• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 120
  • 84
  • 28
  • 14
  • 11
  • 8
  • 4
  • 4
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 291
  • 86
  • 42
  • 41
  • 40
  • 33
  • 32
  • 31
  • 31
  • 27
  • 26
  • 26
  • 24
  • 24
  • 22
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Lagoon Effluent Polishing by Soil Mantle Treatment Using Various Utah Soil Types

Tinkey, Roger Scott 01 May 1975 (has links)
The purpose of this paper is to investigate the effectiveness of four Utah Great Basin soil types in removing particular chemical constituents and select enteric organisms from a sewage lagoon effluent. Sewage taken from the secondary oxidation pond in Logan, Utah was applied daily to lysimeters which allowed samples to be recovered at 7.6 and 38.1 centimeter soil depths. The texture of the soils was the most important physical property affecting their removal capacity. Drainage Farm soil (clay) provided the best bacteriological and overall chemical removal with Nibley (silty clay loam) second, then Draper (sandy loam) and Parleys (silty loam) last. The soils were analyzed before and after the test period to determine any major change which would ultimately affect their removal capacity. Noticeable changes occurred in phosphorus, percent organic matter and cation exchange capacity. The changes that did occur had no apparent effect on the removal capacity of any of the soil during the test period. The paper is dividen into three major parts: the bacteriological, the chemical, the initial and final soil comparison.
82

Biodegradation of xanthate by microbes isolated from a tailings lagoon and a potential role for biofilm and plant/microbe associations

Lam, Kin-San, University of Western Sydney, School of Science January 1999 (has links)
Xanthates, key compounds used in the mining industry for the separation of metals from ores, may have a significant impact on the ecosystems once discarded into the tailings. The aims of this study were to : characterize chemical and microbiological conditions in a tailings lagoon (Brown Creek gold mine); examine the feasability of using indigenous bacteria to degrade xanthate under laboratory conditions; and, optimize the biodegradation process by employing biofilm technology and plant-microbe associations. To achieve these, a simple but accurate HPLC method was developed. The chemical and biological constitution of the tailings lagoon was monitored over a 2 year period from March 1995 to February 1997. Xanthate degradative performance was improved by Phragmites australis and its root associated bacterial community. Cumulative amounts of xanthate degraded by this plant-microbe association were significantly higher than any other treatment, specifically glass-attached and free-living bacterial populations. An increased bacterial number in the extensively developed root, the presence of extracellular layer as revealed from scanning electron microscope and significance of plant removal via uptake were thought to be the possible explanations for the enhanced biodegradation activity observed. In view of the above, use of glass-attached bacteria and plant-microbe associations might provide a feasible solution to degrade xanthate in the tailings lagoon. The results obtained from this study suggest that the plant-microbe associations could provide a cost effective method to degrade/remove xanthate from the tailings lagoon runoff. This approach offers several ecological advantages. Firstly, it offers the advantage of a solar-powered treatment system that is aesthetically pleasing. Secondly, bioremediation can be done on site, thereby eliminating waste transportation costs. Finally, it has the added attraction of a higher potential for public acceptance / Doctor of Philosophy (PhD)
83

Systems management of Glenbrook Lagoon, New South Wales

Keogh, Andrew James, University of Western Sydney, Hawkesbury, Faculty of Science and Technology, School of Applied and Environmental Sciences January 1996 (has links)
Glenbrook Lagoon, an 8 hectare lake receiving rainfall runoff from a residential catchment, is experiencing nutrient enrichment problems expressed as excessive aquatic plant presence. This study aims to assess the relative nutrient contribution of the total system compartments, including catchment loading, water column, aquatic plants and surface sediment. This information is utilised in the formulation of management strategies which may produce a sustainable nutrient reduction and general improvement in the system. The total nutrient content of the aquatic system was determined to be high in comparison with the present nutrient loading from the catchment. The ideal management case considers nutrient reduction of the surface sediment compartment firstly, followed by the aquatic plant community, with the water column and catchment influence as relatively low priority compartments. Various strategies for managing these are proposed. The total system benefits of the ideal management case are reductions in nutrients, aquatic plant biovolume and suspended solid loading. Unavoidable constraints placed upon the ideal management case include the excessive aquatic plant presence restricting accessability to the surface sediment for dredging. The resulting best management case requires aquatic plant eradication prior to sediment management, with the total system benefits associated with the ideal management case being retained. / Master of Science (Hons)
84

Physical and Chemical Behaviour and Management of Intermittently Closed and Open Lakes and Lagoons (ICOLLs) in NSW

