The use of dissolved air flotation (DAF) for drinking water treatment has steadily grown in popularity in Atlantic Canada for the treatment of low turbidity water supplies with high levels of algae or dissolved organic matter. Runoff from high intensity rainfall events may cause a rapid increase in turbidity and dissolved organic matter in rivers and lakes used for drinking water. A technical evaluation of a DAF water treatment plant (WTP) was conducted to determine the contributing factors to clearwell turbidity increases resulting from increased raw water turbidity and colour during intense rainfall and runoff events. The effect of chemical and operational factors on treatment of a low turbidity and colour water source as well as a high turbidity and colour water source were examined, including coagulant dose, coagulation pH, polyaluminum chloride (PACl) coagulant basicity and DAF recycle rate. In response to deteriorating water quality, it was found that increased coagulant addition inadvertently caused the loss of coagulation pH control in a full-scale DAF WTP, resulting in potentially elevated dissolved aluminum residuals entering the clearwell. This would have led to excessive aluminum hydroxide precipitation in the clearwell, and resulted in turbidity increases above the acceptable limit of 0.2 NTU. Turbidity was found to be better removed, and dissolved aluminum residuals minimized, when coagulation pH was set to the pH of minimum aluminum solubility vs. a lower pH of 6.0 during bench-scale DAF testing. A higher dose of coagulant was required to produce optimal removal of turbidity and dissolved organics at the pH of minimum solubility. The difference in bench-scale DAF treatment performance was found to be minimal when comparing sulphated PACl coagulants with 50 and 70+ % basicity. Charge analysis parameters zeta potential and streaming current were found to have a strong correlation in bench-scale testing, though the relationship between the two was affected by the coagulation pH. The results suggest that utilizing streaming current for coagulant dose control at a full-scale WTP would be best accomplished by establishing a consistent relationship between raw water quality, pH and other factors with streaming current experimentally before relying streaming current targets for dose control. Equivalent or improved DAF efficacy for solid-liquid separation was found when the recycle rate was lowered from 12 to 6 % in bench-scale tests and 12 to 8% in full-scale tests. The results suggested that maintaining an optimum air:solids ratio improved treatment performance, possibly by providing adequate bubble contact opportunities while minimizing excess shearing of the sludge blanket. The most significant finding of this research was that maintaining the coagulation pH in WTPs utilizing PACl coagulants is of utmost importance during source water quality deterioration in order to optimize treatment performance as well as prevent excess dissolved and precipitated aluminum from entering a public drinking water supply.

No description available.

The objective of this research project was to investigate the influence of the principal design and operational parameters on the quality of the filtrate from a slow sand filter. These parameters are sand effectivc size, depth of sand bed, rate of filtration, water temperature and influent quality. Attempts were then made to establish relationships between the variables employed by means of regression analyses of the experimental data. To carry out the investigation three laboratory scale filter columns were constructed each measuring 150 mm in diameter and 3010 mm height. The filtration medium in each column consisted of a 1.2 m depth of sand on a 0.3 m depth of gravel. For the three individual columns three different sand sizes were employed. These were 0.17 mm effective size (ES), 0.35 mm ES and 0.45 mm ES. Water to be filtered was abstracted from the Burleigh Brook, adjacent to the Civil Engineering laboratories. As required small amounts of settled sewage, obtained from the Loughborough Water Reclamation Works, were added to increase both the turbidity and the count of indicator bacteria. The filters were operated at five different filtration rates at three different temperatures. These temperatures were 25 degrees C, 15 degrees C, 5 degrees C and the filtration rates repeated for each temperature were 0.1, 0.2, 0.3, 0.4, 0.5 m/h. The filters were operated for not less than one month at each filtration rate. In order to assess the efficiency of the filters water samples were taken and analysed from the influent and from the filtrate and also from a series of sampling taps positioned at various depth down the sand media. These water samples were tested for total coliform bacteria, for faecal coliform bacteria, suspended solids and turbidity. Regression analyses were then carried out on the data obtained and regression models were developped for 100 mm and 1200 mm sand depths of each filter for each period. Occasional tests (i. e. at least once for each flow rate) were also carried out for nitrate and ammoniacal nitrogen, colour, pH, conductivity, total organic carbon (TOC) and dissolved oxygen. Following the completion of the filtration operation at three temperatures and five filtration rates the sands of the filtration media were also examined. Sand samples were taken for examination from 0, 50, 100, 150, 200, 300, 400, 600, 800, 1000 and 1200 mm below the sand surface of each filter. Then in order to assess both the penetration of the removed solids into the filter bed and to investigate the concentration of the biological film developed within the sand bed, sand samples were analysed for suspended solids, turbidity, standard plate count bacteria and particulate organic carbon. Regression analyses were also carried out on these data and variation of each parameter against each filter bed was modelled. The solid and biological deposits on the sand samples were also viewed with a Scanning Electron Microscope.

