Tze Chean Ooi | Sheridan College (original) (raw)
Papers by Tze Chean Ooi
Malaysian Journal of Microbiology, 2008
Growth kinetics of newly isolated diazotrophic Bacillus sphaericus UPMB10 grown in various carbon... more Growth kinetics of newly isolated diazotrophic Bacillus sphaericus UPMB10 grown in various carbon (lactate, acetate, glycerol, malate, fructose, xylose and sucrose) and nitrogen (glutamate, yeast extract, arginine, hystadine, glycine, polypeptone, tryptophan, lysine, NH4Cl and urea) sources was investigated using 2 L stirred tank fermenter. The highest growth was obtained in a medium containing lactate as a carbon source, which gave the highest maximum cell concentration of 2.30 g/L, which is corresponding to maximum viable cell count of 4.60 x 10 9 cfu/mL. However, the highest cell yield (1.06 g cell/g carbon consumed) was obtained in cultivation using glycerol though slightly lower maximum viable cell count was obtained (3.22 x 10 9 cfu/mL). In addition, cost for the production of live cell using glycerol was about 15 times lower than the cost using lactate. Growth performance of this bacterium when yeast extract was used as a nitrogen source was comparable to the use of pure amino acid. The medium containing 1.8 g/L glycerol and 2 g/L yeast extract was suggested as optimal for growth of this bacterium, which gave carbon to nitrogen ratio (C/N) of 10:1. The maximum viable cell count obtained in cultivation using optimised medium in 2 L stirred tank fermenter was 3.34 x 10 9 cfu/mL and the cells maintained its capacity for N2 fixation at 18 nmol C2H2/h.mL.
Abstract Waste gases from iron ore fine preparations for blast furnace ironmaking, or sintering, ... more Abstract Waste gases from iron ore fine preparations for blast furnace ironmaking, or sintering, contain minute quantities of acidic species, dust, and dioxin pollutants, but because of the very large quantities of iron ore processed and the large volume throughput of air involved, sintering is a major source of these emissions and also CO2 into the atmosphere. Sintering plants rank second in terms of toxic emissions after the incineration of municipal solid waste and contribute of the order of 10% of the total CO2 emissions generated during the production of iron and steel. As legislated limits become increasingly more stringent, sinter plants are under scrutiny by local authorities to further decrease emission levels. Extensive efforts have been made in mitigating CO2 and toxic emissions from sinter plants since 1980–1990 and a number of different technologies are now available. However, most of these technologies are secondary measures that take effect only after emissions are formed, adding to the complexity of the operations. To improve the understanding of changes in steelmaking operations in East Asia, CSIRO in conjunction with the Fortescue Metal Group Ltd has evaluated different technologies for the mitigation of pollutants from sinter plants. This chapter will first examine the emission characteristics of CO2 and various toxic species, including SOx, NOx, dioxins, and particulate matter and then discuss available technologies for preventing and reducing the formation of these toxic species from the sintering bed.
The exponential fed-batch cultivation of Bacillus sphaericus UPMB10 in 2 l stirred tank fermenter... more The exponential fed-batch cultivation of Bacillus sphaericus UPMB10 in 2 l stirred tank fermenter was performed by feeding the initial batch culture with 14 g l-1 of glycerol according to the algorithm aimed at controlling the specific growth rate (µ) of the bacterium. Very high viable cell count (1.14 x 1010 cfu ml-1), which was four times higher as compared to batch cultivation, was achieved in the fed-batch with a controlled µ at 0.4 h-1. In repeated exponential fed-batch cultivation, consisting of four cycles of harvesting and recharging, a final cell concentration of 1.9 x 1011 cfu ml-1 was obtained at the end of the fourth cycle (46 h). Meanwhile, acetylene reduction of cell samples collected from repeated fed-batch cultivation remained unchanged and was maintained at around 20 nmol C2H2 h-1 ml-1 after prolonged cultivation period, and was comparable to those obtained in batch and exponential fed-batch cultivation. Glycerol could be used as a carbon source for high performance...
