Deposition of calcium carbonate (CaCO3) and calcium sulfate (CaSO4) causes serious processing problems and limits the productivity of seawater reverse osmosis (RO) desalination. The interactions between CaSO4 and CaCO3 in the dynamic seawater RO systems have been neglected previously because conventional studies mainly focused on individual compounds or mixed compounds in batch systems. The present work evaluates composite fouling behavior of CaSO4 and CaCO3 in a dynamic RO unit. The fouling experiments were performed at constant pressure and velocity by a partial recycling mode which permeate was withdrawn from the system during the recirculation of retentate to simulate the increasing of water recovery level. The fouling phenomena were monitored by the decline of flux. Scanning electron microscopy (SEM) with a combination of elemental dispersive x-ray microanalysis (EDS), and x-ray powder diffraction (XRD) was used to identify the morphological features, chemical compositions and crystalline phases of foulants. The interactions of CaSO4 and CaCO3 were investigated by the comparison between individual CaSO4 or CaCO3 fouling and composite fouling, and by varying SO42-/HCO3- molar ratio of the feed. A recently developed approach, Scaling Potential Index (SPI) incorporated with measured concentration polarization modulus (CP), for assessing the fouling tendency of inorganic salts on the membrane surface was validated in the dynamic tests. In addition, the effectiveness of two generic scale inhibitors, polyacrylic acid (molecular weight =2100, PA) and sodium hexametaphosphate (SHMP) were evaluated. Some of the highlights of the obtained results are as follows: ??????The precipitation kinetics, morphology and adhesive strength of composite scales were different from pure precipitates ??????CaSO4 precipitated as gypsum while CaCO3 precipitated as two crystalline phases: calcite and aragonite ??????The crystalline phases as well as precipitation kinetics were affected by SO42-/HCO3- ratio ??????Scaling Potential Index was able to predict the fouling tendency of CaSO4 and CaCO3 accurately ??????The dosage of PA and SHMP was effective to mitigate fouling Results of this work are significant, not only because they have made contribution to the fundamental understanding of composite inorganic fouling in RO membrane systems which was ignored previously, but also because they may play a key role in the development of scale control.

Cette étude est consacrée au comportement transitoire des cavités salines profondes. Dans la littérature, les auteurs se sont surtout intéressés au calcul du comportement des cavités salines sous chargement constant ou cyclique et à l'analyse du comportement d'éprouvettes de laboratoire en régime transitoire. Dans cette étude, on s'intéresse aux conséquences de ce dernier pour le comportement des cavités salines. Ainsi, on montre qu'une cavité est un système complexe, siège d'évolutions mécanique, thermique, chimique et hydraulique. L'importance des évolutions transitoires, notamment le rôle du fluage inverse dans l'interprétation de l'essai d'étanchéité dans une cavité saline, est mis en évidence. On caractérise le fluage par une formulation de la loi de c! omportement qui présente l'avantage, d'un point de vue pratique, de ne comporter qu'un nombre réduit de paramètres tout en rendant compte de l'essentiel de ce qui est observé en place. On discute l'apparition de la rupture en traction effective dans une cavité saline soumise à un accroissement rapide de la pression. On développe également un modèle adapté au comportement à très long terme (après abandon). Là aussi un grand nombre de phénomènes, plus ou moins couplés, interviennent, alors que la littérature existante n'en prenait en général en compte que quelques uns, ce qui pouvait conduire à une interprétation inexacte des résultats d'essais d'abandon effectués in situ.

Constructed wetland treatment systems are environmental-friendly and economic technologies for wastewater treatments. The Dapeng Bay National Scenic Area Administration collected the wastewaters from the salty water aquacultural ponds and community households in the adjacent areas and discharged them into salty water type of constructed wetland treatment systems, which is quite rare in Taiwan presently. According to the surveying result of water quality in these constructed wetland treatment systems in previous study, we found that some species of macroalgae Gracilaria, were existed in some units of the wetland systems. Further, we found that the wastewater treatment efficiencies of the constructed wetland systems could be substantially enhanced by the macroalgae. Reviewing some literatures also confirmed that the macroalgae, Gracilaria, can be effectively applied to aquaculture wastewater treatment because it is able to absorb the nutrients and benefits its own growth. Besides, it can reduce the algal bloom caused by excess nutrients. In this study, we explored the macroalgae Gracilaria¡¦s role in those saline constructed wetland wastewater treatment systems. In the laboratory scale study, a constructed wetland model tank was designed to culture Gracilaria as a way to explore the situation of wastewater treatment. The experimental results showed that when cultured in the still water system, the macroalgae, Gracilaria, was able to increase both of the levels of dissolved oxygen and pH in wastewater. Moreover, when it was cultured in its biomass density of 10 g/L for 4 days, the removal efficiency of chlorophyll-a concentration could ideally reach to 79.10 ¡Ó 7.62 %, while the total nitrogen, and total phosphorus could reach to 47.10 ¡Ó 25.93 % and 60.49 ¡Ó 45.29 % respectively. However, the reduction of ammonia nitrogen concentration was found rather obvious only one day after culture. Whereas, when the species of Gracilaria was cultured in the continuous flow system, we found that there were significant difference in the test result of the turbidity, chlorophyll-a, and BOD in the experimental group with addition of Gracilaria. After testing the concentrutions of chlorophyll-a over a long period of time, we found that the chlorophyll-a concentration were markedly increased when Gracilaria was not added. On the contrary, the chlorophyll-a concentration was remained stably when Gracilaria was added. When it comes to the nitrogen removal, we found that the removal efficiency of ammonia nitrogen in the experimental group could reach up to 92.27 ¡Ó 3.82 % in average. Other than that, it was found obvious decrease of the ammonia nitrogen concentration on the first day of culture. As to the test of soil¡¦s impact on the phosphorus removal, we found that the removal efficiency in the experimental group was higher than the group without soil. Therefore, the removal efficiency was found obviously higher when there was soil. In the continuous flow system, when the species of Gracilaria was added, the removal efficiency of total nitrogen and total phosphorus in the model tank could reach averagely up to 75.23 ¡Ó 2.46 % and 53.96 ¡Ó 11.18 %, respectively. Comparing the experimental results by growth of Gracilaria for water quality with laboratory study and the saline constructed wetland systems in the Dapeng Bay, we found that the removal efficiencies of contaminants and nutrients could be enhanced by Gracilaria.

