Abstract: Many water desalination technologies have been
developed but in general they are energy intensive and have high cost
and adverse environmental impact. Recently, adsorption technology
for water desalination has been investigated showing the potential of
using low temperature waste heat (50-85oC) thus reducing energy
consumption and CO2 emissions. This work mathematically
compares the performance of an adsorption cycle that produces two
useful effects namely, fresh water and cooling using two different
adsorbents, silica-gel and an advanced zeolite material AQSOA-ZO2,
produced by Mitsubishi plastics. It was found that at low chilled
water temperatures, typically below 20oC, the AQSOA-Z02 is more
efficient than silica-gel as the cycle can produce 5.8 m3 of fresh water
per day and 50.1 Rton of cooling per tonne of AQSOA-ZO2. Above
20oC silica-gel is still better as the cycle production reaches 8.4 m3
per day and 62.4 Rton per tonne of silica-gel. These results show the
potential of using the AQSOA-Z02 at low chilled water temperature
for water desalination and cooling applications.
Abstract: This paper presents effects of distilled water, seawater
and sustained bending strains of 30% and 50% ultimate strain at
room temperature, on the durability of unidirectional pultruded
carbon fiber reinforced polymer (CFRP) plates. In this study,
dynamic mechanical analyzer (DMA) was used to investigate the
synergic effects of the immersions and bending strains on the viscoelastic
properties of (CFRP) such as storage modulus, tan delta and
glass transition temperature. The study reveals that the storage
modulus and glass transition temperature increase while tan delta
peak decreases in the initial stage of both immersions due to the
progression of curing. The storage modulus and Tg subsequently
decrease and tan delta increases due to the matrix plasticization. The
blister induced damages in the unstrained seawater samples enhance
water uptake and cause more serious degradation of Tg and storage
modulus than in water immersion. Increasing sustained bending
decreases Tg and storage modulus in a long run for both immersions
due to resin matrix cracking and debonding. The combined effects of
immersions and strains are not clearly reflected due to the statistical
effects of DMA sample sizes and competing processes of molecular
reorientation and postcuring.
Abstract: Paints are the most widely used methods of protection
against atmospheric corrosion of metals. The aim of this work was to
determine the protective performance of epoxy coating against sea
water before and after damage.
Investigations are conducted using stationary and non-stationary
electrochemical tools such as electrochemical impedance
spectroscopy has allowed us to characterize the protective qualities of
these films. The application of the EIS on our damaged in-situ
painting shows the existence of several capacitive loops which is an
indicator of the failure of our tested paint. Microscopic analysis
(micrograph) helped bring essential elements in understanding the
degradation of our paint condition and immersion training corrosion
products.
Abstract: The crude oil in an oil well exists in various phases
such as gas, seawater, and sand, as well as oil. Therefore, a phase
separator is needed at the front of a single-phase pump for
pressurization and transfer. On the other hand, the application of a
multiphase pump can provide such advantages as simplification of the
equipment structure and cost savings, because there is no need for a
phase separation process. Therefore, the crude oil transfer method
using a multiphase pump is being applied to recently developed oil
wells. Due to this increase in demand, technical demands for the
development of multiphase pumps are sharply increasing, but the
progress of research into related technologies is insufficient, due to the
nature of multiphase pumps that require high levels of skills. This
study was conducted to verify the reliability of pump performance
evaluation using numerical analysis, which is the basis of the
development of a multiphase pump. For this study, a model was
designed by selecting the specifications of this study. The performance
of the designed model was evaluated through numerical analysis and
experiment. The results of the performance evaluation were compared
to verify the reliability of the result using numerical analysis.
Abstract: Qatar’s primary source of fresh water is through
seawater desalination. Amongst the major processes that are
commercially available on the market, the most common large scale
techniques are Multi-Stage Flash distillation (MSF), Multi Effect
distillation (MED), and Reverse Osmosis (RO). Although commonly
used, these three processes are highly expensive down to high energy
input requirements and high operating costs allied with maintenance
and stress induced on the systems in harsh alkaline media. Beside that
cost, environmental footprint of these desalination techniques are
significant; from damaging marine eco-system, to huge land use, to
discharge of tons of GHG and huge carbon footprint.
