الفهرس 
Cobalt ions (source and impact)Only 14 pages are availabe for public view
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Abstract
The contamination of the aquatic systems with toxic heavy metal ions has
recently dramatically increased due to various human activities, such as
agriculture, mining and other industrial processes. The significant
concentrations of these toxic metals in the environment ecosystems cause
contamination of soil and water with deleterious impact on environment life.
Moreover, exceeding concentrations of threshold levels for these toxic elements
have a very detrimental effect on the microbial communities and their vital
activities and must be treated prior to disposal into rivers, seas, and land
surfaces. Also, phenol and phenolic compounds are widely distributed in the
environment as a result of industrial activities and originate mainly from
industrial processes such as resin manufacturing, oil refineries, petrochemicals,
pharmaceuticals, dyes, textiles and plastic industries. They are classified as
highly hazardous chemicals due to their toxic, mutagenic and carcinogenic
characteristics,
Biosorption is a promising technology for pollutant streams treatment. It
is based on the metal–biomaterial interactions. This process has advantages
such as; low cost of materials, ease of operation and selectivity against the
alkaline metals when compared with existing conventional physicochemical
process such as; chemical precipitation, reverse osmosis, ion-exchange and
activated carbon adsorption. Fungal, algal, bacterial and agricultural biomasses
have been employed for the biosorptive removal of different pollutants from
contaminated solutions. Biodegradation has proved to be the most promising,
practical and economical method for the removal of phenol and phenolic
compounds from phenol containing effluents.
The present study was conducted to compare between different
microorganisms such as bacteria and fungi which isolated from liquid
radioactive wastewater in removing toxic and radioactive metal ions such as cobalt, cadmium and cobalt-60 and degrading phenolic compounds (phenol and
nitrophenol) from aqueous solutions. Also, the study involved the evaluation of
using different immobilized shapes (beads and thin film) in improving the
efficiency of immobilized isolates for the treatment process. The isolated
bacteria were Bacillus haynesii and Bacillus aerius according to 16S rRNA
identification, while the isolated fungi were Aspergillus foetidus, Aspergillus
parasiticus, and Pencillium oxalicum according to the gross morphology and
diagnostic structures.
Investigation of cobalt removal was done by screening free wet biomass
weights of 0.025, 0.05, 0.1 and 0.2g for bacteria and fungi. The results showed
that the increase in the free weight increases the percent removal and decreases
the removal capacity for the studied bacteria and fungi. The maximum
capacities obtained at free weight 0.025g for both bacteria and fungi were; 400,
356, 96, 196 and 139 mg/g for B. haynesii, B. aerius, A. foetidus, A. parasiticus
and P. oxalicum, respectively. On using different free dry mycelia weights of
0.005, 0.01, 0.02 and 0.025g for fungi for cobalt removal, the maximum
removal capacities were 272, 298 and 152 mg/g for A. foetidus, A. parasiticus
and P. oxalicum, respectively. Results cleared that the dry free mycelia had
higher capacities than that of wet free mycelia. The order of cobalt removal
efficiency was A. parasiticus > A. foetidus > P. oxalicum for dry free mycelia,
whereas for wet free mycelia was A. parasiticus > P. oxalicum > A. foetidus.
Screening of the immobilized bacteria wet weights of 0.01, 0.025, 0.05
and 0.1g with different shapes beads and thin film showed that the removal
percent and capacity increased with the increase in immobilized weight up to
0.025 g and decreased at 0.1g. The optimum immobilized wet bacterial biomass
for both beads and thin film shape was 0.025g/5 ml sodium alginate. Where, the
removal capacities of immobilized weight 0.025g were 36.57, 37.5 mg/g for B.haynesii and 34.02, 35.83 mg/g of B. aerius for beads and thin film,
respectively.
On using different weights of 0.005, 0.01, 0.025, 0.05 and 0.1g of wet and
dry mycelia were immobilized in beads and thin film shapes to compare between
their removal percent and capacities. The results showed that, for the
immobilized wet mycelia the removal percent and capacity increased with
increase in the immobilized weight up to 0.025g for beads and thin film.
Moreover, the results indicated that the immobilized thin film of wet biomasses
of A. foetidus had high removal percent and capacity than immobilized beads.
The removal capacities were 29.7/35.2, 34.65/34.4 and 34.22/35.38 mg/g for
immobilized A. foetidus, A. parasiticus and P. oxalicum beads and thin film,
respectively. Whereas, the removal capacities were 41.15/36.82, 44.24/35.71 and
42.3/34.46 mg/g for dry immobilized A. foetidus, A. parasiticus and P. oxalicum
beads and thin film, respectively.
