Abstract: In this paper, the dynamic characteristics of a threelobe
journal bearing lubricated with micropolar fluids are determined
by the linear stability theory. Lubricating oil containing additives and
contaminants is modelled as micropolar fluid. The modified
Reynolds equation is obtained using the micropolar lubrication theory
.The finite difference technique has been used to determine the
solution of the modified Reynolds equation. The dynamic
characteristics in terms of stiffness, damping coefficients, the critical
mass and whirl ratio are determined for various values of size of
material characteristic length and the coupling number. The
computed results show that the three-lobe bearing lubricated with
micropolar fluid exhibits better stability compared with that
lubricated with Newtonian fluid. According to the results obtained,
the effect of the parameter micropolar fluid is remarkable on the
dynamic characteristics and stability of the three-lobe bearing.
Abstract: Heavy metals are one of the major groups of
contaminants in the environment and many of them are toxic even at
very low concentration in plants and animals. However, some metals
play important roles in the biological function of many enzymes in
living organisms. Metals such as zinc, iron, and cooper are important
for survival and activity of enzymes in plants, however heavy metals
can inhibit enzyme which is responsible for defense system of plants.
Polyphenol oxidase (PPO) is a copper-containing metalloenzyme
which is responsible for enzymatic browning reaction of plants.
Enzymatic browning is a major problem for the handling of
vegetables and fruits in food industry. It can be increased and
effected with many different futures such as metals in the nature and
ground. In the present work, PPO was isolated and characterized
from green leaves of red poppy plant (Papaverr hoeas). Then, the
effect of some known antibrowning agents which can form
complexes with metals and metals were investigated on the red poppy
PPO activity. The results showed that glutathione was the most
potent inhibitory effect on PPO activity. Cu(II) and Fe(II) metals
increased the enzyme activities however, Sn(II) had the maximum
inhibitory effect and Zn(II) and Pb(II) had no significant effect on the
enzyme activity. In order to reduce the effect of heavy metals, the
effects of metal-antibrowning agent complexes on the PPO activity
were determined. EDTA and metal complexes had no significant
effect on the enzyme. L-ascorbic acid and metal complexes decreased
but L-ascorbic acid-Cu(II)-complex had no effect. Glutathione–metal
complexes had the best inhibitory effect on Red poppy leaf PPO
activity.
Abstract: Diverse contaminants released into the environment through progress of urbanization and industrialization adversely affect human health. Among various sources of contaminants, especially, in big cities, automobiles play a significant role in aggravating the pollution. Various pollutants viz., heavy metals (Pb, Mn, Ni, Zn, As, Hg, Cd) and Polyaromatic hydrocarbons (Benzo-a-pyrene, fluoranthene, pyrene, benzo-b-anthracene, benzo-b-fluoranthene, acenaphthylene, fluorine, phenantherene, anthracene, chrysene, benzo-k-fluoranthene, benzo-e-pyrene, indenol-1,2,3-cd-pyrene, dibenzo-a,h-anthracene, benzo-ghi-perylene) are released by vehicles. Further, these pollutants are expected to cause severe mutagenic, genotoxic and carcinogenic effects. Considering this, many authors monitored the levels of pollution in roadside soil, water and plants. The present review focuses upon the analysis and effects of heavy metals and polycyclic aromatic hydrocarbons from the roadside samples.
Abstract: Composting is a controlled technology to enhance the
natural aerobic process of organic wastes degradation. The resulting
product is a humified material that is principally recyclable for
agricultural purpose. The composting process is one of the most
important tools for waste management, by the European Community
legislation. In recent years composting has been increasingly used as
a remediation technology to remove biodegradable contaminants
from soil, and to modulate heavy metals bioavailability in
phytoremediation strategies. An optimization in the recovery of
resources from wastes through composting could enhance soil
fertility and promote its use in the remediation biotechnologies of
contaminated soils.
Abstract: Soil is a complex physical and biological system that provides support, water, nutrients and oxygen to the plants. Apart from these, it acts as a connecting link between inorganic, organic and living components of the ecosystem. In recent years, presence of xenobiotics, alterations in the natural soil environment, application of pesticides/inorganic fertilizers, percolation of contaminated surface water as well as leachates from landfills to subsurface strata and direct discharge of industrial wastes to the land have resulted in soil pollution which in turn has posed severe threats to human health especially in terms of causing carcinogenicity by direct DNA damage. The present review is an attempt to summarize literature on sources of soil pollution, characterization of pollutants and their consequences in different living systems.
