Dissertations / Theses on the topic 'Water purification research'

Water stress is an ongoing problem in many places in the world, while the demand for clean and safe freshwater is growing due to the increasing population. In many developing countries, water supplies often are contaminated with arsenic, fluoride, etc. Therefore, it is important to realize that water scarcity and contamination issues concern only one sector but many. HVR Water Purification AB is developing a water purification prototype – ELIXIR 500 - using the air gap membrane technology and is implemented in Odisha, India, aiming to supply with 200 litre water daily. This thesis aims to estimate future energy sources to supply this prototype and explore the possibilities of using only renewable energy resources from technical, economic, and environmental perspectives. These are achieved by firstly identifying the energy possibilities in Odisha, India, and then calculating the feasibility of each solution chosen and finally analyzing the results. Among the energy sources, which are power grid, wind and solar power, diesel generator and solar-diesel hybrid system. It is found that the energy source to the prototype supplied by the power grid is 0.057 USD per litre water, which is the cheapest option. However, it is not feasible due to the lack of electrification from the local network. Meanwhile, the solar-diesel hybridized energy system is the most economical option if renewable energy sources are integrated with 0.11 USD per litre water.<br>Vattenstress ett pågående problem på många ställen i världen medan efterfrågan på rent och säkert dricksvatten växer på grund av den ökande befolkningen. I många utvecklingsländer är vattenförsörjningen ofta förorenade med arsenik, fluor osv. Det är därför viktigt att inse att vattenbrist och föroreningar inte bara rör en sektor utan många. HVR Water Purification AB utvecklade en prototyp för vattenrening - ELIXIR 500 - med hjälp av luftspaltmembrantekniken (eng: air gap membrane distillation och implementeras redan i Odisha, Indien, med målet att förse 200 liter rent vatten dagligt. Denna avhandling syftar till att uppskatta de framtida energikällorna för att tillhandahålla denna prototyp och utforska möjligheterna att endast använda förnybara energikällor ur tekniska, ekonomiska och miljömässiga perspektiv. Dessa uppnås genom att först identifiera de olika energimöjligheter i Odisha, Indien, följt av beräkningar om utförbarhet för varje vald lösning och slutligen en analys av resultaten. Bland energikällorna elnät, vind, sol, diesel generator och sol-diesel hybrid system har visat sig att energikällan till prototypen som levereras av elnätet som kostar 0.057 USD per liter vatten som det billigaste alternativet, men det är inte möjligt på grund av bristen på elektrifiering från det lokala elnätet. Å andra sidan är det hybridiserade energiskombinationen med solkrafts och diesel det billigaste alternativet om förnybara energikällor ska integreras, resultatet visade att vara 0.11 USD per liter vatten.

This study was undertaken to examine the feasibilty of a low-cost aerobic system to treat greywater for reuse.Its purpose was to provide a system that would be easy to maintain, flexible and be affordable for households and small communities in developing countries. This thesis outlines and evaluates the key biological and chemical hazards associated with greywater reuse. It discusses the performance of a variety of wastewater treatment options in use. It presents details of the components of the greywater system,namely, an aerobic grease trap and slow sand filter. Reference is made to the evaporation and treatment bed and ultraviolet disinfection components, but these are not examined. The incorporation of vermitechnology in the preliminary stages of the system for reduction of organics in greywater is reviewed. This study takes the traditional approach to water quality assessment with the measurement of physical, chemical and biological indicators. Assessment of the system involved examining the input characteristics of the greywater, monitoring the vermiculture system and sampling the liquid discharge from the aerobic grease trap and slow sand filter for analysis of the quality indicators. The results obtained under the framework of this study have provided recommendations for further use of the aerobic grease trap and slow sand filter, while propsing an approach for an appropriate long-term monitoring program.<br>Master of Engineering (Hons)

