The use of distillation for converting sea water to non-saline water has a history dating back over 400 years. This problem has been especially troublesome in regard to the installation of evaporator units on shipboard, in which operation costs, steam consumption, and space requirements are critical. The major difficulty in the operation of the evaporators has been the deposition of an insulating scale composed of calcium sulfate, calcium carbonate, and magnesium hydroxide on the heat transfer surfaces of the evaporators. Various chemical and mechanical treatments have been successfully used by industry to prevent scale formation in fresh water distilling plants but these processes have not proved successfully used by industry to prevent scale formation in fresh water distilling plants but these processes have not proved successful when applied to salt water evaporators. A possible process for preventing scale formation in salt water evaporators has been proposed bt Armour Research Foundation whereby the carbon dioxide gas present in the sea water either as dissolved gas or combined in the form of carbonate and bicarbonate ions can be removed by heating the feed water to a temperature above 200°F, holding it at this temperature for at least 30 minutes and aerating the feed using compressed air. After about 50 percent of the carbon dioxide has been removed, the feed becomes saturated with magnesium hydroxide. The precipitate can be removed from the feed water by filtration, and the high alkalinity of the saturated solution can be reduced by injecting sufficient sulfuric acid into the feed water to the evaporator. Laboratory tests can indicate that feed water treated in this manner will not deposit calcium carbonate or magnesium hydroxide scale on the heat transfer surfaces of the evaporator. Full scale operational tests of this process are to be conducted at the Army Engineering Research and Development Laboratory, Distillation Test Station, Fort Story, Virginia. The purpose of this investigation is to determine the effect of decarbonation-filtration feed treatment of sea water in reducing scale formation in a 4,000-gallon per day, double effect, low pressure, Solo-shell evaporator. / Master of Science

No description available.

Phosphorus (P) is a requirement for biological growth, but this vital nutrient is present at low or limiting concentrations across vast areas of the global surface ocean. Inorganic polyphosphate (poly-P), a linear polymer of at least three orthophosphate units, is one component of the marine P cycle that has been relatively overlooked as compared to other P species, owing in part to a lack of routine analytical techniques that cleanly evaluate it within samples. This thesis demonstrates that inorganic poly-P is a quantitatively significant and dynamic component of the global marine P cycle while also establishing two new techniques for its analysis in biological and environmental samples. In Chapter 2, experiments using the freshwater algae Chlamydomonas sp. and Chlorella sp. illustrate X-ray fluorescence spectromicroscopy as a powerful tool for the sub-micron scale assessment of poly-P composition in organisms. This method enabled the discovery, detailed in Chapter 3, of a mechanism for the long-term sequestration of the vital nutrient P from marine systems via the initial formation of poly-P in surface waters and its eventual transformation into the mineral apatite within sediments. The importance of marine poly-P is furthermore established in Chapter 3 by observations showing that naturally-occurring poly-P represents 7-11% of total P in particles and dissolved matter in Effingham Inlet, a eutrophic fjord located on Vancouver Island, British Columbia. In Chapter 4, a new fluorometric protocol based on the interaction of inorganic poly-P with 4',6-diamidino-2-phenylindole (DAPI) is established as a technique for the direct quantification of poly-P in environmental samples. Chapter 5 presents work from Effingham Inlet utilizing this method that show that inorganic poly-P plays a significant role in the redox-sensitive cycling of P in natural systems.