Other less energy consuming techniques based on membrane
separation are being sought to reduce both the carbon footprint and
operating costs is membrane distillation (MD).
Emerged in 1960s, MD is an alternative technology for water
desalination attracting more attention since 1980s. MD process
involves the evaporation of a hot feed, typically below boiling point
of brine at standard conditions, by creating a water vapor pressure
difference across the porous, hydrophobic membrane. Main
advantages of MD compared to other commercially available
technologies (MSF and MED) and specially RO are reduction of
membrane and module stress due to absence of trans-membrane
pressure, less impact of contaminant fouling on distillate due to
transfer of only water vapor, utilization of low grade or waste heat
from oil and gas industries to heat up the feed up to required
temperature difference across the membrane, superior water quality,
and relatively lower capital and operating cost.
To achieve the objective of this study, state of the art flat-sheet
cross-flow DCMD bench scale unit was designed, commissioned, and
tested. The objective of this study is to analyze the characteristics and
morphology of the membrane suitable for DCMD through SEM
imaging and contact angle measurement and to study the water
quality of distillate produced by DCMD bench scale unit.
Comparison with available literature data is undertaken where
appropriate and laboratory data is used to compare a DCMD distillate
quality with that of other desalination techniques and standards.
Membrane SEM analysis showed that the PTFE membrane used
for the study has contact angle of 127º with highly porous surface
supported with less porous and bigger pore size PP membrane. Study
on the effect of feed solution (salinity) and temperature on water
quality of distillate produced from ICP and IC analysis showed that
with any salinity and different feed temperature (up to 70ºC) the
electric conductivity of distillate is less than 5 μS/cm with 99.99%
salt rejection and proved to be feasible and effective process capable
of consistently producing high quality distillate from very high feed
salinity solution (i.e. 100000 mg/L TDS) even with substantial
quality difference compared to other desalination methods such as
RO and MSF.
Abstract: Green mussels (Perna viridis) can effectively remove
nutrients from seawater through their filtration process. This study
aims to estimate “net” nutrient removal rate by green mussel through
calculation of nutrient uptake and release. Nutrients (carbon, nitrogen
and phosphorus) uptake was calculated based on the mussel filtration
rate. Nutrient release was evaluated from carbon, nitrogen and
phosphorus released as mussel faeces. By subtracting nutrient release
from nutrient uptake, net nutrient removal by green mussel can be
found as 3302, 380 and 124 mg/year/indv. Mass balance model was
employed to simulate nutrient removal in actual green mussel
farming conditions. Mussels farm area, seawater flow rate, and
amount of mussels were considered in the model. Results show that
although larger quantity of green mussel farms lead to higher nutrient
removal rate, the maximum green mussel cultivation should be taken
into consideration as nutrients released through mussel excretion can
strongly affect marine ecosystem.
Abstract: Seawater desalination has been accepted as one of the most effective solutions to the growing problem of a diminishing clean drinking water supply. Currently two desalination technologies dominate the market – the thermally driven multi-stage flash distillation (MSF) and the membrane based reverse osmosis (RO). However, in recent years membrane distillation (MD) has emerged as a potential alternative to the established means of desalination. This research project intended to determine the viability of MD as an alternative process to MSF and RO for seawater desalination. Specifically the project involves conducting thermodynamic analysis of the process based on the second law of thermodynamics to determine the efficiency of the MD. Data was obtained from experiments carried out on a laboratory rig. To determine exergy values required for the exergy analysis, two separate models were built in Engineering Equation Solver – the ’Minimum Separation Work Model’ and the ‘Stream Exergy Model’. The efficiency of MD process was found to be 17.3 % and the energy consumption was determined to be 4.5 kWh to produce one cubic meter of fresh water. The results indicate MD has potential as a technique for seawater desalination compared to RO and MSF. However it was shown that this was only the case if an alternate energy source such as green or waste energy was available to provide the thermal energy input to the process. If the process was required to power itself, it was shown to be highly inefficient and in no way thermodynamically viable as a commercial desalination process.
