Abstract: novel and simple method is introduced for rapid and
highly efficient water treatment by reverse osmosis (RO) method using
multi-walled carbon nanotubes (MWCNTs) / polyacrylonitrile (PAN)
polymer as a flexible, highly efficient, reusable and semi-permeable
mixed matrix membrane (MMM). For this purpose, MWCNTs were
directly synthesized and on-line purified by chemical vapor deposition
(CVD) process, followed by directing the MWCNT bundles towards an
ultrasonic bath, in which PAN polymer was simultaneously suspended
inside a solid porous silica support in water at temperature to ~70 οC.
Fabrication process of MMM was finally completed by hot isostatic
pressing (HIP) process. In accordance with the analytical figures of
merit, the efficiency of fabricated MMM was ~97%. The rate of water
treatment process was also evaluated to 6.35 L min-1. The results reveal
that, the CNT-based MMM is suitable for rapid treatment of different
forms of industrial, sea, drinking and well water samples.
Abstract: An optimal control of Reverse Osmosis (RO) plant is
studied in this paper utilizing the auto tuning concept in conjunction
with PID controller. A control scheme composing an auto tuning
stochastic technique based on an improved Genetic Algorithm (GA) is
proposed. For better evaluation of the process in GA, objective
function defined newly in sense of root mean square error has been
used. Also in order to achieve better performance of GA, more
pureness and longer period of random number generation in operation
are sought. The main improvement is made by replacing the uniform
distribution random number generator in conventional GA technique
to newly designed hybrid random generator composed of Cauchy
distribution and linear congruential generator, which provides
independent and different random numbers at each individual steps in
Genetic operation. The performance of newly proposed GA tuned
controller is compared with those of conventional ones via simulation.
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 draw solute separation process in Forward
Osmosis desalination was simulated in Aspen Plus chemical process
modeling software, to estimate the energy consumption and compare
it with other desalination processes, mainly the Reverse Osmosis
process which is currently most prevalent. The electrolytic chemistry
for the system was retrieved using the Elec – NRTL property method
in the Aspen Plus database. Electrical equivalent of energy required
in the Forward Osmosis desalination technique was estimated and
compared with the prevalent desalination techniques.
Abstract: In this paper, removal of chromium(VI) from aqueous
solution has been researched using reverse osmosis. The influence of
transmembrane pressure and feed concentration on permeate flux,
water recovery, permeate concentration, and salt rejection was
studied. The results showed that according to the variation of
transmembrane pressure and feed concentration, the permeate flux
and salt rejection were in the range 19.17 to 58.75 l/m2.min and
99.51 to 99.8 %, respectively. The highest permeate flux, 58.75
l/m2.min, and water recovery, 42.47 %, were obtained in the highest
pressure and the lowest feed concentration. On the other hand, the
lowest permeate concentration, 0.01 mg/l, and the highest salt
rejection, 99.8 %, were obtained in the highest pressure and the
lowest feed concentration.
Abstract: In a world worried about water resources with the
shadow of drought and famine looming all around, the quality of
water is as important as its quantity. The source of all concerns is the
constant reduction of per capita quality water for different uses.
Iran With an average annual precipitation of 250 mm compared to
the 800 mm world average, Iran is considered a water scarce country
and the disparity in the rainfall distribution, the limitations of
renewable resources and the population concentration in the margins
of desert and water scarce areas have intensified the problem.
The shortage of per capita renewable freshwater and its poor
quality in large areas of the country, which have saline, brackish or
hard water resources, and the profusion of natural and artificial
pollutant have caused the deterioration of water quality.
Among methods of treatment and use of these waters one can refer
to the application of membrane technologies, which have come into
focus in recent years due to their great advantages. This process is
quite efficient in eliminating multi-capacity ions; and due to the
possibilities of production at different capacities, application as
treatment process in points of use, and the need for less energy in
comparison to Reverse Osmosis processes, it can revolutionize the
water and wastewater sector in years to come. The article studied the
different capacities of water resources in the Persian Gulf and Oman
Sea watershed basins, and processes the possibility of using
nanofiltration process to treat brackish and non-conventional waters
in these basins.
Abstract: Enhancement of the performance of a reverse osmosis
(RO) unit through periodic control is studied. The periodic control
manipulates the feed pressure and flow rate of the RO unit. To ensure
the periodic behavior of the inputs, the manipulated variables (MV)
are transformed into the form of sinusoidal functions. In this case, the
amplitude and period of the sinusoidal functions become the
surrogate MV and are thus regulated via nonlinear model predictive
control algorithm. The simulation results indicated that the control
system can generate cyclic inputs necessary to enhance the closedloop
performance in the sense of increasing the permeate production
and lowering the salt concentration. The proposed control system can
attain its objective with arbitrary set point for the controlled outputs.
Successful results were also obtained in the presence of modeling
errors.