Water science and technology : a journal of the International Association on Water Pollution Research, 2003
A mechanistic mathematical model for nutrient and organic matter removal was used to describe the... more A mechanistic mathematical model for nutrient and organic matter removal was used to describe the behavior of a nitrification denitrification enhanced biological phosphorus removal (NDEBPR) system. This model was implemented in a user-friendly software DESASS (design and simulation of activated sludge systems). A 484-L pilot plant was operated to verify the model results. The pilot plant was operated for three years over three different sludge ages. The validity of the model was confirmed with data from the pilot plant. Also, the utility of DESASS as a valuable tool for designing NDEBPR systems was confirmed.
Water science and technology : a journal of the International Association on Water Pollution Research, 2001
A modification to the ASM2 is proposed which permits representation of the competition between ph... more A modification to the ASM2 is proposed which permits representation of the competition between phosphorus accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) in a nutrient removal activated sludge system. Some important aspects, which are not considered in ASM2, are discussed. The proposed modification includes denitrification by PAOs, PAO glycogen storage capability and GAO metabolism model. It is shown that the proposed modification is capable of describing pilot plant data using a single set of stoichiometric and kinetic parameters over three different sludge ages (16, 14 and 12 days). The modified ASM2 may be applicable to a wide range of situations where PAOs and GAOs can compete. This modification may well provide a better understanding about GAO behaviour.
This paper presents laboratory scale experimentation carried out to study enhanced biological pho... more This paper presents laboratory scale experimentation carried out to study enhanced biological phosphorus removal at high phosphorus concentrations in a sequencing batch reactor. Four series of data obtained in a sequencing batch reactor are examined in light of the Activated Sludge Model No. 2. This model was calibrated using data from the first and second series working at low phosphorus concentrations. The Activated Sludge Model No. 2 successfully characterised the enhanced biological phosphorus removal performance of the sequencing batch reactor at low phosphorus concentrations. The calibrated model was then used to adjust experimental results of the other series working at high phosphorus concentration. Differences between model predictions and experimental data could be explained by redissolution in the anaerobic phase and precipitation in the aerobic phase of calcium phosphates not taken into account by the model. This hypothesis can be justified by the conditions of pH and phosphorus concentration prevailing in the experiments and it was confirmed by the results of another experiment in which precipitated phosphorus profile was measured during the cycle.
PURPOSE The establishment of a positive HIV serologic status of an individual could have been an ... more PURPOSE The establishment of a positive HIV serologic status of an individual could have been an inhibitory factor to prevent risk behaviours in people living with HIV/AIDS. We conducted a cross-sectional study in order to assess the prevalence and predictors of risk behaviors among HIV-positive people in Douala-Cameroon. METHODS We used pre-checked questionnaires to systematically collect data from four HIV Treatment centers in Douala. This was done to some of them during the distribution of drugs, and to others during their classical rendezvous, between the months of May and July 2012. The Chi-Square and Student t-test were used forcross tabulation of variables; multiple regression analysis was performed to identify predictors of risky sexual behaviours. RESULTS Of the 330 persons interviewed. Sixty percent were reported to have had sexual intercourse after the diagnosis of HIV. We obtained 37% HIV-positive partners and 63% had HIV-negative partners or partners with unknown status...
Proceedings of the Water Environment Federation, 2004
This paper compares two methods for designing compensators for dual actuated motion systems [3] .... more This paper compares two methods for designing compensators for dual actuated motion systems [3] . Usually H , control is used, including p-synthesis. This method gives very little insight in the controller design proces. The methods compared in this article treat the design of the controller as the design of two SISO controllers, which leads to much more insight. In this paper both methods are explained and illustrated by an example of a servo-positioning system using two actuators.
Obesity is a worldwide public health problem, and its burden has been poorly explored in Cameroon... more Obesity is a worldwide public health problem, and its burden has been poorly explored in Cameroon, especially in work place. We therefore carried out in April 2010, an analytic cross-sectional study aiming to determine the prevalence of obesity, associated risk factors and health risk in six randomly selected enterprises based in Douala. Among the 552 participants, 383 (69.4%) were males. Most of the workers (55.4%) were aged less than 35 years old. There was 191 (34.60%) office staff as against 361 (65.40%) labourers. In each participant, blood pressures, and fasting blood glucose were recorded, as well as obesity indexes comprising body mass index and waist circumference. They were calculated and data analyzed using SPSS 16 and Win Pepi 11.8. The prevalence of obesity in workers was 23.4%, and was more pronounced in women than in men (36.1% vs 17.8%; P < 0.005). The workers aged > or = 45 years old exhibited highest obesity rate than other age group (P = 0.03). Importantly, ...
The aim of this work is to present an overview about an experimental study for biological nitroge... more The aim of this work is to present an overview about an experimental study for biological nitrogen removal implemented in a pilot-scale plant, located in the Universidad Del Norte in Barranquilla, Colombia. This plant was studied in two different periods. The first period, which was carried out in 90 days, was dedicated to study the influence of the daily variations on the influent and effluent wastewater, and prove some control routines for nitrogen removal. In the second period, which was carried out in 120 days, the removal process was optimized with the addition of acetic acid as an external carbon source, and the implementation of the final control strategy was performed based on the results of the previous period.