The production of locally isolated N2-fixing bacteria was undertaken in Fermentation Technology U... more The production of locally isolated N2-fixing bacteria was undertaken in Fermentation Technology Unit, Enzyme and Microbial Technology Laboratory, Institute of Bioscience, Universiti Putra Malaysia. Cellular studies and biochemical tests conducted on Bacillus sp UPMB10 suggests that the bacterium is Bacillus sphaericus. Optimization of medium for cultivation of the N2-fixing Bacillus was achieved using 1.4 g/L of glycerol and 2.0 g/L of yeast extract. Addition of biotin and thiamine did not improve growth of the bacteria. Optimum culture condition for growth of UPMB10 in the 2L: stirred tank fermenter was obtained at initial pH range between pH 6.0-8.0, 30°C, at agitation speed of 600 rpm and airflow rate of 0.5 VVM. Viable cell counts obtained under these conditions were approximately 3.5 X 109 cfu/mL. A model employing the logistic equation was proposed to describe growth of this newly isolated Bacillus. The values of the general kinetic parameters were calculated from the analysis...
Chemosphere, 2016
An earlier demonstration that the relative concentrations of isomers of polychlorinated dibenzofu... more An earlier demonstration that the relative concentrations of isomers of polychlorinated dibenzofuran do not vary as the flamefront of an iron ore sinter plant progresses through the bed, and profiles are similar for two sinter strands has been widened to include studies of the similarity or otherwise between full scale strand and sinter pot profiles, effect of addition of suppressants and of coke fuel substitution with other combustible materials. For dioxin suppressant addition, a study of the whole of the tetra- penta- and hexaCDF isomer range as separated by the DB5MS chromatography column, indicates no significant change in profile: examination of the ratios of the targeted penta- and hexaCDF isomers suggests the profile is similarly unaffected by coke fuel replacement. Addition of KCl at varied levels has also been shown to have no effect on the 'fingerprint' and there is no indication of any effect by the composition of the sinter mix. The recently published full eluti...
Minerals Engineering, 2008
An investigation was carried out into the use of sunflower seed husks as a supplementary fuel in ... more An investigation was carried out into the use of sunflower seed husks as a supplementary fuel in the iron ore sintering process. Fuel blends were prepared by mixing different amounts of sunflower seed husks and coke in order to produce the same heat output as 5% coke breeze. Sinter pot experiments with fuels containing different amounts of sunflower seed husks and coke indicate that substituting 10% coke with sunflower seed husks did not significantly change the combustion characteristics of the sintering process or the sinter quality. The relative abundances of PCDD/Fs and PAHs obtained with the experimental sintering pot were almost identical to those of a production sinter plant, which indicates that the mechanism of formation of the organic compounds in the sintering pot were very similar. Similar values of PCDD/F I-TEQ and B[a]P-eq were obtained in the waste gas with both coke and coke with 10% coke substitution with biomass, although sintering with biomass substitution resulted in slightly higher concentrations of 2,3,7,8-tetraCDF, 1,2,3,7,8-pentaCDF and OCDD. The emission profile of targeted PAHs was also altered to a limited extent, particularly with regard to concentrations of fluorene, phenanthrene and anthracene. Overall the results suggest that it is feasible to substitute 10% coke breeze with biomass in the iron ore sintering process.
Combustion and Flame, 2011
A study was carried out into the use of hardwood charcoal as a supplementary fuel in the iron-ore... more A study was carried out into the use of hardwood charcoal as a supplementary fuel in the iron-ore sintering process. The primary fuel was coke breeze with 0%, 20%, 50% and 100% replacement of the energy input with charcoal to produce raw blends with the same heat output as 4.0 wt.% coke breeze. Experimental results indicate that fuel blends where 20% of the heat input was provided by charcoal may improve both the sinter yield and sintering productivity by up to 8%, under normal sintering conditions. In addition, the 20% replacement of coke energy with charcoal would mean that part of the carbon dioxide emitted from the process would be from a renewable source and could be used to offset carbon dioxide emissions from non-renewable fossil fuels. At higher rates of coke breeze energy substitution with charcoal, the lower sintering performance observed was mainly attributed to the lower fixed carbon content and higher volatile matter content of the fuel mix. At the optimum rate of 20% substitution of coke breeze energy input with charcoal, the emission of dioxins were similar to those observed with coke breeze alone as the fuel. However, sintering with 20% energy input from charcoal resulted in a slight increase in middle molecular weight and lower molecular weight PAHs, contributing to a minor increase in B[a]P-eq from 0.15 lg/m 3 to 0.17 lg/m 3. Overall the results from the laboratory scale tests suggest that it is feasible to substitute 20% of the coke breeze energy input with an equivalent amount of energy from charcoal in the iron-ore sintering process.