In anticipation of government mandates regulating the quantity of the toxic mutagen, 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone, which can be released into potable waters or from industrial facilities, technologies for monitoring the concentration, reducing the quantity, and inhibiting the formation of this compound were investigated. Adsorption of the chlorinated hydroxyfuranone from laboratory systems (pH 7.2, 22°) utilizing the non-polar, polymeric resin, Amberlite XAD-4, was successful. As these system conditions are comparable to those present in drinking water treatment facilities, application of this resin to such systems should be investigated. However, typical concentrations of the chlorinated mutagen released from such facilities are some 100 times less then those employed in laboratory experiments. As such, highly sensitive analytical technology, such as fluorescent spectroscopy, would be required for direct detection of the mutagen in these aqueous systems. Since development of a fluorescent adduct of the mutagen, through either Schiff's base or halogen replacement reactions, failed, application of the adsorption methodology was not investigated. Approaching the problem in a different manner lead to ° investigations aimed at reducing the formation of the mutagenic compound. Since the mutagen is formed upon chlorination of waters containing lignin derived materials, lignification in intact growing plants, and the effects of modified substrates on this process, were investigated. All modified substrates tested increased the uptake of a C¹⁴ labelled lignin precursor into the lignin containing fraction of a living poplar stem. Research continues in this area to determine through what mechanism these compounds are affecting lignification.<br>Master of Science<br>incomplete_metadata

This study was undertaken to examine the feasibilty of a low-cost aerobic system to treat greywater for reuse.Its purpose was to provide a system that would be easy to maintain, flexible and be affordable for households and small communities in developing countries. This thesis outlines and evaluates the key biological and chemical hazards associated with greywater reuse. It discusses the performance of a variety of wastewater treatment options in use. It presents details of the components of the greywater system,namely, an aerobic grease trap and slow sand filter. Reference is made to the evaporation and treatment bed and ultraviolet disinfection components, but these are not examined. The incorporation of vermitechnology in the preliminary stages of the system for reduction of organics in greywater is reviewed. This study takes the traditional approach to water quality assessment with the measurement of physical, chemical and biological indicators. Assessment of the system involved examining the input characteristics of the greywater, monitoring the vermiculture system and sampling the liquid discharge from the aerobic grease trap and slow sand filter for analysis of the quality indicators. The results obtained under the framework of this study have provided recommendations for further use of the aerobic grease trap and slow sand filter, while propsing an approach for an appropriate long-term monitoring program.

Removal of nitrogenous compounds from precious metal refinery (PMR) wastewater is important in terms of avoiding eutrophication (environmental protection), metal recovery (increased overall process efficiency and value recovery) and reuse of treated water (maximum use of natural resources). Extreme pH conditions (4 to 13 depending on the wastewater stream), high chemical oxygen demand (> 10,000 mg/I), numerous metals and high concentrations of those metals (> 20 mg/l of platinum group metals) in the wastewater are the main challenges for biological removal of nitrogenous compounds from PMR wastewater. Nitrogenous compounds such as NH₄⁺-N and N0₃-N are strong metal ligands, which make it difficult to recover metals from the wastewater. Therefore, a bioprocess was developed for removal of nitrogenous compounds from carefully simulated PMR wastewater. A preliminary investigation of metal wastewater was carried out to determine its composition and physico-chemical properties, the ability to nitrify and denitrify under different pH conditions and denitrification with different carbon Source compounds and amounts. Even at pH 4, nitrification could be carried out. A suitable hydraulic retention time was found to be 72 hours. There was no significant difference between sodium acetate and sodium lactate as carbon sources for denitrification. Based on these results, a reactor comparison study was carried out using simulated PMR wastewater in three types of reactors: continuously stirred tank reactor (CSTR), packed-bed reactor (PBR) and airlift suspension reactor (ALSR). These reactors were fed with 30 mg/l of Rh bound in an NH₄⁺ based compound (Claus salt: pentaaminechlororhodium (III) dichloride). Total nitrogen removal efficiencies of > 68 % , > 79 % and > 45 % were obtained in the CSTR, PBR and ALSR, respectively. Serially connected CSTR-PBR and PBR-CSTR reactor configurations were then studied to determine the best configuration for maximum removal of nitrogenous compounds from the wastewater. The PBR-CSTR configuration gave consistent biomass retention and automatic pH control in the CSTR. Ammonium removal efficiencies > 95 % were achieved in both reactors. As poor nitrate removal was observed a toxicity study was carried out using respirometry and the half saturation inhibition coefficients for Pt, Pd, Rh and Ru were found to be 15.81, 25.00, 33.34 and 39.25 mg/l, respectively. A mathematical model was developed to describe the nitrogen removal in PMR wastewater using activated sludge model number 1 (ASMl), two step nitrification and metal toxicity. An operational protocol was developed based on the literature review, experimental work and simulation results. The optimum reactor configuration under the set conditions (20 mg/I of Rh and < 100 mg/I of NH₄⁺-N) was found to be PBR-CSTR-PBR process, which achieved overall NH₄⁺-N and N0₃⁻-N removal efficiencies of > 90 % and 95 %, respectively. Finally, a rudimentary microbial characterisation was carried out on subsamples from the CSTR and PBRsecondary. It was found that the CSTR biomass consisted of both rods and cocci while PBRsecondary consisted of rods only. Based on these experimental works, further research needs and recommendations were made for optimisation of the developed bioprocess for removal of nitrogenous compounds from PMR wastewater.