Haines, Philip Edward, n/a January 2006 (has links)
The term 'Intermittently Closed and Open Lake or Lagoon (ICOLL)' has been adopted in NSW to described wave dominated barrier estuaries with an intermittent connection to the ocean. ICOLLs can also be found in south east Queensland, south-west Western Australia, and some parts of Victoria and Tasmania, although they are not the dominant estuary type as in NSW. From an international perspective, ICOLLs are also found in South Africa, New Zealand, Mexico and the Atlantic coast of Brazil and Uruguay. Within NSW, ICOLLs are mostly located south of Sydney, due to the high wave activity and close proximity of the Great Dividing Range to the coast, which results in small coastal catchments and thus small fluvial and sediment runoff. The distinguishing difference between ICOLLs and other estuary types is the variable condition of their entrances, which also makes them the most sensitive type of estuary to human interference (HRC, 2002; Boyd et al., 1992). The sensitivity of ICOLLs to external inputs has been described in this thesis based on their morphometric characteristics, which includes their size, shape and predominant entrance condition. NSW ICOLLs exhibit a wide range of physical conditions. Some ICOLLs are rarely open to the ocean, while others are rarely closed. Also, some ICOLLs have experienced extensive development within their catchments, while some are located mostly or wholly within National Parks and other protected reserves. When closed, ICOLLs behave like terminal lakes, retaining and assimilating 100% of the external inputs delivered to the system. When open, tidal flushing assists with advection and dispersion of inputs, however, significant tidal attenuation across the entrance still limits opportunities for effective removal of pollutants. The majority of NSW ICOLLs are considered to be mostly closed (i.e., have a closed entrance for more than 60% of the time), while remaining ICOLLs tend to be mostly open (i.e., have a closed entrance for less than 20% of the time). Few ICOLLs have entrances that are open and closed for roughly equal proportions of time, thus resulting in a distinctive bimodal behaviour of entrance condition (i.e., mostly open or mostly closed). NSW ICOLLs tend to be mostly closed unless (i) the catchment is larger than 100km2, and/or (ii) the exposure of the entrance to ocean swell waves is less than 60 degrees and/or (iii) the entrance channel contains geomorphic controls (e.g. shallow bedrock outcrops). Unless opened artificially, ICOLLs will generally remain closed until a sufficient volume of catchment runoff accumulates within the waterway to increase water levels to a level that overtops (breaches) the entrance sand berm. Once breached, high velocity flows over the berm cause scour and the development of a formalised entrance channel, which increases exponentially until an optimum width and depth has been reached (determined by the hydrostatic head, geomorphic controls and tidal conditions at the time). Following entrance breakout and lowering of the lagoon level, sand is reworked back into the entrance under the influence of flood tides and wave processes. The environmental condition of ICOLLs has generally been assumed as being dependent on the state of the catchment and the associated input of nutrients (form and magnitude) to the system. Biogeochemical processes also are reported to influence the condition of ICOLLs, particularly denitrification, which is controlled by the organic load on the bed and the extent of benthic algae and macrophytic productivity. In addition to this, however, it is demonstrated that the predominant and prevailing entrance conditions (i.e. open or closed) also influence the physical, chemical and biological environments. ICOLLs are particularly susceptible to the impacts of future climate change. This thesis provides a description of expected impacts on NSW ICOLLs environments associated in response to future climate changes, based on a detailed appreciation of physical processes and their follow-on consequences. Impacts on ICOLLs are expected as a result of increasing sea level, altered rainfall patterns, and modified offshore wave climate. A survey of relevant government officials has revealed that more than 50% of NSW ICOLLs are artificially opened before water levels reach the height of the natural entrance sand berm. Artificial entrance opening is mostly carried out to mitigate inundation of public and/or private assets around ICOLL foreshores, such as roads, backyards, farming lands and on-site sewage (septic) systems. Truncation of the hydraulic regime of ICOLLs can modify other physical, chemical and biological processes, and can result in deleterious impacts such as the terrestrialisation of estuarine wetlands and foreshores. Few statutory environmental planning mechanisms protect ICOLLs from future degradation. This thesis has identified the key issues that potentially compromise ICOLL integrity and sustainability, which include the expected future population growth in coastal NSW (thus increasing pressure for intensification of development within ICOLL catchments), future climate change (particularly increases in sea level), and the increased demand for amenity, particularly during summer holiday periods (i.e. 'summer impacts'). A series of management models have been developed to address key issues. The models comprise a suite of strategies that target future development and existing management practices, through a range of new or modified planning instruments. Models for the future management of ICOLL entrances aim to prevent artificial openings in the long-term. This requires, however, the systematic relocation, raising or flood-proofing of public and private assets that have been established on land that is potentially subject to inundation. Increasing sea levels in the future will compound the need for improved entrance management. Pro-active, integrated and adaptive management strategies need to be implemented today to minimise the on-going conflict and potential for continued environmental degradation in the future.
85

