Abstract: The main objective of this study was to remove and recover Ni, Cu and Fe from a mixed metal system using sodium hypophosphite as a reducing agent and nickel powder as seeding material. The metal systems studied consisted of Ni-Cu, Ni-Fe and Ni-Cu-Fe solutions. A 5 L batch reactor was used to conduct experiments where 100 mg/l of each respective metal was used. It was found that the metals were reduced to their elemental form with removal efficiencies of over 80%. The removal efficiency decreased in the order Fe>Ni>Cu. The metal powder obtained contained between 97-99% Ni and was almost spherical and porous. Size enlargement by aggregation was the dominant particulate process.
Abstract: The aim of this study is to compare the effect of the ultrasonic pre treatment on the removal of heavy metals (Iron, Zinc and Copper) from Acid Mine Drainage (AMD) by Denver Cell flotation. Synthetic AMD and individual metal solutions are used in the initial experiments to optimise the process conditions for real AMD. Three different process methods, ultrasound treatment followed by Denver flotation cell, Denver flotation cell alone and ultrasonic treatments run simultaneously with the Denver flotation cell were tested for every sample. Precipitation of the metal solutions by using sodium hydroxide (NaOH) and application of the optimum frother dosage followed by flotation significantly reduced the metal content of the AMD.
Abstract: Fly ash is a significant waste that is released of
thermal power plants and defined as very fine particles that are drifted upward with up taken by the flue gases due to the burning of
used coal [1]. The fly-ash is capable of removing organic
contaminants in consequence of high carbon content, a large surface area per unit volume and contained heavy metals. Therefore, fly ash
is used as an effective coagulant and adsorbent by pelletization [2, 3].
In this study, the possibility of use of fly ash taken from Turkey like low-cost adsorbent for adsorption of zinc ions found in waste
water was investigated. The fly ash taken from Turkey was pelletized with bentonite and molass to evaluate the adsorption capaticity. For
this purpose; analyses such as sieve analysis, XRD, XRF, FTIR and SEM were performed. As a result, it was seen that pellets prepared
from fly ash, bentonite and molass would be used for zinc adsorption.
Abstract: Soil washing process with a surfactant solution is a potential technology for the rapid removal of hydrophobic organic compound (HOC) from soil. However, large amount of washed water would be produced during operation and this should be treated effectively by proper methods. The soil washed water for complex contaminated site with HOC and heavy metals might contain high amount of pollutants such as HOC and heavy metals as well as used surfactant. The heavy metals in the soil washed water have toxic effects on microbial activities thus these should be removed from the washed water before proceeding to a biological waste-water treatment system. Moreover, the used surfactant solutions are necessary to be recovered for reducing the soil washing operation cost. In order to simultaneously remove the heavy metals and HOC from soil-washed water, activated carbon (AC) was used in the present study. In an anionic-nonionic surfactant mixed solution, the Cd(II) and phenanthrene (PHE) were effectively removed by adsorption on activated carbon. The removal efficiency for Cd(II) was increased from 0.027 mmol-Cd/g-AC to 0.142 mmol-Cd/g-AC as the mole ratio of SDS increased in the presence of PHE. The adsorptive capacity of PHE was also increased according to the SDS mole ratio due to the decrement of molar solubilization ratios (MSR) for PHE in an anionic-nonionic surfactant mixture. The simultaneous adsorption of HOC and cationic heavy metals using activated carbon could be a useful method for surfactant recovery and the reduction of heavy metal toxicity in a surfactant-enhanced soil washing process.
Abstract: In an assessment of the extractability of metals in
green liquor dregs from the chemical recovery circuit of semichemical
pulp mill, extractable concentrations of heavy metals in
artificial gastric fluid were between 10 (Ni) and 717 (Zn) times
higher than those in artificial sweat fluid. Only Al (6.7 mg/kg; d.w.),
Ni (1.2 mg/kg; d.w.) and Zn (1.8 mg/kg; d.w.) showed extractability
in the artificial sweat fluid, whereas Al (730 mg/kg; d.w.), Ba (770
mg/kg; d.w.) and Zn (1290 mg/kg; d.w.) showed clear extractability
in the artificial gastric fluid. As certain heavy metals were clearly
soluble in the artificial gastric fluid, the careful handling of this
residue is recommended in order to prevent the penetration of green
liquor dregs across the human gastrointestinal tract.
