r hassan - Academia.edu (original) (raw)

Papers by r hassan

Research paper thumbnail of Measuring the economic impact of climate change on major South African field crops: a Ricardian approach

Global and Planetary Change, 2005

This study measured the economic impacts of climate change on crop and livestock farming in Afric... more This study measured the economic impacts of climate change on crop and livestock farming in Africa based on a cross-sectional survey of over 8000 farming households from 11 countries in east, west, north and southern Africa. The response of net revenue from crop and livestock agriculture across various farm types and systems in Africa to changes in climate normals (i.e. mean rainfall and temperature) is analysed. The analyses controlled for effects of key socioeconomic, technology, soil and hydrological factors influencing agricultural production. Results show that net farm revenues are in general negatively affected by warmer and drier climates. The small-scale mixed crop and livestock system predominantly typical in Africa is the most tolerant whereas specialized crop production is the most vulnerable to warming and lower rainfall. These results have important policy implications, especially for the suitability of the increasing tendency toward large-scale mono-cropping strategies for agricultural development in Africa and other parts of the developing world in light of expected climate changes. Mixed crop and livestock farming and irrigation offered better adaptation options for farmers against further warming and drying predicted under various future climate scenarios.

Research paper thumbnail of Mesothelin: A New Target for Immunotherapy

Clinical Cancer Research, 2004

Mesothelin is a differentiation antigen present on normal mesothelial cells and overexpressed in ... more Mesothelin is a differentiation antigen present on normal mesothelial cells and overexpressed in several human tumors, including mesothelioma and ovarian and pancreatic adenocarcinoma. The mesothelin gene encodes a precursor protein that is processed to yield the 40-kDa protein, mesothelin, attached to the cell membrane by a glycosylphosphatidyl inositol linkage and a 31-kDa shed fragment named megakaryocyte-potentiating factor. The biological function of mesothelin is not known. Mesothelin is a promising candidate for tumor-specific therapy, given its limited expression in normal tissues and high expression in several cancers. SS1(dsFv)PE38 is a recombinant anti-mesothelin immunotoxin that is undergoing clinical evaluation in patients with mesothelin-expressing tumors. There is evidence that mesothelin is an immunogenic protein and could be exploited as a therapeutic cancer vaccine. A soluble mesothelin variant has been identified and could be a useful tumor marker for malignant mesotheliomas.

Research paper thumbnail of Mesothelin: A New Target for Immunotherapy

Clinical Cancer Research, 2004

Mesothelin is a differentiation antigen present on normal mesothelial cells and overexpressed in ... more Mesothelin is a differentiation antigen present on normal mesothelial cells and overexpressed in several human tumors, including mesothelioma and ovarian and pancreatic adenocarcinoma. The mesothelin gene encodes a precursor protein that is processed to yield the 40-kDa protein, mesothelin, attached to the cell membrane by a glycosylphosphatidyl inositol linkage and a 31-kDa shed fragment named megakaryocyte-potentiating factor. The biological function of mesothelin is not known. Mesothelin is a promising candidate for tumor-specific therapy, given its limited expression in normal tissues and high expression in several cancers. SS1(dsFv)PE38 is a recombinant anti-mesothelin immunotoxin that is undergoing clinical evaluation in patients with mesothelin-expressing tumors. There is evidence that mesothelin is an immunogenic protein and could be exploited as a therapeutic cancer vaccine. A soluble mesothelin variant has been identified and could be a useful tumor marker for malignant mesotheliomas.

Research paper thumbnail of Effect of pH control on the growth and survival of Kluveromyces fragilis in cheese whey under aerobic condition

Applied Biochemistry and Biotechnology, 1992

Many biological and chemical systems involve acid-base equilibria and thus depend critically on t... more Many biological and chemical systems involve acid-base equilibria and thus depend critically on the pH of the solution. Small fluctuations of pH must be corrected by the addition of an acid or base to maintain the pH at the required optimum level during the fermentation process. The effect of pH control on the growth of Kluveromyces fragilis, used for the production of single-cell protein from cheese whey, was investigated. Maintaining the pH at 4.5 was found essential for the survival of the yeast. Without pH control, the pH of the medium continued to rise, resulting in the death and/or sporulation of the yeast cells. Diauxic growth was observed, caused by the growth of contaminant bacteria when the pH was not controlled.

