151,001 research outputs found
Review of breeding and propagation techniques for grey mullet, Mugil cephalus L
No full textThis review is a compendium of most of the available biological and engineering knowledge relevant to the breeding and mass propagation of the Mugilidae species, particularly the grey mullet Mugil cephalus Linn.Induced breeding, Fish culture, Hatcheries, Aquaculture techniques Mugil cephalus
Disinfection of grey water
No full textThe reuse of grey water, for applications such as toilet flushing and irrigation,
represents a potential sustainable solution to water shortages experienced by regions
worldwide. Although reused grey water is not intended for potable use, the potential for
transmission of waterborne pathogens by aerosol inhalation, topical contact, or indirect
ingestion is a key concern for grey water reuse. This thesis explores the pathogen
content of grey water and investigates pathogen removal through treatment and
disinfection processes. The impacts of organic and particulate material in grey water on
the efficacy of disinfection processes are investigated in depth.
Grey water can potentially harbour a range of pathogenic microorganisms, with
opportunistic bacterial pathogens in grey water indicating a particular risk of grey water
reuse for the vulnerable members of society. The disinfection of grey water is therefore
critical prior to reuse. Particulate material in grey water limits the efficacy of
disinfection by chlorine, ultraviolet light, and origanum essential oil, by shielding
microorganisms from the applied disinfectant. Microbial resistance to the disinfectants
was linked to the particle size distribution of the grey water, with increasing particle
size offering greater protection to associated microorganisms. Additional organic
material was shown to reduce the applied disinfectant but no impact on microorganism
resistance to disinfection was observed when a constant disinfectant dose was
maintained. Treatment of grey water, targeting the removal of large particulate material,
improves the efficacy of grey water disinfection, allowing compliance with stringent
microbiological standards for urban water reuse
The pathology and occurrence of pathogens in Scottish grey seals (Halichoerus grypus).
No full textNeonatal mortality in grey seals on the Isle of May breeding colony and in a rehabilitation centre were investigated by detailed systematic post-mortem examinations (n=59), on-site bacteriology and advanced molecular diagnostic techniques for specific pathogens. Causes of death on the breeding colony included starvation (30%), omphalitis-peritonitis (26%), septicaemia (22%), stillbirth (10%) and trauma (4%) and in the rehabilitation centre starvation (44%) and septicaemia (22%). Detailed key gross and histopathological findings and pathogens are described and include the first report of Listeria monocytogenes in any marine mammal.
Phocid herpes virus 1 nucleic acids were detected in nasal swabs of 58% live, free-ranging grey seal pups (n=90) and 28% yearlings (n=19), suggesting recrudescence in the latter. Previously undetected in Scotland, phocid herpes virus 2 nucleic acids were identified only in yearlings (15%); sealpox was detected in a single live stranded grey seal pup and phocine distemper virus was not detected.
Given their unique characteristics and potential for acting as sentinels of coastal marine health several pathogens of putative anthropogenic origin were investigated: Toxoplasma gondii, Neospora caninum, Salmonella spp. and Campylobacter spp. Toxoplasma gondii DNA was detected in 6% dead free-ranging grey seal pups (n=50) but N. caninum was not found. Salmonella (20%) and Campylobacter (50%) were isolated from rectal swabs of live and dead grey seal pups and Campylobacter was significantly associated with moderate to severe colitis implying pathogenicity. These findings imply a land-sea-land transfer of T. gondii and early exposure of pups to this parasite. Extensive genetic fingerprinting suggested an exchange of Salmonella between grey seal, cattle and human populations and that the Campylobacter isolates may share the same origin as human clinical isolates.