Abstract: Soil microbial activity is adversely affected by pollutants such as heavy metals, antibiotics and pesticides. Organic amendments including sewage sludge, municipal compost and vermicompost are recently used to improve soil structure and fertility. But, these materials contain heavy metals including Pb, Cd, Zn, Ni and Cu that are toxic to soil microorganisms and may lead to occurrence of more tolerant microbes. Among these, Pb is the most abundant and has more negative effect on soil microbial ecology. In this study, Pb levels of 0, 100, 200, 300, 400 and 500 mg Pb [as Pb(NO3)2] per kg soil were added to the pots containing 2 kg of a loamy soil and incubated for 6 months at 25°C with soil moisture of - 0.3 MPa. Dehydrogenase activity of soil as a measure of microbial activity was determined on 15, 30, 90 and 180 days after incubation. Triphenyl tetrazolium chloride (TTC) was used as an electron acceptor in this assay. PICTs (IC50 values) were calculated for each Pb level and incubation time. Soil microbial activity was decreased by increasing Pb level during 30 days of incubation but the induced tolerance appeared on day 90 and thereafter. During 90 to 180 days of incubation, the PICT was gradually developed by increasing Pb level up to 200 mg kg-1, but the rate of enhancement was steeper at higher concentrations.
Abstract: The main objective of this research was to investigate
the biosorption capacity for biofilms of sulphate reducing bacteria
(SRB) to remove heavy metals, such as Zn, Pb and Cd from
rainwater using laboratory-scale reactors containing mixed support
media. Evidence showed that biosorption had contributed to removal
of heavy metals including Zn, Pb and Cd in presence of SRB and
SRB were also found in the aqueous samples from reactors.
However, the SRB and specific families (Desulfobacteriaceae and
Desulfovibrionaceae) were found mainly in the biomass samples
taken from all reactors at the end of the experiment. EDX-analysis
of reactor solids at end of experiment showed that heavy metals Zn,
Pb and Cd had also accumulated in these precipitates.
Abstract: Several different cements have been tested to evaluate
their potential to leach calcium, chromium and aluminum ions in soft
water environment. The research allows comparing some different
cements in order to the potential risk of water contamination. This
can be done only in the same environment. To reach the results in
reasonable short time intervals and to make heavy metals
measurements with high accuracy, demineralized water was used. In
this case the conditions of experiments are far away from the water
supply practice, but short time experiments and measurably high
concentrations of elements in the water solution are an important
advantage. Moreover leaching mechanisms can be recognized, our
experiments reported here refer to this kind of cements evaluation.
Abstract: Zeolite A and MCM-41 have extensive applications in basic science, petrochemical science, energy conservation/storage, medicine, chemical sensor, air purification, environmentally benign composite structure and waste remediation. However, the use of zeolite A and MCM-41 in these areas, especially environmental remediation, are restricted due to prohibitive production cost. Efficient recycling of and resource recovery from coal fly ash has been a major topic of current international research interest, aimed at achieving sustainable development of human society from the viewpoints of energy, economy, and environmental strategy. This project reported an original, novel, green and fast methods to produce nano-porous zeolite A and MCM-41 materials from coal fly ash. For zeolite A, this novel production method allows a reduction by half of the total production time while maintaining a high degree of crystallinity of zeolite A which exists in a narrower particle size distribution. For MCM-41, this remarkably green approach, being an environmentally friendly process and reducing generation of toxic waste, can produce pure and long-range ordered MCM-41 materials from coal fly ash. This approach took 24 h at 25 oC to produce 9 g of MCM-41 materials from 30 g of the coal fly ash, which is the shortest time and lowest reaction temperature required to produce pure and ordered MCM-41 materials (having the largest internal surface area) compared to the values reported in the literature. Performance evaluation of the produced zeolite A and MCM-41 materials in wastewater treatment and air pollution control were reported. The residual fly ash was also converted to zeolite Na-P1 which showed good performance in removal of multi-metal ions in wastewater. In wastewater treatment, compared to commercial-grade zeolite A, adsorbents produced from coal fly ash were effective in removing multi heavy metal ions in water and could be an alternative material for treatment of wastewater. In methane emission abatement, the zeolite A (produced from coal fly ash) achieved similar methane removal efficiency compared to the zeolite A prepared from pure chemicals. This report provides the guidance for production of zeolite A and MCM-41 from coal fly ash by a cost-effective approach which opens potential applications of these materials in environmental industry. Finally, environmental and economic aspects of production of zeolite A and MCM-41 from coal fly ash were discussed.
Abstract: This study aimed to evaluate regional soil Borkhar of
the metals Lead has been made. In this field study fires visits to the
regions. The limit of this study located in the East refineries,
petrochemical and power plant to 20 km was selected. The 41 soil
samples from depths of 0 to 10 cm in area and were randomized. Soil
samples were transported to the laboratory and by air was dry and
passed through 2-mil thickness sieve. In the laboratory of physical
and chemical characteristics and concentrations of total absorption
was measured. The results showed that the amount of lead in soil in
many parts of the range higher than the standard limit. Survey maps
show that the lead spatial distribution of the region does not special
pattern.