Research paper thumbnail of Effect of pH control on the growth and survival of Kluveromyces fragilis in cheese whey under aerobic condition

Applied Biochemistry and Biotechnology, 1992

Many biological and chemical systems involve acid-base equilibria and thus depend critically on t... more Many biological and chemical systems involve acid-base equilibria and thus depend critically on the pH of the solution. Small fluctuations of pH must be corrected by the addition of an acid or base to maintain the pH at the required optimum level during the fermentation process. The effect of pH control on the growth ofKluveromyces fragilis, used for the production of single-cell protein from cheese whey, was investigated. Maintaining the pH at 4.5 was found essential for the survival of the yeast. Without pH control, the pH of the medium continued to rise, resulting in the death and/or sporulation of the yeast cells. Diauxic growth was observed, caused by the growth of contaminant bacteria when the pH was not controlled.

Research paper thumbnail of A computer-based ph measurement and control system for fermentation processes

Applied Biochemistry and Biotechnology, 1991

The measurement and control of pH is essential in most fermentation processes. The highly nonline... more The measurement and control of pH is essential in most fermentation processes. The highly nonlinear response of pH to the addition of acid or base makes pH control by conventional means very difficult. This paper presents a description of the hardware and software of a computer-based pH measurement and control system. The system is applicable to any fermentation process requiring in situ pH measurement and control and is capable of controlling the pH within + 0.1 U with a very short response time. It has a proportional metering device capable of adding the required amount of acid (or alkaline) solution with high accuracy, thereby preventing overshooting.

Research paper thumbnail of A computer-based ph measurement and control system for fermentation processes

Applied Biochemistry and Biotechnology, 1991

The measurement and control of pH is essential in most fermentation processes. The highly nonline... more The measurement and control of pH is essential in most fermentation processes. The highly nonlinear response of pH to the addition of acid or base makes pH control by conventional means very difficult. This paper presents a description of the hardware and software of a computer-based pH measurement and control system. The system is applicable to any fermentation process requiringin situ pH measurement and control and is capable of controlling the pH within ±0.1 U with a very short response time. It has a proportional metering device capable of adding the required amount of acid (or alkaline) solution with high accuracy, thereby preventing overshooting.

Research paper thumbnail of Continuous production of biogas from dairy manure using an innovative no-mix reactor

Applied Biochemistry and Biotechnology, 1989

... from Dairy Manure Using an Innovative No-Mix Reactor AE GHALY* AND RM BEN-HASSAN Agricultural... more ... from Dairy Manure Using an Innovative No-Mix Reactor AE GHALY* AND RM BEN-HASSAN Agricultural Engineering Department, Technical University of Nova Scotia, PO Box 1000, Halifax, Nova Scotia, Canada, B3J 2X4 ... Page 2. 542 Ghaly and Ben-Hassan three stages. ...

Research paper thumbnail of Continuous propagation of Kluyveromyces fragilis in cheese whey for pollution potential reduction

Applied Biochemistry and Biotechnology, 1994

A 25-L working volume, upright cylindrical fermenter made of stainless steel was used to investig... more A 25-L working volume, upright cylindrical fermenter made of stainless steel was used to investigate cheese whey yeast fermentation for pollution potential reduction. The effluent total and soluble chemical oxygen demand, total and volatile solids, and total Kjeldahl and ammonium nitrogen concentrations were significantly affected by the hydraulic retention time, air flow rate, and mixing speed. The system removal efficiencies were 15.90-58.61%, 25.20-69.33%, 12.43-49.90%, 9.22-51.77%, 1.66-10.06%, and 54.82-72.22% for total chemical oxygen demand, soluble chemical oxygen demand, total solids, volatile solids, total Kjeldahl nitrogen, and ammonium nitrogen, respectively, depending on the hydraulic retention time, air flow rate, and mixing speed used.

Research paper thumbnail of Continuous production of biogas from dairy manure using an innovative no-mix reactor

Applied Biochemistry and Biotechnology, 1989

A 25 L no-mix anaerobic digester was designed and fabricated. The digester was designed to act as... more A 25 L no-mix anaerobic digester was designed and fabricated. The digester was designed to act as liquid-solid separator. The sludges obtained from the bottom of the digester had high nitrogen and ash concentrations while the effluent had no offensive odor. The performance of the no-mix digester was compared to that of a continuous stirred tank reactor at two temperatures and five hydraulic retention times. The no-mix digester had higher biogas production rate and pollution potential reduction.

