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Domestic wastewater is one of the most interested environmental issues in Vietnam, especially in big cities and suburban residential areas. Most of the wastewater was not treated in the right way before discharging to environment. In this research, the author used water hyacinth as a main aquatic plant in aquatic pond model to treat wastewater. The experiment was operated continuously in 1 year with hydraulic retention time (HRT) is 11 and 18 days. Hydraulic loading rate (HRL) is 300 and 500 m3/ha/day, respectively. Treatment efficiency of the model for TSS is 90% (remaining 6 -12mg/l); COD, BOD5 is 63 - 81% (remaining 10 - 48mg/l); TP is 48 – 50% (remaining 3.5 - 9.8mg/l); TKN is 63 - 75% (remaining 8 - 17mg/l). Polluted parameters in effluent were lower than A and B levels of Vietnam standard QCVN 14: 2008/BTNMT and QCVN 40: 2011/BTNMT. The doubling time of water hyacinth in summer is 18days, and in autumn and winter is 28.5 days. Experiment results showed that we can use water hyacinth in aquatic pond to treat domestic wastewater with medium scale. We can apply this natural treatment method for residential areas by utilizing existing natural ponds and abandoned agricultural land with capacity up to 500m3/ha day. However, to get better efficiency we should combine with other aquatic plant species to treat wastewater and improve environmental landscape. / Nước thải – xử lý nước thải sinh hoạt hiện đang là một trong những vấn đề môi trường được quan tâm tại Việt Nam nhất là tại các thành phố lớn và các khu dân cư. Hầu hết lượng nước thải chưa được xử lý đúng cách trước khi thải ra môi trường. Trong nghiên cứu này, tác giả sử dụng mô hình hồ thủy sinh và sử dụng cây Bèo lục bình để xử lý nước thải sinh hoạt của một khu dân thuộc huyện Từ Liêm, tại khu vực này nước thải bị thải trực tiếp vào sông Nhuệ. Thực nghiệm đã được tiến hành trong khoảng thời gian một năm, trải qua các mùa của khu vực miền Bắc với hai chế độ vận hành HRT là 18 và 11 ngày, tương ứng với tải trọng thủy lực HRL là 300 và 500 m3/ha/ngày. Kết quả cho thấy mô hình thủy sinh sử dụng cây bèo lục bình cho kết quả tốt, hiệu suất xử lý với các chất ô nhiễm đạt được như sau: chất rắn lơ lửng đạt 90%, COD, BOD5 đạt 63 - 81%, Phốt pho tổng giảm tới 48 -50%, Nitơ tổng giảm tới 63 - 75%. Hàm lượng các chất ô nhiễm trong nước thải đầu ra của mô hình đều thấp hơn ngưỡng A và B của các tiêu chuẩn QCVN 14: 2008/BTNMT và QCVN 40: 2011/BTNMT. Bên cạnh đó tác giả cũng đã xác định định được tốc độ sinh trưởng của cây bèo tại khu vực miền Bắc là 18 ngày vào mùa hè và 28.5 ngày vào mùa thu đông. Kết quả nghiên cứu cho thấy có thể sử dụng bèo lục bình để xử lý nước thải sinh hoạt, với qui mô vừa và nhỏ và nên áp dụng cho các khu vực ven đô, nông thôn nơi có diện tích đất rộng hoặc tại các hồ sinh thái của các khu đô thị. Tuy nhiên, để hiệu quả tốt hơn ta cần kết hợp với nhiều loại thực vật thủy sinh khác để ngoài tác dụng xử lý nước thải mà còn tạo cảnh quan môi trường xung quanh.