博士<br>國立臺灣大學<br>生物環境系統工程學研究所<br>104<br>The purpose of this study is to utilize wasted oyster shells as the media of the contact bed to purify domestic wastewater on Erchong Floodway, Taipei County. There are three horizontal flow tanks in this system, horizontal flow and aerated oyster shell tank (HAOS), horizontal flow oyster shell tank (HOS), and horizontal flow gravel tank (HG), respectively. In the experiment site, use NaCl as the tracer to perform pulse tracer tests to discuss residence time distribution of the oyster shell constructed wetland and dispersion effects of solute transport by using longitudinal dispersion theory. Besides, I set an experimental tank beside the laboratory in the Department of Bioenvironmental System Engineering in NTU. The experimental tank was set to find the water purification efficiency and the dispersion effect in different water flow condition in the oyster shell. In the results of the horizontal flow and aerated oyster shell tank (HAOS), the average mass removal of BOD5, SS, NH4-N, NO3-N, PO4-P, and TP were 18.78, 58.95, 11.74, -1.19, 0.50, and 0.87 g/m2/day. The BOD5 first-order reaction reducing rate constant in 20°C was 2.20/day. Consequently, using oyster shells as the material of the subsurface flow, constructed wetland had better water purification efficiency than using gravels. In this system, part of the BOD5 was removed because of the removal of SS, and there was better blocking effect when using oyster shells as the materials than gravels. Aeration can effectively remove ammonia nitrogen, but the main purpose was to strengthen the nitrification in the water, so that ammonia nitrogen was converted into nitrate nitrogen. Oyster shells as the material still had better removal effect of nitrogen than gravels. The results reveal that hydraulic retention time will be underestimated by using nominal retention time. Mean hydraulic retention time is about 2.68~2.75 nominal retention time in 7.8 meter length wetland. This underestimation will cause errors of the efficiency of water purification. By tracer tests, the mean dispersion coefficient of oyster shell wetlands is 0.014~0.016 m2/min. The study also points out that the dispersion coefficient can be seen as a constant in such low velocity surroundings. The relationship between flow rate and HRT of the oyster shell tank can be found by using tracer test. The average HRT was 195.4 min (Q=2.0 LPM) ~125.6 min (Q=4.0 LPM). Using oyster shells as the material, when the distance was 2.0m, and the flow rate was 2.0~4.0 LPM, the dispersion coefficient and the dispersion number was about 0.002~0.008 m2/min and 0.09~0.27, respectively. Compare the normal plug flow model and the plug flow modified by dispersion. If we ignore the dispersion effect, the treatment efficiency will be overestimated. In this study, to consider the effects of dispersion. As average HRT was 125.6 min (Q=4.0 LPM), the treatment efficiency of plug flow modified by dispersion was 89.7% of the normal plug flow model without dispersion coefficient. In the beginning of the experiment, biofilm grew fast, about 36 days to reach the maximum. In the initial of the growth, the specific growth rate was 2.95/day, then the biomass reduced and oscillated. The average removal rate of BOD5 and NH4-N in the tank were 65.97% and 22.98%. They were related to the growth of biofilm and the maximum removal occurred in 36 days. The average removal rate of PO4-P in the tank was 17.74%. Phosphate was mainly adsorbed by oyster shell in the initial of the experiment.