Research paper thumbnail of Kinetics of batch production of single-cell protein from cheese whey

Applied Biochemistry and Biotechnology, 1995

A kinetic model for single-cell protein batch fermentation was developed using the numerical simu... more A kinetic model for single-cell protein batch fermentation was developed using the numerical simultaneous integration approach of the fourth-order Runge-Kutta method. The model takes into account the effect of substrate inhibtion, maintenance energy, and cell death on the cell growth and substrate utilization during the fermentation process. The theoretical results obtained from the model compared well with the experimental data. The model was used to study the effect of the initial substrate concentration on the lag period, fermentation time, specific growth rate, population size, and cell productivity of batch fermentation. Increasing the initial substrate concentration increased the lag period and fermentation time and decreased the specific growth rate and cell yield. The growth limiting substrate concentration was 2.9 g/L, whereas the growth inhibiting substrate concentration was 69.0 g/L. Increasing the initial substrate concentration above 150 g/L significantly decreased the yeast population size.

Research paper thumbnail of Continuous propagation of Kluyveromyces fragilis in cheese whey for pollution potential reduction

Applied Biochemistry and Biotechnology, 1994

A 25-L working volume, upright cylindrical fermenter made of stainless steel was used to investig... more A 25-L working volume, upright cylindrical fermenter made of stainless steel was used to investigate cheese whey yeast fermentation for pollution potential reduction. The effluent total and soluble chemical oxygen demand, total and volatile solids, and total Kjeldahl and ammonium nitrogen concentrations were significantly affected by the hydraulic retention time, air flow rate, and mixing speed. The system removal efficiencies were 15.90-58.61%, 25.20-69.33%, 12.43-49.90%, 9.22-51.77%, 1.66-10.06%, and 54.82-72.22% for total chemical oxygen demand, soluble chemical oxygen demand, total solids, volatile solids, total Kjeldahl nitrogen, and ammonium nitrogen, respectively, depending on the hydraulic retention time, air flow rate, and mixing speed used.

Research paper thumbnail of Effect of pH control on the growth and survival of Kluveromyces fragilis in cheese whey under aerobic condition

Applied Biochemistry and Biotechnology, 1992

Many biological and chemical systems involve acid-base equilibria and thus depend critically on t... more Many biological and chemical systems involve acid-base equilibria and thus depend critically on the pH of the solution. Small fluctuations of pH must be corrected by the addition of an acid or base to maintain the pH at the required optimum level during the fermentation process. The effect of pH control on the growth ofKluveromyces fragilis, used for the production of single-cell protein from cheese whey, was investigated. Maintaining the pH at 4.5 was found essential for the survival of the yeast. Without pH control, the pH of the medium continued to rise, resulting in the death and/or sporulation of the yeast cells. Diauxic growth was observed, caused by the growth of contaminant bacteria when the pH was not controlled.

Research paper thumbnail of Kinetics of batch production of single-cell protein from cheese whey

Applied Biochemistry and Biotechnology, 1995

A kinetic model for single-cell protein batch fermentation was developed using the numerical simu... more A kinetic model for single-cell protein batch fermentation was developed using the numerical simultaneous integration approach of the fourth-order Runge-Kutta method. The model takes into account the effect of substrate inhibtion, maintenance energy, and cell death on the cell growth and substrate utilization during the fermentation process. The theoretical results obtained from the model compared well with the experimental data. The model was used to study the effect of the initial substrate concentration on the lag period, fermentation time, specific growth rate, population size, and cell productivity of batch fermentation. Increasing the initial substrate concentration increased the lag period and fermentation time and decreased the specific growth rate and cell yield. The growth limiting substrate concentration was 2.9 g/L, whereas the growth inhibiting substrate concentration was 69.0 g/L. Increasing the initial substrate concentration above 150 g/L significantly decreased the yeast population size.

Research paper thumbnail of A computer-based ph measurement and control system for fermentation processes

Applied Biochemistry and Biotechnology, 1991

The measurement and control of pH is essential in most fermentation processes. The highly nonline... more The measurement and control of pH is essential in most fermentation processes. The highly nonlinear response of pH to the addition of acid or base makes pH control by conventional means very difficult. This paper presents a description of the hardware and software of a computer-based pH measurement and control system. The system is applicable to any fermentation process requiringin situ pH measurement and control and is capable of controlling the pH within ±0.1 U with a very short response time. It has a proportional metering device capable of adding the required amount of acid (or alkaline) solution with high accuracy, thereby preventing overshooting.