Aquaculture is an essential developing sector for world food production, however the attainment of sexual maturity during commercial on-growing is a major bottleneck to industry expansion. Sexual maturation brings a commercial loss due to reduced growth performance as well as reduced immune function. Furthermore, serious concerns exist over potential genetic interaction with native stocks through broadcast spawning or spawning interaction by escapees. In the north Atlantic region, the Atlantic cod (Gadus morhua) and Atlantic halibut (Hippoglossus hippoglossus) are key aquaculture species in which industry expansion is limited by pre-harvest sexual maturation. However, through a species specific combination of modern technologies and refinement in management practices it is possible that this sexual maturation can be controlled and on-growing potential enhanced. Thus the overall aim of this thesis was to conduct novel research that will improve our understanding of the underlying mechanisms that regulate sexual maturation, whilst also advancing the optimisation of technologies for the management of maturation in cod and halibut. In Atlantic cod, owing to the inconsistent inhibition of maturation in commercial conditions, ever increasing intensities of light and in some cases narrow spectrum technologies are being used to try to combat this problem. Firstly, this PhD project investigated the potential welfare impacts of high intensity artificial lighting which have not been studied to date (Chapter 2). The work specifically investigated the effect of traditional metal halide and novel green cathode lighting on the stress response, innate immunity, retina structure, feeding activity and light perception of Atlantic cod. Results indicated that although acute responses to light were observed, there were no clear significant long term effects of any of the lighting treatments on these parameters. Regarding light perception, interestingly even when subjected to high intensity constant lighting (metal halide mean tank intensity: 16.6 watts m-2), cod still demonstrated a day/night rhythm in melatonin release which suggests perception of the overlying ambient photoperiod. The second trial of this PhD project investigated the efficacy of shading of ambient photoperiod in addition to constant lighting to inhibit maturation of cod outdoors (Chapter 3). This aimed at improving the performance of artificial lighting regimes in the open cage system during commercial on-growing by reducing the relative difference between day/night light intensities. The trial was conducted over a one year period where a low and high shade treatment were tested in outdoor tanks. Shading increased the relative night time illumination to 6.6% and 31.3% of daytime levels respectively, compared to <2% in an unshaded set-up. Both shading treatments were effective at suppressing sexual development in cod as confirmed through measurements of gonadosomatic index, histological analysis of gonadal development, oocyte diameter measurements and sex steroid profiles as well as measurements of growth. In addition to research at the applied level in Atlantic cod, this thesis has also extended to the fundamental level and explored one of the potential mechanisms relaying photoperiod signal to the endogenous regulation of sexual maturation in cod, namely the kisspeptin system (Chapter 4). Partial sequences for the signal peptide Kiss2 and its receptor Kissr4 were isolated and described showing similarity to other teleost species such as the medaka, Oryzias latipes and stickleback, Danio rerio. Novel molecular qPCR assays were designed and developed to measure the expression of both genes in male and female cod over a maturation cycle and compared to cod under constant lighting which remained immature. Interestingly, expression patterns of kiss2 and kissr4 did not reveal any clear association with season or photoperiod treatment. However, pituitary expression of gonadotropins (FSH, follicle stimulating hormone; LH, luteinising hormone) did show a differential expression in relation to treatment from early winter approximately 4-6 months after the photoperiod change. These new results are in contradiction with the hypothesis that the kisspeptin system would be involved in the initiation of gametogenesis, as shown in mammals. However, the FSH/LH data defines a window during which time kisspeptin or another GnRH stimulating mechanism must be active, this compels the need further investigation. In Atlantic halibut farming, all-female production removes the concerns of production losses through sexual maturation. Accordingly, this thesis investigated the potential/feasibility of generating monosex populations by FACS (fluorescence activated cell sorting) semen sexing based on cellular DNA content, as proven in terrestrial agriculture. Results however did not show any clear differences between the DNA of sperm in a range of species tested (Atlantic halibut, cod, sea bass, perch) suggesting that this technique may not be applicable in such species. The project also focussed on the production of a population of sex reversed halibut broodstock (neomales) that will generate, in the long term, a basis for traditional monosex population generation in the UK. Two in feed MDHT (17α-methyldihydrotestosterone) treatments were tested with the aim to reduce the use of hormone. Results were very successful with a hormone treatment of 5ppm MDHT generating a 97% phenotypic male population thus suggesting the presence of sex-reversed halibut which can be used for future monosex production. Overall, this work aimed to develop and/or refine potential remediation techniques for sexual maturation in two key commercially important farmed marine fish species, cod and halibut, as well as further our understanding on the regulation of puberty. The knowledge gained from this work provides a means to optimise the techniques employed in the industry and has the potential to increase production and profitability without compromising farmed animal welfare, thus ultimately promoting the sustainable expansion of the Atlantic cod and halibut aquaculture.