Abstract: Changes in the sensory, chemical and microbiological quality of the Mediterranean hake during post-catch handling and distribution were investigated. 115 fish samples were seasonally received during three stages of the transfer route from the sea to the consumer and two storage methods were recorded, seawater and ice storage. Microbiological evaluation revealed higher status for the ice stored samples regarding heterotrophic bacteria (2.68 log cfu/g and 1.92 log cfu/g at 22oC and 37°C respectively) and psychrotrophic counts (3.20 log cfu/g), with statistically significant differences among storage methods. Sensory evaluation also revealed higher status for the ice stored samples with a mean quality index of 0.17 and a spoilage time estimated at 30 hours, in contrast to seawater storage, which varied from 0.28 to 0.3, and a 14-hour estimated spoilage. Detected pathogens were identified mainly in the seawater stored samples, posing questions on the quality of the product reaching the seafood markets.
Abstract: The hard clam (meretrix lusoria) cultivated industry
has been developed vigorously for recent years in Taiwan, and
seawater quality determines the cultivated environment. The pH
concentration variation affects survival rate of meretrix lusoria
immediately. In order to monitor seawater quality, solid-state sensing
electrode of ruthenium-doped titanium dioxide (TiO2:Ru) is developed
to measure hydrogen ion concentration in different cultivated
solutions. Because the TiO2:Ru sensing electrode has high chemical
stability and superior sensing characteristics, thus it is applied as a pH
sensor. Response voltages of TiO2:Ru sensing electrode are readout by
instrument amplifier in different sample solutions. Mean sensitivity
and linearity of TiO2:Ru sensing electrode are 55.20 mV/pH and 0.999
from pH1 to pH13, respectively. We expect that the TiO2:Ru sensing
electrode can be applied to real environment measurement, therefore
we collect two sample solutions by different meretrix lusoria
cultivated ponds in the Yunlin, Taiwan. The two sample solutions are
both measured for 200 seconds after calibration of standard pH buffer
solutions (pH7, pH8 and pH 9). Mean response voltages of sample 1
and sample 2 are -178.758 mV (Standard deviation=0.427 mV) and
-180.206 mV (Standard deviation =0.399 mV), respectively. Response
voltages of the two sample solutions are between pH 8 and pH 9 which
conform to weak alkali range and suitable meretrix lusoria growth. For
long-term monitoring, drift of cultivated solutions (sample 1 and
sample 2) are 1.16 mV/hour and 1.03 mV/hour, respectively.
Abstract: The effects of seawater and slurry ice bleeding methods on the sensory, microbiological and chemical quality changes of cod fillets during chilled storage were examined in this study. The results from sensory evaluation showed that slurry ice bleeding method prolonged the shelf life of cod fillets up to 13-14 days compared to 10-11 days for fish bled in seawater. Slurry ice bleeding method also led to a slower microbial growth and biochemical developments, resulting lower total plate count (TPC), H2S-producing bacteria count, total volatile basic nitrogen (TVB-N), trimethylamine (TMA), free fatty acid (FFA) content and higher phospholipid content (PL) compared to those of samples bled in seawater. The results of principle component analysis revealed that TPC, H2S-producing bacteria, TVB-N, TMA and FFA were in significant correlation. They were also in negative correlation with sensory evaluation (Torry score), PL and water holding capacity (WHC).
Abstract: The high world interest given to the researches concerning the study of moderately halophilic solvent-tolerant bacteria isolated from marine polluted environments is due to their high biotechnological potential, and also to the perspective of their application in different remediation technologies. Using enrichment procedures, I isolated two moderately halophilic Gram-negative bacterial strains from seawater sample, which are tolerant to organic solvents. Cell tolerance, adhesion and cells viability of Aeromonas salmonicida IBBCt2 and Pseudomonas aeruginosa IBBCt3 in the presence of organic solvents depends not only on its physicochemical properties and its concentration, but also on the specific response of the cells, and the cellular response is not the same for these bacterial strains. n-hexane, n-heptane, propylbenzene, with log POW between 3.69 and 4.39, were less toxic for Aeromonas salmonicida IBBCt2 and Pseudomonas aeruginosa IBBCt3, compared with toluene, styrene, xylene isomers and ethylbenzene, with log POW between 2.64 and 3.17. The results indicated that Aeromonas salmonicida IBBCt2 is more susceptible to organic solvents than Pseudomonas aeruginosa IBBCt3. The mechanisms underlying solvent tolerance (e.g., the existance of the efflux pumps) in Aeromonas salmonicida IBBCt2 and Pseudomonas aeruginosa IBBCt3 it was also studied.