Research paper thumbnail of Continuous production of biogas from dairy manure using an innovative no-mix reactor

Applied Biochemistry and Biotechnology, 1989

A 25 L no-mix anaerobic digester was designed and fabricated. The digester was designed to act as... more A 25 L no-mix anaerobic digester was designed and fabricated. The digester was designed to act as liquid-solid separator. The sludges obtained from the bottom of the digester had high nitrogen and ash concentrations while the effluent had no offensive odor. The performance of the no-mix digester was compared to that of a continuous stirred tank reactor at two temperatures and five hydraulic retention times. The no-mix digester had higher biogas production rate and pollution potential reduction.

Research paper thumbnail of Continuous propagation of Kluyveromyces fragilis in cheese whey for pollution potential reduction

Applied Biochemistry and Biotechnology, 1994

A 25-L working volume, upright cylindrical fermenter made of stainless steel was used to investig... more A 25-L working volume, upright cylindrical fermenter made of stainless steel was used to investigate cheese whey yeast fermentation for pollution potential reduction. The effluent total and soluble chemical oxygen demand, total and volatile solids, and total Kjeldahl and ammonium nitrogen concentrations were significantly affected by the hydraulic retention time, air flow rate, and mixing speed. The system removal efficiencies were 15.90-58.61%, 25.20-69.33%, 12.43-49.90%, 9.22-51.77%, 1.66-10.06%, and 54.82-72.22% for total chemical oxygen demand, soluble chemical oxygen demand, total solids, volatile solids, total Kjeldahl nitrogen, and ammonium nitrogen, respectively, depending on the hydraulic retention time, air flow rate, and mixing speed used.

Research paper thumbnail of Kinetics of batch production of single-cell protein from cheese whey

Applied Biochemistry and Biotechnology, 1995

A kinetic model for single-cell protein batch fermentation was developed using the numerical simu... more A kinetic model for single-cell protein batch fermentation was developed using the numerical simultaneous integration approach of the fourth-order Runge-Kutta method. The model takes into account the effect of substrate inhibtion, maintenance energy, and cell death on the cell growth and substrate utilization during the fermentation process. The theoretical results obtained from the model compared well with the experimental data. The model was used to study the effect of the initial substrate concentration on the lag period, fermentation time, specific growth rate, population size, and cell productivity of batch fermentation. Increasing the initial substrate concentration increased the lag period and fermentation time and decreased the specific growth rate and cell yield. The growth limiting substrate concentration was 2.9 g/L, whereas the growth inhibiting substrate concentration was 69.0 g/L. Increasing the initial substrate concentration above 150 g/L significantly decreased the yeast population size.

Research paper thumbnail of Effect of pH control on the growth and survival of Kluveromyces fragilis in cheese whey under aerobic condition

Applied Biochemistry and Biotechnology, 1992

Many biological and chemical systems involve acid-base equilibria and thus depend critically on t... more Many biological and chemical systems involve acid-base equilibria and thus depend critically on the pH of the solution. Small fluctuations of pH must be corrected by the addition of an acid or base to maintain the pH at the required optimum level during the fermentation process. The effect of pH control on the growth ofKluveromyces fragilis, used for the production of single-cell protein from cheese whey, was investigated. Maintaining the pH at 4.5 was found essential for the survival of the yeast. Without pH control, the pH of the medium continued to rise, resulting in the death and/or sporulation of the yeast cells. Diauxic growth was observed, caused by the growth of contaminant bacteria when the pH was not controlled.

Research paper thumbnail of A computer-based ph measurement and control system for fermentation processes

Applied Biochemistry and Biotechnology, 1991

The measurement and control of pH is essential in most fermentation processes. The highly nonline... more The measurement and control of pH is essential in most fermentation processes. The highly nonlinear response of pH to the addition of acid or base makes pH control by conventional means very difficult. This paper presents a description of the hardware and software of a computer-based pH measurement and control system. The system is applicable to any fermentation process requiringin situ pH measurement and control and is capable of controlling the pH within ±0.1 U with a very short response time. It has a proportional metering device capable of adding the required amount of acid (or alkaline) solution with high accuracy, thereby preventing overshooting.

