The development of nanostructured materials for environmental applications has received considerable attention in recent years. The properties of nanoparticles or nanostructured materials, such as large surface areas or high aspect ratios, translate into large improvements in the performance of existing devices and in the discovery of novel applications. On the other hand, photocatalysis is an attractive technology for the elimination of organic pollutants in water due to its simplicity, ease of implementation and reasonable cost compared to other advanced oxidation processes. A key disadvantage of many photocatalysts is their use in powder form which makes their recovery from treated water costly. In addition, incomplete removal can lead to accumulation over time with adverse effects to the environment. As a result significant effort has been placed in immobilizing photocatalytic materials on different substrates. The immobilization of photocatalyst results in a decrease in photocatalytic performance mainly due to reduction of surface area; therefore, research is now focusing on developing nanostructured materials which combine the attributes of nanotechnology and photocatalysis. In the present thesis, a systematic study of the relationship between properties of supported ZnO nanostructures and their photocatalytic activity was performed. Analysis was carried out by producing ZnO nanostructured films via anodization. The effects of voltage, temperature, reaction time and type of electrolyte on the morphology of ZnO nanostructures was studied. Results show that the type of electrolyte and its concentration determine the morphology and size of the nanostructures. Voltage, time and temperature affect the distribution and density of the nanostructures along the surface and affect the crystal size of the ZnO. The band gaps of the films were in the range of 3.27 and 3.50 eV. Although ZnO is a hydrophilic material, some of the films displayed hydrophobic and super-hydrophobic behaviour. The results obtained in this study and some data already published in the literature were correlated to the synthesis parameters, and were used to devise design guidelines to obtain ZnO films with specific nanostructures and macroscopic properties by controlling the anodization parameters. The photocatalytic activity of the ZnO nanostructured films (ZnO-NFs) were studied using three different photocatalytic reactors, (i) a thermo-stated batch reactor, (ii) a recirculating flat plate reactor, and (iii) a recirculating tubular annular reactor. Phenol and methyl orange (MO) were used as a model compounds. It was found that crystal size does not affect the photocatalytic performance of the films while morphology has an important impact on the degradation of phenol. The stability of the ZnO nanostructures was tested under different levels of oxygen, degradation of phenol occurred even at anoxic conditions following the Mars-van Krevelen mechanism. The formation of new nanostructures produced during the photocatalytic reaction was studied and a mechanism of formation was proposed. The study of the photocatalytic performance in the flat plate reactor showed that there was a mass transfer limitation in the process. ZnO nanostructures showed higher photocatalytic activity and morphology stability in the tubular annular reactor. Degradation of MO and phenol was produced in darkness by the nanostructures supported in Zn foil. It was also demonstrated that oxygen plasma post-treatment enhances the photocatalytic activity of the ZnO-NF by 36% while making the photocatalyst more stable for the photocatalytic degradation of phenol compared to those treated with heat. An electrical current was applied to the photocatalyst in the tubular annular reactor, which improved the degradation of phenol and participated in the formation of nanostructures in the Zn wire surface.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1976. / Also available via the Internet.

Increasingly stringent water quality regulations concerning microbiological parameters govern the use of groundwater resources that are vulnerable to mixing with surface waters. These drinking water sources are at higher risk for infiltration by pathogenic microorganisms, including the oocysts of the human enteroparasite Cryptosporidium spp. Cryptosporidium can cause severe gastroenteritis in humans, and the characteristics of Cryptosporidium oocysts, including low infectious dose, high resistance to inactivation, and long survival in the environment pose a significant risk to public health if present in treated drinking water. Bacillus subtilis is widely used as a surrogate for biocolloid transport in saturated porous media, and recognized as a conservative indicator for the transport of Cryptosporidium parvum oocysts during filtration. However, no study has directly compared the transport of spores from different strains within the Bacillus subtilis species. Strain variability has the potential to impact retention in porous media based on differences in size and electrophoretic mobility. The transport behaviour of four strains of Bacillus subtilis (wild-type and laboratory type, subspecies subtilis and subspecies spizizenii; 1.9 to 2.9µm diameter) is contrasted in this research to two sizes of fluorescent polystyrene microspheres (1.1µm and 4.5µm diameter) through packed saturated crushed quartz sand. A peristaltic pump was used to introduce (bio)colloids into the duplicate column apparatus at a loading rate of 0.1m/day. (Bio)colloid removal was assessed and compared by constructing breakthrough curves of normalized concentrations and box-and-whisker diagrams of percent removal of Bacillus subtilis strains. Under unfavourable conditions minimal reduction (<0.22log10) in effluent spore concentration was observed over the column depth of 15cm. In favourable attachment conditions up to 0.69 log10 reduction was observed but the sampling schedule employed was insufficient to clearly identify a pseudo steady-state plateau. An analysis of variance was used to determine the statistical significance of spore strain, subspecies, and type. A significant difference between the four strains was observed at the lower ionic strength, with spore subspecies and type affecting spore removal in unfavourable conditions (p < 0.05). Some sensitivity to settling and laboratory storage suggests that standardized sample handling procedures are required. Differences observed here between the strains of Bacillus subtilis spores indicate that riverbank filtration performance assessments and drinking water treatment plant process demonstrations may benefit from a recommended strain for use.