The thesis explores the role of Catchment Management Planning [CMP] in promoting sustainable water uses within a river catchment and develops a framework and procedures whereby CMP could be implemented in Malaysia. The study links the concepts of sustainable development and the principles underlying the sustainability of water uses, which are explicit throughout the thesis, with land use, water resources, environmental planning and management controls, using the river catchment or basin as the basis of the framework for water resource management. The mismatch between the intended uses of river water and the prevailing water quality condition of rivers arises from conflicts of interest and can be attributed to the lack of land use and water resource management and control. The thesis emphasises the essential elements of integrating the concept of sustainable development into planning and management activities, while advocating the need for a multidisciplinary and integrative approach to catchment water quality management. The thesis describes the research framework and methodologies, and analyses the concept of sustainable development, the environmental policy for Malaysia, and the land use, water resource and environmental planning and management systems within the Malaysian context. The use of GIS in this area of spatial planning has been very promising, and the thesis demonstrates the functional capabilities of GIS in the identification of pollution problems and problematic areas through water quality modelling and approaches to decision making; this forms the basis for recommended actions in the proposed plan. The plan proposals, which are based on a holistic approach towards sustainability, contain: strategies for improving river water quality through source control and minimising impacts of land use development, while sustaining beneficial river uses; components of planning decision making and implementation; the functions, recommended format and framework for the Malaysian CMP; and opportunities and needs for further research.