Kartläggning och nedbrytning av komplexbildare i ett integrerat kartongbruk / Mapping and degradation of chelating agents in an integrated board mill

Löfgren, Lina, Olsson, Robert January 2006 (has links)
<p>Skoghalls Bruk fick i juni 2005 tillstånd av miljödomstolen att öka kartongproduktionen från 665 000 till 800 000 ton kartong per år. Villkoren för tillståndet var att under en prövotidsperiod bl.a. utreda möjligheten att minska utsläpp till omkringliggande vatten.</p><p>Syftet med examensarbetet var att kartlägga Skoghalls Bruks avloppssystem med avseende på komplexbildarna EDTA (etylendiamintetraättiksyra) och DTPA (dietylentriaminpentaättiksyra), kväve samt fosfor.</p><p>Dessutom genomfördes nedbrytningsförsök i luftade dammar i laboratorieskala.</p><p>För att få en klarare bild av nedbrytningen i Skoghalls Bruks luftade damm gjordes även en molekylviktsfraktionering på inkommande och utgående avloppsvatten.</p><p>Komplexbildare används inom pappers- och massaindustrin för sin förmåga att binda till sig metalljoner som kan vara skadliga i processen. Metalljoner katalyserar nedbrytningen av väteperoxid i blekningen och påskyndar bildandet av aldehyder i kartongen vilket kan leda till lukt- och smakpåverkan.</p><p>EDTA och DTPA anses vara stabila ämnen, vilket innebär att de är biologiskt svårnedbrytbara. Under den litteraturstudie som genomfördes fanns motsägande uppgifter angående nedbrytningen av komplexbildare, där vissa menade att de genomgår biologisk nedbrytning, men att det sker mycket långsamt. Andra påstod att komplexbildare inte bryts ner överhuvudtaget.</p><p>Komplexbildare kan elimineras genom fotokemisk oxidativ nedbrytning. Då EDTA och DTPA bildar komplex med Fe3+ blir de fotokemiskt labila och oxideras till mindre föreningar vid belysning med ultraviolett ljus. Sammanfattningsvis gav litteraturstudien att det mest effektiva sättet att minska komplexbildare i avloppsvatten innan det släpps till recipienten är att UV-bestråla vid optimala förhållanden, dvs. rätt pH och eventuellt tillsats av Fe3+ om det behövs.</p><p>Provtagning av avloppsvatten i Skoghalls Bruks reningsanläggning gjordes under 6 veckor för att kartlägga utsläppen och de olika delströmmarnas bidrag.</p><p>Nedbrytningsförsök genomfördes i två luftade dammar i laboratorieskala. För att studera temperaturens inverkan konstruerades en sommar- och en vinterdamm med temperaturerna 27 respektive 16°C. Efter referensförsöket, som gjordes för att se eventuella skillnader mellan försöken, undersöktes inverkan av ultraviolett ljus på nedbrytningen av komplexbildare. Sedan tillsattes Fe3+ i form av järnklorid i ett försök att öka den fotokemiska nedbrytningen. Alla försök pågick under två veckor vardera.</p><p>I syfte att undersöka partikelstorleksfördelningen före och efter nedbrytning i Skoghalls Bruks luftade damm gjordes en molekylviktsfraktionering. Inkommande och utgående avloppsvatten från dammen ultrafiltrerades och analyserades med avseende på COD (Chemical Oxygen Demand), komplexbildare, kväve och fosfor.</p><p>Kartläggningen visade att EDTA bröts ner effektivt i reningsanläggningen medan nedbrytningen av DTPA var obetydlig. EDTA reducerades med 88 % över den luftade dammen.</p><p>Avlopp från kartongmaskinerna samt CTMP-fabriken var de avlopp som innehöll mest EDTA. Största mängden DTPA återfanns i blekerifiltratet och i KM 8:s avlopp.</p><p>Skoghalls Bruk släppte ut komplexbildare motsvarande 0,188 kg/ton kartong, i form av 100 % syra i obunden form, under karteringsperioden vilket var klart lägre än gränsvärdet som är 1,6 kg 100 % syra/ton kartong.</p><p>Kväve reducerades med 67 % över den luftade dammen. Det nuvarande gränsvärdet för kväveutsläpp till recipient är 500 kg/dygn, men ett av målen med prövotidsutredningen är att minska utsläppen till 300 kg/dygn. Enligt resultaten från karteringsperioden var kväveutsläppet 204 kg/dygn vilket uppfyller målet för prövotidsutredningen. Av det totala kväveutsläppet kom 39 kg/dygn från komplexbildare. Utsläppet av kväve från mixeriavloppet var 56 kg/dygn till recipient vilket var klart högre än förväntat.</p><p>Den totala fosforreduceringen över reningsanläggningen var 78 %. Utsläppet av fosfor till recipient var 19 kg/dygn vilket är klart lägre än gränsvärdet som är 50 kg/dygn.</p><p>På grund av komplexbildaranalysens mätosäkerhet var det svårt att få entydiga resultat från laboratorieförsöken. Det fastställdes dock att DTPA var svårare att bryta ner än EDTA och att järntillsats i kombination med ultraviolett ljus gav en positiv effekt på nedbrytningen av båda komplexbildarna. Även nedbrytningen av COD, kväve och fosfor ökade vid järntillsats.</p><p>Att DTPA är svårare att bryta ner än EDTA framkom även av resultaten från molekylviktsfraktioneringen. Det visade sig också att EDTA och DTPA inte är helt vattenlösliga utan kan binda till fast material. Största delen av komplexbildarna fanns dock i fraktionen med partiklar med molekylvikt mindre än 1 kDa. Kväve och fosfor fanns i de låg- och högmolekylära fraktionerna.