TThe objective of the current study was to investigate the backwashing behavior of granular media filters used in water treatment under realistic conditions and to develop better models of the backwash process based on both fundamental and practical considerations. The focus of this study was on water only backwash but the applicability of the results to auxiliary backwash systems is discussed. The effects of filter backwash rate, coagulant used, degree of filter clogging and age of filter deposits on backwash behavior and efficiency were investigated in a pilot scale in-line filtration plant treating low turbidity raw water from a large dam. The results of these experiments and their implications both for modeling and managing filter backwash are discussed. The initial stages of backwashing are shown to be dominated by mixing and flow localization effects not accounted for in existing models of backwash. These effects appear to be dependent on both the equipment and the experimental conditions making the development of an accurate model of transient backwash behavior extremely difficult. However, it is shown that the overall efficiency of backwash can be predicted based on data about the filter and backwash design and operation that should be available at any treatment plant. This is an important first step in the development of modeling tool for the design and optimization of the complete filter cycle. A significant finding of this study was that the average age of filter deposits is one of the most important factors determining the ease with which they are detached during backwashing. Deposits become more difficult to remove the longer they remain in the filter. This has important implications for the robust design and operation of filters in applications where optimal backwash cannot be guaranteed. The rate of accumulation of mud in a filter over multiple filter cycles was determined experimentally for one set of backwash conditions and a procedure for estimating the useful life of a filter bed with sub-optimal backwash is proposed.

It is a common problem that the cooling water loop in an HVAC or refrigeration plant is suffering from scaling, corrosion, and bacteria attacks, especially in an open-loop designs. The reason is that, through the open water loop, various kinds of contaminants were trapped and migrated along the water flow, causing condenser scaling, which in turn, leading to its poor thermal performances. The experiment conducted in this study revealed that each condenser temperature increase of 1 ¢J, accounts for a COP decrease of 2.4% to 2.8%.Serious scaling problem might even lead to system malfunction, and hazardous environmental problems. Conventionally, water-treatment in the condenser cooling water loop can be categorized into two parts, namely, the chemical and the physical methods. The chemical treatment is mainly performed by injecting chemicals, mostly acids, into the water loop so that it can circulate through the system and causing scales to peer off from the condenser tubes. In response to the cry of environmental protection, physical treatment has become increasingly important, which utilizes magnetic forces as the primary working principle. The main theme of this study is to validate this principle by full-scale experiments. The Zeta Rod system has been developed under the DLVO theory, with significant performance and is environmentally friendly. Experimental investigation has been performed in comparing the temperature differentials across a condenser, before and after the treatment. The result validated that it has increased from 3.9¢J to 4.2¢J and enhanced the thermal performances of the condenser accordingly.

Without water, as is known, there is no life. A person uses about 75 tons of water for the whole life. Thereby, about 80% of diseases come with water people drink because it is simply dirty, according to Louis Pasteur. The fact is that consuming tap water leads to 85 known diseases that result in twenty-five million deaths each year. In addition, dirty water consumption accelerates the aging process by 30%. Tap water is drinkable, but not necessarily beneficial. The fact that the dirty water flows out of the tap means that the water contains a large quantity of chemical and mechanical impurities as well as a variety of viruses and bacteria. For example, if a person drinks water with high content of iron for a long time, the possibility of getting liver disease is high. The tap water quality that has always been consumed by people from Zhezkazgan, Republic of Kazakhstan violates even the required standards for tap water. Therefore, any kind of water business is encouraged in that area. The most viable way to help this problem is bottled water production. The great number of papers and materials was used, analyzed and delivered in this report. In addition, a Russian company, Ecodar LLP, was contacted to acquire information about the most advanced technology in water treatment field. This report provides general description of water treatment technology to start a bottled water production business in Zhezkazgan / text

No description available.