Using seawater in cooling systems is a common practice in many parts of the world where there is a shortage of freshwater. However, biofouling is one of the major operational problems associated with the usage of seawater in cooling systems. Microfouling is caused by the activities of microorganisms, such as bacteria and algae, producing a very thin layer that sticks to the inside surface of the tubes in heat exchangers. This thin layer has a tremendously negative impact on heat transferred across the heat exchanger tubes in the system. In some instances, even a 250 micrometer thickness of fouling film can reduce the heat exchanger's heat transfer coefficient by 50 percent. On the other hand, macrofouling is the blockage caused by relatively large marine organisms, such as oysters, mussels, clams, and barnacles. A biocide is typically added to eliminate, or at least reduce, biofouling. Typically, microfouling can be controlled by intermittent dosages, and macrofouling can be controlled by continuous dosages of biocide. The aim of this research work is to develop a systematic approach to the optimal operating and design alternatives for integrated seawater cooling systems in industrial facilities. A process integration framework is used to provide a holistic approach to optimizing the design and operation of the seawater cooling system, along with the dosage and discharge systems. Optimization formulations are employed to systematize the decision-making and to reconcile the various economic, technical, and environmental aspects of the problem. Building blocks of the approach include the biocide water chemistry and kinetics, process cooling requirements, dosage scenarios and dynamic profiles, biofilm growth, seawater discharge, and environmental regulations. Seawater chemistry is studied with emphasis on the usage of biocide for seawater cooling. A multi-period optimization formulation is developed and solved to determine: * The optimal levels of dosing and dechlorination chemicals * The timing of maintenance to clean the heat-exchange * The dynamic dependence of the biofilm growth on the applied doses, the seawater-biocide chemistry, the process conditions, and seawater characteristics for each time period. The technical, economic, and environmental considerations of the system are accounted for and discussed through case studies.

Thesis (Ph. D.)--University of California, San Diego, 1998. / Vita. Includes bibliographical references (p. 150-155).

Thesis (doctoral)--Chalmers Tekniska högskola, 1972. / "Akademisk avhandling för filosofie doktorsexamen i kemi ... fredagen den 2 juni 1972 ... Chalmers tekniska högskola."

Freshwater rainbow trout were exposed to 9.2 µg/L total Ag (as AgNO3, a level approximately equal to the 168 h LC50) for 144 h to clarify the toxic mechanism of silver in freshwater teleosts. It was found that silver inhibits active Na+ and Cl- uptake at the gills, resulting in a net loss of both ions from the fish and creating a metabolic acidosis. This leads to a classic stress response (mobilization of cortisol and glucose into the blood plasma), and hyperventilation as a respiratory response to decreased blood pH. Plasma ammonia levels rise without any decrease in ammonia excretion; ammonia excretion later increases. This suggests that the increased plasma levels are due to increased metabolic production. Increased [H+] (decreased pH) results in excess