</p> / <p>In June of 2005 Skoghall Mill got permission from the Environmental Court to increase their production of board from 665 000 tons to 800 000 tons per year. The condition for the permission was to, during a trial period, investigate the possibility to decrease the emissions to the surrounding water. The purpose of this master thesis is to do a mapping of Skoghall Mill’s waste water treatment system regarding the chelating agents EDTA (ethylenediaminetetraacetic acid) and DTPA (diethylenetriaminepentaacetic acid), nitrogen and phosphor.</p><p>Also degradation-trials were made with aerated lagoons in laboratory-scale.</p><p>To get a more complete view of the degradation in Skoghalls Mills aerated lagoon a molecular weight fractionation of the incoming and the outgoing water was made.</p><p>Chelating agents are used in the pulp- and paper industry due to its ability to bind metal-ions which are hazardous for the process. The metal-ions catalyze the decomposition of hydrogen peroxide in the bleaching process and the forming of aldehydes in the board which can lead to problems with taste and odour.</p><p>EDTA and DTPA are regarded to be very stable, which means that they are hard to degrade biologically. There was contradictory information about the degradation of chelating agents during the literature survey. Some say that chelating agents are degraded biologically but very slowly. Others say that they don’t degrade at all.</p><p>Chelating agents can be eliminated through photochemical oxidative degradation. When EDTA and DTPA form complexes with Fe3+ they become photolabile and oxidize to smaller compounds at illumination with ultraviolet light. To sum up the literature survey, the most efficient way to reduce chelating agents in sewage water before discharge to receiving waters, is UV treatment at optimal conditions i.e., at the right pH and with addition of Fe3+ if necessary.</p><p>The sampling of the waste water in Skoghalls waste water treatment plant was made during 6 weeks to map the emissions and the contribution of the different sub-streams.</p><p>The degradation-trials were made in two aerated lagoons in laboratory-scale. To study the influence of temperature a summer- and a winter-lagoon were made and the temperatures were sat to, respectively, 27 and 16°C. After the reference-trial, which was made to determine possible differences between the trials, the influence of ultraviolet light on degradation of chelating agents were investigated. In an attempt to enhance the photochemical degradation, Fe3+ in the form of ferric chloride was then added. All trials went on for two weeks each.</p><p>In order to investigate the particle size distribution, before and after degradation in Skoghall Mill’s aerated lagoon, a molecule weight fractionation was made. Incoming and outgoing sewage water from the lagoon was ultra-filtrated and analyzed regarding COD (Chemical Oxygen Demand), chelating agents, nitrogen and phosphor.</p><p>The mapping showed that EDTA was efficiently degraded in the waste water treatment plant, while degradation of DTPA was insignificant. EDTA was reduced by 88 % trough the aerated lagoon.</p><p>Waste water from the board machines and the CTMP-plant contained the largest amount EDTA. DTPA was recovered mostly in the bleaching filtrate and KM 8’s waste water.</p><p>The emission of chelating agents, counted as acid, from Skoghall Mill during the period of the mapping was 0,188 kg/ton board which is well below the emission limit value of 1,6 kg/ton board.</p><p>Nitrogen was reduced by 67 % through the aerated lagoon. The present emission limit value for nitrogen is 500 kg/day. According to the results from the period of the mapping the emission of nitrogen was 204 kg/day which is well below the emission limit value. The contribution of chelating agents to the nitrogen emission was 39 kg/day. 56 kg nitrogen /day were recovered in the waste water from the causticizing area, which is remarkably higher than expected.</p><p>The total reduction of phosphor through the waste water treatment plant was 78 %. The emission of phosphor to receiving waters was 19 kg/day which is well below the emission limit value of 50 kg/day.</p><p>Due to the insecurity in measurement of chelating agents, it was difficult to retain unambiguous results from the laboratory-trials. However it was determined that DTPA was more difficult to degrade than EDTA and that a combination of ultraviolet light and addition of ferric iron had a favourable effect on the degradation of both chelating agents. Also the degradation of COD, nitrogen and phosphor increased when ferric iron was added.</p><p>The fact that DTPA are more difficult to degrade than EDTA was also stated in molecular weight fractionation. It was also shown that EDTA and DTPA weren’t totally water-soluble but can bind to solid material. The largest amount of chelating agents was recovered in the fraction with particles whose molecular weight is less than 1 kDa. Nitrogen and phosphor were recovered in the low- and high-molecular fractions.</p>
86