Abstract: The aim of this paper is to compare the effectiveness and electrochemical behavior of typical oilfield corrosion inhibitors with previous oilfield corrosion inhibitors under the same electrochemical techniques to control preferential weld corrosion of X65 pipeline steel in artificial seawater saturated with carbon dioxide at a pressure of one bar. A secondary aim is to investigate the conditions under which current reversal takes place. A flow channel apparatus was used in the laboratory to simulate the actual condition that occurs in marine pipelines. Different samples from the parent metal, the weld metal and the heat affected zone in the pipeline steel were galvanically coupled. The galvanic currents flowing between the weld regions were recorded using zero-resistance ammeters and tested under static and flowing conditions in both inhibited and uninhibited media. The results show that a current reversal took place when 30ppm of both green oilfield inhibitors were present, resulting in accelerated weld corrosion.
Abstract: Monitoring of microbial flora in aquacultured sea bream, in relation to the physicochemical parameters of the rearing seawater, ended to a model describing the influence of the last to the quality of the fisheries. Fishes were sampled during eight months from four aqua farms in Western Greece and analyzed for psychrotrophic, H2S producing bacteria, Salmonella sp., heterotrophic plate count (PCA), with simultaneous physical evaluation. Temperature, dissolved oxygen, pH, conductivity, TDS, salinity, NO3 - and NH4 + ions were recorded. Temperature, dissolved oxygen and conductivity were correlated, respectively, to PCA, Pseudomonas sp. and Shewanella sp. counts. These parameters were the inputs of the model, which was driving, as outputs, to the prediction of PCA, Vibrio sp., Pseudomonas sp. and Shewanella sp. counts, and fish microbiological quality. The present study provides, for the first time, a ready-to-use predictive model of fisheries hygiene, leading to an effective management system for the optimization of aquaculture fisheries quality.
Abstract: Multiport diffusers are the effective engineering
devices installed at the modern marine outfalls for the steady
discharge of effluent streams from the coastal plants, such as
municipal sewage treatment, thermal power generation and seawater
desalination. A mathematical model using a two-dimensional
advection-diffusion equation based on a flat seabed and incorporating
the effect of a coastal tidal current is developed to calculate the
compounded concentration following discharges of desalination
brine from a sea outfall with multiport diffusers. The analytical
solutions are computed graphically to illustrate the merging of
multiple brine plumes in shallow coastal waters, and further
approximation will be made to the maximum shoreline's
concentration to formulate dilution of a multiport diffuser discharge.
Abstract: Membrane distillation (MD) is a rising technology for
seawater or brine desalination process. In this work, an air gap
membrane distillation (AGMD) performance was investigated for
aqueous NaCl solution along with natural ground water and seawater.
In order to enhance the performance of the AGMD process in
desalination, that is, to get more flux, it is necessary to study the
effect of operating parameters on the yield of distillate water. The
influence of operational parameters such as feed flow rate, feed
temperature, feed salt concentration, coolant temperature and air gap
thickness on the membrane distillation (MD) permeation flux have
been investigated for low and high salt solution. the natural
application of ground water and seawater over 90 h continuous
operation, scale deposits observed on the membrane surface and
reduction in flux represents 23% for ground water and 60% for
seawater, in 90 h. This reduction was eliminated (less than 14 %) by
acidification of feed water. Hence, promote the research attention in
apply of AGMD for the ground water as well as seawater
desalination over today-s conventional RO operation.