Research paper thumbnail of Measuring the economic impact of climate change on major South African field crops: a Ricardian approach

Global and Planetary Change, 2005

This study measured the economic impacts of climate change on crop and livestock farming in Afric... more This study measured the economic impacts of climate change on crop and livestock farming in Africa based on a cross-sectional survey of over 8000 farming households from 11 countries in east, west, north and southern Africa. The response of net revenue from crop and livestock agriculture across various farm types and systems in Africa to changes in climate normals (i.e. mean rainfall and temperature) is analysed. The analyses controlled for effects of key socioeconomic, technology, soil and hydrological factors influencing agricultural production. Results show that net farm revenues are in general negatively affected by warmer and drier climates. The small-scale mixed crop and livestock system predominantly typical in Africa is the most tolerant whereas specialized crop production is the most vulnerable to warming and lower rainfall. These results have important policy implications, especially for the suitability of the increasing tendency toward large-scale mono-cropping strategies for agricultural development in Africa and other parts of the developing world in light of expected climate changes. Mixed crop and livestock farming and irrigation offered better adaptation options for farmers against further warming and drying predicted under various future climate scenarios.

Research paper thumbnail of Mesothelin: A New Target for Immunotherapy

Clinical Cancer Research, 2004

Mesothelin is a differentiation antigen present on normal mesothelial cells and overexpressed in ... more Mesothelin is a differentiation antigen present on normal mesothelial cells and overexpressed in several human tumors, including mesothelioma and ovarian and pancreatic adenocarcinoma. The mesothelin gene encodes a precursor protein that is processed to yield the 40-kDa protein, mesothelin, attached to the cell membrane by a glycosylphosphatidyl inositol linkage and a 31-kDa shed fragment named megakaryocyte-potentiating factor. The biological function of mesothelin is not known. Mesothelin is a promising candidate for tumor-specific therapy, given its limited expression in normal tissues and high expression in several cancers. SS1(dsFv)PE38 is a recombinant anti-mesothelin immunotoxin that is undergoing clinical evaluation in patients with mesothelin-expressing tumors. There is evidence that mesothelin is an immunogenic protein and could be exploited as a therapeutic cancer vaccine. A soluble mesothelin variant has been identified and could be a useful tumor marker for malignant mesotheliomas.

Research paper thumbnail of Mesothelin: A New Target for Immunotherapy

Clinical Cancer Research, 2004

Mesothelin is a differentiation antigen present on normal mesothelial cells and overexpressed in ... more Mesothelin is a differentiation antigen present on normal mesothelial cells and overexpressed in several human tumors, including mesothelioma and ovarian and pancreatic adenocarcinoma. The mesothelin gene encodes a precursor protein that is processed to yield the 40-kDa protein, mesothelin, attached to the cell membrane by a glycosylphosphatidyl inositol linkage and a 31-kDa shed fragment named megakaryocyte-potentiating factor. The biological function of mesothelin is not known. Mesothelin is a promising candidate for tumor-specific therapy, given its limited expression in normal tissues and high expression in several cancers. SS1(dsFv)PE38 is a recombinant anti-mesothelin immunotoxin that is undergoing clinical evaluation in patients with mesothelin-expressing tumors. There is evidence that mesothelin is an immunogenic protein and could be exploited as a therapeutic cancer vaccine. A soluble mesothelin variant has been identified and could be a useful tumor marker for malignant mesotheliomas.

Research paper thumbnail of Effect of pH control on the growth and survival of Kluveromyces fragilis in cheese whey under aerobic condition

Applied Biochemistry and Biotechnology, 1992

Many biological and chemical systems involve acid-base equilibria and thus depend critically on t... more Many biological and chemical systems involve acid-base equilibria and thus depend critically on the pH of the solution. Small fluctuations of pH must be corrected by the addition of an acid or base to maintain the pH at the required optimum level during the fermentation process. The effect of pH control on the growth of Kluveromyces fragilis, used for the production of single-cell protein from cheese whey, was investigated. Maintaining the pH at 4.5 was found essential for the survival of the yeast. Without pH control, the pH of the medium continued to rise, resulting in the death and/or sporulation of the yeast cells. Diauxic growth was observed, caused by the growth of contaminant bacteria when the pH was not controlled.