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: The lignite-fired power plants in the Western Macedonia Lignite Center produce more than 8106 t of fly ash per year. Approximately 90% of this quantity is used for restoration-reclamation of exhausted open-cast lignite mines and slope stabilization of the overburden. The purpose of this work is to evaluate the environmental behavior of the mixture of waste rock and fly ash that is being used in the external deposition site of the South Field lignite mine. For this reason, a borehole was made within the site and 86 samples were taken and subjected to chemical analyses and leaching tests. The results showed very limited leaching of trace elements and heavy metals from this mixture. Moreover, when compared to the limit values set for waste acceptable in inert waste landfills, only few excesses were observed, indicating only minor risk for groundwater pollution. However, due to the complexity of both the leaching process and the contaminant pathway, more boreholes and analyses should be made in nearby locations and a systematic groundwater monitoring program should be implemented both downstream and within the external deposition site.
Abstract: The health and environmental risk of eating mushrooms grown in Abakaliki were evaluated in terms of heavy metals accumulation. Mushroom samples were collected from four different farms located at Izzi, Amajim, Amana and Amudo and analyzed for (iron, lead, manganese and cadmium) using Bulk Scientific Atomic Absorption Spectrophotometer 205. Results indicates mean range of concentrations of the trace metals in the mushrooms were Fe (0.22-152. 03), Mn (0.74-9.76), Pb (0.01.0.80), Cd (0.61-0.82) mg/L respectively. Accumulation of Cd on the four locations under investigation was higher than the UK Government Food Science Surveillance and World Health Organization maximum recommended levels in mushroom for human consumption. The Fe and Mn contaminants of Amudo were significant and show the impact of anthropogenic/atmospheric pollution. The potential sources of the heavy metals in the mushrooms were from urban waste, dust from mining and quarrying activities, natural geochemistry of the area, and use of inorganic fertilizers
Abstract: The aim of the study is to improve removal of trace organic contaminants dissolved in activated sludge by the process of filtration with membrane bioreactor combined with modified activated carbon, for a maximum removal of organic compounds characterized by low molecular weight. Special treatment was conducted in laboratory on activated carbon. Tow reaction parameters: the pH of aqueous middle and the type of granular activated carbon were very important to improve the removal and to motivate the electrostatic Interactions of organic compounds with modified activated carbon in addition to physical adsorption, ligand exchange or complexation on the surface activated carbon. The results indicate that modified activated carbon has a strong impact in removal 21 of organic contaminants and in percentage of 100% of the process.
Abstract: This research involves the design and analysis of pinch-based water/wastewater networks to minimize water utility in the petrochemical and petroleum industries. A study has been done on Tehran Oil Refinery to analyze feasibilities of regeneration, reuse and recycling of water network. COD is considered as a single key contaminant. Amount of freshwater was reduced about 149m3/h (43.8%) regarding COD. Re-design (or retrofitting) of water allocation in the networks was undertaken. The results were analyzed through graphical method and mathematical programming technique which clearly demonstrated that amount of required water would be determined by mass transfer of COD.
Abstract: Rapid industrialization has led to increased disposal of heavy metals into the environment. Activated carbon adsorption has proven to be an effective process for the removal of trace metal contaminants from aqueous media. This paper was investigated chromium adsorption efficiency by commercial activated carbon. The sorption studied as a function of activated carbon particle size, dose of activated carbon and initial pH of solution. Adsorption tests for the effects of these factors were designed with Taguchi approach. According to the Taguchi parameter design methodology, L9 orthogonal array was used. Analysis of experimental results showed that, the most influential factor was initial pH of solution. The optimum conditions for chromium adsorption by activated carbons were found to be as follows: initial feed pH 6, adsorbent particle size 0.412 mm and activated carbon dose 6 g/l. Under these conditions, nearly %100 of chromium ions was adsorbed by activated carbon after 2 hours.
Abstract: Geophagic and cosmetic clays are among potential nanomaterial which occur naturally and are of various forms. The use of these nanoclays is a common practice in both rural and urban areas mostly due to tradition and medicinal reasons. These naturally occurring materials can be valuable sources of nanomaterial by serving as nanocomposites. The need to ascertain the safety of these materials is the motivation for this research. Physical Characterization based on the hue value and microbiological qualities of the nanoclays were carried out. The Microbial analysis of the clay samples showed considerable contamination with both bacteria and fungi with fungal contaminants taking the lead. This observation may not be unlikely due to the ability of fungi species to survive harsher growth conditions than bacteria. ‘Atike pupa’ showed no bacterial growth. The clay with the largest bacterial count was Calabash chalk (Igbanke), while that with the highest fungal count was ‘Eko grey’. The most commonly isolated bacteria in this study were Clostridium spp. and Corynebacterium spp. while fungi included Aspergillus spp. These results are an indication of the need to subject these clay materials to treatments such as heating before consumption or topical usage thereby ascertaining their safety.