Testing the coastal decline model with flaked stone artifacts from the San Diego region of California

Iversen, David Richard. January 2007 (has links) (PDF)
Thesis (M.A. in anthropology)--Washington State University, May 2007. / Includes bibliographical references (p. 121-133).
87

The Legal and Social Repercussions of the Media on the Sleepy Lagoon Trial and the Zoot Suit Riots

Romero, Lori 12 May 2012 (has links)
People v. Zamora was a case that was decided on January 12, 1943, which led to the conviction and sentencing of five defendants guilty of assault, nine guilty of second degree murder, and three of first degree murder. This equals a total of seventeen convictions for the murder of one man, out of twenty two who were arrested. Along with those convictions, five women were arrested and, due mainly to their refusal to cooperate were sent to a woman’s reformatory (Barajas, 36). Yet there emerged many different problems that were relevant in this trial, which were brought about by both legal and social injustices. Even prior to the start of the trial there began to be a growing suspicious sentiment surfacing amongst the American people, due in large part to the yellow journalism that was going on at the moment. There were also many legal injustices that came about due to personal and social prejudice that governed the trial from beginning to end. Through the analysis of this trial, and the ensuing events, I will analyze the trial and focus on how pivotal the Zamora trial was legally. I will also examine the results of the trial and if they had any effect on the severe police brutality and the injustices being faced by the Mexican American people in the following years, specifically focusing on the Zoot Suit Riots. I will in conjunction with that analyze the social and political effects that both of these occurrences had on Chicanos, and their growing awareness of their rights. This case and the effects of it had long lasting consequences, changing the lives of many people, “this case involves the civil rights of the Mexican people, and, as an attack upon the democratic fabric, it involves all the people” (Cullen, 5).
88

Kartläggning och nedbrytning av komplexbildare i ett integrerat kartongbruk / Mapping and degradation of chelating agents in an integrated board mill