H+ ions in the internal fluids, which are either complexed with ammonia to form NH4+ or are buffered in muscle tissue. The latter results in increased movement of K+ ions into the plasma, which are then excreted at the gills, preventing hyperkalemia. In the end, freshwater teleosts probably die from iono-and osmo-regulatory failure and associated cardiovascular collapse. Seawater teleosts (rainbow trout, tidepool sculpins, English sole, and plainfin midshipmen) and elasmobranchs (Pacific spiny dogfish and long nose skate) were exposed to constant concentrations on total Ag (as AgNO3) ranging from 1.5 to 50.0 µg/L for periods of up to 21 d at salinities of 18 ppt or 30 ppt. These exposure levels are well below those causing acute toxicity in seawater. Silver appears to enter marine teleosts and marine elasmobranchs differently. Seawater teleosts drink the seawater, so the intestines are a major site of silver uptake, along with the gills. Since marine elasmobranchs do not drink, the gills appear to be the sole site of silver uptake from the water. As in freshwater, the liver is the main site for silver accumulation in all marine fish studied. Despite similar terminal liver silver concentrations, marine elasmobranchs have a higher rate of silver accumulation since the livers in elasmobranchs are 10-20 fold larger than in teleosts. Both environmental salinity and exposure concentration play direct roles in determining silver bioaccumulation in marine teleosts. Increasing salinity alters the speciation of silver in the water, which decreases the amount of silver able to enter the fish. Increased silver concentrations mean more silver is available to enter the fish and subsequently cause sublethal toxic effects. Oxygen consumption decreased during the first 7 d of chronic exposure to sublethal silver levels in marine teleosts, with the decrease being more pronounced at higher (still sublethal) silver levels. Ammonia excretion, unaltered during acute exposure (48 h) to high silver levels (250 µg/L), was decreased during the first 7 d of exposure to sublethal silver levels (14.5-50.0 µg/L). This suggests that silver interferes with energy demanding processes such as protein synthesis or iono-regulation. Activity levels of the main enzyme involved in iono-regulation, namely Na+/K+ -ATPase, was affected differently in different fish. In a marine teleost that lives solely in seawater (plainfin midshipmen), silver inhibited the gill ATPase activity after 7 d of exposure, with the inhibition being more effective at higher silver levels. In the tidepool sculpin, a truly euryhaline species, gill ATPase activity increased as the silver levels increased, the latter probably representing a compensatory strategy. Similarly, intestinal ATPase activity was unchanged in the midshipmen, but was increased in the sculpins. Drinking rate in tidepool sculpins, which is involved with both iono-and osmo-regulation, was unaffected by salinity, but was decreased in fish exposed to silver for 8 d. Overall, Ag is far less toxic in seawater than in freshwater, but the mechanisms of toxicity are similar. In both waters, Ag interferes with iono- and osmo-regulation. In seawater, Ag exhibits a significant potential for bioaccumulation and interference with physiological processes during long term low level exposures of marine fish, especially at lower salinity levels. / Thesis / Master of Science (MSc)