碩士<br>國立雲林科技大學<br>工業設計系<br>106<br>In the product design process, industrial designers usually visualize the creating concept through using Prototype. Prototyping is the initial process of product development, the important device to context, which plays an important role not only in the conceptual stage but also in the whole design process. Prototype makes designers understand the existing user experience and collection, exploring, evaluating ideas and expressing to the public, which is helpful for the purpose of learning, analyzing, modifying, testing and reviewing. Demonstrability of Prototype can display the professionalism, in fact under non-professional clients de point of view given, allow design team, users and client to have the same point of discussion, this will become some collaboration between different departments/ teams, this can help solve underlying problems, which will help the teams’ formation (“backbone”). When building the model, industrial designers can gain more in-depth design knowledge/ experience, can straight bring the designer into the real problem field. Generally, the design thinking process can be separated into three stages. The first stage is defining the problem, the second stage is ideas development, the final stage is testing and evaluating results. The defining problem can mainly through collecting to build foundational background and understand the needs of users. In this stage, involving in the prototype can explore the background effectively. The first-hand experience provides feedback to the designers directly, it can help to clarify the details of the problem. In the making prototype process of the idea development stage, looking into details can help generate design ideas effectively, the experience of the interaction with operating prototype and environment can inspire the industrial designers to figure out more possible action programs. The final stage, test functions, and express concept through the prior defined prototype. To conclude, the earlier to apply prototype into the design thinking process, the better will be for the creativity. Prototype produces different efforts and helps in the different stages. Therefore, this study strengthens the design thinking in the making prototype stage, discuss the influence on the design process, and discover and review by using case study and implementing action research in a prototype of water purification. To compare the difference from other design processes through applying practical verification in the making prototype process, inducing and analyzing the advantage. The study uses practical verification to record the change process to emphasize the importance of making prototype. Expecting the findings of this study can remind the industrial designers of the importance to make the prototype, also making prototype can improve the design quality and benefits of the developing project.

碩士<br>國立雲林科技大學<br>環境與安全工程系碩士班<br>95<br>A wetland was constructed on the Puzi river flood plains in this research. Several aquatic plants were grown on this wetland. By the interaction among plants, soil, and microorganisms, which is the natural autonomous purification measure, a certain section of Puzi River in Chiayi County was purified to improve the water quality and the utility. The sewage treatment by using constructed wetlands has been widely used in both international and domestic area and has concrete effects. It，s advantage is low capital investment cost, easy to operation and maintenance, low utility requirement and energy conservation, enhancement of the natural landscape, and the rechargement of underground water…etc. This research was conducted on the flood plain near Puzi River. The total measure of area about 4.41 ha. Where Ipomoea aquatica, Pistia stratiotes L., and Eichhornia crassipes(Mart.) Solms…etc were planted. There are take the water from Puzi River to this constructed wetlands. The flow rate was about 3,000 CMD. The purpose of this research was to compare the capability among two-stage （FWS and SSF）constructed wetlands above to purify the water quality of a seriously polluted river, and the water quality of which was improved. The result has shown that two-stage constructed wetlands have obvious effect to purify the water quality of a polluted river. However, the constructed wetlands is easily influenced by climate, especially typhoons. The facility will be totally ruined by typhoon because of no artificial protection. The selection of location, therefore, needs to be considered carefully. The results of this study could be used as a reference for developing constructed wetlands to purify the water quality of a river.

