Back grinding (BG) wastewater consists mainly of high-purity water and high concentrations of inorganic particles. If the BG wastewater could be treated and recycled efficiently, it should be sort of economic benefit. In this study, appropriate pre-treatment technologies are evaluated to obtain the feasible recycle system. From the chemical coagulation experiment, the addition of PAC or FeCl3, both of them can obviously reduce the turbidity and suspended solid concentrations (SS). In addition, polymer can advance the sedimentation process. Considering the cost of practical operation, the turbidity of BG waste water could be removed up to 97% by using polyaluminum chloride as the coagulant (2.2 mg/L) and polymer as the coagulant aid (0.5 mg/L) in the pH=7 condition . In sand filtration experiment, the turbidity and SS can¡¦t be effectively removed if the coagulation isn¡¦t used on BG wastewater. It demonstrates that BG wastewater contains high concentration of nano-scale particles. The rate of removable turbidity can reach 99% under applying coagulation, sedimentation, and sand filtration. In ultra-filtration experiment, both of spiral-wound (SW) and hollow-fiber (HF) can remove more than 99.9% of turbidity. For the flux of behavior, the performance of pre-treatment water is better than non-treatment water. Thus, it reveals that appropriate pre-treatment can lower the load of membrane filtration system. For the obtained recycle water, the grade of standard can achieve the grade of the cooling tower required. However, due to its high particle-containing characteristics, the commonly used reverse-osmoses (RO) membrane filtration technology can not be directly applied for purification process because the fouling/clogging problem would cause the frequent membrane replacement. In this lab-scale feasibility study, pre-treatment technologies (e.g., sand filtration, chemical coagulation, ultra-filtration) were applied to reduce the turbidity and particle concentrations of the BG wastewater (collected from a semiconductor manufacturing plant) before RO filtration unit. The BG wastewater contained turbidity and suspended solid concentrations of 3,200 NTU and 96 mg/L, respectively. The measured pH and conductivity of the BG wastewater were in the ranges of 6.8 to 7.2 and 14 to 18 £gS/cm, respectively. Moreover, the particle sizes of the solids varied from 300 to 700 nm. Thus, applying conventional sand filtration along could not effectively remove the nano-scale particles. Results from the chemical coagulation experiment reveal that the turbidity and particles of the BG wastewater could be significantly removed (up to 95% of turbidity and particle removal) by the coagulation/sedimentation process using polyaluminum chloride as the coagulant (2.2 mg/L) and polymer as the coagulant aid (0.5 mg/L). Results also indicate that up to 99% of turbidity and particle removal could be obtained with the application of ultra-filtration unit after the coagulation/sedimentation process. Results from this study indicate that applying appropriate pre-treatment technologies (coagulation and ultra-filtration) would lower the fouling rate and extend the life of RO membrane used for BG wastewater purification.

Thesis (Ph.D.)--Murdoch University, 2008. / Thesis submitted to the Faculty of Sustainability, Environmental and Life Sciences. Includes bibliographical references (leaves 118-134)

Eradicating poverty, malnutrition, and the burden of disease have been included as three of the major issues facing the world. The United Nation member countries, having set forth the Millennium Development Goals, have committed themselves to solving these problems. Two major factors which affect solutions to these problems are increasing water stress and implementing improved sanitation. Integration of tilapia aquaculture and reuse of wastewater has been suggested as a solution which addresses both of these factors. The objective of this study is to examine the feasibility, and explore the benefits and drawbacks, to implementing small community wastewater fed (WWF) aquaculture systems in the developing world. The water quality characteristics of treated effluent from nine wastewater treatment (WWT) plants were compiled from other studies. The concentration of total nitrogen in the effluent and the flow rate were of most importance, as they were used to calculate the nitrogen loading at each WWT plant. The nitrogen loading was then used to estimate the total pond size which could be supported by each WWT plant, the expected yearly yield for tilapia, and the percentage of the population who would benefit from provision of protein associated with the integration a fish farming system with the WWT plant. Results show that WWF, semi-intensive tilapia culture can provide 10 grams per day of dietary protein for 11% - 52% of the population of the communities in this study when integrated with a community managed wastewater treatment system. To assess potential risks to human health, associated with WWF aquaculture, the level of fecal coliform (FC) contamination was compared to the standard set by the World Health Organization; less than 105 FC per 100 mL for reuse in fish ponds. The level of FC contamination in the WWT plant effluents ranged from 653 to 1.78 × 105 FC per 100 mL, exceeding this standard. Given the context, the level of fecal coliforms should not rule out integrated reuse and aquaculture as an option. The nutrients found in wastewater are valuable resources in tilapia culture; therefore, allowing their persistence through treatment for reuse, while optimizing wastewater treatment technologies for pathogen removal is an appropriate solution for small communities in developing countries for reducing poverty, malnutrition, and disease burden of waterborne illnesses.