Abstract: The concentrations of As, Hg, Co, Cr and Cd were
tested for each soil sample, and their spatial patterns were analyzed
by the semivariogram approach of geostatistics and geographical
information system technology. Multivariate statistic approaches
(principal component analysis and cluster analysis) were used to
identify heavy metal sources and their spatial pattern. Principal
component analysis coupled with correlation between heavy metals
showed that primary inputs of As, Hg and Cd were due to
anthropogenic while, Co, and Cr were associated with pedogenic
factors. Ordinary kriging was carried out to map the spatial patters of
heavy metals. The high pollution sources evaluated was related with
usage of urban and industrial wastewater. The results of this study
helpful for risk assessment of environmental pollution for decision
making for industrial adjustment and remedy soil pollution.
Abstract: The present work is concerned with sulfidation of Cu,
Zn and Ni containing plating wastewater with CaS. The sulfidation
experiments were carried out at a room temperature by adding solid
CaS to simulated metal solution containing either single-metal of Ni,
Zn and Cu, or Ni-Zn-Cu mixture. At first, the experiments were
conducted without pH adjustment and it was found that the complete
sulfidation of Zn and Ni was achieved at an equimolar ratio of CaS to a
particular metal. However, in the case of Cu, a complete copper
sulfidation was achieved at CaS to Cu molar ratio of about 2. In the
case of the selective sulfidation, a simulated plating solution
containing Cu, Zn and Ni at the concentration of 100 mg/dm3 was
treated with CaS under various pH conditions. As a result, selective
precipitation of metal sulfides was achieved by a sulfidation treatment
at different pH values. Further, the precipitation agents of NaOH,
Na2S and CaS were compared in terms of the average specific
filtration resistance and compressibility coefficients of metal sulfide
slurry. Consequently, based on the lowest filtration parameters of the
produced metal sulfides, it was concluded that CaS was the most
effective precipitation agent for separation and recovery of Cu, Zn and
Ni.
Abstract: Fermented cassava flours (lafun) sold in Ogun and Oyo
States of Nigeria were collected from 10 markets for a period of two
months and analysed to determine their safety status. The presence of
trace metals was due to high vehicular movement around the drying
sites and markets. Cyanide and moisture contents of samples were
also determined to assess the adequacy of fermentation and drying.
The result showed that sample OWO was found to have the highest
amount of 16.02±0.12mg/kg cyanide while the lowest was found in
sample OJO with 10.51±0.10mg/kg. The results also indicated that
sample TVE had the highest moisture content of 18.50±0.20% while
sample OWO had the lowest amount of 12.46±0.47%. Copper and
lead levels were found to be highest in TVE with values 28.10mg/kg
and 1.1mg/kg respectively, while sample BTS had the lowest values
of 20.6mg/kg and 0.05mg/kg respectively. High value of cyanide
indicated inadequate fermentation.
Abstract: Two seperate experiments by barley and alfalfa were
conducted to a 2×8 factorial completely randomised design, with four
replicates. Factors were inoculation (M) with Gomus mosseae or uninoculation
(M0) and seven levels of contaminants (Co, Cd, Pb and
combinations) plus an uncontaminated control treatment (C). Heavy
metals in plant tissues and soil were quantified by Inductively
Coupled Plasma Optical Emission Spectrometer (ICP-OES) (Variant-
Liberty 150AX Turbo). Phytoextraction coefficient of contaminants
calculated by concentration of heavy metals in the shoot (mgkg-1) /
concentration of heavy metals in soil (mgkg-1). In the barley, the
highest rate of phytoextraction coefficient of Pb, Cd and Co was in
M0Pb, M0PbCoCd and MCo, respectively (P
Abstract: The reduction of hexavalent chromium by scrap iron
was investigated in continuous system, using long-term column
experiments, for aqueous Cr(VI) solutions having low buffering
capacities, over the Cr(VI) concentration range of 5 – 40 mg/L. The
results showed that the initial Cr(VI) concentration significantly
affects the reduction capacity of scrap iron. Maximum reduction
capacity of scrap iron was observed at the beginning of the column
experiments; the lower the Cr(VI) concentration, the greater the
experiment duration with maximum scrap iron reduction capacity.