This work provides a solid base line study of diseases present in grey seal pups and demonstrates that they are useful indicators of coastal marine microbial contamination
Assessing grey seal (Halichoerus grypus) diet in western Scotland
No full textGrey seal diet was last comprehensively studied in western Scotland in 1985. Since then, the grey seal population has increased by approximately 30% and relative abundance of fish stocks in the area has changed markedly. The aim of this study was to provide a current assessment of diet to inform policy issues related to the impact of the still increasing grey seal population on commercial fish populations. During 2002, nine sampling trips totalling 56 days were completed around western Scotland, resulting in the collection of 1,589 grey seal scats. Forty-nine prey species were recorded in these samples revealing that grey seals on the west coast of Scotland remain highly catholic in their diet. Seasonal and regional variation in diet composition was assessed and the annual consumption of commercial fish species estimated. Proportions, by weight, of prey species indicated that gadoids were the main prey. Sandeels were also an important component of the diet. Comparisons between 1985 and 2002 revealed many similarities in diet composition but declines in the importance of sandeels, ling and megrim were balanced by increases in haddock, lemon sole, pelagic species and several benthic species. Changes in the size of fish stocks partially explain some of these changes. One exception is cod, which, despite very low abundance in 2002, formed a significant part of grey seal diet in western Scotland. Results from this study highlight the need for better methods for assessing absolute stock abundances for ‘critical’ fish species west of Scotland. Reducing the uncertainty over estimates of grey seal population size would also improve consumption estimates. The results from this study will be important to conservation and fisheries managers in Scotland
Grey seals (Halichoerus grypus) in the Dutch North sea: population ecology and effects of wind farms
No full textThis study was setup to gain an understanding of the possible effects of large-scale development of wind farms in Dutch waters on grey seals (Halichoerus grypus). This should be considered a first step in doing so as up until now relatively little was known about the species in Dutch waters. The study was carried out in the framework of WE@SEA a foundation aimed at acquiring knowledge in the field of offshore wind energy
Haul-out behaviour, site fidelity and vigilance of common seals (Phoca vitulina) and grey seals (Halichoerus grypus) in the tees Estuary
No full textThe project was carried out from the beginning of May to the beginning of July 1994, at Seal Sands, in the Tees estuary. The study aimed to examine (i) ecological and (ii) behavioural aspects of two species of seals, common seals (Phoca vitulina) and grey seals (Halichoerus grypus). The aims of the study were (i): (a) to document the seasonal fluctuation in number of seals using haul-out sites during May and June, (b) To compare activities between day and night time, (c) To examine possible factors influencing the proportion of the Tees population of common and grey seals hauling-out at Seal Sands, and factors conditioning haul- out site choice, (ii): (a) To examine distribution on haul-out sites and haul-out site fidelity, group and individual behaviour, (b) To determine vigilance behaviour in common and grey seals in relation to time of the day and group size. The number of seals hauled-out at Seal Sands, varied from day to day and night to night, and between successive low tides. The common seal number hauling-out, varied from a minimum of 13 to a maximum of 39, at day time, and from 9 to 15 at night time, these number increased gradually during the study period. The number of grey seals varied from nil on two occasions to 27 at daytime, and from 2 to 26 at night time. Both high and low number of common and grey seals tended to occur on the same days. The number of animals hauling out could be influenced by both environmental factors and population size at Teesmouth. Numbers of common seals at site C during day time was significantly and inversely related to the tide level at low water. The numbers of grey seals at site C at night time were inversely related to wind speed and positively related to maximum temperature. The changes in sites use are discussed in relation to physical characteristics of the sites and tide levels. Common and grey seals were observed to haul-out in restricted areas, although space availability was not a limiting factor. Common seals showed site fidelity both as individuals and as a group. Grey seals, show site fidelity as a group. Vigilance behaviour varied considerably within the two species of seals. In relation to the time of the day, the percentage of common seals alert, tended to decrease progressively after low tide. The percentage of grey seals alert was lower than in common seals with few peaks caused by sudden disturbance. Common seals show a strong negative correlation between the percentage of individuals alert and group size, whereas grey seals did not show any relation to the size of the group
Removal of micropollutants from grey water : combining biological and physical/chemical processes
No full textGrey water consists of the discharges from kitchen sinks, showers, baths, washing machines and hand basins. The amount of grey water produced per person in The Netherlands is about 90 Ld-1, accounting for up to 75 % of the wastewater volume produced by households, and over 90 % if vacuum toilets are installed. Grey water is relatively low in pollution and therefore, after appropriate treatment, has great potential for reuse in non-potable applications such as infiltration, irrigation, toilet flushing, laundry water, etc. The goal of this thesis was to develop a treatment concept for grey water to exploit its reuse potential. A special focus of this thesis was set on the study of organic micropollutants from personal care and household chemicals. Grey water (from 32 houses in Sneek, The Netherlands) contains, on average, 724-150 mgL-1 of chemical oxygen demand (COD), 27-12 mgL-1 of total nitrogen, 7.2-4.2 mgL-1 of phosphorus and 41-12 mgL-1 of anionic surfactants. The high biodegradability of grey water (70-5 %) indicated the possibility of recovering COD as methane. Biological treatment of grey water was conducted in three systems, aerobic, anaerobic and combined anaerobic + aerobic, at a total hydraulic retention time (HRT) of 12-13 hours at 32 °C. Aerobic treatment in a sequencing batch reactor resulted in COD removal of 90 %, which was significantly higher than 51 % removal by