Abstract: Some of the main problems man contends with are the quantity (source and amount) and quality of water in Nigeria. Scarcity leads to water being obtained from various sources and microbiological contamination of the water may thus occur between the collection point and the point of usage. This study thus aims to assess the general and microbiological quality of domestic water sources and household stored water used within selected areas in Ile-Ife, South-Western part of Nigeria for microbial contaminants. Physicochemical and microbiological examination were carried out on 45 source and stored water samples collected from well and spring in three different local government areas i.e. Ife east, Ife-south and Ife-north. Physicochemical analysis included pH value, temperature, total dissolved solid, dissolved oxygen and biochemical oxygen demand. Microbiology involved most probable number analysis, total coliform, heterotrophic plate, faecal coliform and streptococcus count.
The result of the physicochemical analysis of samples showed anomalies compared to acceptable standards with the pH value of 7.20-8.60 for stored and 6.50-7.80 for source samples. The total dissolved solids (TDS of stored 20-70mg/L, source 352-691mg/L), dissolved oxygen (DO of stored 1.60-9.60mg/L, source 1.60-4.80mg/L), biochemical oxygen demand (BOD stored 0.80-3.60mg/L, source 0.60-5.40mg/L). General microbiological quality indicated that both stored and source samples with the exception of a sample were not within acceptable range as indicated by analysis of the MPN/100ml which ranges between (stored 290-1100mg/L, source 9-1100mg/L). Apart from high counts, most samples did not meet the World Health Organization standard for drinking water with the presence of some pathogenic bacteria and fungi such as Salmonella and Aspergillus spp. To annul these constraints, standard treatment methods should be adopted to make water free from contaminants. This will help identify common and likely water related infection origin within the communities and thus help guide in terms of interventions required to prevent the general populace from such infections.
Abstract: This research investigated treatment of crude carbon black produced from pyrolysis of waste tyres in order to evaluate its quality and possible industrial applications. A representative sample of crude carbon black was dry screened to determine the initial particle size distribution. This was followed by pulverizing the crude carbon black and leaching in hot concentrated sulphuric acid for the removal of heavy metals and other contaminants. Analysis of the refined carbon black showed a significant improvement of the product quality compared to crude carbon black. It was discovered that refined carbon black can be further classified into multiple high value products for various industrial applications such as filler, paint pigment, activated carbon and fuel briquettes.
Abstract: A water treatment technology employing the adsorption of dissolved organic contaminants from water and their electrochemical regeneration has been commercialized by Arvia Technology Ltd, UK. This technology focuses the adsorption of pollutants onto the surface of low surface area graphite based adsorbents followed by the anodic oxidation of adsorbed species in an electrochemical cell. However, some of the adsorbed species may lead to the formation of intermediate breakdown products due to incomplete oxidation. The information regarding the formation of breakdown products during electrochemical regeneration of these adsorbents is important for the effective application of this process to water treatment. In the present paper, the formation of the break down products during electrochemical regeneration of various graphite based adsorbents has been demonstrated.
Abstract: One of the major pollutants in the environment is arsenic (As). Due to the toxic effects of As to all organisms, its remediation is necessary. Conventional technologies used in the remediation of As contaminated soils are expensive and may even compromise the structure of the soil. An attractive alternative is phytoremediation, which is the use of plants which can take up the contaminant in their tissues. Plant growth promoting bacteria (PGPB) has been known to enhance growth of plants through several mechanisms such as phytohormone production, phosphate solubilization, siderophore production and 1-aminocyclopropane-1- carboxylate (ACC) deaminase production, which is an essential trait that aids plants especially under stress conditions such as As stress. Twenty one bacteria were isolated from As-contaminated soils in the vicinity of the Janghang Smelter in Chungnam Province, South Korea. These exhibited high tolerance to either arsenite (As III) or arsenate (As V) or both. Most of these isolates possess several plant growth promoting traits which can be potentially exploited to increase phytoremediation efficiency. Among the identified isolates is Pseudomonas sp. JS1215, which produces ACC deaminase, indole acetic acid (IAA), and siderophore. It also has the ability to solubilize phosphate. Inoculation of JS1215 significantly enhanced root and shoot length and biomass accumulation of maize under normal conditions. In the presence of As, particularly in lower As level, inoculation of JS1215 slightly increased root length and biomass. Ethylene increased with increasing As concentration, but was reduced by JS1215 inoculation. JS1215 can be a potential bioinoculant for increasing phytoremediation efficiency.