Research paper thumbnail of Effect of pH control on the growth and survival of Kluveromyces fragilis in cheese whey under aerobic condition

Applied Biochemistry and Biotechnology, 1992

Many biological and chemical systems involve acid-base equilibria and thus depend critically on t... more Many biological and chemical systems involve acid-base equilibria and thus depend critically on the pH of the solution. Small fluctuations of pH must be corrected by the addition of an acid or base to maintain the pH at the required optimum level during the fermentation process. The effect of pH control on the growth ofKluveromyces fragilis, used for the production of single-cell protein from cheese whey, was investigated. Maintaining the pH at 4.5 was found essential for the survival of the yeast. Without pH control, the pH of the medium continued to rise, resulting in the death and/or sporulation of the yeast cells. Diauxic growth was observed, caused by the growth of contaminant bacteria when the pH was not controlled.

Research paper thumbnail of A computer-based ph measurement and control system for fermentation processes

Applied Biochemistry and Biotechnology, 1991

The measurement and control of pH is essential in most fermentation processes. The highly nonline... more The measurement and control of pH is essential in most fermentation processes. The highly nonlinear response of pH to the addition of acid or base makes pH control by conventional means very difficult. This paper presents a description of the hardware and software of a computer-based pH measurement and control system. The system is applicable to any fermentation process requiring in situ pH measurement and control and is capable of controlling the pH within + 0.1 U with a very short response time. It has a proportional metering device capable of adding the required amount of acid (or alkaline) solution with high accuracy, thereby preventing overshooting.

Research paper thumbnail of A computer-based ph measurement and control system for fermentation processes

Applied Biochemistry and Biotechnology, 1991

The measurement and control of pH is essential in most fermentation processes. The highly nonline... more The measurement and control of pH is essential in most fermentation processes. The highly nonlinear response of pH to the addition of acid or base makes pH control by conventional means very difficult. This paper presents a description of the hardware and software of a computer-based pH measurement and control system. The system is applicable to any fermentation process requiringin situ pH measurement and control and is capable of controlling the pH within ±0.1 U with a very short response time. It has a proportional metering device capable of adding the required amount of acid (or alkaline) solution with high accuracy, thereby preventing overshooting.

Research paper thumbnail of Continuous production of biogas from dairy manure using an innovative no-mix reactor

Applied Biochemistry and Biotechnology, 1989

... from Dairy Manure Using an Innovative No-Mix Reactor AE GHALY* AND RM BEN-HASSAN Agricultural... more ... from Dairy Manure Using an Innovative No-Mix Reactor AE GHALY* AND RM BEN-HASSAN Agricultural Engineering Department, Technical University of Nova Scotia, PO Box 1000, Halifax, Nova Scotia, Canada, B3J 2X4 ... Page 2. 542 Ghaly and Ben-Hassan three stages. ...

Research paper thumbnail of Continuous propagation of Kluyveromyces fragilis in cheese whey for pollution potential reduction

Applied Biochemistry and Biotechnology, 1994

A 25-L working volume, upright cylindrical fermenter made of stainless steel was used to investig... more A 25-L working volume, upright cylindrical fermenter made of stainless steel was used to investigate cheese whey yeast fermentation for pollution potential reduction. The effluent total and soluble chemical oxygen demand, total and volatile solids, and total Kjeldahl and ammonium nitrogen concentrations were significantly affected by the hydraulic retention time, air flow rate, and mixing speed. The system removal efficiencies were 15.90-58.61%, 25.20-69.33%, 12.43-49.90%, 9.22-51.77%, 1.66-10.06%, and 54.82-72.22% for total chemical oxygen demand, soluble chemical oxygen demand, total solids, volatile solids, total Kjeldahl nitrogen, and ammonium nitrogen, respectively, depending on the hydraulic retention time, air flow rate, and mixing speed used.

Research paper thumbnail of Continuous production of biogas from dairy manure using an innovative no-mix reactor

Applied Biochemistry and Biotechnology, 1989

A 25 L no-mix anaerobic digester was designed and fabricated. The digester was designed to act as... more A 25 L no-mix anaerobic digester was designed and fabricated. The digester was designed to act as liquid-solid separator. The sludges obtained from the bottom of the digester had high nitrogen and ash concentrations while the effluent had no offensive odor. The performance of the no-mix digester was compared to that of a continuous stirred tank reactor at two temperatures and five hydraulic retention times. The no-mix digester had higher biogas production rate and pollution potential reduction.