Dams and weirs are widely implicated in large-scale declines in both the range and abundance of aquatic fauna. Although many factors are involved, such declines are commonly attributed to the prevention or reduction of migration, reductions in available habitat, alteration of natural flow regimes and changes to physicochemical characteristics. In Australia, studies into the ecological effects of these impacts are limited, and have concentrated mainly on species of recreational and commercial importance. Subsequently, the adverse effects of dams and weirs, and suitable methods of mitigation, remain largely unknown for many other taxa. Therefore, the major aim of this thesis is to investigate the ecological effects of dam and weir construction on previously unstudied migratory assemblages of fish and macroinvertebrates in the Murray-Darling Basin. It is anticipated that the results of these studies will feed back into improved management strategies that help arrest the previously observed declines of aquatic fauna. Initially, fish communities were sampled, by boat electrofishing, from both reference sites and downstream of Balranald and Redbank weirs on the lower reaches of the Murrumbidgee River, Australia. Sampling was stratified over large spatial and temporal scales to gain a comprehensive understanding of species most affected by the presence of these two barriers. In general, the weirs obstructed fish migrations during summer and autumn and many species of small-bodied fish such as Australian smelt, western carp gudgeon, fly-specked hardyhead and crimson-spotted rainbowfish accumulated downstream of Balranald Weir. In addition, downstream accumulations of juveniles of larger-bodied species such as bony herring, common carp and goldfish were also detected. Although many previous studies had either documented or hypothesised that upstream migrating fish accumulate downstream of migration barriers, none attempted to quantify the size of such populations. Therefore, a simple but efficient method to estimate the size of migratory populations was assessed at the Balranald Weir site. The application of two commonly used estimation techniques yielded relatively reliable results for seven species that accumulated downstream of the weir. Population size estimates were greatest for most species during summer and autumn, where accumulations as high as 800 fish per day were detected. The largest calculated population size estimates, in addition to the greatest temporal variation, of any individual species was observed in bony herring. Given the simplicity of the technique and the relative accuracy of population estimates, it was concluded that these methods could easily be applied to other weirs where the size of migratory populations is of particular interest. A study investigating the effects of Yanco Weir on the diets of three migratory percichthyid species, Murray cod, trout cod and golden perch was also conducted. Observed spatial variation in a number of trophic processes strongly implicated Yanco Weir as a major contributor to increased competition among percichthyid species on the Murrumbidgee River. The greater relative abundance of percichthyids from downstream samples, combined with increases in dietary overlap and a greater percentage of empty stomachs, also suggested percichthyids may be significantly affecting the relative abundance of potential prey items such as freshwater prawns and Australian smelt. These significant changes in dietary composition were likely related to migratory behaviour, as these species accumulated downstream of the weir, and could be readily expected at other sites where passage is obstructed. It was suggested that the construction of suitable fish passage facilities would effectively reduce the probability of migratory fish accumulating and, subsequently, potential effects of dams and weirs on trophic processes. Since it was established that dams and weirs of the Murrumbidgee River were significantly affecting migratory fish communities, an innovative but relatively inexpensive fishway design, the Deelder fish lock (after Deelder, 1958), was constructed and assessed for wider application throughout the Murray-Darling Basin. The Deelder lock was effective at mitigating the effects of Balranald Weir by providing passage for a wide range of size classes and species of fish; but importantly, the structure enabled the passage of most species previously observed to accumulate downstream of the structure. Most significant was the ability of the fish lock to pass substantial numbers of small-bodied fish, which were previously not considered migratory, suggesting that these species should be considered when developing options to mitigate the effects of other dams and weirs throughout the Murray-Darling Basin. A significant finding of this study was the realisation that substantially more species and size classes of Australian native fish are migratory than previously thought. Subsequently, it is recommended that, when designing facilities to mitigate the effects of a dam or weir, the structure of the entire migratory community is considered when developing operating parameters. Various options for mitigating the effects of dams and weirs are discussed, but it was concluded that the construction of effective fishways would be the most appropriate means of restoring migration pathways to Australian native fish. A strategic approach for assessing and adaptively mitigating the effects of dams and weirs is presented and discussed.