However, due to passivation of active surface, scrap iron reduction
capacity continuously decreased in time, especially after Cr(VI)
breakthrough. The experimental results showed that highest
reduction capacity recorded until Cr(VI) breakthrough was 22.8 mg
Cr(VI)/g scrap iron, at CI = 5 mg/L, and decreased with increasing
Cr(VI) concentration. In order to assure total reduction of greater
Cr(VI) concentrations for a longer period of time, either the mass of
scrap iron filling, or the hydraulic retention time should be increased.
Abstract: The progress of concentrations of particular heavy metals was assessed in chosen localities in region Moravia, the Czech Republic, from 2007 to 2009. Particular metals were observed in localities with various types and characterization of zone. Pb, Ni, As and Cd were emphasized as a result of their toxicity and potential adverse health effect to the exposed population. The progress of metal concentrations and their health effects in the most polluted localities were examined. According to the results, the air pollution limit values were not exceeded. Based on the health risk assessment, the probability of developing tumorous diseases is acceptable, except for the increased probability of cancer risk from long-term exposure to As.
Abstract: Two freshwater fishes, Rasbora sumatrana
(Cyprinidae) and Poecilia reticulata (guppy) (Poeciliidae) were
exposed for a four-day period in the laboratory condition to a range
of copper (Cu) and cadmium (Cd) concentrations. Mortality was
assessed and median lethal concentrations (LC50) were calculated.
LC50 increased with decrease in mean exposure times for both metals.
For R. sumatrana, LC50s for 24, 48, 72 and 96 hours for Cu were
54.2, 30.3, 18.9 and 5.6 μg/L and for Cd 1440.2, 459.3, 392.3 and
101.6 μg/L respectively. For P. reticulata, LC50s for 24, 48, 72 and
96 hours for Cu were 348.9, 145.4, 61.3 and 37.9 μg/L and for Cd
8205.6, 2827.1, 405.8 and 168.1 μg/L, respectively. Results indicated
that the Cu was more toxic than Cd to both fishes (Cu>Cd) and R.
sumatrana was more sensitive than P. reticulata to the metals.
Abstract: The volume of biosolids produced in Malaysia
nowadays had increased proportionally to its population size. The end
products from the waste treatments were mounting, thus inevitable
that in the end the environment will be surrounded by the waste. This
study was conducted to investigate the suitability of biosolids to be
reused as fertilizer for non-food crop. By varying the concentration of
biosolids applied onto the soil, growth of five ornamental plant
samples were tested for eight consecutive weeks. The results show
that the pH of the soil after the addition of biosolids ranges from 6.45
to 6.56 which is suitable for the plant growth. The soil samples that
contains biosolid also show higher amount of macronutrients (N, P,
K) and the heavy metals content are significantly increased in the
plant however it does not exceed the guidelines drawn by the
Environmental Protection Agency. It is also proven that there was
only small significant different in the performance of plant growth
between biosolids and commercial fertilizer. It can be seen that
biosolids was able to perform just as well as commercial fertilizer.
Abstract: The presence of heavy metals in the environment
could constitute a hazard to food security and public health. These
can be accumulated in aquatic animals such as fish. Samples of four
popular brands of canned fish in the Iranian market (yellowfin tuna,
common Kilka, Kawakawa and longtail tuna) were analyzed for level
of Cr after wet digestion with acids using graphite furnace atomic
absorption spectrophotometry. The mean concentrations for Cr in the
different brands were: 2.57, 3.24, 3.16 and 1.65 μg/g for brands A, B,
C and D respectively. Significant differences were observed in the Cr
levels between all of the different brands of canned fish evaluated in
this study. The Cr concentrations for the varieties of canned fishes
were generally within the FAO/WHO, U.S. FDA and U.S. EPA
recommended limits for fish.
Abstract: Considering toxicity of heavy metals and their
accumulation in domestic wastes, immobilization of lead and
cadmium is envisaged inside glass-ceramics. We particularly
focused this work on calcium-rich phases embedded in a
glassy matrix.
Glass-ceramics were synthesized from glasses doped with
12 wt% and 16 wt% of PbO or CdO. They were observed and
analyzed by Electron MicroProbe Analysis (EMPA) and
Analytical Scanning Electron Microscopy (ASEM). Structural
characterization of the samples was performed by powder XRay
Diffraction.
Diopside crystals of CaMgSi2O6 composition are shown to
incorporate significant amounts of cadmium (up to 9 wt% of
CdO). Two new crystalline phases are observed with very
high Cd or Pb contents: about 40 wt% CdO for the cadmiumrich
phase and near 60 wt% PbO for the lead-rich phase. We
present complete chemical and structural characterization of
these phases. They represent a promising way for the
immobilization of toxic elements like Cd or Pb since glass
ceramics are known to propose a “double barrier" protection
(metal-rich crystals embedded in a glass matrix) against metal
release in the environment.