Thesis (Ph. D.)--University of Nebraska, 1932. / Published also without thesis note under title: Pioneer days in Crete, Nebraska. eContent provider-neutral record in process. Description based on print version record. Bibliography: p. 224-236.

Implementing geological carbon sequestration at a scale large enough to mitigate emissions will involve the injection of supercritical CO₂ into deep saline aquifers. The principal technical risks associated with such injection are that (i) buoyant CO₂ will migrate out of the storage formation; (ii) pressure elevation during injection will limit storage rates and/or fracture the storage formation; and (iii) groundwater resources will be contaminated, directly or indirectly, by brine displaced from the storage formation. An alternative to injecting CO₂ as a buoyant phase is to dissolve it into brine extracted from the storage formation, then inject the CO₂-saturated brine into the storage formation. This "surface dissolution" strategy completely eliminates the risk of buoyant migration of stored CO₂. It greatly mitigates the extent of pressure elevation during injection. It nearly eliminates the displacement of brine. To gain these benefits, however, it is essential to determine the costs of this method of risk reduction. This work provides a framework for optimization of the process, and hence for cost minimization. Several investigations have tabulated the storage capacity for CO₂ in regions around the world, and it is widely accepted that sufficient pore volume exists in deep subsurface formations to permit large-scale sequestration of anthropogenic CO₂. Given the urgency of implementing geologic sequestration and other emissions-mitigating technologies (storage rates of order 1 Gt C per year are needed within a few decades), the time required to fill a target formation with CO₂ is just as important as the pore volume of that formation. To account for both these practical constraints we describe in this work a time-weighted storage capacity. This modified capacity integrates over time the maximum injection rate into a formation. The injection rate is a nonlinear function of time, formation properties and boundary conditions. The boundary conditions include the maximum allowable injection pressure and the nature of the storage formation (closed, infinite-acting, constant far-field pressure, etc.) The time-weighted storage capacity approaches the volumetric capacity as time increases. For short time intervals, however, the time-weighted storage capacity may be much less than the volumetric capacity. This work describes a method to compute time-weighted storage capacity for a database of more than 1200 North American oil reservoirs. Because all of these reservoirs have been commercially developed, their formation properties can be regarded as representative of aquifers that would be attractive targets for CO₂ storage. We take the product of permeability and thickness as a measure of injectivity for a reservoir, and the product of average areal extent, net thickness and porosity as a measure of pore volume available for storage. We find that injectivity is not distributed uniformly with volume: the set of reservoirs with better than average injectivity comprises only 10% of the total volumetric storage capacity. Consequently, time weighted capacity on time scale of a few decades is 10% to 20% of the nominal volumetric capacity. The non-uniform distribution of injectivity and pore volume in the database coupled with multiphase flow effects yields a wide distribution of “filling times”, i.e. the time required to place CO₂ up to the boundaries of the formation. We define two limiting strategies based on fill times of the storage structures in the database and use them to calculate resource usage for a target storage rate. Since fill times are directly proportional to injectivity, smallest fill time corresponds to best injectivity and largest fill time corresponds to smallest injectivity. If best injectivity structures are used first, then the rate at which new structures would be needed is greater than if worst injectivity structures are used first. A target overall storage rate could be maintained for longer period of time when worst injectivity structures are used first. Because of the kh vs PV correlation, most of the pore volume remains unused when no extraction wells are used. Extraction wells require disposal of produced brine, which is a significant challenge, or beneficial use of the brine. An example of the latter is the surface dissolution process described in this thesis, which would enable use of a much greater fraction of the untouched pore volume. / text

Final Report, Investigations on the Subsurface Disposal of Waste Effluents at Inland Sites / Grant No. 14-01-0001-1805 / United States Department of the Interior, The Office of Saline Water / By L.G. Wilson, Hydrologist, The Water Resources Research Center, The University of Arizona / February 1971.