<p>This report deals with the performance of a batch flow treatment of landfillleachate compared with a continuous flow system. The parameters in focus were total Kjeldahl nitrogen (TKN), BOD5 and COD. The pilot-scale experiment used eight barrels with a volume of 150 liters. Each barrel was constructed differently concerning its flow, its bed material grain size and its presence of plants or not. Four of the barrels worked in batch mode, thus four in continuous flow mode. The continuous flow systems were provided with water trough small tubes with regulators. Samples were collected once a week and analysis was carried out yielding results of BOD5, COD, TKN, pH and conductivity of the effluents. The same parameters were analyzed for the influent every week. The result shows that a wetland is a good way of treating the landfill leachate as the BOD5, COD and TKN decreases. Moreover the color, which contravenes with legislative demands in the region, was distinctly decreased. Yet the report failed to show a significant difference between batch loaded and continuous flow wetlands. More studies have to be carried out in order to determine or contradict whether batch mode in fact provides a better treatment.</p>

This report deals with the performance of a batch flow treatment of landfillleachate compared with a continuous flow system. The parameters in focus were total Kjeldahl nitrogen (TKN), BOD5 and COD. The pilot-scale experiment used eight barrels with a volume of 150 liters. Each barrel was constructed differently concerning its flow, its bed material grain size and its presence of plants or not. Four of the barrels worked in batch mode, thus four in continuous flow mode. The continuous flow systems were provided with water trough small tubes with regulators. Samples were collected once a week and analysis was carried out yielding results of BOD5, COD, TKN, pH and conductivity of the effluents. The same parameters were analyzed for the influent every week. The result shows that a wetland is a good way of treating the landfill leachate as the BOD5, COD and TKN decreases. Moreover the color, which contravenes with legislative demands in the region, was distinctly decreased. Yet the report failed to show a significant difference between batch loaded and continuous flow wetlands. More studies have to be carried out in order to determine or contradict whether batch mode in fact provides a better treatment.

Thesis (M.M.S.)--Memorial University of Newfoundland, 2001. / Bibliography: leaves 67-70.

Under tillverkningsprocessen i massa- och pappersindustrin bildas avloppsflöden i flera olika steg. Ett av de miljöbelastande utsläppen utgörs av organiskt material. Organiskt material kan mätas som biokemisk syreförbrukning (BOD), kemisk syreförbrukning (COD) eller som totalt organiskt kol (TOC). Analys av COD inkluderar ofta miljöfarliga ämnen (till exempel kvicksilver). Naturvårdsverket har under flera år aviserat att analysen kan komma att förbjudas och därmed blir analys av TOC allt mer vanligt. EU:s referensgränsvärden anges dock i COD och design av reningsanläggningar utgår oftast från COD. Detta leder till att båda parametrarna kommer att fortsätta att vara aktuella. Med syftet att förbättra kunskapen om sambanden mellan COD och TOC för olika typer av avlopp inom massa- och pappersindustrin samlades jämförande serier över COD och TOC in från olika svenska bruk. Serierna analyserades med hjälp av regressions- och korrelationsanalys, för att sedan jämföras med medelvärdet av brukens COD/TOC faktorer (omvandlingsfaktorer). Studien innehöll även en del där information om analyser, förbehandlingar och övergången från COD till TOC samlades in genom intervjuer med personer ute på bruken. Som en avslutande del av projektet genomfördes ett laborativt arbete i mindre skala med främsta syfte att se hur konstant omvandlingsfaktorn var över tiden. Resultaten visade att korrelationen mellan COD och TOC ofta var hög men att omvandlingsfaktorn var beroende av typ av tillverkningsprocess och rening. Värdet på omvandlingsfaktorn varierade därför mycket mellan olika bruk och delströmmar. Bruk med tillverkningsprocesser som använder få kemikalier hade en mer lika omvandlingsfaktor sinsemellan än bruk med kemikaliekrävande processer. Dessutom gav en högre reningsgrad en lägre omvandlingsfaktor. Omvandlingsfaktorn föreföll varken påverkas av halten suspenderat material eller vara årstidsberoende. Dessutomvar den också relativt konstant över tiden. / The industrial production of pulp and paper generates wastewater in several different steps in the production chain. Organic material from the wastewater will have an impacton the surrounding environment. Biological oxygen demand (BOD), chemical oxygendemand (COD) and total organic carbon (TOC) are three ways to measure organicmaterial. When analyzing COD, harmful substances such as mercury are often used. The Swedish Environmental Agency has for several years forecasted that this analysis might be banned, and therefore analysis of TOC has become more and more common in Sweden. However, COD is often used as a design parameter when designing new wastewater treatment plants and the European Union’s reference values are given as COD. Hence, both parameters will continue to be used and both need to be taken into consideration. With the aim to improve the knowledge of the relationship between COD and TOC, data series with TOC and COD were collected. The data originated from several different Swedish pulp and paper mills, as well as from different types of waste water streams within each mill. The data series were analyzed using linear regression and correlation analysis, and then compared with the companies’ mean value of the ratio between COD and TOC (the conversion factor). Information about the shift from COD to TOC, and the analyzing methods and pretreatment methods was gathered by conducting interviews with employees at the different mills. The final part of the project was a laboratory study, with the main focus to examine if the conversion factor changed over time. The results showed that the correlation between COD and TOC often was high, but that the conversion factor depended on type of manufacturing process and waste water treatment. Mills with a low use of chemicals had a more similar conversion factor than mills with a more chemical demanding process. Furthermore, a high degree of purification resulted in a lower conversion factor. The conversion factor did not seem to depend on neither the content of suspended solids nor the time of the year. Additionally, the conversion factor was relatively constant over time.