Abstract: Air pollution is still considered as one of the major
environmental and health issues. There is enough research evidence
to show a strong relationship between exposure to air contaminants
and respiratory illnesses among children and adults. In this paper we
used the Copula approach to study a potential relationship between
selected air pollutants (PM10 and NO2) and hospital admissions for
respiratory diseases. Kendall-s tau and Spearman-s rho rank
correlation coefficients are calculated and used in Copula method.
This paper demonstrates that copulas can be used to provide
additional information as a measure of an association when compared
to the standard correlation coefficients. The results find a significant
correlation between the selected air pollutants and hospital
admissions for most of the selected respiratory illnesses.
Abstract: The occurrence and removal of trace organic
contaminants in the aquatic environment has become a focus of
environmental concern. For the selective removal of carbamazepine
from loaded waters molecularly imprinted polymers (MIPs) were
synthesized with carbamazepine as template. Parameters varied were
the type of monomer, crosslinker, and porogen, the ratio of starting
materials, and the synthesis temperature. Best results were obtained
with a template to crosslinker ratio of 1:20, toluene as porogen, and
methacrylic acid (MAA) as monomer. MIPs were then capable to
recover carbamazepine by 93% from a 10-5 M landfill leachate
solution containing also caffeine and salicylic acid. By comparison,
carbamazepine recoveries of 75% were achieved using a nonimprinted
polymer (NIP) synthesized under the same conditions, but
without template. In landfill leachate containing solutions
carbamazepine was adsorbed by 93-96% compared with an uptake of
73% by activated carbon. The best solvent for desorption was
acetonitrile, with which the amount of solvent necessary and dilution
with water was tested. Selected MIPs were tested for their reusability
and showed good results for at least five cycles. Adsorption
isotherms were prepared with carbamazepine solutions in the
concentration range of 0.01 M to 5*10-6 M. The heterogeneity index
showed a more homogenous binding site distribution.
Abstract: Exposure to ambient air pollution has been linked to a
number of health outcomes, starting from modest transient changes in
the respiratory tract and impaired pulmonary function, continuing to
restrict activity/reduce performance and to the increase emergency
rooms visits, hospital admissions or mortality. The increase of
allergenic symptoms has been associated with air contaminants such
as ozone, particulate matter, fungal spores and pollen.
Considering the potential relevance of crossed effects of nonbiological
pollutants and airborne pollens and fungal spores on
allergy worsening, the aim of this work was to evaluate the influence
of non-biological pollutants (O3 and PM10) and meteorological
parameters on the concentrations of pollen and fungal spores using
multiple linear regressions.
The data considered in this study were collected in Oporto which
is the second largest Portuguese city, located in the North. Daily
mean of O3, PM10, pollen and fungal spore concentrations,
temperature, relative humidity, precipitation, wind velocity, pollen
and fungal spore concentrations, for 2003, 2004 and 2005 were
considered. Results showed that the 90th percentile of the adjusted
coefficient of determination, P90 (R2aj), of the multiple regressions
varied from 0.613 to 0.916 for pollen and from 0.275 to 0.512 for
fungal spores. O3 and PM10 showed to have some influence on the
biological pollutants. Among the meteorological parameters
analysed, temperature was the one that most influenced the pollen
and fungal spores airborne concentrations. Relative humidity also
showed to have some influence on the fungal spore dispersion.
Nevertheless, the models for each pollen and fungal spore were
different depending on the analysed period, which means that the
correlations identified as statistically significant can not be, even so,
consistent enough.
Abstract: This work addresses the problem of optimizing
completely batch water-using network with multiple contaminants
where the flow change caused by mass transfer is taken into
consideration for the first time. A mathematical technique for
optimizing water-using network is proposed based on
source-tank-sink superstructure. The task is to obtain the freshwater
usage, recycle assignments among water-using units, wastewater
discharge and a steady water-using network configuration by
following steps. Firstly, operating sequences of water-using units are
determined by time constraints. Next, superstructure is simplified by
eliminating the reuse and recycle from water-using units with
maximum concentration of key contaminants. Then, the non-linear
programming model is solved by GAMS (General Algebra Model
System) for minimum freshwater usage, maximum water recycle and
minimum wastewater discharge. Finally, numbers of operating periods
are calculated to acquire the steady network configuration. A case
study is solved to illustrate the applicability of the proposed approach.