Löfgren, Lina, Olsson, Robert January 2006 (has links)
Skoghalls Bruk fick i juni 2005 tillstånd av miljödomstolen att öka kartongproduktionen från 665 000 till 800 000 ton kartong per år. Villkoren för tillståndet var att under en prövotidsperiod bl.a. utreda möjligheten att minska utsläpp till omkringliggande vatten. Syftet med examensarbetet var att kartlägga Skoghalls Bruks avloppssystem med avseende på komplexbildarna EDTA (etylendiamintetraättiksyra) och DTPA (dietylentriaminpentaättiksyra), kväve samt fosfor. Dessutom genomfördes nedbrytningsförsök i luftade dammar i laboratorieskala. För att få en klarare bild av nedbrytningen i Skoghalls Bruks luftade damm gjordes även en molekylviktsfraktionering på inkommande och utgående avloppsvatten. Komplexbildare används inom pappers- och massaindustrin för sin förmåga att binda till sig metalljoner som kan vara skadliga i processen. Metalljoner katalyserar nedbrytningen av väteperoxid i blekningen och påskyndar bildandet av aldehyder i kartongen vilket kan leda till lukt- och smakpåverkan. EDTA och DTPA anses vara stabila ämnen, vilket innebär att de är biologiskt svårnedbrytbara. Under den litteraturstudie som genomfördes fanns motsägande uppgifter angående nedbrytningen av komplexbildare, där vissa menade att de genomgår biologisk nedbrytning, men att det sker mycket långsamt. Andra påstod att komplexbildare inte bryts ner överhuvudtaget. Komplexbildare kan elimineras genom fotokemisk oxidativ nedbrytning. Då EDTA och DTPA bildar komplex med Fe3+ blir de fotokemiskt labila och oxideras till mindre föreningar vid belysning med ultraviolett ljus. Sammanfattningsvis gav litteraturstudien att det mest effektiva sättet att minska komplexbildare i avloppsvatten innan det släpps till recipienten är att UV-bestråla vid optimala förhållanden, dvs. rätt pH och eventuellt tillsats av Fe3+ om det behövs. Provtagning av avloppsvatten i Skoghalls Bruks reningsanläggning gjordes under 6 veckor för att kartlägga utsläppen och de olika delströmmarnas bidrag. Nedbrytningsförsök genomfördes i två luftade dammar i laboratorieskala. För att studera temperaturens inverkan konstruerades en sommar- och en vinterdamm med temperaturerna 27 respektive 16°C. Efter referensförsöket, som gjordes för att se eventuella skillnader mellan försöken, undersöktes inverkan av ultraviolett ljus på nedbrytningen av komplexbildare. Sedan tillsattes Fe3+ i form av järnklorid i ett försök att öka den fotokemiska nedbrytningen. Alla försök pågick under två veckor vardera. I syfte att undersöka partikelstorleksfördelningen före och efter nedbrytning i Skoghalls Bruks luftade damm gjordes en molekylviktsfraktionering. Inkommande och utgående avloppsvatten från dammen ultrafiltrerades och analyserades med avseende på COD (Chemical Oxygen Demand), komplexbildare, kväve och fosfor. Kartläggningen visade att EDTA bröts ner effektivt i reningsanläggningen medan nedbrytningen av DTPA var obetydlig. EDTA reducerades med 88 % över den luftade dammen. Avlopp från kartongmaskinerna samt CTMP-fabriken var de avlopp som innehöll mest EDTA. Största mängden DTPA återfanns i blekerifiltratet och i KM 8:s avlopp. Skoghalls Bruk släppte ut komplexbildare motsvarande 0,188 kg/ton kartong, i form av 100 % syra i obunden form, under karteringsperioden vilket var klart lägre än gränsvärdet som är 1,6 kg 100 % syra/ton kartong. Kväve reducerades med 67 % över den luftade dammen. Det nuvarande gränsvärdet för kväveutsläpp till recipient är 500 kg/dygn, men ett av målen med prövotidsutredningen är att minska utsläppen till 300 kg/dygn. Enligt resultaten från karteringsperioden var kväveutsläppet 204 kg/dygn vilket uppfyller målet för prövotidsutredningen. Av det totala kväveutsläppet kom 39 kg/dygn från komplexbildare. Utsläppet av kväve från mixeriavloppet var 56 kg/dygn till recipient vilket var klart högre än förväntat. Den totala fosforreduceringen över reningsanläggningen var 78 %. Utsläppet av fosfor till recipient var 19 kg/dygn vilket är klart lägre än gränsvärdet som är 50 kg/dygn. På grund av komplexbildaranalysens mätosäkerhet var det svårt att få entydiga resultat från laboratorieförsöken. Det fastställdes dock att DTPA var svårare att bryta ner än EDTA och att järntillsats i kombination med ultraviolett ljus gav en positiv effekt på nedbrytningen av båda komplexbildarna. Även nedbrytningen av COD, kväve och fosfor ökade vid järntillsats. Att DTPA är svårare att bryta ner än EDTA framkom även av resultaten från molekylviktsfraktioneringen. Det visade sig också att EDTA och DTPA inte är helt vattenlösliga utan kan binda till fast material. Största delen av komplexbildarna fanns dock i fraktionen med partiklar med molekylvikt mindre än 1 kDa. Kväve och fosfor fanns i de låg- och högmolekylära fraktionerna. / In June of 2005 Skoghall Mill got permission from the Environmental Court to increase their