Activated carbons are used widely for the adsorption of environmentally unfriendly species from both liquid and gas phases, the separation of gases and adsorption of species from aqueous solution. Examples of the processes are the adsorption of Au(CN)2 and Ag(CN)2 from aqueous solution for the recovery of precious metals, the treatment of waste water containing organic chemicals and toxic metal species and the preparation of metal catalysts supported on carbon. This investigation has involved the study of the influence of porous structure and surface functional groups on the adsorption of both anionic and cationic metal species in order to understand the mechanism of adsorption of these species on active carbon from aqueous solution. Various types of oxygen functional groups were introduced onto the surface of coconut shell derived activated carbon through oxidation using nitric acid. Fourier transform infrared spectroscopy (FTIR), temperature programmed desorption (TPD) and selective neutralisation were used to characterise the surface oxygen functional groups. The oxidised carbons were also heat treated to provide a suite of carbons where the oxygen functional groups of various thermal stability were varied progressively. It was found that acidic oxygen functional groups mainly as carboxylic acid groups were incorporated into activated carbon by HNO3 oxidation. The phenol and quinone groups were also introduced by the oxidation process while the lactone groups were formed during heat treatment. The oxygen functional groups had a range of thermal stabilities with carboxylic acid groups being the least stable. A coconut shell derived active carbon was treated with ammonia and nitric acid followed by ammonia to incorporate nitrogen functional groups into the carbon. Active carbon with high nitrogen content was also prepared from nitrogen-rich precursor polyacrylonitrile (PAN). X-ray absorption near edge structure spectroscopy (XANES) and FTIR were used to investigate the structures of the nitrogen functional groups in carbons. The possible nitrogen functional groups present on carbon surface were pyridinic, pyrrolic (or indolic), pyridonic and aromatic amine-like structures. The adsorption characteristics of gold and silver cyanide anionic species on a suite of active carbons derived from coconut shell, polyacrylonitrile and chemical modification of the coconut shell carbon were investigated. The gold and silver cyanide adsorption capacities for coconut shell derived carbons correlate with total pore volume. Nitric acid oxidation treatment of the carbon was detrimental to gold adsorption in spite of the incorporation of oxygen content of carbon. The influence of nitrogen functional groups in the carbon structure on gold and silver adsorption was investigated using carbons derived from polyacrylonitrile. The addition of ethanol and butanol to the solution had an adverse effect on gold adsorption. Adsorption of silver cyanide ionic species on the active carbon was suppressed in the presence of excess free cyanide ions in solution whereas gold cyanide adsorption was not greatly affected at room temperature. The adsorption of gold cyanide was suppressed by the excess free cyanide and sodium sulphide at 70 °C. The adsorption of cadmium ions was enhanced dramatically by oxidation of the carbon. The ratio of released proton to adsorbed cadmium on oxidised carbon was approximately 2 indicating cation exchange was involved in the adsorption process. Na+ exchange studies with the oxidised carbon gave a similar ratio. After heat treatment of the oxidised carbons to remove oxygen functional groups, the ratio of H+/Cd2+ decreased significantly as well as the adsorption capacity. Both reversible and irreversible adsorption were involved in the process of cadmium adsorption with reversible adsorption having higher enthalpy. The irreversible adsorption resulted from cation exchange with carboxylic acid groups whereas the reversible adsorption probably involved physisorption of the partially hydrated cadmium ion. The nitrogen functional groups may act as ligands which can coordinate with transition metal cations. The adsorption of transition metal cations such as Cd 2+, Ni2+ and Cu2+ on active carbon was appreciably increased by the nitrogen functional groups present on carbon surface whereas ammonia treatment of the carbon showed little effect on the adsorption of alkali earth metal cation Cat+. There is little difference in the adsorption capacities of cadmium ions on coconut shell derived carbon at pH 4.1 and pH 7 whereas the adsorption of cadmium ions was significantly enhanced with increasing pH for the carbons with high nitrogen content. The nitrogen rich carbons show selectivity towards various transition metal cations reflected by adsorbing more Cu 2+ than Cd2+. This is consistent with the fact that the coordination compound of Cu 2+ with pyridine has higher stability constant than that of cadmium.

Iodine number, BET surface area, taste and odour compound isotherms, and trace capacity number tests were used to rank five different granular activated carbons according to thermodynamic adsorption performance. These tests were compared to expected activated carbon service life and loading results of rapid small-scale column tests (RSSCTs) run with water from two lake sources spiked with geosmin and 2-methylisoborneol (MIB). Trace capacity number, used to specifically identify high adsorption energy sites on activated carbon, was hypothesized to be correlated to geosmin/MIB breakthrough and loading performance of different activated carbons. This study found no such clear correlation. However, when only bituminous coal activated carbons were considered, correlations to MIB breakthrough were strengthened. Natural organic matter (NOM) adversely affected adsorption, resulting in decreased RSSCT throughput to breakthrough in surface water with higher total organic carbon (TOC). Methods for improving characterization tests and RSSCTs when NOM is present are discussed.

Iodine number, BET surface area, taste and odour compound isotherms, and trace capacity number tests were used to rank five different granular activated carbons according to thermodynamic adsorption performance. These tests were compared to expected activated carbon service life and loading results of rapid small-scale column tests (RSSCTs) run with water from two lake sources spiked with geosmin and 2-methylisoborneol (MIB). Trace capacity number, used to specifically identify high adsorption energy sites on activated carbon, was hypothesized to be correlated to geosmin/MIB breakthrough and loading performance of different activated carbons. This study found no such clear correlation. However, when only bituminous coal activated carbons were considered, correlations to MIB breakthrough were strengthened. Natural organic matter (NOM) adversely affected adsorption, resulting in decreased RSSCT throughput to breakthrough in surface water with higher total organic carbon (TOC). Methods for improving characterization tests and RSSCTs when NOM is present are discussed.