Using Environmental Protection Agency occurrence and concentration data, it is estimated that about 6 million pounds of arsenic-bearing residuals (ABSR) will be generated annually in the United States when full compliance with the new standard for arsenic in drinking water (10 μg/L) is realized. Effective management of disposal of ABSR requires both a full characterization of the materials and an understanding of the environment in which the disposal will occur. Currently, there are different testing methods to evaluate the stability of ABSR, the principal of which is the EPA Toxicity Characteristics Leaching Procedure (TCLP). These tests indicate that common ABSRs may be disposed in mixed-solid waste landfills. However, this and previous work shows that these testing methods may significantly underestimate the degree and mechanism of arsenic mobilization from the residuals, because critical physical and chemical dissimilarities exist between the tests and landfill conditions. In addition, no current testing methods simulate the mineralogic aging in those ABSR, which exhibit further complexity. Landfill disposal involves liquid and solid residence times on the order of months and decades, respectively, whereas leaching tests are completed in two days or less. Consequently, time dependent re-mineralization of residuals that would be routinely expected in landfill time scales is not addressed by standard leaching tests. Treating arsenic brines by co-precipitation with iron oxyhydroxides is an established and effective remediation method for small quantities of highly concentrated liquid arsenic waste, such as brines derived from mine tailings, ion exchange resin regeneration, and reverse osmosis treatment of drinking water. However, amorphous ferric hydroxide (AFH) is expected to exhibit mineralogical aging analogous to the observed natural evolution of ferrihydrite to goethite and hematite. The aim of this research is to develop methods for characterization of AFH sludges precipitated from concentrated arsenic brines which exhibit mineralogical aging and to evaluate the impact of such aging on arsenic leachability. Overall, aging the sludge resulted in consistently higher arsenic release.

Increasingly stringent water quality regulations concerning microbiological parameters govern the use of groundwater resources that are vulnerable to mixing with surface waters. These drinking water sources are at higher risk for infiltration by pathogenic microorganisms, including the oocysts of the human enteroparasite Cryptosporidium spp. Cryptosporidium can cause severe gastroenteritis in humans, and the characteristics of Cryptosporidium oocysts, including low infectious dose, high resistance to inactivation, and long survival in the environment pose a significant risk to public health if present in treated drinking water. Bacillus subtilis is widely used as a surrogate for biocolloid transport in saturated porous media, and recognized as a conservative indicator for the transport of Cryptosporidium parvum oocysts during filtration. However, no study has directly compared the transport of spores from different strains within the Bacillus subtilis species. Strain variability has the potential to impact retention in porous media based on differences in size and electrophoretic mobility. The transport behaviour of four strains of Bacillus subtilis (wild-type and laboratory type, subspecies subtilis and subspecies spizizenii; 1.9 to 2.9µm diameter) is contrasted in this research to two sizes of fluorescent polystyrene microspheres (1.1µm and 4.5µm diameter) through packed saturated crushed quartz sand. A peristaltic pump was used to introduce (bio)colloids into the duplicate column apparatus at a loading rate of 0.1m/day. (Bio)colloid removal was assessed and compared by constructing breakthrough curves of normalized concentrations and box-and-whisker diagrams of percent removal of Bacillus subtilis strains. Under unfavourable conditions minimal reduction (<0.22log10) in effluent spore concentration was observed over the column depth of 15cm. In favourable attachment conditions up to 0.69 log10 reduction was observed but the sampling schedule employed was insufficient to clearly identify a pseudo steady-state plateau. An analysis of variance was used to determine the statistical significance of spore strain, subspecies, and type. A significant difference between the four strains was observed at the lower ionic strength, with spore subspecies and type affecting spore removal in unfavourable conditions (p < 0.05). Some sensitivity to settling and laboratory storage suggests that standardized sample handling procedures are required. Differences observed here between the strains of Bacillus subtilis spores indicate that riverbank filtration performance assessments and drinking water treatment plant process demonstrations may benefit from a recommended strain for use.

Nitrate, arsenic and vanadium are all potential groundwater contaminants. Traditional physical/chemical methodologies are often too technical or expensive for rural environments. Biofiltration has been shown to remove a wide range of contaminants depending on the operating parameters. This research examined the possibility of using the denitrifying bacteria, Paracoccus denitrificans, to remove nitrate, arsenic and vanadium simultaneously from groundwater with varying iron concentrations. During bench-scale testing nitrate concentrations were reduced by up to 73%, even with the metals present. Without iron, arsenic and vanadium removal was insignificant. Removal increased when iron was added as it was found that arsenic and vanadium could be removed adsorptively by iron hydroxides. With 1 mg/L of iron present, removal rates of 67% and 91% were achieved for arsenic and vanadium, respectively. When the iron was increased to 2 mg/L, the removal rates increased to 85% and 96%, respectively.