production of board from 665 000 tons to 800 000 tons per year. The condition for the permission was to, during a trial period, investigate the possibility to decrease the emissions to the surrounding water. The purpose of this master thesis is to do a mapping of Skoghall Mill’s waste water treatment system regarding the chelating agents EDTA (ethylenediaminetetraacetic acid) and DTPA (diethylenetriaminepentaacetic acid), nitrogen and phosphor. Also degradation-trials were made with aerated lagoons in laboratory-scale. To get a more complete view of the degradation in Skoghalls Mills aerated lagoon a molecular weight fractionation of the incoming and the outgoing water was made. Chelating agents are used in the pulp- and paper industry due to its ability to bind metal-ions which are hazardous for the process. The metal-ions catalyze the decomposition of hydrogen peroxide in the bleaching process and the forming of aldehydes in the board which can lead to problems with taste and odour. EDTA and DTPA are regarded to be very stable, which means that they are hard to degrade biologically. There was contradictory information about the degradation of chelating agents during the literature survey. Some say that chelating agents are degraded biologically but very slowly. Others say that they don’t degrade at all. Chelating agents can be eliminated through photochemical oxidative degradation. When EDTA and DTPA form complexes with Fe3+ they become photolabile and oxidize to smaller compounds at illumination with ultraviolet light. To sum up the literature survey, the most efficient way to reduce chelating agents in sewage water before discharge to receiving waters, is UV treatment at optimal conditions i.e., at the right pH and with addition of Fe3+ if necessary. The sampling of the waste water in Skoghalls waste water treatment plant was made during 6 weeks to map the emissions and the contribution of the different sub-streams. The degradation-trials were made in two aerated lagoons in laboratory-scale. To study the influence of temperature a summer- and a winter-lagoon were made and the temperatures were sat to, respectively, 27 and 16°C. After the reference-trial, which was made to determine possible differences between the trials, the influence of ultraviolet light on degradation of chelating agents were investigated. In an attempt to enhance the photochemical degradation, Fe3+ in the form of ferric chloride was then added. All trials went on for two weeks each. In order to investigate the particle size distribution, before and after degradation in Skoghall Mill’s aerated lagoon, a molecule weight fractionation was made. Incoming and outgoing sewage water from the lagoon was ultra-filtrated and analyzed regarding COD (Chemical Oxygen Demand), chelating agents, nitrogen and phosphor. The mapping showed that EDTA was efficiently degraded in the waste water treatment plant, while degradation of DTPA was insignificant. EDTA was reduced by 88 % trough the aerated lagoon. Waste water from the board machines and the CTMP-plant contained the largest amount EDTA. DTPA was recovered mostly in the bleaching filtrate and KM 8’s waste water. The emission of chelating agents, counted as acid, from Skoghall Mill during the period of the mapping was 0,188 kg/ton board which is well below the emission limit value of 1,6 kg/ton board. Nitrogen was reduced by 67 % through the aerated lagoon. The present emission limit value for nitrogen is 500 kg/day. According to the results from the period of the mapping the emission of nitrogen was 204 kg/day which is well below the emission limit value. The contribution of chelating agents to the nitrogen emission was 39 kg/day. 56 kg nitrogen /day were recovered in the waste water from the causticizing area, which is remarkably higher than expected. The total reduction of phosphor through the waste water treatment plant was 78 %. The emission of phosphor to receiving waters was 19 kg/day which is well below the emission limit value of 50 kg/day. Due to the insecurity in measurement of chelating agents, it was difficult to retain unambiguous results from the laboratory-trials. However it was determined that DTPA was more difficult to degrade than EDTA and that a combination of ultraviolet light and addition of ferric iron had a favourable effect on the degradation of both chelating agents. Also the degradation of COD, nitrogen and phosphor increased when ferric iron was added. The fact that DTPA are more difficult to degrade than EDTA was also stated in molecular weight fractionation. It was also shown that EDTA and DTPA weren’t totally water-soluble but can bind to solid material. The largest amount of chelating agents was recovered in the fraction with particles whose molecular weight is less than 1 kDa. Nitrogen and phosphor were recovered in the low- and high-molecular fractions.
89