Water treatment residual solids (WTRS) were characterized and studied as a potential phosphorus (P) adsorbent for application in sewage lagoons and stormwater runoff retention ponds. Three conventional WTRS sludge types (mixed Fe(OH)3-CaCO3, mixed Al(OH)3-CaCO3, and Al(OH)3) were collected from the Saskatoon, Prince Albert, and Buffalo Pound water treatment plants (WTP), respectively. The WTRS were collected in slurry form (i.e. not dried) from WTP clarifiers. Samples were collected during the summer and fall in an effort to observe seasonal effects. WTRS characterization involved determining selected chemical parameters which included pH, ammonium oxalate-extractable aluminum and iron content, and ammonium acetate-extractable calcium content. The pH of the WTRS samples ranged from approximately 6 to 8. Saskatoon WTRS samples had Feox content in the range of 55.2-55.8 g kg-1 of dry WTRS solid. Prince Albert WTRS samples had Alox in the range of 41.8-46.7 g kg-1 of dry WTRS solid. Buffalo Pound had Alox content in the range of 56.0-67.2 g kg-1 of dry WTRS solid. Saskatoon and Prince Albert WTRS samples had Ca content ranging between 34.3-38.1 g kg-1 of dry WTRS solid due to lime softening. Typically the fall WTRS samples had higher Al, Fe, and Ca content than the summer WTRS samples. Phosphorus adsorption behaviour and the maximum adsorption capacity of the WTRS were investigated through batch adsorption and settling experiments of WTRS in P-spiked deionized water. The Langmuir isotherm model best described the P adsorption behaviour of the WTRS (R2 = 0.97-1.00 linearized transformed data). The Freundlich isotherm model had not as good a fit with R2 ranging from 0.63 to 0.87 for the WTRS. The summer WTRS samples achieved maximum adsorption capacities (Qmax) in the following order: Buffalo Pound (78.1 mg P/g solid) > Prince Albert (70.4 mg P/g solid) > Saskatoon (7.37 mg P/g solid). The fall WTRS samples resulted in similar Qmax results in the following order: Buffalo Pound (82.0 mg P/g solid) > Prince Albert (70.4 mg P/g solid) > Saskatoon (6.41 mg P/g solid). Seasonal variations appeared to have minor impact on WTRS P adsorption. Phosphorus removal from sewage lagoons and stormwater runoff retention ponds was examined through batch adsorption and settling experiments of WTRS. Municipal primary wastewater effluent from the Saskatoon wastewater treatment plant (WWTP) was used as a surrogate for lagoon effluent during spring discharge. Stormwater runoff was collected from an agricultural runoff pond outside Saskatoon. Aluminum and iron based WTRS were effective at adsorbing phosphorus from municipal primary wastewater effluent in batch adsorption treatment. WTRS dosages removed P to within 6.4% of their target final P concentrations. However, the WTRS were not effective at adsorbing P from agricultural runoff water. After remixing the settled WTRS and doubling the dosage in the agricultural runoff water the WTRS only removed approximately 20-25% P. Re-suspension and resettling of WTRS after an initial cycle of P adsorption and settling had negligible effect upon the P concentration in the water column. The WTRS had a negligible effect on the pH of the wastewater solutions at the dosed concentrations. Short term (14 days) desorption of P from the WTRS utilized in P adsorption tests was low, typically less than 2% and reaching as high as 10.6% of the total P adsorbed. WTRS were found to be an effective P adsorbent from municipal primary wastewater effluent. The WTRS had high adsorption capacities compared to other WTRS and P adsorbents in the literature. The high adsorption capacities of the Al-based WTRS make them more practical than Fe-based WTRS for application.

Thesis (M.S.)--Virginia Polytechnic Institute, 1942. / Includes bibliographical references (leaves 47-49). Also available via the Internet.

Thesis (M.S.)--University of Alabama at Birmingham, 2010. / Title from PDF t.p. (viewed July 19, 2010). Includes bibliographical references (p. 35-37).