid Cys group at the N-terminus right after the first Met, and due to the aquaporin tetrameric nature, these Cys groups became four anchors for attachment. The presence of these four Cys anchors per aquaporin tetramer was used to attach on the membrane surface in alignment with the feed water flow direction. Membranes modified with mutated aquaporins showed consistently higher salt rejection values of ~70% irrespective of feed concentration, along with higher flux recoveries and lower flux declines. Commercial NF-270 membranes provide a monovalent salt (NaCl) rejection of ~50% and divalent salt (MgCl2) rejection of 97%. Also, approximate coverage of membrane surface with attached aquaporins was calculated using simulation studies. Simulation studies showed that immobilized aquaporins with PVA-alkyl provided a diffusion rate equivalent to 64% coverage on the membrane surface. This showed that aquaporins didn’t cover the entire surface area of the membrane. However, immobilized aquaporins were responsible for the rejection of a portion of ions passing through the membrane. In order to overcome the limitations of aquaporin incorporation into polymer membranes, artificial organic frameworks were added as surface modification on PBI membranes. Organic frameworks were synthesized as derivatives of hybrid bisamides. The series of bisamides 1-4 consist of 6-amino-pyridine-2-dicarboxylic acid, 6-hydroxymethyl-pyridine-2-carboxylic acid and ethylenediamine, trimethylenediamine, putrescine, and cadaverine depending on the length of carbon chain. These frameworks are amphiphilic in nature and have strong chemical attachment due to the presence of amines and carboxylic acids into each building block. These molecules were introduced into the membrane matrix using carbodiimide chemistry. FTIR results showed the attachment of these bisamide molecules onto the surface of a modified PBI membrane. Also, modified membranes showed a reduced molecular weight cut off (MWCO) for neutral organic molecules. Overall, membranes modified with aquaporins have shown a potential to provide consistently high salt rejections with increasing feed solutions. Also, preliminary results have shown that bisamide molecules can be attached onto the membrane surface as organic frameworks and have a potential to be an alternative for aquaporins based biomimetic membranes.

Relief organizations and governments strive to provide safe drinking water to natural disaster survivors as quickly as possible. However, drinking water is typically provided either as bottled water or via mobile water treatment equipment, both of which can be difficult or expensive to transport rapidly into disaster zones. An alternative is the waterbag point-of-use treatment device developed at Cal Poly that allows survivors to produce safe drinking water from contaminated local sources. The waterbag is a 10-L bladder designed for use with Procter & Gamble Purifier of Water (PŪR®) sachets, which contain coagulant and chlorine compounds. Following treatment with PŪR®, treated water in the waterbag is flowed through an outlet port to a filter, primarily for parasitic cyst removal. Currently, the commercial version of the waterbag uses an effective but expensive hollow-fiber membrane microfilter (>$10 each). This cost will likely decrease the use of the waterbag by relief organizations responding to large disasters. The goal of the present thesis research was to develop a novel, low cost (~$5), effective, low-profile filter to be used with the waterbag in large-scale disaster relief. This new filter is referred to as an envelope filter due to its geometry and size. Various prototype envelope filters were constructed using layers of nonwoven polypropylene filter cloth. Two types of cloth were used: a nominally-rated 1-µm pore size cloth and an absolute-rated 1-µm cloth. The filters tested were both internal and external to the waterbag and of various geometries. Filters were attached to the waterbag and used to filter defined test water after it had been treated with a PŪR® sachet. Test water for design experiments consisted of tap water with addition of standard dust (to increase turbidity) and seasalts (to increase salinity). In addition to this basic test water, mock U.S. EPA Challenge Water #2 with added bacteria and cyst surrogates (fluorescent microspheres) was used to evaluate the filter prototype designs prior to testing according to U.S. EPA Guide Standard and Protocol for Testing Microbiological Water Purifiers in a commercial laboratory. The filter design and mock challenge experiment results indicated that a 2-ply filter with one nominal and one absolute layer was the optimal filter design. In the mock U.S. EPA challenge tests, a flowrate of 20 mL/min allowed this filter met the turbidity, bacteria, and microsphere removal requirements determined by the WHO and The Sphere Project for emergency drinking water treatment as well as the U.S. EPA Guide Standard and Protocol for Testing Microbiological Water Purifiers.. This filter design was further tested using the U.S. EPA Challenge Water #2 with triplicate waterbags at the U.S. EPA-certified BioVir Laboratories in Benicia, Calif. All three waterbags with envelope filters met the recommendations for turbidity (<5 >NTU) and for virus removal (>4-log removal). Two of the three waterbags met the bacteria and microsphere removal requirements (>6- and >3-log removal, respectively). The failure of one of the prototypes to meet the requirements could have been due to improper setting of valve that throttled the flowrate through the filter or due to a slightly leaking hose pinch valve. Future work should include incorporating more reliable valves and improving the envelope filter design and materials to achieve higher allowable flowrates.