Water and other volatiles (e.g. CO2, H2, CH4, etc.) are crucial components on Earth that ensure the habitability of the planet and play an important role in many geological processes. Small aliquots of these fluids can be preserved in the geological record as fluid inclusions and can provide valuable information about the physical and chemical environment in which they formed. The ocean is the largest water reservoir on the Earth's surface, and seawater participates in important water-rock reactions such as hydrothermal alteration of the ocean floor, a process that is currently in the spotlight for hypotheses on the origin of life, as it is an environment where generation of abiotic carbohydrates occur. The ocean chemistry varied in the geologic past to reflect major changes in the intensity of weathering, rates of midocean ridge hydrothermal discharge, changes in the climate and atmospheric CO2 concentration, and also played an important part in mass extinction events. Understanding the history of Earth's ancient oceans may hold the key to answer some of the important questions about the future of the Earth. Today, oceans hold valuable resources, such as offshore basalt formations which have been considered for submarine CO2 sequestration to mitigate greenhouse gas emissions associated with global warming. In the chapters of this dissertation, the reader will be presented with studies using fluid inclusions to advance our knowledge about the chemical evolution of seawater and reaction kinetics involving CO2, seawater and olivine – an abundant mineral in the oceanic lithosphere. Chapter I "Redox conditions in Late Permian seawater based on trace element ratios in fluid inclusions in halite from the Polish Zechstein Basin" describes application of a new redox proxy for paleo-seawater that involves analysis of redox-sensitive trace elements (e.g., Fe, Mn, U, V, Mo) in ancient seawater trapped as fluid inclusions in halite. Chapter II "Partitioning behavior of trace elements during evaporation of seawater" investigates the behavior of trace elements during the evaporation of seawater. This information is required to interpret trace element data from fluid inclusions in halite. In Chapter III "In situ monitoring of the carbonation of olivine under conditions relevant to carbon capture and storage using synthetic fluid inclusion micro-reactors: Determination of reaction rates", fluid inclusions are used as micro-reactors to monitor the reaction progress of olivine carbonation in situ and in real time at elevated temperatures (50-200 °C) and pressures using non-destructive analytical techniques such as Raman spectroscopy. / Doctor of Philosophy / Many geological processes on Earth involve water and other volatiles (e.g. CO2, H2, CH4, etc.) which are crucial components that ensure the habitability of the planet. These fluids can be preserved in the geological record in the form of fluid inclusions which are small aliquots of fluids trapped in minerals that provide information about the physical and chemical environment in which they formed. The majority of water on the Earth's surface is stored in the oceans. Seawater participates in important water-rock reactions, one of which is the hydrothermal alteration of the ocean floor. This reaction is in the spotlight currently because it represents an environment where generation of abiotic carbohydrates occur, giving rise for hypotheses about the origin of life on Earth. The chemical composition of seawater varied in the geologic past reflecting major changes in the intensity of weathering, discharge rate of midocean ridge hydrothermal systems, climate, and atmospheric CO2 concentration, and affected the survival of various marine species throughout Earth's history. For example, periodic extensions of oxygen minimum zones in the oceans played an important part in mass extinction events in the last 488 million years. Understanding the history of Earth's ancient oceans may hold the key to answer some of the important questions about the future of the Earth. Today, oceans hold valuable resources, such as offshore basalt formations which have been considered for submarine CO2 sequestration to mitigate greenhouse gas emissions associated with global warming. This dissertation explores ways to use fluid inclusions to advance our knowledge about the chemical evolution of seawater in the past and present, and the reaction of seawater with CO2 and olivine – an abundant mineral in the oceanic lithosphere – to facilitate long-term storage of CO2 in minerals to decrease the rate of global warming. Chapter I describes the application of a new redox proxy for paleo-seawater that involves analysis of redox-sensitive trace elements (elements whose solubility changes significantly as the oxidation state changes, such as Fe, Mn, U, V, Mo) in ancient seawater trapped as fluid inclusions in halite. The results suggest that trace element abundances in fluid inclusions in halite vary in response to redox changes in seawater and provide a potential redox proxy. Chapter II investigates the behavior of trace elements during the evaporation of seawater. This information is required to interpret trace element data from fluid inclusions in halite. The results of this study indicate that some elements remain in the water during evaporation of seawater (e.g. Li, B, Mo, U), while others are partially removed by precipitation of various mineral phases (e.g. Ba, Sr, Cs, Rb, Mn, V) as seawater evaporates. In Chapter III, fluid inclusions are used as micro-reactors to monitor the reaction progress of olivine carbonation in situ and in real time at elevated temperatures (50-200 °C) and pressures using non-destructive analytical techniques such as Raman spectroscopy. The results highlight that this reaction occurs rapidly, which makes it an ideal candidate for safe storage of CO2 by commercial CO2 injection projects in mafic and ultramafic rocks.