The effect of environmental conditions on the removing of Co (II) ions
from aqueous waste solutions were studied using immobilized 0.025g of B.
haynesii beads and thin film, whereas, beads of immobilized 0.01g dry A.
parasiticus and thin film of immobilized 0.025g dry A. foetidus were used.
The effect of pH on Co (II) ions biosorption cleared that as the pH
increased the removal percent increased and the maximum removal percent was
achieved at pH 6.5 for both bacterial and fungal species. The effect of pH on Co
(II) ions biosorption by the immobilized B. haynesii beads or thin film is greater
than that on immobilized fungi. It was found that the biosorption process reached
equilibrium for both bacteria and fungi using the studied immobilized shapes
after 90 minutes. The effect of temperature on the removal of Co II ions showed
that the highest removal percent was at 25 ºC for B. haynesii beads and thin film,
and then followed by sharp decrease. Whereas, the highest removal percent is up
to 25 ºC for immobilized dry beads of A. parasiticus and up to 37 ºC forimmobilized dry thin film of A. foetidus followed by slight decreased in the
removal percent up to 50 °C.
The effect of initial cobalt ions concentration was studied at different
values of 250, 500, 750 and 1000 ppm. Results indicated that as the initial
concentration increased the removal percent decreased and the removal
capacities increased. The maximum removal capacities obtained at initial
concentration 750 ppm were; 49.03 and 69.46 mg/g for immobilized B. haynesii
beads and thin film, respectively. Whereas, the capacities were; 56.07 and 64.96
mg/g for immobilized dry beads of A. parasiticus and dry thin film of A.
foetidus, respectively.
Scanning Electron Microscope (SEM) investigation of bacteria and fungi
immobilized in beads and thin film before and after removal of Co (II) ions at
different magnification powers showed that the surface density of immobilized
bacteria or fungi either beads or thin film become more dense after removal of
Co (II) ions. However, the biosorption of the Co (II) ions was confirmed by
EDX analysis which illustrated the present of Co (II) ions in the immobilized
beads and thin film after removal of cobalt ions.
On the removing of cobalt-60 from aqueous solution, the results cleared
that immobilization increases the removal percent and capacities. Also, the
immobilized beads for bacteria and fungi showed higher removal percent than
immobilized thin film. The optimum immobilized wet weight of B. haynesii
beads were found to be 0.2g/5ml sodium alginate, while the optimum
immobilized dry weight of P. oxalicum beads was 0.02g/5ml sodium alginate.
Results showed that the highest removal percent obtained at activity of 15000
count/600sec were 79.3 and 53.4% for dry immobilized beads of P. oxalicum
and wet immobilized beads of B. haynesii, respectively. The increase in activity
from 20000 to 25000 count/600sec causes decrease in the removal percent of
dry immobilized beads of P. oxalicum.Investigation of cadmium removal was done by screening free wet
biomass weights of 0.025, 0.05, 0.1 and 0.2g of both bacteria and fungi. The
increase in the free weight increases the percent removal and decreases the
removal capacity for bacteria and fungi. The maximum capacities obtained at
free weight 0.025g for bacteria were 400 and 368, mg/g for B. haynesii and B.
aerius, respectively. While, for wet fungi mycelia, the removal capacities were
144, 160 and 144 mg/g for A. foetidus, A. parasiticus and P. oxalicum,
respectively.
Different free dry mycelia weights of 0.005, 0.01, 0.02 and 0.025g for
fungi were examined for cadmium removal. The removal capacities were 140,
220 and 106 mg/g for A. foetidus, A. parasiticus and P. oxalicum, respectively.
The order of cadmium removal was A. parasiticus > A. foetidus > P. oxalicum
for dry free mycelia, whereas for wet mycelia was A. parasiticus > A. foetidus ≥
P. oxalicum.
Screening of the immobilized bacteria wet weights of 0.01, 0.025, 0.05
and 0.1g in different shapes (beads and thin film) showed that the removal
percent and capacity increased with the increase in immobilized weight and
decreased at 0.1g. The optimum immobilized wet bacterial biomass for both
beads and thin film shape was 0.05g/5 ml sodium alginate. The removal
capacities were 45.5, 49.2 mg/g for B. haynesii, while for B. aerius were 32.9,
35.1 mg/g for beads and thin film, respectively.
On using different immobilized weights of 0.01, 0.025, 0.05 and 0.1g for
wet and dry fungal mycelia were immobilized in beads and thin film shapes to
compare between their removal percent and capacities. The results cleared that
for the immobilized wet mycelia the removal percent and capacity increased
with increase in the immobilized weight up to 0.025g for beads and thin film.