<p><!--[if !mso]> <object classid="clsid:38481807-CA0E-42D2-BF39-B33AF135CC4D" id=ieooui></object><mce:style><! st1\:*{behavior:url(#ieooui) } --></p><p>Hydrological investigations were performed in the Lubigi papyrus wetland in suburban Kampala, Uganda, impacted by human encroachment for settlement and agriculture. The first aim was to investigate the water flow variations and the dampening effect of the wetland. A second aim was to estimate the effective wetland volume and area, and relate this to the wetland function for treatment of the suburban runoff. A study site with well defined inflows and outflows was chosen, and three transects were cut through the papyrus to be able to study the water movement beneath the floating papyrus mat. Water flow measurements showed a flow dampening effect of the wetland on peak flows after rains, and the water balance revealed that the precipitation on the wetland was only 4 % of the inflow during the study. The tracer added at the inlet was rapidly detected downstream in the canal in the middle of the wetland, indicating a strong short-circuiting effect of the human made canal. At the outlet the tracer concentration was lower than the detection limit, suggesting a good mixing in the downstream part of the wetland, which was also supported by other water quality measurements in the transects. Ammonium-N concentrations at the inflow and outflow indicated a net export of ammonium-N, but the observed flow variations suggest that intensive water sampling campaigns are necessary for a proper evaluation of the water treatment function. The calculated effective volume and area amounted to 74 and 46 %, respectively, of the theoretically estimated, with a corresponding loss in the flow dampening and water treatment function of the wetland.</p><p> </p> / Rapporten är ett resultat av ett Minor Field Study stipendium finansierad av Sida.

<p>This is a project about The Water Treatment System at Djupdalen. The leakage water comes to the Water Treatment System from a deposition plant through the land. The leakage water is characterized by a high concentration of nitrogen and the system is based on biological removing of the nitrogen in the water, by nitrifying and denitrifying bacteria. Four different problems are found in the system: 1. High level of nitrogen concentration in the outgoing water of the system. It should be due to the lack of phosphate in the water, that do not let the bacteria to grow. 2. Low temperature during the most part of the year. Nitrifying and denitrifying bacteria are temperature-dependent, that are very slow at low temperatures. 3. High oxygen concentration in one of the anoxic pond, where the denitrification process take place. This oxygen concentration is too high for denitrifying bacteria to work. 4. The nitrification and denitrification bacteria need to be “old” to work efficiently. They need a surface to attach, because if not they flow with the water and they leave the system. And four possible solutions for the system are presented: 1. Phosphate should be added to the system to let bacteria growth. 2. Store the water at a store pond during the winter months and transport it to the system when the temperature is optimum for the bacteria to work. 3. Add carbon matter to improve the carbon oxidation and to low down the oxygen levels at the anoxic ponds. 4. Two options are presented to improve the system, the first one is based on the construction of a dark wavy bottom in the channel system, which will give a surface for bacteria to attaché, it will produce oxygenation in the water, and it will also improve the water temperature; and the second one is based on the addition of panels made of black material, which will give to bacteria a surface to attach, and improve the water temperature.</p>

Disinfection byproducts (DBPs), such as organic chloramines, THMs, HAAs, and nitrosamines, are formed during mandatory disinfection processes in drinking water treatment. Many of these DBPs have been shown to be potentially carcinogenic. Extensive research has been conducted on the occurrence and formation of these DBPs. However, there has been limited research on their relationships with each other, which may be important for the understanding of their formation mechanisms, and the nature of their precursors is still relatively unknown. Ultimately, this information will be key for the development of possible improvements in treatment technologies. Results of this study improve the understanding of DBP formation in swimming pool water. Some BFAs and PCP additives were identified as potential DBP precursors. Influence of BFAs and PCP additives on DBP formation in swimming pool water was also illustrated. Results provided feasible strategies to minimize DBP formation while maintaining the efficiency of disinfection.

Disinfection byproducts (DBPs), such as organic chloramines, THMs, HAAs, and nitrosamines, are formed during mandatory disinfection processes in drinking water treatment. Many of these DBPs have been shown to be potentially carcinogenic. Extensive research has been conducted on the occurrence and formation of these DBPs. However, there has been limited research on their relationships with each other, which may be important for the understanding of their formation mechanisms, and the nature of their precursors is still relatively unknown. Ultimately, this information will be key for the development of possible improvements in treatment technologies. Results of this study improve the understanding of DBP formation in swimming pool water. Some BFAs and PCP additives were identified as potential DBP precursors. Influence of BFAs and PCP additives on DBP formation in swimming pool water was also illustrated. Results provided feasible strategies to minimize DBP formation while maintaining the efficiency of disinfection.