Research paper thumbnail of Kinetics of batch production of single-cell protein from cheese whey

Applied Biochemistry and Biotechnology, 1995

A kinetic model for single-cell protein batch fermentation was developed using the numerical simu... more A kinetic model for single-cell protein batch fermentation was developed using the numerical simultaneous integration approach of the fourth-order Runge-Kutta method. The model takes into account the effect of substrate inhibtion, maintenance energy, and cell death on the cell growth and substrate utilization during the fermentation process. The theoretical results obtained from the model compared well with the experimental data. The model was used to study the effect of the initial substrate concentration on the lag period, fermentation time, specific growth rate, population size, and cell productivity of batch fermentation. Increasing the initial substrate concentration increased the lag period and fermentation time and decreased the specific growth rate and cell yield. The growth limiting substrate concentration was 2.9 g/L, whereas the growth inhibiting substrate concentration was 69.0 g/L. Increasing the initial substrate concentration above 150 g/L significantly decreased the yeast population size.

Research paper thumbnail of Continuous propagation of Kluyveromyces fragilis in cheese whey for pollution potential reduction

Applied Biochemistry and Biotechnology, 1994

A 25-L working volume, upright cylindrical fermenter made of stainless steel was used to investig... more A 25-L working volume, upright cylindrical fermenter made of stainless steel was used to investigate cheese whey yeast fermentation for pollution potential reduction. The effluent total and soluble chemical oxygen demand, total and volatile solids, and total Kjeldahl and ammonium nitrogen concentrations were significantly affected by the hydraulic retention time, air flow rate, and mixing speed. The system removal efficiencies were 15.90-58.61%, 25.20-69.33%, 12.43-49.90%, 9.22-51.77%, 1.66-10.06%, and 54.82-72.22% for total chemical oxygen demand, soluble chemical oxygen demand, total solids, volatile solids, total Kjeldahl nitrogen, and ammonium nitrogen, respectively, depending on the hydraulic retention time, air flow rate, and mixing speed used.

Research paper thumbnail of Effect of pH control on the growth and survival of Kluveromyces fragilis in cheese whey under aerobic condition

Applied Biochemistry and Biotechnology, 1992

Many biological and chemical systems involve acid-base equilibria and thus depend critically on t... more Many biological and chemical systems involve acid-base equilibria and thus depend critically on the pH of the solution. Small fluctuations of pH must be corrected by the addition of an acid or base to maintain the pH at the required optimum level during the fermentation process. The effect of pH control on the growth ofKluveromyces fragilis, used for the production of single-cell protein from cheese whey, was investigated. Maintaining the pH at 4.5 was found essential for the survival of the yeast. Without pH control, the pH of the medium continued to rise, resulting in the death and/or sporulation of the yeast cells. Diauxic growth was observed, caused by the growth of contaminant bacteria when the pH was not controlled.

Research paper thumbnail of Kinetics of batch production of single-cell protein from cheese whey

Applied Biochemistry and Biotechnology, 1995

A kinetic model for single-cell protein batch fermentation was developed using the numerical simu... more A kinetic model for single-cell protein batch fermentation was developed using the numerical simultaneous integration approach of the fourth-order Runge-Kutta method. The model takes into account the effect of substrate inhibtion, maintenance energy, and cell death on the cell growth and substrate utilization during the fermentation process. The theoretical results obtained from the model compared well with the experimental data. The model was used to study the effect of the initial substrate concentration on the lag period, fermentation time, specific growth rate, population size, and cell productivity of batch fermentation. Increasing the initial substrate concentration increased the lag period and fermentation time and decreased the specific growth rate and cell yield. The growth limiting substrate concentration was 2.9 g/L, whereas the growth inhibiting substrate concentration was 69.0 g/L. Increasing the initial substrate concentration above 150 g/L significantly decreased the yeast population size.

Research paper thumbnail of A computer-based ph measurement and control system for fermentation processes

Applied Biochemistry and Biotechnology, 1991

The measurement and control of pH is essential in most fermentation processes. The highly nonline... more The measurement and control of pH is essential in most fermentation processes. The highly nonlinear response of pH to the addition of acid or base makes pH control by conventional means very difficult. This paper presents a description of the hardware and software of a computer-based pH measurement and control system. The system is applicable to any fermentation process requiringin situ pH measurement and control and is capable of controlling the pH within ±0.1 U with a very short response time. It has a proportional metering device capable of adding the required amount of acid (or alkaline) solution with high accuracy, thereby preventing overshooting.