anaerobic treatment in an upflow anaerobic sludge blanket (UASB) reactor. Grey water treatment in a combined anaerobic + aerobic system resulted in a COD removal efficiency of 89 %. The application of a UASB reactor for the pre-treatment of grey water yielded a small amount of energy. Therefore, the aerobic system was preferred for grey water treatment. Bioflocculation of grey water in a high loaded membrane bioreactor was tested as alternative to aerobic treatment. The concentrated grey water of this process can potentially increase the methane yield by 73 % within ‘new sanitation' concepts. Eighteen compounds of personal care products and household chemicals (UV- filters, fragrances, preservatives, biocides, surfactants) were measured in grey water at low gL-1 levels. During biological treatment most of these compounds were partially removed. In general, the treatment in the aerobic system lead to the highest removal efficiencies of these compounds, where biodegradation and adsorption to sludge were the most likely removal mechanisms. However, the UV-filters PBSA and EHMC and the fragrance tonalide were poorly removed in the tested biological systems. Although reuse standards for these compounds do not exist, the post-reatment of aerobically treated effluent was recommended prior to reuse. Adsorption on activated carbon and ozonation were proven effective as post-treatment options for grey water
Characterization and treatment of grey water : option for (re)use
No full textAddressing the issues of water shortage and appropriate sanitation in Jordan, domestic grey water treatment receives growing interest. Grey water comprises the domestic wastewater flows excluding waters associated with the toilet. The topics of concern for grey water are its characteristics, treatment and potentials for use after treatment. The target of this thesis is to develop a concept for treating grey water on-site for agricultural usage, thus sustaining a recycling process of grey water in Jordan. A review was made regarding the currently available grey water treatment technologies. In addition, grey water was quantitatively and qualitatively characterized, and then grey water reuse requirements including treatment, were analyzed. Biodegradability and biodegradation rates of the grey water were investigated for selecting appropriate design and operation criteria of the treatment technology to be developed. A low-tech semi-technical scale treatment system was tested to treat grey water discharges from a dormitory at the Jordan University campus. The treatment system was evaluated on obtained removal efficiencies and conformity of the effluent to the guidelines for the use of reclaimed water for irrigation in Jordan. Finally, the objectives, approaches and the results of each chapter are summarized, and then both the results and the potential of applying decentralised sanitation and reuse (DeSaR) concepts in Jordan are discussed. Results show that storage and treatment are prerequisites for any type of grey water use. Grey water is aerobically and anaerobically biodegradable but the conversion rates are low. The core of the treatment concept consists of an integrated storage and anaerobic treatment unit, fed with a natural influent flow pattern, in a down-flow mode, up to a one day operational cycle, i.e. a variable HRT ≤ 24 hours. The second step consists of an aerobic post-treatment, mechanically aerated in a down-flow mode and a one day operational cycle, i.e. 24 hours HRT. Both units need insulation in the winter period. The final effluent, stable in winter and summer, meets the Jordanian standard, except for the pathogens, for usage in restricted irrigation. The achievable treatment efficiency for the CODtot is 44% in the anaerobic unit and 70% in the combined anaerobic-aerobic, unlike the high anaerobic and aerobic biodegradability in batch experiments, viz. 70 and 86%, respectively. The highest removal efficiency achieved was for the CODss fraction, viz. 71% in the anaerobic and 85% in the combined system. Therefore, it is expected that the CODtot removal efficiency of the system can be improved, by enhancing the CODcol and CODdis, removal, i.e. applying filtration and/or adding chemicals such as adsorbents, coagulants and/or flocculants to the treatment units. <br/
Information System for NGO Libraries in Pakistan: A Proposed Model for Organizing the Grey Literature by Syed Attaullah Shah and Humera Ilhaq
No full textAbstract
In recent years, especially in developed countries, various systems have been created to advance the management and organization of grey literature. Such systems use the latest communication technology and electronic and digital resources, and have developed huge networking systems to distribute and mange grey literature. Because of the scarcity of a global standardized organization system for grey literature and often limited access to computer technology, however, awareness of existence and access to grey literature is still seriously lacking, particularly in developing countries. Based on a survey of selected Pakistani NGOs from various sectors, this study proposes a new model. This paper explains the current usage patterns of grey literature in Pakistani organizations, then assesses their needs and resources for grey literature and finally recommends anew standardized model for organizing grey literature in the developing world. In this model a separate subject and classification scheme to control various types of grey literature, a shelving arrangement system and a networking system have been introduce
Copyright licenses and legal deposit practices of grey multimedia materials
No full textThe purpose of this study is to determine whether the type of copyright license under which grey multimedia materials are published makes a difference in terms of their inclusion in library catalogs. The two types of copyright licenses examined are Creative Commons and traditional copyright, and the library catalogs examined is that of the United States Library of Congress and national catalogs of countries represented in the population of the study. The population included grey multimedia materials whose main use is as educational materials, with half the items licensed under traditional copyright license and half licensed under Creative Commons license. The main finding of the study is that Creative Commons license is a barrier to access in traditional bibliographic utilities, and that traditional copyright is a barrier to access in web 2.0 environments. In addition, the study found weak enforcement of legal deposit laws regarding multimedia materials.Includes: Conference preprint, Powerpoint presentation, Abstract and Biographical notes, Pratt student commentaryXAInternationa
- …