Chemosphere, 2008
Plastics are potentially suitable for the removal of vapour phase PCDD/Fs in emissions from the e... more Plastics are potentially suitable for the removal of vapour phase PCDD/Fs in emissions from the electric arc furnace (EAF) steelmaking process. Three different commercial plastics, i.e. polypropylene BE170MO (Borealis A/S, Denmark), polypropylene in the form of 5 mm spheres (The Precision Plastic Ball Co. Ltd., UK) and polyethylene LD605BA (ExxonMobil Chemical, Belgium), have been studied using a novel experimental apparatus for the removal of vapour phase PCDD/Fs. Polypropylene BE170MO was identified to be the most suitable product amongst the three plastics in terms of PCDD/F sorption and potential industrial application. The optimum temperature for PCDD/F sorption on polypropylene BE170MO was below 90°C for a removal efficiency of >99% at an average vapour phase PCDD/F concentration of 3.5 ng I-TEQ/ Nm 3. At 130°C, 53% of the PCDD/Fs trapped on polypropylene BE170MO were desorbed.
Mineral Processing and Extractive Metallurgy Review, 2013
Parallel experimentation allowing comparison of magnetite–hematite–goethite inland and hematite–g... more Parallel experimentation allowing comparison of magnetite–hematite–goethite inland and hematite–goethite coastal mill blends in terms of sintering performance is reported. Magnetite–hematite–goethite blend affords slightly lower productivity, tumble index, and yield than hematite–goethite blend. However, magnetite–hematite–goethite blend required 9.2 kg · t−1 lower solid fuel rate than the hematite–goethite blend. The lower sintering temperature of the magnetite–hematite–goethite blend than that of the hematite–goethite blend contributed to higher reducibility and lower low temperature degradation under reduction. Its sinter product also contained lower proportions of columnar silico-ferrite of calcium and alumina, magnetite, and fayalite.
The sintering of iron ore is presently a significant industrial source of polychlorinated dibenzo... more The sintering of iron ore is presently a significant industrial source of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) worldwide owing to the fundamental requirement of the operation of a high temperature process to pre-treat fines and to recycle plant by-products arising from the integrated iron and steelworks. The process is a noteworthy contributor of PCDD/F indirectly due to decreasing PCDD/F releases from municipal solid waste incineration. Commonly PCDD/F formation from the process is associated with the addition of oily mill scales although raw material containing a combination of C, Cl and specific metal catalyst has been shown to drastically increase PCDD/F formation in the process. The degenerate graphitic structure of carbon present in coke fuel and soot formed and the chemistry of catalytic metals and Cl are important factors. A review on PCDD/F emission in this process has been carried out, including examination of its formation mechanis...
Chemosphere, 2018
It has been previously shown that the isomer profile of PCDF emissions from iron ore sinter plant... more It has been previously shown that the isomer profile of PCDF emissions from iron ore sinter plant only varies within limits even when suppressants or alternative fuels are added, to the extent that it can be said to have a 'fingerprint'. The isomer profiles of PCDD from tetra- to hexacholrodibenzo-p-dioxin from the same samples examined for PCDF emissions have been obtained, and show the same tendency for a 'fingerprint ' isomer distribution to occur. Occasional exceptionally high isomer abundances are observed, but these are uncommon. The potential for comparison of the abundances of PCDF and PCDD isomers with similar chlorination patterns to determine whether the same formation process is involved has been examined. It is found that co-elutions prevent extensive comparisons irrespective of whether the SP2331 or DB5ms column is used in the analyses for separation of isomers to provide the results used for comparisons, although they allow limited results to be obtain...