Research paper thumbnail of Continuous production of biogas from dairy manure using an innovative no-mix reactor

Applied Biochemistry and Biotechnology, 1989

A 25 L no-mix anaerobic digester was designed and fabricated. The digester was designed to act as... more A 25 L no-mix anaerobic digester was designed and fabricated. The digester was designed to act as liquid-solid separator. The sludges obtained from the bottom of the digester had high nitrogen and ash concentrations while the effluent had no offensive odor. The performance of the no-mix digester was compared to that of a continuous stirred tank reactor at two temperatures and five hydraulic retention times. The no-mix digester had higher biogas production rate and pollution potential reduction.

Research paper thumbnail of Continuous propagation of Kluyveromyces fragilis in cheese whey for pollution potential reduction

Applied Biochemistry and Biotechnology, 1994

A 25-L working volume, upright cylindrical fermenter made of stainless steel was used to investig... more A 25-L working volume, upright cylindrical fermenter made of stainless steel was used to investigate cheese whey yeast fermentation for pollution potential reduction. The effluent total and soluble chemical oxygen demand, total and volatile solids, and total Kjeldahl and ammonium nitrogen concentrations were significantly affected by the hydraulic retention time, air flow rate, and mixing speed. The system removal efficiencies were 15.90-58.61%, 25.20-69.33%, 12.43-49.90%, 9.22-51.77%, 1.66-10.06%, and 54.82-72.22% for total chemical oxygen demand, soluble chemical oxygen demand, total solids, volatile solids, total Kjeldahl nitrogen, and ammonium nitrogen, respectively, depending on the hydraulic retention time, air flow rate, and mixing speed used.

Research paper thumbnail of Kinetics of batch production of single-cell protein from cheese whey

Applied Biochemistry and Biotechnology, 1995

A kinetic model for single-cell protein batch fermentation was developed using the numerical simu... more A kinetic model for single-cell protein batch fermentation was developed using the numerical simultaneous integration approach of the fourth-order Runge-Kutta method. The model takes into account the effect of substrate inhibtion, maintenance energy, and cell death on the cell growth and substrate utilization during the fermentation process. The theoretical results obtained from the model compared well with the experimental data. The model was used to study the effect of the initial substrate concentration on the lag period, fermentation time, specific growth rate, population size, and cell productivity of batch fermentation. Increasing the initial substrate concentration increased the lag period and fermentation time and decreased the specific growth rate and cell yield. The growth limiting substrate concentration was 2.9 g/L, whereas the growth inhibiting substrate concentration was 69.0 g/L. Increasing the initial substrate concentration above 150 g/L significantly decreased the yeast population size.

Research paper thumbnail of Effect of pH control on the growth and survival of Kluveromyces fragilis in cheese whey under aerobic condition

Applied Biochemistry and Biotechnology, 1992

Many biological and chemical systems involve acid-base equilibria and thus depend critically on t... more Many biological and chemical systems involve acid-base equilibria and thus depend critically on the pH of the solution. Small fluctuations of pH must be corrected by the addition of an acid or base to maintain the pH at the required optimum level during the fermentation process. The effect of pH control on the growth ofKluveromyces fragilis, used for the production of single-cell protein from cheese whey, was investigated. Maintaining the pH at 4.5 was found essential for the survival of the yeast. Without pH control, the pH of the medium continued to rise, resulting in the death and/or sporulation of the yeast cells. Diauxic growth was observed, caused by the growth of contaminant bacteria when the pH was not controlled.

Research paper thumbnail of A computer-based ph measurement and control system for fermentation processes

Applied Biochemistry and Biotechnology, 1991

The measurement and control of pH is essential in most fermentation processes. The highly nonline... more The measurement and control of pH is essential in most fermentation processes. The highly nonlinear response of pH to the addition of acid or base makes pH control by conventional means very difficult. This paper presents a description of the hardware and software of a computer-based pH measurement and control system. The system is applicable to any fermentation process requiringin situ pH measurement and control and is capable of controlling the pH within ±0.1 U with a very short response time. It has a proportional metering device capable of adding the required amount of acid (or alkaline) solution with high accuracy, thereby preventing overshooting.