The optimum immobilized wet biomass was 0.025g/5ml sodium alginate for
beads and thin film forms. It was found that 0.01g and 0.025g/5ml sodium alginate were the optimum immobilized dry weight for thin film and beads,
respectively. Results indicated that the immobilized wet and dry biomasses of A.
foetidus and A. parasiticus thin film form had high removal percent and
capacity than beads forms; while the beads shape of immobilized dry biomass
of P. oxalicum had high removal percent and capacity than thin film shape.
The environmental conditions for the removing of Cd (II) ions were
studied using immobilized B. haynesii beads and thin film, whereas, for fungi
beads of immobilized dry P. oxalicum and thin film of immobilized dry A.
parasiticus were studied. The effect of pH on biosorption of Cd (II) showed that
as the pH increased the removal percent increased. The maximum removal
percent was achieved at pH 6.5 for both bacterial and fungal species. The effect
of low pH 2.5 on the immobilized B. haynesii beads or thin film is greater than
that on immobilized fungi. The biosorption equilibrium for both bacteria and
fungi in the studied immobilized shapes achieved after 120 minutes. The effect
of temperature indicated that the highest removal percent of B. haynesii beads
and thin film observed at 25 ºC and then followed by sharp decrease. Whereas,
the effect on immobilized fungi either beads or thin film is lower than that on
immobilized bacteria. The effect of initial cadmium ions concentrations was
studied at different values of 250, 500, 750 and 1000 ppm. Results indicated
that as the initial concentration increased the removal percent decreased while
the removal capacities increased. The maximum capacities were 49.03 and
69.46 mg/g for immobilized B. haynesii beads and thin film obtained at initial
concentration 750 ppm. However, the removal capacities were 89.86 and 55.19
mg/g for immobilized dry P. oxalicum beads and immobilized dry A.
parasiticus thin film, respectively at initial concentration 1000 ppm.
Scanning Electron Microscope (SEM) investigations of calcium alginate
beads and thin film either control or immobilized with the studied bacteria and
fungi before and after accumulated with Cd (II) ions at different magnification powers. The surface density of calcium alginate beads and thin film
immobilized bacteria or fungi become denser after removal of Cd (II) ions.
Studding the biodegradation of phenol by the free wet biomass of
bacteria and fungi showed that, the increase in the free biomass weight
increased the rate of phenol degradation from 3 days for 0.1 and 0.2 g to 5 days
for 0.02g. Also, the free biomass of B. aerius had higher phenol degradation
rate than free biomass of B. haynesii. Whereas, and that free bacterial biomass
had faster degradation rate and higher degradation capacities. On the other
hand, the free fungal biomass had the following order A. parasiticus > P.
oxalicum > A. foetidus for phenol biodegradation. The maximum capacities
were 2275 and 2500 mg/g biomass of B. haynesii and B. aerius, respectively.
While, the maximum capacities were 362, 400 and 400 mg/g for A. foetidus, A.
parasiticus and P. oxalicum, respectively; for free biomass weight 0.05g after 5
days.
Results for screening different immobilized weights of 0.025, 0.05, and
0.1g for bacteria and fungi in different shapes indicated that immobilized thin
film had fast phenol degradation rate. Also, the increase in the immobilized
weight increased the degradation rate, where complete degradation obtained
after 1 day for 0.1g immobilized thin film of bacteria and fungi. The maximum
degradation capacity was obtained at 0.025g/ 5ml sodium alginate in both
bacteria and fungi.
The effect of initial phenol concentration on biodegradation process rate
and efficiency was investigated at different phenol concentrations of 50, 100,
150 and 200 ppm using 0.1g/5ml and 0.025g/5ml sodium alginate for
immobilized bacterial and mycelia weight, respectively. Results showed that the
immobilized B. aerius beads and thin film had faster biodegradation rate than
immobilized B. haynesii beads and thin film. Also, results showed that complete
biodegradation was achieved after 24 hours at phenol concentration 50 ppm for immobilized B. haynesii and B. aerius beads and thin film. While, complete
biodegradation was achieved for immobilized fungal thin film after 2 days at
phenol concentration 100 ppm for all studied fungal. Besides, results showed
that fungal species had high efficiency in degradation of phenol at high initial
concentration 200 ppm.
In screening of free biomass of bacteria and fungi for biodegradation of
nitrophenol using high biomasses weights of 0.1, 0.2 and 0.3g. The results
indicated that as bacterial biomass increased the biodegradation capacity
decreased. Moreover, the results showed that free biomass of B. haynesii had
more biodegradation efficiency than free biomass of B. aerius. Also, the
increase in free mycelia weight increased the nitrophenol biodegradation
percent, and decreased the biodegradation capacity. The biodegradation percent
were; 86, 73.2, 96.03, 97.1 and 93.7% for B. haynesii, B. aerius, A. foetidus, A.
parasitic and P. oxalicum, respectively after five days and at 0.3g free weight.