Application of low pressure membranes in drinking water treatment, including both microfiltration (MF) and ultrafiltration (UF), have witnessed a rapid increase in the past decades. Low pressure membranes are considered a good technology in retrofitting existing conventional drinking water treatment plants or in newly constructed plants to meet the stringent regulations for drinking water treatment that aim at preventing health risks of waterborne diseases. Enteric viruses are one of the major types of waterborne pathogens, and they can be commonly found and are persistent in the environment. Both the United States and Canada require a 99.99% (4-log) removal of viruses during the drinking water treatment train. Unlike MF membranes, UF membranes have a very good potential for removing enteric viruses from the water due to their smaller pores comparable to the size of viruses. Drinking water regulations/guidelines in both the United States and Canada do not grant UF membranes any removal credit for viruses by default; however they have the provision that, in certain cases, virus removal credit may be granted based on pilot scale challenge testing. A better understanding of the interaction between the UF membranes and virus rejection can help to establish a removal credit for UF membranes. An essential part of this will be the effect of the membrane operation on the rejection of viruses to determine if UF membranes can offer a consistent removal of viruses. Membrane fouling is one of the major problems in membrane operation and it can affect the rejection characteristics of the membrane and improve its performance. The aim of this study was to investigate the removal of virus surrogates (MS2 and φX174 bacteriophage) using a commercial UF membrane under different conditions, to obtain information about the removal mechanisms of viruses. The experimental filtration unit was designed to have similar conditions like the full scale membrane treatment plants. The UF membrane used in this study provided very good removal of both MS2 and φX174 bacteriophage. The obtained results were consistent and in agreement with the expected removals based on the membrane characterization results and types of virus surrogate. As part of this work, a detailed study to improve methods for characterizing the pore size distribution of membranes was conducted. In the second part of the study, two different types of surface waters were used to study the effect of membrane fouling on virus removal. It was found that mainly hydraulically irreversible fouling could significantly improve the virus removal by UF membranes. Different cleaning regimes that are used in treatment plants had varying effects on virus removal. After maintenance cleaning, virus removal remained higher than that of clean membranes, and only chemical cleaning was effective for completely removing membrane foulants and returning virus removal back to base levels. Advanced analytical techniques were used to define the nature of the fouling layer on the membrane surface and how the foulants affected the rejection of viruses. Finally, our study showed that UF membranes are a robust treatment technology for removing different types of enteric virus surrogates from water under different operational conditions. Close monitoring of the UF unit performance and direct integrity testing can possibly detect membrane problems that can affect the rejection of viruses. Based on the virus physical characteristics and a detailed study of the membrane surface characteristics, especially the pore size distribution of the membrane, the removal of the specific virus can be closely estimated.

<!--[if !mso]> <object classid="clsid:38481807-CA0E-42D2-BF39-B33AF135CC4D" id=ieooui></object><mce:style><! st1\:*{behavior:url(#ieooui) } --> Hydrological investigations were performed in the Lubigi papyrus wetland in suburban Kampala, Uganda, impacted by human encroachment for settlement and agriculture. The first aim was to investigate the water flow variations and the dampening effect of the wetland. A second aim was to estimate the effective wetland volume and area, and relate this to the wetland function for treatment of the suburban runoff. A study site with well defined inflows and outflows was chosen, and three transects were cut through the papyrus to be able to study the water movement beneath the floating papyrus mat. Water flow measurements showed a flow dampening effect of the wetland on peak flows after rains, and the water balance revealed that the precipitation on the wetland was only 4 % of the inflow during the study. The tracer added at the inlet was rapidly detected downstream in the canal in the middle of the wetland, indicating a strong short-circuiting effect of the human made canal. At the outlet the tracer concentration was lower than the detection limit, suggesting a good mixing in the downstream part of the wetland, which was also supported by other water quality measurements in the transects. Ammonium-N concentrations at the inflow and outflow indicated a net export of ammonium-N, but the observed flow variations suggest that intensive water sampling campaigns are necessary for a proper evaluation of the water treatment function. The calculated effective volume and area amounted to 74 and 46 %, respectively, of the theoretically estimated, with a corresponding loss in the flow dampening and water treatment function of the wetland. / Rapporten är ett resultat av ett Minor Field Study stipendium finansierad av Sida.

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.