Malaysian Journal of Microbiology, 2008
Growth kinetics of newly isolated diazotrophic Bacillus sphaericus UPMB10 grown in various carbon... more Growth kinetics of newly isolated diazotrophic Bacillus sphaericus UPMB10 grown in various carbon (lactate, acetate, glycerol, malate, fructose, xylose and sucrose) and nitrogen (glutamate, yeast extract, arginine, hystadine, glycine, polypeptone, tryptophan, lysine, NH4Cl and urea) sources was investigated using 2 L stirred tank fermenter. The highest growth was obtained in a medium containing lactate as a carbon source, which gave the highest maximum cell concentration of 2.30 g/L, which is corresponding to maximum viable cell count of 4.60 x 10 9 cfu/mL. However, the highest cell yield (1.06 g cell/g carbon consumed) was obtained in cultivation using glycerol though slightly lower maximum viable cell count was obtained (3.22 x 10 9 cfu/mL). In addition, cost for the production of live cell using glycerol was about 15 times lower than the cost using lactate. Growth performance of this bacterium when yeast extract was used as a nitrogen source was comparable to the use of pure amino acid. The medium containing 1.8 g/L glycerol and 2 g/L yeast extract was suggested as optimal for growth of this bacterium, which gave carbon to nitrogen ratio (C/N) of 10:1. The maximum viable cell count obtained in cultivation using optimised medium in 2 L stirred tank fermenter was 3.34 x 10 9 cfu/mL and the cells maintained its capacity for N2 fixation at 18 nmol C2H2/h.mL.
Abstract Waste gases from iron ore fine preparations for blast furnace ironmaking, or sintering, ... more Abstract Waste gases from iron ore fine preparations for blast furnace ironmaking, or sintering, contain minute quantities of acidic species, dust, and dioxin pollutants, but because of the very large quantities of iron ore processed and the large volume throughput of air involved, sintering is a major source of these emissions and also CO2 into the atmosphere. Sintering plants rank second in terms of toxic emissions after the incineration of municipal solid waste and contribute of the order of 10% of the total CO2 emissions generated during the production of iron and steel. As legislated limits become increasingly more stringent, sinter plants are under scrutiny by local authorities to further decrease emission levels. Extensive efforts have been made in mitigating CO2 and toxic emissions from sinter plants since 1980–1990 and a number of different technologies are now available. However, most of these technologies are secondary measures that take effect only after emissions are formed, adding to the complexity of the operations. To improve the understanding of changes in steelmaking operations in East Asia, CSIRO in conjunction with the Fortescue Metal Group Ltd has evaluated different technologies for the mitigation of pollutants from sinter plants. This chapter will first examine the emission characteristics of CO2 and various toxic species, including SOx, NOx, dioxins, and particulate matter and then discuss available technologies for preventing and reducing the formation of these toxic species from the sintering bed.
The exponential fed-batch cultivation of Bacillus sphaericus UPMB10 in 2 l stirred tank fermenter... more The exponential fed-batch cultivation of Bacillus sphaericus UPMB10 in 2 l stirred tank fermenter was performed by feeding the initial batch culture with 14 g l-1 of glycerol according to the algorithm aimed at controlling the specific growth rate (µ) of the bacterium. Very high viable cell count (1.14 x 1010 cfu ml-1), which was four times higher as compared to batch cultivation, was achieved in the fed-batch with a controlled µ at 0.4 h-1. In repeated exponential fed-batch cultivation, consisting of four cycles of harvesting and recharging, a final cell concentration of 1.9 x 1011 cfu ml-1 was obtained at the end of the fourth cycle (46 h). Meanwhile, acetylene reduction of cell samples collected from repeated fed-batch cultivation remained unchanged and was maintained at around 20 nmol C2H2 h-1 ml-1 after prolonged cultivation period, and was comparable to those obtained in batch and exponential fed-batch cultivation. Glycerol could be used as a carbon source for high performance...