Soil-aquifer treatment (SAT) has been proposed as a method for reusing treated municipal wastewater. SAT is characterized by alternating cycles of aerobic and anaerobic conditions in the subsurface, in response to alternating cycles of flooding and drainage of a surface impoundment. It is not yet known how these alternating redox conditions affect the removal of potentially harmful endocrine-disrupting compounds (EDCs) from treated effluent. The overall objective of my doctoral research is to determine the fate of EDCs in alternating aerobic/anoxic/anaerobic conditions under simulated SAT conditions. To assess the fate of EDCs in simulated SAT conditions, I first had to develop appropriate analytical methods. Prior researchers have developed sophisticated analytical methods for measuring low concentrations of EDCs in water. However, it is not inherently clear which of these methods is preferable for analysis of any particular set of environmental samples. Therefore, in order to compare the analytical methods, solid-phase extraction (SPE) and solid-phase micro-extraction (SPME) were compared for the analysis of two EDCs, bisphenol-A (BPA) and 17B-estradiol (E2), in water samples of water. Following extraction by SPE or SPME, the target EDCs were derivatized (silylated) and then analyzed by gas chromatography (GC) with mass spectrometry (MS). Also, the performance of two candidate derivatization agents, N,O-bis-(trimethylsiyl) trifluoroacetamide (BSTFA), N-methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA), was compared. SPME is more convenient, is less labor-intensive, and allows for analysis of smaller sample volumes, but it is expensive because fibers need frequent replacement, and the range of linearity was limited. SPE has a lower material cost and allows for the analysis of a broader range of concentrations, but it is more labor-intensive and large sample volumes may be required. Therefore, the selection of which method is "best" depends upon the constraints (time, money, sample volume, acceptable detection limit) associated with any particular set of samples. The two derivatization agents performed equally when used in conjunction with SPE, but MSFTA yielded higher peak areas for headspace (on-fiber) derivatization during SPME. To investigate how alternating redox conditions of SAT may affect the removal of harmful EDCs, a simulated SAT systems were constructed in 4-L reactors with 500 g of sediment (collected from a wetland) and 3 L of treated effluent from a municipal wastewater treatment plant; then BPA and E2 were spiked into reactors, two common EDCs often found in treated wastewater. Redox conditions in the mesocosms were controlled by switching the air between air (to induce aerobic conditions) and nitrogen (to induce anaerobic conditions); the length of the anoxic/anaerobic cycles was varied to determine how this affects biodegradation of the target EDCs. The mesocosm environment was supplemented with either nitrate or sulfate to serve as potential electron acceptors during the anoxic/anaerobic cycles. In addition to monitoring the concentrations of the target EDCs in the mesocosms over time, I also monitored the concentration of dissolved oxygen in the water; the redox potential; the concentrations of nitrate, nitrite, and sulfate; and the concentration of bacteria in the water (estimated via flow cytometry). BPA was biodegraded only during aerobic cycles, but E2 was biodegraded during both aerobic and anoxic/anaerobic cycles. Whenever the redox conditions in the system were switched, there was a temporary drop in the bacterial population, followed by a recovery of the population. When redox conditions were switched from anoxic/anaerobic to aerobic, biodegradation of the target EDCs commenced after a lag period during which no biodegradation was observed. The lag time for biodegradation in the aerobic cycle was longer when the anaerobic cycles were longer in duration. More biodegradation of E2 was observed under anoxic conditions than under anaerobic conditions. SPE and SPME methods that included derivatization agent are useful method for detection and quantification of EDCs in water. I concluded that SAT is a viable technology to produce potable water from treated WWTP effluent, but the optimal length of flooding and drying cycles of SAT required removing the targeted contaminants during infiltration through the vadose zone.

As water stresses increase across the U.S., interest in household water reuse is growing. Such reuse typically focuses on light greywater, that is all wastewater generated in the house excluding toilet waste and kitchen wastewater. As this practice becomes more widespread, higher level reuse is expected to require greater greywater treatment prior to reuse. Membrane bioreactors (MBRs) are an attractive technology for this application because they offer a robust combination of treatment processes and are already used in some households in countries such as Japan. This research sought to understand the role of phosphorus availability in determining the quality of effluent from MBR treatment of light greywater because phosphorus concentrations are expected to be low with phosphorus phased out of many consumer products. Less than 30 [mu]g/L of dissolved orthophosphate was present in synthetic greywater made from three common household products, and no measurable amount of dissolved orthophosphate was found in real greywater, but low concentrations of particulate phosphate were detected. These concentrations were well below levels believed necessary to achieve full BOD₅ removal in biological treatment. Nevertheless, MBR performance was not adversely affected until no supplemental phosphorus was provided. Measurement of extracellular enzyme activity showed an increase in the ratio of phosphatase activity to total glycosidase activity with declining phosphorus concentration, providing an early indication of nutrient stress before changes in effluent water quality were detected. Removal of three xenobiotic organic compounds (XOCs) in treatment of synthetic greywater was also evaluated under conditions of phosphorous limitation and balance. Abiotic removal mechanisms were not deemed to be important, but removal of methylparaben and sodium lauryl sulfate via biodegradation responded to nutrient limitation similarly to overall COD removal while removal of diethyl phthalate was affected to a greater extent. Measurement of plasmid DNA concentrations was evaluated as a potential indicator of the effect of nutrient limitation on plasmid-mediated biodegradation of XOCs. An overall reduction in the plasmid content was observed in all cases under conditions of phosphorus limitation; however, the extent of reduction was reactor dependent. / text