This dissertation surveyed the validities of teaching the chemistry of water purification in South African schools using locally available materials (LAM) through the scientific inquiry (SI) approach. The researcher randomly selected four secondary schools that provided a small and purposive study sample of thirty-two Grade 11 learners and four teachers. The research design applied a mixed-method approach, consisting of qualitative and quantitative methods of data collection. Within this approach, the outcome of SI instruction that integrated LAM was compared with that of conventional instruction through a quasi-experimental control groups design. The researcher identified in the analysis of interviews and questionnaires the most complex aspects of the chemistry of water purification for learners to understand as redox reactions, acid-base systems, precipitations, and chlorination. However, the use of LAM through the scientific inquiry approach made it easier for learners to understand the concepts. The high mean scores ( =80.88; SD=10.28) in Research-based Test 2 (RBT2), of the experimental groups taught through SI signified that those learners immensely benefited from an active and collaborative learning environment. The lowly scores ( =61.69; SD=4.21) of control groups could be attributed to a linear and passive participation of learners in the conventional classroom instruction. The marks of the two groups in post-test RBT2 were paired and contrasted using GraphPad software. The results showed that t =6.699, df =21 with a significant value of 0.0001, which is less than 0.05 (p<0.05), hence it can be inferred that the difference between the means of the two groups was not only statistically important but also worth an explanation. The higher performance scores in RBT2 and the Rubric Assessment Tool (RAT) in experimental groups represents that the intervention was successful in the implementation of instructional design in the the study. In addition, the learners had mastered the crucial aptitudes that included self-discipline in understanding, cooperative learning, searching relevant text on topic, hands-on or laboratory practice and logical thinking in problem solving by working through the SI activities that used LAM.<br>Mathematics, Science and Technology Education<br>M. Sc. (Mathematics, Science and Technology Education with specialization in Chemistry Education)

The effects of Electromagnetism on potable water and waste water has been proven in practice but not scientifically proven to the extent that it is accepted by Engineers and Engineering Consultants. The operating principle of magnetic filtration or separation is based on the interaction of electromagnetic fields with the materials under test. Technical water system (TWS) system configuration has been analysed to determine the system characteristics. Three field trials and some laboratory experiments have been reported in this report. Finite element software has been used for the analysis of magnetic field distribution of the TWS system and also for magnetic separation modelling. There is a need to do some more experiments for more convincing and conclusive outcome.

碩士<br>中原大學<br>建築研究所<br>97<br>Abstract At Tou-chian River of Hsin-chu county, the area of 1st and 2nd stages of constructed wetland is 1.9 hectare. It includes 16 different pounds from A to P. During the period of research, Sep. of 2007 to Aug. of 2008, the plants spatial heterogeneity had reach the highest percentage of 39% in Jan.2008, and the lowest of 22% in Aug. 2008. The percentage under maintenance control was between 20 to 40%. Plant species proportion in maintenance plots appears a well mix status, the species in the vegetation succession environment plots are mainly Bidens pilosa L.radiata（B1.）Sherff. The species in maintenance plots are much more divers than the vegetation succession environment plots. Plant species proportion in vegetation succession environment plots was gradually becoming even, the proportion of plant species was in an average status. From the observation of the plants’ formation of the wetlands surrounding, suppose in the undisturbed natural succession, it will eventually become a low altitude river basin vegetation structure of Taiwan. Melia azedarach L. and Trema orientalis (L.) Bl. will become the main members of this plants composition. There are 20 family and 166 species of water plants recorded in the survey of Aug. 2008. It has 4 fmaily and 7 species more than the record of Dec. 2004 when the construction was finished. Nuphar shimadai Hayata, Bacopa monnieri（L.）Wettst. and Polygonum orientale L., these three species did not have record during the survey period. During the research period, the on land plants appeared the most in spring, total 61 family and 166 species. The least in the winter, 57 family and 149 species were recorded. However, there are 26 family, 50 genus, and 64 species more than the survey record of wetland planning in May 2004. Among the wetlands region, there are average 63% of native species in all seasons. Creating more chances for the native plants to survive by maintenance, the native plants increase 36 species in compare to the record of 2004. Ammonia Nitrogen removed treatment was 71% in Aug.2008, had not reached the design standard. Excluding this month, all other months had exceeded the standard. It even reach 98% percent in Sept. 2007. The annual treatment average had reached 86%. However, the suspended solid (SS) treatment is not very effective, it might be caused by the lack of plants in the pond, therefore did not meet the design standard. BOD5 and NH3-N concentration in monthly average had reached the designed standard. Suspended solid (SS) concentration did not meet the standard in Sept., Oct. of 2007 and Apr., Mar., Jun. of 2008. The monthly average of water quality out concentration is above the expectation of design standard. After the relative analysis of the plants spatial heterogeneity and NH3-N removed treatment in every pond, the reliability analysis result of the Cronbach’s α coefficient is 0.83. In pond A,H and J, the analysis result shows the changing of plant spatial coverage is highly related to the NH3-N removed treatment, and pond A had the most remarkable result. From the results of analyzing the plant diversity, pond A also had the most different and divers plants in all seasons. Therefore, we conjectured that the diversity of plants might also be close related to the NH3-N removed treatment. The P value in pond D is 0.096. However, it does not mean that the greater area of plant spatial heterogeneity is the better of NH3-N removed treatment would be.

