Abstract: A shaft-type activated sludge reactor has been
developed in order to study the feasibility of high-rate wastewater
treatment. The reactor having volume of about 14.5 L was operated
with the acclimated mixed activated sludge under batch and
continuous mode using a synthetic wastewater as feed. The batch
study was performed with varying chemical oxygen demand (COD)
concentrations of 1000–3500 mg·L-1 for a batch period up to 9 h. The
kinetic coefficients: Ks, k, Y and kd were obtained as 2040.2 mg·L-1
and 0.105 h-1, 0.878 and 0.0025 h-1 respectively from Monod-s
approach. The continuous study showed a stable and steady state
operation for a hydraulic retention time (HRT) of 8 h and influent
COD of about 1000 mg·L-1. A maximum COD removal efficiency of
about 80% was attained at a COD loading rate and food-tomicroorganism
(F/M) ratio (COD basis) of 3.42 kg·m-3d-1 and 1.0
kg·kg-1d-1 respectively under a HRT of 8 h. The reactor was also
found to handle COD loading rate and F/M ratio of 10.8 kg·m-3d-1
and 2.20 kg·kg-1d-1 respectively showing a COD removal efficiency
of about 46%.
Abstract: The compressive strength development through
polymerization process of alkaline solution and fly ash blended with Microwave Incinerated Rice Husk Ash (MIRHA) is described in this
paper. Three curing conditions, which are hot gunny curing, ambient
curing, and external humidity curing are investigated to obtain the suitable curing condition for cast in situ provision. Fly ash was
blended with MIRHA at 3%, 5%, and 7% to identify the effect of blended mixes to the compressive strength and microstructure
properties of geopolymer concrete. Compressive strength results
indicated an improvement in the strength development with external humidity curing concrete samples compared to hot gunny curing and
ambient curing. Blended mixes also presented better performance
than control mixes. Improvement of interfacial transition zone (ITZ)
and micro structure in external humidity concrete samples were also
identified compared to hot gunny and ambient curing.
Abstract: Since water resources of desert Naein City are very
limited, a approach which saves water resources and meanwhile
meets the needs of the greenspace for water is to use city-s sewage
wastewater. Proper treatment of Naein-s sewage up to the standards
required for green space uses may solve some of the problems of
green space development of the city. The present paper closely
examines available statistics and information associated with city-s
sewage system, and determines complementary stages of sewage
treatment facilities of the city. In the present paper, population, per
capita water use, and required discharge for various greenspace
pieces including different plants are calculated. Moreover, in order to
facilitate the application of water resources, a Crude water
distribution network apart from drinking water distribution network is
designed, and a plan for mixing municipal wells- water with sewage
wastewater in proposed mixing tanks is suggested. Hence, following
greenspace irrigation reform and complementary plan, per capita
greenspace of the city will be increased from current amount of 13.2
square meters to 32 square meters.
Abstract: It has been shown that the solution of water shortage problem in Central Asia closely connected with inclusion of atmosphere water vapour into the system of response and water resources management. Some methods of water extraction from atmosphere have been discussed.
Abstract: This paper tries to study the effect of geosynthetic inclusion on the improvement of the load-settlement characters of two layered soil. In addition, the effect of geogrid and geotextile in reduction of the required thickness of subbase layer in unpaved roads is studied. Considering the vast application of bearing ratio tests in road construction projects, this test is used in present investigation. Bearing ratio tests were performed on two layered soil including a granular soil layer at the top (as the subbase layer) and a weak clayey soil placed at the bottom (as the subgrade layer). These tests were performed for different conditions including unreinforced and reinforced by geogrid and geotextile and three thicknesses for top layer soil (subbase layer). In the reinforced condition the reinforcing element was placed on the interface of the top granular layer and the beneath clayey layer to study the separation effect of geosynthetics. In all tests the soils (both granular and clayey soil layers) were compacted according to optimum water content. At the end, the diagrams were plotted and were compared with each other. Furthermore, a comparison between geogrids and geotextiles behaviors on two layer soil is done in this paper. The results show an increase in compression strength of reinforced specimen in comparison with unreinforced soil sample. The effect of geosynthetic inclusion reduces by increasing the subbase thickness. In addition it was found that geogrids have more desirable behavior rather than geotextiles due to interlocking with the subbase layer aggregates.