This work is part of a broader, multi-year investigation of Maui Island’s freshwater resources. Maui Island faces multiple resource constraints, including water, land, energy, and capital, and these resource constraints could become relevant over the next forty years. Not only does Maui face potential changes to its water and other systems due to external factors beyond its control, like anthropogenic and other climate changes, but Maui also could make developmental choices that will impact how its resource systems interact. In particular, this work looks at Maui’s freshwater systems as they relate to energy, waste, and environmental systems. This report provides a foundation for future scenario analysis on the island that will aim to characterize potential synergies and hazards of choices like increased food production, local fuel production, and increased use of renewable energies. / text

To protect public health, detection and treatment technologies have been improved to monitor and inactivate pathogens in drinking water. The goal of this dissertation is to evaluate and utilize multiple online sensors and advanced oxidation processes to document both the detection as well as destruction of microbial contaminants in real-time. Reviews of rapid detection technologies for real-time monitoring of pathogens in drinking water and advanced technologies to inactivate pathogens in water are shown in Appendices A and B. The study in Appendix C evaluated the efficacy of real-time sensors for the detection of microbial contaminants. Bacillus thuringiensis was used in this research as a surrogate for Bacillus anthracis to determine each sensor response and detection capability. The minimum threshold responses of sensors were determined by injecting B.thuringiensis into deionized (DI), raw (unfiltered) tap water, or filtered tap water over a concentration range of 10² - 10⁵ spores/ml. The BioSentry sensor responded to increases in concentration over the range of 10² - 10⁵ spores/ml. Below this range, sensors provided signals undistinguishable from background noise. The select sensors can detect microbial water quality changes, and these advanced technologies can be integrated to monitor intrusion events in water distribution systems. The study in Appendix D evaluated the efficiency of the UV reactor for inactivation of MS2 coliphage. The virus MS2 coliphage (ATCC 15597-B1) has been proposed by the U.S. Environmental Protection Agency as a standard for UV reactor validation in the United States. In addition, MS2 is used as a surrogate for enteric viruses due to its similar size and morphology. Following UV radiation at a flow rate of 2gpm, infective MS2 showed a reduction of 5.3- log₁₀ when quantified with cultural plaque counts, whereas corresponding quantitative polymerase chain reaction (qPCR) data showed only a 1.7- log₁₀ reduction in viral RNA copy number. In contrast, plaque assay revealed a 5.8- log₁₀ inactivation; a slight increase in infective MS2 coliphage reduction at 1 gal per min but qPCR results indicate a 2.8- log₁₀ reduction in viral RNA copy number; a one log more inactivation compared to 2 gpm. When H₂O₂ was added at either 2.5 or 5 mg/l with UV at either flow rate, enhanced MS2 inactivation occurred with a greater than 7 log₁₀ reduction observed via plaque counts, indicating that all added MS2 had been inactivated, since no plaques were formed after incubation at 37°C for 24 hours. Correspondingly, qPCR data only showed a 3-4 log₁₀ reduction in viral RNA copy number. The study in Appendix E utilized online sensor to document the destruction of E.coli and Bacillus thuringiensis spores by UV/H₂O₂ treatment. In this study, Escherichia coli was tested for potential UV/H2O2 treatment in DI water and online sensors were also integrated to monitor the destruction in real-time. Pilot-scale experiments were performed using a Trojan UVSwift SC reactor (Trojan Technologies, London, ON, Canada) at a flow rate of 1 gal./min (gpm). UV radiation and UV/H₂O₂ combination in E.coli cell suspensions resulted in a >6 log₁₀ reduction of the viable counts. Similar exposure to B.thuringiensis spores resulted in a 3 log₁₀ reduction in viable counts. Scanning electron microscopy of the treated samples revealed severe damage on the surface of most E.coli cells, yet there was no significant change observed in the morphology of the B. thuringiensis spores. Following UV/H₂O₂ exposure, the BioSentry sensor showed an increase in the unknown, rod and spores counts, and did not correspond well when compared to viable counts assays. Data from this study show that advanced oxidation processes effectively inactivate E. coli vegetative cells, but not B.thuringiensis spores which were more resistant to UV/H₂O₂.