Concentrations and distribution of polycyclic aromatic hydrocarbons(PAHs) and polychlorinated biphenyls(PCBs) in Kaohsiung Harbor

Chen, kai-ting 18 March 2010 (has links)
This study investigated the concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the particulate and dissolved phase, as well as concentrations of PAHs in the sediment in Kaohsiung Harbor lagoon. Sources of PAHs in the water column were determined by isomer ratios, hierarchical cluster analysis (HCA) and principal components analysis (PCA). The net and annual fluxes of PAHs were calculated after a lagoon-wide water sampling campaign and compared with those found in a previous study (Fang, 2007) in which data from only one water sampling station was used. ¡@¡@In rain season, total PAH concentrations ranged from 21.6 to 36.2 ng/L for water samples, with dissolved and particulate phase concentrations ranged from 15.5 to 27.2 ng/L and from 3.4 to 8.6 ng/L, respectively. In dry season, total PAH concentrations ranged from 13.2 to 31.5 ng/L for water samples, with dissolved and particulate phase concentrations ranged from 8.0 to 21.1 ng/L and from 5.3 to 10.5 ng/L, respectively. Total PAH concentrations were found higher in rain season than in dry season. The highest total PAH concentration in dry season was observed in Chianjen River estuary. Relatively high PAH concentrations were also observed in these southern stations of Kaohsiung Harbor because of their location near Dalin industrial park. Total PAH concentrations ranged from 81.7 to 2279 ng/g for sediment samples, with average of 895 ng/g. The correlations between PAH concentrations and organic carbons, water temperature, salinity and suspended particles were also examined in this study. PAH concentration in dissolved phase was negatively correlated with water temperature (p<0.05). PAH concentration in sediment was positively correlated with organic carbons (p<0.05), and negatively correlated with median diameter (p<0.01). The logKoc¡ÐlogKow relationship in rain and dry season was compared with literature. It was found that the logKoc values were higher than those reported in literature, suggesting that soot particles might play an important role in the transport and distribution of PAHs in the study area. In rain season, PAHs in dissolved phase were mainly from pyrogenic origins; while mainly from petrogenic origins in particulate phase. In contrast, in dry season, PAHs in dissolved phase were mainly from petrogenic origins; while mainly from pyrogenic origins in particulate phase. In addition, it was found, relatively, that petrogenic pollution was introduced maily from the northern area of the lagoon. In rain season, total PCB concentrations ranged from 1.1 to 2.7 ng/L for water samples, with dissolved and particulate phase concentrations ranged from 0.42 to 2.1 ng/L and from 0.24 to 1.4 ng/L, respectively. In dry season, total PCB concentrations ranged from 0.54 to 1.3 ng/L for water samples, with dissolved and particulate phase concentrations ranged from 0.20 to 0.74 ng/L and from 0.32 to 0.76 ng/L, respectively. The direction of net fluxes of PAHs in this study are from water to air (net volatilization) in summer. In winter, however, the absorptive PAH fluxes obtained for four to six-ring PAH, such as fluoranthrene, chrysene + triphenylene and benzo[a]anthracene, indicating that PAHs were absorbed into surface waters. According to our results, it was suggested that the results from previous study (Fang, 2007) might underestimate the net fluxes of Pyrene and total fluxes in dry season. The annual fluxes of PAHs estimated in this study were 212 mg/m2 /year and 5.7 kg of PAHs were emitted annually from the harbor lagoon surface waters to the ambient atmosphere.
90

Tidal Exchange Process at Ta-pon Bay

Cheng, Po-Hsin 29 August 2002 (has links)
The study site, Ta-pon Bay, is located in southwestern Taiwan that has the total volume of 9.92 x 106 m3, surface area of 4.46 x 106 m2, and an average depth of 2.19 m. The Ta-pon Bay is a shallow and semi-enclosed lagoon. The tidal regime at the Ta-pon Bay inlet is mixed, with diurnal dominance. There is noticeable amount of land-derived freshwater inflow in Ta-pon Bay and the mixing between the sea water and freshwater is largely determined by the tide. In order to understand the tidal exchange process between Ta-pon Bay and the coastal sea, the observation focused on the physiographic and hydrographic characteristics of this lagoon. The bathymetry of the study area was also surveyed. From the spatial sediment grain-size distribution pattern, the high energy region is at the inlet and the low energy region is in the interior of the lagoon. Our observation results indicate that freshwater outflow from the Kao-ping River was not transported into Ta-pon Bay. Tides are also the dominant cause for the water level fluctuations in the lagoon. In our winter observation, the local wind effects and atmospheric forcing dominated the subtidal sea surface fluctuations. In summer observation, the subtidal variability was strongly influenced by freshwater inflow. In Ta-pon Bay, the spatial salinity distribution was controlled by the flood and ebb tides, and the spatial temperature distribution was controlled by the different seasons. The tidal prism model can help us understand the tidal exchange between a shallow coastal lagoon and the open sea, and estimate the volume of freshwater inflow, return flow factor, and the turn-over time. Furthermore, we used a one-dimensional model to simulate the hydrodynamics of tidal inlet. The model results show good agreement with observations. We found that the superelevation of the lagoon was 20 cm. This mean sea level difference was caused by freshwater inflow and accumulation of lagoonward tidal transport of water.

Page generated in 0.0202 seconds