Paleoclimatic research in the Canadian Arctic has increased in recent decades; however, there is still much to learn about the nature and extent of past climate change in this vast, environmentally sensitive region. This thesis uses diatom assemblages in dated lake sediment cores as proxy indicators to infer how climate has changed over the Holocene in two very different lakes in the central Canadian Arctic: one located in a poorly-studied geographical region, and another possessing limnological characteristics that are unusual in an Arctic context. Lake TK-2 is located in the low Arctic tundra. Paleolimnological studies from this region are lacking, as most have centered on sites in the High Arctic Archipelago or around Subarctic treeline. Marked changes in the diatom assemblages in TK-2 throughout the Holocene included potential evidence for the 8.2k cooling event, which has not been previously reported from other Canadian Arctic paleolimnological studies. In addition, diatom shifts occurring ~7000 and ~3500 cal yr BP are indicative of mid-Holocene warming and subsequent Neoglacial cooling, respectively, the timings of which agree with those from other studies farther south. Finally, shifts in the diatom assemblages in the upper sediment layers, beginning in the early-to-mid 19th century, are consistent with reduced ice cover, related to recent warming. Stygge Nunatak Pond, a small, closed-basin pond located on a nunatak in the High Arctic on Ellesmere Island, is characterized by unusually high ionic concentrations for an inland Arctic pond. As in TK-2, Stygge’s diatom assemblages changed substantially throughout the Holocene, but especially in the most recent sediments. Diatom shifts near ~10,500 cal yr BP suggest an early onset for the Holocene Thermal Maximum (and for the successive Neoglacial cooling trend) in this region, consistent with previous studies from the High Arctic. Marked diatom assemblage changes occurred in the most recent sediments, and are indicative of climate warming and reduced ice cover, as well as increased ionic concentration due to enhanced evaporative concentration. The dynamic nature of the diatom assemblage changes at the Stygge site suggests that sediments from these rare athalassic ponds represent an especially sensitive archive of Arctic climatic and environmental change. / Thesis (Master, Biology) -- Queen's University, 2008-11-12 16:46:47.174

Arid and semi-arid countries are facing the exhaustion of their water resources and are being forced to use saline water (brackish groundwater and drainage water) for irrigated agriculture. The result is often disastrous as extensive productive regions become salinized. Nevertheless, there is potential to expand irrigated agriculture through the increasing use of saline waters for irrigation. / This study presents an analysis of the performance of a transient state, model for numerical simulation of water and solute transport, known as LEACHM-C. It is assessed for areas where saline water may be an option for crop production. The model estimates the salt and water balance of a soil profile given certain irrigation and crop rotation strategies. / First, the predictive capability of the model was successfully tested using one year of data from a field experiment in a dry region of India. / Second, potential usefulness of the LEACHM-C model as a tool in the planning of reclamation activities was examined for a semi-arid basin in Syria. (Abstract shortened by UMI.)

Salinity is one of the most critical environmental problems for water scarce countries, / Thesis (Ph.D.Eng.)-University of KwaZulu-Natal, 2006.

Deposition of calcium carbonate (CaCO3) and calcium sulfate (CaSO4) causes serious processing problems and limits the productivity of seawater reverse osmosis (RO) desalination. The interactions between CaSO4 and CaCO3 in the dynamic seawater RO systems have been neglected previously because conventional studies mainly focused on individual compounds or mixed compounds in batch systems. The present work evaluates composite fouling behavior of CaSO4 and CaCO3 in a dynamic RO unit. The fouling experiments were performed at constant pressure and velocity by a partial recycling mode which permeate was withdrawn from the system during the recirculation of retentate to simulate the increasing of water recovery level. The fouling phenomena were monitored by the decline of flux. Scanning electron microscopy (SEM) with a combination of elemental dispersive x-ray microanalysis (EDS), and x-ray powder diffraction (XRD) was used to identify the morphological features, chemical compositions and crystalline phases of foulants. The interactions of CaSO4 and CaCO3 were investigated by the comparison between individual CaSO4 or CaCO3 fouling and composite fouling, and by varying SO42-/HCO3- molar ratio of the feed. A recently developed approach, Scaling Potential Index (SPI) incorporated with measured concentration polarization modulus (CP), for assessing the fouling tendency of inorganic salts on the membrane surface was validated in the dynamic tests. In addition, the effectiveness of two generic scale inhibitors, polyacrylic acid (molecular weight =2100, PA) and sodium hexametaphosphate (SHMP) were evaluated. Some of the highlights of the obtained results are as follows: ??????The precipitation kinetics, morphology and adhesive strength of composite scales were different from pure precipitates ??????CaSO4 precipitated as gypsum while CaCO3 precipitated as two crystalline phases: calcite and aragonite ??????The crystalline phases as well as precipitation kinetics were affected by SO42-/HCO3- ratio ??????Scaling Potential Index was able to predict the fouling tendency of CaSO4 and CaCO3 accurately ??????The dosage of PA and SHMP was effective to mitigate fouling Results of this work are significant, not only because they have made contribution to the fundamental understanding of composite inorganic fouling in RO membrane systems which was ignored previously, but also because they may play a key role in the development of scale control.