Yes / Multistage Flash (MSF) desalination process is still a dominant process, especially in the Gulf region, to produce high quality freshwater. Although there has been energy price surge in recent years, MSF process will continue to operate in that region for some foreseeable future. The key challenge is how to make such processes still profitable. Understanding the dynamics of any processes under uncertainty and disturbances is very important to make a process operationally feasible and profitable. The main aim of this work is to understand the dynamics of industrial scale MSF process using high fidelity and reliable process model. For this purpose, a detailed dynamic model for the MSF process incorporating key and new features is developed and validated against the actual data of a large-scale seawater desalination plant. The model is then used to study the behaviour of large scale MSF processes for disturbances in steam temperature, feed temperature and the recycle brine flow rate. The simulation results show that the last stage requires a longer time to settle compared to the preceding stages. In addition, steam temperature shows insignificant influence on the performance ratio compared to the inlet seawater temperature and recycle brine flow rate. Furthermore, it is found that the productivity of plant can increase in the winter compared to that in the summer. However, this benefit comes at the expense of increased steam consumption in the winter, resulting in a low performance ratio.

This study investigates the interactions between dissolved trace metals and plastic debris under controlled laboratory conditions by using polyethylene pellets as a model plastic particle. Specifically, the study compared virgin pellets sourced from a local moulding plant with those collected from local beaches and subjected to aging, attrition and deposition of extraneous material. Pellets collected from the coastline of Southwest England were mainly polyethylene according to Fourier transform infra-red spectroscopy (FTIR), although occasional polypropylene pellets were present. Additionally, FTIR was used to identify the extent of degradation of pellets according to a photo-oxidation index derived from the relative magnitudes of specific absorbance peaks, and suggests pellet colour may give an indication of polymer degradation. Acid extractions of pellets collected from the coastline of Southwest England yielded metal concentrations ranging from low ng g-1 for metals such as Cd, Ni and Cr, to 7.7, 10.3 and 290 g g-1 for Cu Pb and Zn, respectively, while Al, Fe and Mn were present on beached pellets at concentrations of up to 171, 314 and 308 g g-1, respectively. Metal concentrations exhibited a high degree of inter- and intra-site variability. Correlation of metal concentrations with the photo-oxidation index indicates that pellet age is not a reliable indicator of metal concentrations. Batch experiments where metals (Cd, Co, Cr, Cu, Ni, Pb, Zn) were added to suspensions of pellets in seawater and estuarine water were performed in order to understand the extent and rates of trace metal adsorption to pellets. Langmuir modelling of adsorption isotherms in seawater indicated a range of maximum values for the accumulation of trace metals on beached pellets from 10 ng g-1 to 720 ng g-1 for Cd and Pb, respectively, in seawater spiked with 5 g L-1 of each trace metal. Langmuir constants for these relationships ranged from 0.140 (Cd) to 2.67 (Ni) mL g-1. Differences between trace metal affinities for pellets collected from the environment (beached) and those obtained directly from a plastics processing facility (virgin) were also identified. Adsorption maxima for virgin pellets ranged from < 1 ng g-1 (Cd) to 300 ng g-1 (Cr) with corresponding, respective Langmuir constants of 0.413 and 0.127 mL g-1. Adsorption of trace metals to beached pellets exceeds that to virgin pellets owing to the development of viable surface sites by photo-oxidation, biofouling and deposition of fine sediment particles on the former during exposure to environmental conditions. Adsorption kinetics were modelled successfully using a pseudo first-order reversible model. Chemical response times derived from kinetic constants ranged from 1.5 – 12 h for beached pellets and 0.2 to 4.5 h for virgin pellets, and were generally lower in seawater than in river water. Applying a similar batch approach to a system simulating an estuarine salinity gradient, the controlling effects of ionic strength and pH on the adsorption of trace metals to pellets were identified. Partitioning of Cd, Co and Ni exhibited inverse relationships with salinity, with partition coefficients (KD) decreasing from values of the order 101 to 10-1 or 10-2 mL g-1 (for beached pellets) as salinity is increased from < 0.05 to 33. Chromium exhibited contrasting behaviour within the estuarine gradient, with partitioning increasing with salinity, while Pb appears to be independent of salinity within this system. Chemical modelling was used to explain the results in context of changes in trace metal speciation which occur through the estuarine gradient. The bioaccessibility of metals on beached pellets to avian species was determined using an in vitro approach. Metal bioaccessibility in a simulated avian gastric environment comprising 10 g L-1 pepsin, 0.1 M NaCl and HCl at pH 2.8 indicated metals on pellets are labile (bioaccessibility ranges from < 10 % (Cr) to > 80 % (Mn)) and may be released readily within the digestive tract. Dissolution kinetics were modelled using the Noyes-Whitney equation, from which rate constants were determined in the range 3.1 x10-4 (Cr) to 8.7 x10-1 %-1 h-1 (Mn). This study has shown, for the first time, that plastic pellets have the potential to accumulate and transport trace metals in the marine environment. Furthermore, metal accumulation on plastic pellets is controlled by estuarine master variables such that conditions which favour or limit adsorption can be defined. Pellets present a previously unreported vector for the transport of metals in the environment, and have the potential to convey metals to organisms upon ingestion. The findings of this thesis have implications for interactions between metals and plastics more generally in the marine environment.