Les nanoparticules (NPs) métalliques présentent un grand intérêt dans de nombreuses applications, pour lesquelles un contrôle précis de la taille, de la composition et de la morphologie est requis. Cependant, ce contrôle demeure un défi. Les liquides ioniques (LIs) sont des sels fondus liquides à température ambiante. Ils possèdent des propriétés uniques, à michemin entre le liquide (ce sont des solvants, de bons électrolytes,…) et du solide (ils ne s’évaporent pas). Les LIs sont connus pour être des solvants intelligents, qui permettent, par décomposition de précurseur organométallique, de former des NPs de taille calibrée et contrôlée. Ceci en absence de ligands organiques contrairement aux solvants conventionnels. Cependant, le mécanisme de leur formation reste mal connu. Dans cette thèse, nous identifions les facteurs clés influant sur la taille finale des NPs. Cela permettra de développer des voies de synthèse de NPs de tailles prédéterminées. Par ailleurs, le silicium poreux (PSi) est un matériau prometteur qui peut trouver de multiples utilisations dans les systèmes intégrés ou dans les secteurs photovoltaïque et biomédical. Ses propriétés peuvent être ajustées par l'introduction de métaux dans ses pores. Dans ce cas également, les LIs peuvent être avantageusement utilisés. Dans ce travail, la métallisation de PSi par Cu est réalisée par imprégnation du PSi puis décomposition d’une solution de CuMes dans le LI. En fait, il est observé que c’est le PSi qui décompose le précurseur. Pour cette raison, l’utilisation d’analogues solubles du PSi est étudiée pour remplacer H2 dans la synthèse des NPs. Cela pourrait permettre d’améliorer encore le contrôle de ce procédé / Among nano-objects, metallic nanoparticles (NPs) certainly have a prominent position. This is because they offer a variety of compositions, sizes, shapes and structures that make them suitable for a variety of applications. In the same time, the accurate control of their size, shape and structure is still a challenge, mainly because NPs do not correspond to the thermodynamic stable state of metals. Recently, ionic liquids (ILs) have been shown to stabilize metallic NPs without the need of ligands required in conventional solvents. ILs are liquid molten salt at room temperature. These compounds uniquely combine properties of the liquid (they are good solvents, electrolytes…) and of the solid (they do not evaporate). In the process of decomposing organometallic precursors into metallic NPs, ILs play a central role in controlling the size and ensuring narrow size distribution. However, the corresponding mechanism remains unclear. This PhD work aims at identifying key factors influencing the final size (average and distribution) of metallic NPs chemically formed in ILs. Among nanoporous materials, porous silicon (PSi) is popular due to its exceptional characteristics for microelectronics, integrated optoelectronics, microelectromechanical systems (MEMS), layer transfer technology, solar and fuel cells, biomedicine, etc. Its properties are modified by introducing different materials into its pores. Unique properties of ILs may also be advantageous. In this work, the process used to synthesize metallic NPs is adapted into an easy, efficient, versatile, and safe process to metallise PSi. The metallisation of PSi by Cu is tentatively conducted by impregnation with a solution of CuMes in IL followed by the decomposition of the precursor. In fact, CuMes is shown to be readily decomposed by PSi. Finally, this knowledge is transposed back to the synthesis of metallic NPs, replacing H2 by chemical analogues of PSi as alternative reducing agents. This approach is believed to bring even more control in this process