Abstract: Nanotechnology is the science of creating, using and
manipulating objects which have at least one dimension in range of
0.1 to 100 nanometers. In other words, nanotechnology is
reconstructing a substance using its individual atoms and arranging
them in a way that is desirable for our purpose.
The main reason that nanotechnology has been attracting
attentions is the unique properties that objects show when they are
formed at nano-scale. These differing characteristics that nano-scale
materials show compared to their nature-existing form is both useful
in creating high quality products and dangerous when being in
contact with body or spread in environment.
In order to control and lower the risk of such nano-scale particles,
the main following three topics should be considered:
1) First of all, these materials would cause long term diseases that
may show their effects on body years after being penetrated in human
organs and since this science has become recently developed in
industrial scale not enough information is available about their
hazards on body.
2) The second is that these particles can easily spread out in
environment and remain in air, soil or water for very long time,
besides their high ability to penetrate body skin and causing new
kinds of diseases.
3) The third one is that to protect body and environment against
the danger of these particles, the protective barriers must be finer than
these small objects and such defenses are hard to accomplish.
This paper will review, discuss and assess the risks that human and
environment face as this new science develops at a high rate.
Abstract: The present paper reports results of an experimental
program conducted to study performance of fly ash based
geopolymer pastes at elevated temperature. Three series of
geopolymer pastes differing in Na2O content (8.5%, 10% and 11.5%)
were manufactured by activating low calcium fly ash with a mixture
of sodium hydroxide and sodium silicate solution. The paste
specimens were subjected to temperatures as high as 900oC and the
behaviour at elevated temperatures were investigated on the basis of
physical appearance, weight losses, residual strength, shrinkage
measurements and sorptivity tests at different temperatures. Scanning
electron microscopy along with EDX and XRD tests were also
conducted to examine microstructure and mineralogical changes
during the thermal exposure. Specimens which were initially grey
turned reddish accompanied by appearance of small cracks as the
temperature increased to 900oC. Loss of weight was more in
specimens manufactured with highest Na2O content. Geopolymer
paste specimen containing minimum Na2O performed better than
those with higher Na2O content in terms of residual compressive
strength.
Abstract: Climate change leading to global warming affects the
earth through many different ways such as weather (temperature, precipitation, humidity and the other parameters of weather), snow coverage and ice melting, sea level rise, hydrological cycles, quality of water, agriculture, forests, ecosystems and health. One of the most
affected areas by climate change is hydrology and water resources.
Regions where majority of runoff consists of snow melt are more
sensitive to climate change. The first step of climate change studies
is to establish trends of significant climate variables including precipitation,
temperature and flow data to detect any potential climate
change impacts already happened. Two popular non-parametric trend
analysis methods, Mann-Kendal and Spearman-s Rho were applied
to Upper Euphrates Basin (Turkey) to detect trends of precipitation,
temperatures (maximum, minimum and average) and streamflow.
Abstract: The usual method of river flow diversion involves construction of tunnels and cofferdams. Given the fact that the cost of diversion works could be as high as 10-20% of the total dam construction cost, due attention should be paid to optimum design of the diversion works. The cost of diversion works depends, on factors, such as: the tunnel dimensions and the intended tunneling support measures during and after excavation; quality and characterizes of the rock through which the tunnel should be excavated; the dimensions of the upstream (and downstream) cofferdams; and the magnitude of river flood the system is designed to divert. In this paper by use of the cost of unit prices for tunnel excavation, tunnel lining, tunnel support (rock bolt + shotcrete) and cofferdam fill the cost function was determined. The function is then minimized by the aid of PSO Algorithm (particle swarm optimization). It is found that the optimum diameter and the total diversion cost are directly related to the river flood discharge (Q). It has also shown that in addition to optimum diameter design discharge (Q), river length, tunnel length, is mainly a function of the ratios (not the absolute values) of the unit prices and does not depend on the overall price levels in the respective country. The results of optimization use in some of the case study lead us to significant changes in the cost.