Abstract: The possibility of producing drinking water from
brackish ground water using Vacuum membrane distillation (VMD)
process was studied. It is a rising technology for seawater or brine
desalination process. The process simply consists of a flat sheet
hydrophobic micro porous PTFE membrane and diaphragm vacuum
pump without a condenser for the water recovery or trap. In this
work, VMD performance was investigated for aqueous NaCl solution
and natural ground water. The influence of operational parameters
such as feed flow rate (30 to 55 l/h), feed temperature (313 to 333 K),
feed salt concentration (5000 to 7000 mg/l) and permeate pressure
(1.5 to 6 kPa) on the membrane distillation (MD) permeation flux
have been investigated. The maximum flux reached to 28.34 kg/m2 h
at feed temperature, 333 K; vacuum pressure, 1.5 kPa; feed flow rate,
55 l/h and feed salt concentration, 7000 mg/l. The negligible effects
in the reduction of permeate flux found over 150 h experimental run
for salt water. But for the natural ground water application over 75 h,
scale deposits observed on the membrane surface and 29% reduction
in the permeate flux over 75 h. This reduction can be eliminated by
acidification of feed water. Hence, promote the research attention in
apply of VMD for the ground water purification over today-s
conventional RO operation.
Abstract: Perth will run out of available sustainable natural
water resources by 2015 if nothing is done to slow usage rates,
according to a Western Australian study [1]. Alternative water
technology options need to be considered for the long-term
guaranteed supply of water for agricultural, commercial, domestic
and industrial purposes. Seawater is an alternative source of water for
human consumption, because seawater can be desalinated and
supplied in large quantities to a very high quality.
While seawater desalination is a promising option, the technology
requires a large amount of energy which is typically generated from
fossil fuels. The combustion of fossil fuels emits greenhouse gases
(GHG) and, is implicated in climate change. In addition to
environmental emissions from electricity generation for desalination,
greenhouse gases are emitted in the production of chemicals and
membranes for water treatment. Since Australia is a signatory to the
Kyoto Protocol, it is important to quantify greenhouse gas emissions
from desalinated water production.
A life cycle assessment (LCA) has been carried out to determine
the greenhouse gas emissions from the production of 1 gigalitre (GL)
of water from the new plant. In this LCA analysis, a new desalination
plant that will be installed in Bunbury, Western Australia, and known
as Southern Seawater Desalinization Plant (SSDP), was taken as a
case study. The system boundary of the LCA mainly consists of three
stages: seawater extraction, treatment and delivery. The analysis
found that the equivalent of 3,890 tonnes of CO2 could be emitted
from the production of 1 GL of desalinated water. This LCA analysis
has also identified that the reverse osmosis process would cause the
most significant greenhouse emissions as a result of the electricity
used if this is generated from fossil fuels
Abstract: The effect of varying holding temperature on hatching success, occurrence of deformities and mortality rates were investigated for goldlined seabream eggs. Wild broodstock (600 g) were stocked at a 2:1 male-female ratio in a 2 m3 fiberglass tank supplied with filtered seawater (37 g L-1 salinity, temp. range 24±0.5 oC [day] and 22±1 oC [night], DO2 in excess of 5.0mg L-1). Females were injected with 200 IU kg-1 HCG between 08.00 and 10.00 h and returned to tanks to spawn following which eggs were collected by hand using a 100μm net. Fertilized eggs at the gastrulation stage (120 L-1) were randomly placed into one of 12 experimental 6 L aerated (DO2 5 mg L-1) plastic containers with water temperatures maintained at 24±0.5 oC (ambient), 26±0.5 oC, 28± 0.5 oC and 30±0.5 oC using thermostats. Each treatment was undertaken in triplicate using a 12:12 photophase:scotophase photoperiod. No differences were recorded between eggs reared at 24 and 26 oC with respect to viability, deformity, mortality or unhatched egg rates. Increasing temperature reduced the number of viable eggs with those at 30 oC returning poorest performance (P < 0.05). Mortality levels were lowest for eggs incubated at 24 and 26 oC. The greatest level of deformities recorded was that for eggs reared at 28 oC.
Abstract: The world demand for potable water is
increasing every day with growing population. Desalination
using solar energy is suitable for potable water production
from brackish and seawater. In this paper, we present a
theoretical study of solar distillation in a single basin under
the open environmental conditions of Chabahar-Iran. The still
has a base area of 2000mm×500mm with a glass cover
inclined at 25° in order to obtain extra solar energy. We model
the still and conduct its energy balance equations under minor
assumptions. We computed the temperatures of glass cover,
seawater interface, moist air and bottom using numerical
method. The investigation addressed the following: The still
productivity, distilled water salinity and still performance in
terms of the still efficiency. Calculated still productivity in
July was higher than December. So in this paper, we show
that still productivity is directly functioning of solar radiation.