The production of locally isolated N2-fixing bacteria was undertaken in Fermentation Technology U... more The production of locally isolated N2-fixing bacteria was undertaken in Fermentation Technology Unit, Enzyme and Microbial Technology Laboratory, Institute of Bioscience, Universiti Putra Malaysia. Cellular studies and biochemical tests conducted on Bacillus sp UPMB10 suggests that the bacterium is Bacillus sphaericus. Optimization of medium for cultivation of the N2-fixing Bacillus was achieved using 1.4 g/L of glycerol and 2.0 g/L of yeast extract. Addition of biotin and thiamine did not improve growth of the bacteria. Optimum culture condition for growth of UPMB10 in the 2L: stirred tank fermenter was obtained at initial pH range between pH 6.0-8.0, 30°C, at agitation speed of 600 rpm and airflow rate of 0.5 VVM. Viable cell counts obtained under these conditions were approximately 3.5 X 109 cfu/mL. A model employing the logistic equation was proposed to describe growth of this newly isolated Bacillus. The values of the general kinetic parameters were calculated from the analysis...
Chemosphere, 2016
An earlier demonstration that the relative concentrations of isomers of polychlorinated dibenzofu... more An earlier demonstration that the relative concentrations of isomers of polychlorinated dibenzofuran do not vary as the flamefront of an iron ore sinter plant progresses through the bed, and profiles are similar for two sinter strands has been widened to include studies of the similarity or otherwise between full scale strand and sinter pot profiles, effect of addition of suppressants and of coke fuel substitution with other combustible materials. For dioxin suppressant addition, a study of the whole of the tetra- penta- and hexaCDF isomer range as separated by the DB5MS chromatography column, indicates no significant change in profile: examination of the ratios of the targeted penta- and hexaCDF isomers suggests the profile is similarly unaffected by coke fuel replacement. Addition of KCl at varied levels has also been shown to have no effect on the 'fingerprint' and there is no indication of any effect by the composition of the sinter mix. The recently published full eluti...
Minerals Engineering, 2008
An investigation was carried out into the use of sunflower seed husks as a supplementary fuel in ... more An investigation was carried out into the use of sunflower seed husks as a supplementary fuel in the iron ore sintering process. Fuel blends were prepared by mixing different amounts of sunflower seed husks and coke in order to produce the same heat output as 5% coke breeze. Sinter pot experiments with fuels containing different amounts of sunflower seed husks and coke indicate that substituting 10% coke with sunflower seed husks did not significantly change the combustion characteristics of the sintering process or the sinter quality. The relative abundances of PCDD/Fs and PAHs obtained with the experimental sintering pot were almost identical to those of a production sinter plant, which indicates that the mechanism of formation of the organic compounds in the sintering pot were very similar. Similar values of PCDD/F I-TEQ and B[a]P-eq were obtained in the waste gas with both coke and coke with 10% coke substitution with biomass, although sintering with biomass substitution resulted in slightly higher concentrations of 2,3,7,8-tetraCDF, 1,2,3,7,8-pentaCDF and OCDD. The emission profile of targeted PAHs was also altered to a limited extent, particularly with regard to concentrations of fluorene, phenanthrene and anthracene. Overall the results suggest that it is feasible to substitute 10% coke breeze with biomass in the iron ore sintering process.
Combustion and Flame, 2011
A study was carried out into the use of hardwood charcoal as a supplementary fuel in the iron-ore... more A study was carried out into the use of hardwood charcoal as a supplementary fuel in the iron-ore sintering process. The primary fuel was coke breeze with 0%, 20%, 50% and 100% replacement of the energy input with charcoal to produce raw blends with the same heat output as 4.0 wt.% coke breeze. Experimental results indicate that fuel blends where 20% of the heat input was provided by charcoal may improve both the sinter yield and sintering productivity by up to 8%, under normal sintering conditions. In addition, the 20% replacement of coke energy with charcoal would mean that part of the carbon dioxide emitted from the process would be from a renewable source and could be used to offset carbon dioxide emissions from non-renewable fossil fuels. At higher rates of coke breeze energy substitution with charcoal, the lower sintering performance observed was mainly attributed to the lower fixed carbon content and higher volatile matter content of the fuel mix. At the optimum rate of 20% substitution of coke breeze energy input with charcoal, the emission of dioxins were similar to those observed with coke breeze alone as the fuel. However, sintering with 20% energy input from charcoal resulted in a slight increase in middle molecular weight and lower molecular weight PAHs, contributing to a minor increase in B[a]P-eq from 0.15 lg/m 3 to 0.17 lg/m 3. Overall the results from the laboratory scale tests suggest that it is feasible to substitute 20% of the coke breeze energy input with an equivalent amount of energy from charcoal in the iron-ore sintering process.