The aims of this doctoral study were to: isolate naturally occurring bacteria, able to degrade microcystins (MCs), from New Zealand waterbodies; to understand the biological processes of microcystin degradation by bacteria; and to develop small scale biofilm technology for testing the effectiveness of bacteria for microcystin degradation and/or remediation. A significant amount of microcystins were required for biodegradation experiments. A modified method, using DEAE and Strata-X cartridge chromatography, was optimized for purifying microcystin variants from lyophilized bloom samples of the cyanobacterium Microcystis aeruginosa, collected en masse from Lake Horowhenua. Seven microcystin variants, MC-RR, MC-dMe-RR, MC-YR, MC-LR, [Dha7]MC-LR, MC-FR, and MC-AR were purified by chromatography and then identified by reverse-phase High Performance Liquid Chromatography (HPLC) with UV detector (UVD) and Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS). A mixture of [Dha7]MC-LR and MC-LR, the main microcystin variants present, was used for examining biodegradation of microcystins by degrading bacteria. Three isolates of bacteria—NV-1, NV-2 and NV-3—purified from Lake Rotoiti, New Zealand were capable of degrading [Dha7]MC-LR and MC-LR. Among these isolates, NV-3 demonstrated the strongest degradative activity and was identified as a member of the genus Sphingomonas. On the basis of 16S rRNA sequencing, and 100% nucleotide sequence homology, it aligned most closely to strain MD-1. Based on the detection of two intermediate by-products (linearized peptides and a tetrapeptide) and the identification of four genes (mlrA, mlrB, mlrC and mlrD), that encode four putative proteins (enzymes) involved in microcystin degradation, it was suggested that the degradation of [Dha7]MC-LR and MC-LR by the Sphingomonas isolate NV-3 occurred by a similar mechanism previously described for Sphingomonas strain MJ-PV (ACM-3962). The bacterium Sphingomonas isolate NV-3 was examined for its ability to inhibit the growth of the cyanobacterium Microcystis aeruginosa strain SWCYNO4. It was found that the bacterium did not have any significant affect on the growth of the cyanobacterium, either by means of secretion of bacterial extracellular products or cell-to-cell contact between bacterial and cyanobacterial cells. It was established that Sphingomonas isolate NV-3 was a moderate biofilm former, based on two types of biofilm formation assays, namely, microtiter plate assays and coupon biofilm assays. This was carried out in preparation for using the bacterium in a bioreactor for biodegradation of [Dha7]MC-LR and MC-LR. The bacterium attached most effectively to ceramic, followed by PVC, polystyrene, stainless steel, and finally glass coupons. Biodegradation of MCs by the bacterium, in an internal airlift loop ceramic honeycomb support bioreactor (IAL-CHS bioreactor), was established in batch and continuous-flow experiments. In the batch experiment, NV-3 degraded a combination of [Dha7]MC-LR and MC-LR at an initial concentration of 25 µg/ml at 30 degrees C in 30 hours, whereas in the continuous-flow experiment, NV-3 degraded the same concentration of [Dha7]MC-LR and MC-LR in 36 hours with an hydraulic retention time (HRT) of 8 hours. This study has demonstrated that microcystin-degrading bacteria are present in New Zealand waterbodies and that these bacteria could be used, potentially on a larger scale, for removing microcystins from water.