Screening the biodegradation of 100 ppm nitrophenol using different
weights of 0.05, 0.1 and 0.2 g for the studied bacteria and fungi immobilized in
thin film and beads. The immobilized B. haynesii showed greater affinity in
biodegrading of nitrophenol than B. aerius for beads and thin film. The
biodegradation efficiency of immobilized fungal beads was nearly the same as
that of the immobilized fungal thin film in the three studied species. The order
of the biodegradation efficiency was A. parasiticus ≥ P. oxalicum ≥ A. foetidus.
The maximum biodegradation efficiency was obtained at 0.1 g mycelia cell / 5
ml sodium alginate.
The effect of initial nitrophenol concentration on biodegradation rate and
efficiency of immobilized bacteria and fungi was investigated at different
nitrophenol concentrations of 50, 100, 150 and 200 ppm using 0.1g/5ml sodium
alginate. Results indicated that the immobilized thin film for both bacterial
species had higher nitrophenol biodegradation percent than that of immobilized beads. It was also observed that immobilized B. haynesii beads and thin film
were more efficient in nitrophenol biodegradation than immobilized B. aerius
beads and thin film. Complete biodegradation was achieved by immobilized B.
haynesii and B. aerius thin film after 4 and 5 days for nitrophenol
concentrations of 50 and 100 ppm, respectively. The order of nitrophenol
biodegradation by the studied fungal species was P. oxalicum ˃ A. foetidus ˃
A. parasiticus. Also, results illustrated that as the concentration increased the
nitrophenol biodegradation percent decreased and capacity increased.
The statistical analysis showed significant high mean for the removal
percentage and capacity of bacteria versus fungi either free or immobilized in
beads and thin film shapes. The immobilized thin film shape showed significant
high mean than bead shape for the removal percentage for both bacteria and
fungi. On the other hand, there was no significant difference for the removal
capacity of immobilized beads between bacteria, and fungi. Also, there was no
significant difference in removal percentage and capacity between different
bacterial species and fungal species in the free form or immobilized in any used
shape.
Statistical analysis for the effect of environmental conditions on the
bacterial or fungal species showed that, there was a statistically no significant
difference in both removal percent and capacity in different bacterial or fungal
species when using any shape of gel. Also there was no significant difference
in each bacterial or fungal species and when use any form of gel.
Comparing the removal efficiency of cobalt, cadmium and cobalt-60,
showed statistically significant high mean for both removal percent and
capacity in cadmium versus cobalt and cobalt-60 in immobilized beads and thin
film shapes. A significant high mean of removal percent and capacity was
observed in both cobalt and cadmium heavy metals when use immobilized thin
film and beads shapes higher than free biomass. However, there was significant high mean for cobalt-60 removal capacity by using immobilized beads more
than immobilized thin film and no difference between two immobilized shapes
in removal percentage.
Statistical comparison between heavy metal removal and organic
compounds degradation cleared that, there was a statistically significant high
mean for organic compounds degradation percent versus heavy metals removal
percent in free microorganism biomass or immobilized in beads and thin film.
Also, immobilized thin film showed significant high mean versus immobilized
beads for degradation percentage of organic compounds than removal
percentage of heavy metals. There was significant high mean for phenol
degradation percent and capacity versus nitrophenol in free biomass and
immobilized shapes.
Column studies conducted for continuous removal of cobalt and cadmium
by control and immobilized alginate beads and thin film showed that the
adsorption breakthrough curves by thin film either control or immobilized had
higher exhaustion time/treated volume and column equilibrium capacity than
beads. Column studies for continuous cobalt removal showed the following
efficiency order for both beads and thin film shapes; control calcium alginate <
immobilized dry mycelia of A. parasiticus < immobilized B. haynesii. The
column capacities were 285, 369.4 and 336.7 mg Co (II)/ g dry beads weight of
control calcium alginate, immobilized B. haynesii and dry mycelia of A.
parasiticus, respectively. While the capacities were; 347.9, 443.8 and 425.7 mg
Co (II) /g dry Thin film weight of control calcium alginate, immobilized B.
haynesii and dry mycelia of A. foetidus, respectively.
The results for continuous cadmium removal showed that the following
efficiency order; control calcium alginate < immobilized dry mycelia of P.
oxalicum < immobilized B. haynesii. The column equilibrium capacities were
353.0, 634.0 and 508.9 mg Cd (II)/g dry beads weight of the control calcium alginate, immobilized B. haynesii and dry mycelia of P. oxalicum, respectively.
While the column equilibrium capacities were 441.3, 688.1 and 546.1 mg Cd
(II)/g dry thin film weight of the control calcium alginate, immobilized B.
haynesii and dry mycelia of A. parasiticus, respectively.