Chemosphere, 2008
Plastics are potentially suitable for the removal of vapour phase PCDD/Fs in emissions from the e... more Plastics are potentially suitable for the removal of vapour phase PCDD/Fs in emissions from the electric arc furnace (EAF) steelmaking process. Three different commercial plastics, i.e. polypropylene BE170MO (Borealis A/S, Denmark), polypropylene in the form of 5 mm spheres (The Precision Plastic Ball Co. Ltd., UK) and polyethylene LD605BA (ExxonMobil Chemical, Belgium), have been studied using a novel experimental apparatus for the removal of vapour phase PCDD/Fs. Polypropylene BE170MO was identified to be the most suitable product amongst the three plastics in terms of PCDD/F sorption and potential industrial application. The optimum temperature for PCDD/F sorption on polypropylene BE170MO was below 90°C for a removal efficiency of >99% at an average vapour phase PCDD/F concentration of 3.5 ng I-TEQ/ Nm 3. At 130°C, 53% of the PCDD/Fs trapped on polypropylene BE170MO were desorbed.
Mineral Processing and Extractive Metallurgy Review, 2013
Parallel experimentation allowing comparison of magnetite–hematite–goethite inland and hematite–g... more Parallel experimentation allowing comparison of magnetite–hematite–goethite inland and hematite–goethite coastal mill blends in terms of sintering performance is reported. Magnetite–hematite–goethite blend affords slightly lower productivity, tumble index, and yield than hematite–goethite blend. However, magnetite–hematite–goethite blend required 9.2 kg · t−1 lower solid fuel rate than the hematite–goethite blend. The lower sintering temperature of the magnetite–hematite–goethite blend than that of the hematite–goethite blend contributed to higher reducibility and lower low temperature degradation under reduction. Its sinter product also contained lower proportions of columnar silico-ferrite of calcium and alumina, magnetite, and fayalite.
The sintering of iron ore is presently a significant industrial source of polychlorinated dibenzo... more The sintering of iron ore is presently a significant industrial source of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) worldwide owing to the fundamental requirement of the operation of a high temperature process to pre-treat fines and to recycle plant by-products arising from the integrated iron and steelworks. The process is a noteworthy contributor of PCDD/F indirectly due to decreasing PCDD/F releases from municipal solid waste incineration. Commonly PCDD/F formation from the process is associated with the addition of oily mill scales although raw material containing a combination of C, Cl and specific metal catalyst has been shown to drastically increase PCDD/F formation in the process. The degenerate graphitic structure of carbon present in coke fuel and soot formed and the chemistry of catalytic metals and Cl are important factors. A review on PCDD/F emission in this process has been carried out, including examination of its formation mechanis...
Chemosphere, 2018
It has been previously shown that the isomer profile of PCDF emissions from iron ore sinter plant... more It has been previously shown that the isomer profile of PCDF emissions from iron ore sinter plant only varies within limits even when suppressants or alternative fuels are added, to the extent that it can be said to have a 'fingerprint'. The isomer profiles of PCDD from tetra- to hexacholrodibenzo-p-dioxin from the same samples examined for PCDF emissions have been obtained, and show the same tendency for a 'fingerprint ' isomer distribution to occur. Occasional exceptionally high isomer abundances are observed, but these are uncommon. The potential for comparison of the abundances of PCDF and PCDD isomers with similar chlorination patterns to determine whether the same formation process is involved has been examined. It is found that co-elutions prevent extensive comparisons irrespective of whether the SP2331 or DB5ms column is used in the analyses for separation of isomers to provide the results used for comparisons, although they allow limited results to be obtain...