Thesis (M.Tech.: Chemical Engineering)-Dept. of Chemical Engineering, Durban University of Technology, 2005 1 v. (various pagings)<br>In bubble-less aeration oxygen diffuses through the membrane in a molecular form and dissolves in the liquid. Oxygen is fed through the lumen side of silicone rubber tube. On the outer surface of the membrane there is a boundary layer that is created by oxygen. This then gets transported to the bulk liquid by convective transport created by water circulation through the pump. The driving force of the convective transport is due to concentration difference between the dissolved oxygen in water and oxygen saturation concentration in water at a particular temperature and pressure. The design of a membrane aerated bioreactor needs an understanding of the factors that govern oxygen mass transfer. It is necessary to know the effects of operating conditions and design configurations. Although various methods of bubble-less aeration have been reported, there still exists a lack of knowledge on the immersed membrane systems. This study is aiming at contributing to the development of an immersed membrane bioreactor using silicone rubber tubular membrane as means of providing oxygen. The secondary objective was to investigate the influence that the operating conditions and module configuration have on the system behaviour. From the experimental study, the characteristic dissolved oxygen -time curve show that there is a saturation limit equivalent to the equilibrium dissolved oxygen concentration, after which there is no increase in dissolved oxygen with time. At ambient conditions the equilibrium dissolved oxygen is approximately 8 mg/L. This is when water is in contact with air at one atmospheric pressure. At the same conditions the equilibrium dissolved oxygen concentration when water is in contact with pure oxygen is approximately 40 mg/L. This is why all the experiments were conducted from 2mg/L dissolved oxygen concentration in water, to enable enough time to reach equilibrium so as to determine mass transfer coefficient. The most important parameters that were investigated to characterise the reactor were, oxygen supply pressure, crossflow velocity, temperature and module orientation. Observations from the experimental study indicated that when the system is controlled by pressure, crossflow does not have a significant effect on mass transfer. When the system is controlled by the convective transport from the membrane surface to the bulk liquid, pressure does not have a significant effect on mass transfer. All four effects that were investigated in the study are discussed.