This work explores the hydraulic performance of a wastewater lagoon system located in San Antonio, Bolivia. The system consists of one facultative pond and two maturation ponds in series and is managed through a locally elected water committee. A tracer study was performed on the primary facultative pond and an analysis of the solids accumulation on the bottom of the facultative lagoon was also performed. The results were used to generate residence time distribution curves and provide an estimate of mean residence time in the system. The data was used to examine hydraulic efficiency as it relates to short-circuiting and dead zones. A sludge study accumulation study was performed using the white towel method and the resulting measurements were interpolated to determine a total estimated sludge volume of 169 m3 (which is 8% of the facultative pond volume). An orange study was also performed to assess the surface flow pattern in the system. The results were compared with a computational 2-d model. The 2-d model incorporated the estimated sludge distribution and provided a good fit for the tracer dye concentrations measured in the field over the 12 day study period. Simple models such as the Tanks in Series and the Completely mixed model were evaluated and abandoned because of their inability to model the physical behavior in the system. The Completely mixed model did however perform better than the Plug flow model. After comparing the tracer results from the reactor models that were considered: Tanks in Series, Completely mixed fluid, manual interpolation and the results from the 2-d cfd flow simulation, the results that provided the best fit for the data over 12 days was the manual interpolation method at a flow rate of 98 m3/day and configuration D at 60 m3/day. However, because of uncertainty as to what depth to obtain a representative area for the 2-d simplification and sensitivity to flow; all four configurations were considered for estimating the MHRT at the lowest measured flow rate of 60 m3/day. The results at a flow rate of 60 m3/day varied between 10.88 and 13.04 days for the MHRT with a hydraulic efficiency that varied between 33-51.6% (accounting for sludge volume). This is much shorter than the actual nominal retention time of 37 days and the design nominal retention time of 26 days. As a result it was concluded that short-circuiting was occurring in the facultative lagoon.

The ubiquity of pharmaceuticals and personal care products in water systems is well known. With the increasing implementation of water reuse schemes in the US, concern about potential health effects of these compounds in humans has risen. While potential synergistic effects of chronic low doses exposure to a cocktail of these compounds is still being studied, it is prudent to monitor and attenuate these trace organic compounds (TOrCs) from our water sources. This research initially focused on identifying suitable `indicator' TOrCs based on theoretical physico-chemical parameters and actual experimental data. It was concluded that an indicator list will be specific to the goal targeted with dependence on treatment process, occurrence and analytical ease. Quantification of these TOrCs are part per trillion levels in water requires accurate, precise and robust analytical techniques. The next part of this research was spent on developing three different analytical methods with LC-MS/MS for the sensitive detection of TOrCs in several different water matrices including raw sewage and final drinking water. The treatment efficacy of granular activated carbon for attenuation of TOrCs is studied in detail with emphasis on developing correlations between TOrC removal and bulk organic parameters of water like UV absorbance and fluorescence by using rapid small-scale column testing. The results indicate a correlation between removal of TOrCs and bulk organic parameters that is independent of water quality. The effectiveness of commercially available activated carbon based point-of-use (POU) devices for removal of a set of TOrCs from water was evaluated. The data indicated that POUs are a viable option for treatment of TOrCs but specific removal depends on type of device, water quality and amount of water treated. Finally, further research was targeted at identifying transformation products as a result of oxidation of polyfluorinated precursor materials in reclaimed waters. The results illustrated that toxic perfluorocarboxylic acids can be formed on oxidation of fluorotelomer unsaturated carboxylic acids that are known to be present in water.

Grey water reuse has attracted more and more attention among researchers and professionals in recent years. As most of the Chinese cities are undergoing the process of fast urbanization and economic development, many water-related problems have occurred and urban water resources management has become a strategic issue. The urge to reconsider the conventional ways of utilizing water and discharging the wastewater in cities is calling. As a relatively simple and flexible way, decentralized grey water reuse system can help to make the first step in achieving a sustainable urban water management. However, whether it is feasible in China is still a question. This paper aims at looking for the answer based on a survey and interviews with professionals in the fields from different Chinese cities. The result shows “reuse” as one of the solutions of solving water shortage and achieving sustainable water management is not as simple as one may think. In general, decentralized urban grey water / wastewater reuse is not easy to flourish in China in the near future though most of the respondents hold a positive attitude about reuse itself. To explain this difference between attitude and actual planning we need more historical, political and social-economic understanding with a touch of “Chinese characteristics”.