Degrading catchments and water shortages are the most immediate and arguably the biggest environmental issues affecting the world today. In recent years, wastewater irrigation has gained popular support as a substitute to irrigation of potable water. The use of wastewater for irrigation is considered beneficial recycling of a limited resource; in this case freshwater within Australia. Although it has economic, environmental and social benefits, it is sometimes questioned as an environmentally sound method, because wastewater irrigation has been shown to change the chemical, physical and biological properties of soil. Soil is an excellent medium for the removal of some contaminants in wastewater. However, there is a lack of in-depth knowledge and the need for further research into the influence of site conditions and climate which may inhibit the performance of the wastewater irrigation scheme. This research is focused on determining the impacts of wastewater irrigation on the chemical and physical properties of the soils at selected sites within the Australian Capital Territory. Specifically, this study of wastewater irrigation of urban greenspaces sets out to (a) determine the differences in chemical and physical properties of the irrigated soils to nearby control sites for a single time slice, and (b) evaluate any changes that occurred over a six-year monitoring period. Temporal data analysis for a six-year monitoring period of Southwell Park and North Canberra Water Reuse Scheme revealed some broadscale trends in the chemical and physical properties of wastewater-irrigated soils. Generally, the chemical properties pH, electrical conductivity (EC), total dissolved solids (TDS), and nutrients have increased and the physical property hydraulic conductivity has decreased over the monitoring period. Non-wastewater-irrigated (control) soils were used to provide background concentrations to assess the extent of change as a result of wastewater irrigation. This study found that soil pH, total phosphorus (TP), exchangeable sodium percentage (ESP) and sodium significantly increased from application of wastewater. Soil hydraulic conductivity and permeability were significantly reduced by the application of wastewater. The application of wastewater to land increased soil pH, EC, chloride, organic carbon, total nitrogen (TN), TP, nitrate, total oxidised nitrogen (NOx), bulk density, ESP, sodium, calcium and sodium adsorption ratio (SAR) and reduced the levels of nitrite, hydraulic conductivity, soil permeability, magnesium, aluminium and P sorption. Ammonia, cation exchange capacity (CEC) and potassium showed no variation between the sites irrigated with wastewater and the control sites. This research found that responses to the soil chemical and physical properties occurred, some of which could be tentatively attributed to wastewater irrigation, but other factors were also contributing. The influence of climate, contrasting ratios of wastewater to potable water used for irrigation, and other management strategies were important factors that emerged during this research. These factors not only represented important constraints but also clarified the specific role that wastewater irrigation played in defining soil characteristics. Climate was a dominant factor in defining soil chemical and physical properties. Under high evaporation, if there were going to be negative impacts imposed by wastewater irrigation, then this is when they would be most pronounced. The responses under wastewater irrigation are independent to the ratio of wastewater to potable water used for irrigation. The responses observed at the Belconnen Magpies Golf Course, which uses 100% wastewater for irrigation, were also observed at the other study sites. Because wastewater irrigation is not the dominant factor controlling soil properties, additional land-management strategies are playing a crucial role. Those strategies occurring pene-contemporaneously with wastewater irrigation include: the use of sites for recreation with consequent impacts on soil compaction and hydraulic conductivity, and the application of a range of agri-chemicals to optimise soil fertility and plant growth. Overall, it can be concluded that the wastewater irrigation is not the dominant factor controlling the soil chemical and physical properties. Although the soils in the study area have experienced physical and chemical changes following wastewater irrigation, the soils have so far retained most of their functions. Land application of wastewater at the study sites has been shown to cause no negative effects on the environment. Therefore, the wastewater irrigation on soils within the Australian Capital Territory is sustainable and does not adversely affect the chemical and physical properties of the soils.

碩士<br>國立中山大學<br>環境工程研究所<br>96<br>During the water treatment process, each processing unit releases the sludge from the sedimentation process, and the wastewater from the rapid sand wash and filtration process, to the wastewater pond followed by the wastewater sedimentation pond. The sediment sludge is allowed to enter the sludge thickening pond while the supernatant is recycled for further treatment. The sludge is released to the sludge pond where it is treated with certain chemicals and squeezed to form the sludge cake. The sludge cake is removed and transported by a legitimate cleaning service company to an authorized location. The present study is focused on the investigation of the feasibility of recycling the wastewater and the dewatering of the sludge from the water treatment plant. The analysis of the samples collected from the wastewater treatment plant showed that the recycled supernatant had a pH of 7.16~8.21, a conductivity of 371.1~769.1 μmho/cm, a total dissolved solid (TDS) of 193.3~399.9 mg/L, and a turbidity of 0.901~54.3 NTU. The suspended solids (SS) of the recycled supernatant was found to be 0.4~45.6 mg/L, lower than the standard value in the Effluent Standards (50 mg/L). The ammonia nitrogen (NH3-N) and the Total Organic Carbon (TOC) of the recycled supernatant were found to be 0.06~1.5 mg/L and 1.533~17.437 mg/L, respectively. The analysis of the Chemical Oxygen Demand (COD) of the wastewater treatment plant showed a concentration of 12.1~128.5 mg/L in the sample of the recycled supernatant. The COD in the Effluent Standards is required to be no more than 100 mg/L. For sludge conditioning and dewatering, a sludge conditioning experiment was conducted in the laboratory to plot the curve of the experimental result. The curve was used for the actual sludge conditioning and dewatering in the Fongshan Water Treatment Plant to verify the feasibility of the application for the actual process in the water treatment plant.