This paper presents laboratory scale experimentation carried out to study enhanced biological pho... more This paper presents laboratory scale experimentation carried out to study enhanced biological phosphorus removal at high phosphorus concentrations in a sequencing batch reactor. Four series of data obtained in a sequencing batch reactor are examined in light of the Activated Sludge Model No. 2. This model was calibrated using data from the first and second series working at low phosphorus concentrations. The Activated Sludge Model No. 2 successfully characterised the enhanced biological phosphorus removal performance of the sequencing batch reactor at low phosphorus concentrations. The calibrated model was then used to adjust experimental results of the other series working at high phosphorus concentration. Differences between model predictions and experimental data could be explained by redissolution in the anaerobic phase and precipitation in the aerobic phase of calcium phosphates not taken into account by the model. This hypothesis can be justified by the conditions of pH and phosphorus concentration prevailing in the experiments and it was confirmed by the results of another experiment in which precipitated phosphorus profile was measured during the cycle.
Introduction : La multiplication des thérapeutiques, le caractère chronique et souvent asymptomat... more Introduction : La multiplication des thérapeutiques, le caractère chronique et souvent asymptomatique de la maladie poussent souvent à la mauvaise observance thérapeutique chez le diabétique. L'objectif de cette étude était d'évaluer l'influence du niveau socio-économique et du niveau d'instruction sur l'observance thérapeutique chez le diabétique de type 2. Patients et méthodes : Il s'agit d'une étude prospective qui a intéressée 61 diabétiques de type 2, âgés en moyenne de 63 ans, ayant une durée moyenne du diabète de 17,7 ans et traités par antidiabétiques oraux (ADO) et insuline. Tous les patients ont répondu à un questionnaire concernant la qualité de l'observance de leur traitement depuis la dernière consultation en précisant les causes de mauvaise observance. Le niveau intellectuel et le niveau socio-économique étaient évalués par l'interrogatoire. Résultats : Depuis la dernière consultation, 42 % des patients n'avaient interrompu aucune fois leur traitement, 15 % avaient interrompu les ADO et l'insuline, 20 % l'insuline seulement et 23 % les ADO seulement. Les principales causes de l'arrêt du traitement étaient l'oubli (28 % des cas) et la non disponibilité au dispensaire local (22 % des cas). Les patients mal observants étaient plus âgés (pþ= 0,04), avaient un taux d'analphabétisme plus élevé (pþ= 0,03). Le niveau socio-économique (p = 0,6) n'avaient pas d'influence sur la qualité de l'observance thérapeutique. Conclusion : L'évaluation de la qualité de la prise médicamenteuse est nécessaire chez le diabétique à chaque consultation. L'éducation thérapeutique doit tenir compte du niveau intellectuel du patient diabétique.
... E! rel-isa de aguas iesieízraies se PFL&#x27;SI.Ï&#x27;IÍI&#x27;J vaina un FUCIJ... more ... E! rel-isa de aguas iesieízraies se PFL&#x27;SI.Ï&#x27;IÍI&#x27;J vaina un FUCIJFSU nidrici) disponible ¡{ni-I&#x27;ll combatir ia escasez deagua y ... en di-ferentes países muestra que es posible desarrollar empresas que gestionen in-tegradamente el reuso de aguas resi-duales (Moscoso j., 1993). ...
This paper presents a very useful software tool to design, simulate and optimise wastewater treat... more This paper presents a very useful software tool to design, simulate and optimise wastewater treatment plants. The program is called DESASS (DEsign and Simulation of Activated Sludge Systems) and has been developed by CALAGUA research group. The mathematical model implemented is the Biological Nutrient Removal Model No.1 (BNRM1) which allows simulating the most important physical, chemical and biological processes taking place in treatment plants. DESASS calculates the performance under steady or transient state of whole treatment schemes including primary settlers, volatile fatty acid generation systems by primary sludge fermentation, activated sludge systems for biological organic matter and nutrient removal, chemical phosphorus precipitation, secondary settlers, gravity thickeners and sludge digesters (aerobic and anaerobic). Biological conversions occurring in settlers and thickeners (primary sludge fermentation, denitrification) are also taken into account, i.e. they are considered as reactive elements. DESASS also includes pH calculation coupled to biological processes in all the elements, so pH effect on biological processes can be directly simulated. Furthermore, the effect of sidestreams on nutrient removal efficiency can be estimated because the performance of the whole plant can be simulated.
Water science and technology : a journal of the International Association on Water Pollution Research, 2003
A mechanistic mathematical model for nutrient and organic matter removal was used to describe the... more A mechanistic mathematical model for nutrient and organic matter removal was used to describe the behavior of a nitrification denitrification enhanced biological phosphorus removal (NDEBPR) system. This model was implemented in a user-friendly software DESASS (design and simulation of activated sludge systems). A 484-L pilot plant was operated to verify the model results. The pilot plant was operated for three years over three different sludge ages. The validity of the model was confirmed with data from the pilot plant. Also, the utility of DESASS as a valuable tool for designing NDEBPR systems was confirmed.
Water science and technology : a journal of the International Association on Water Pollution Research, 2001
A modification to the ASM2 is proposed which permits representation of the competition between ph... more A modification to the ASM2 is proposed which permits representation of the competition between phosphorus accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) in a nutrient removal activated sludge system. Some important aspects, which are not considered in ASM2, are discussed. The proposed modification includes denitrification by PAOs, PAO glycogen storage capability and GAO metabolism model. It is shown that the proposed modification is capable of describing pilot plant data using a single set of stoichiometric and kinetic parameters over three different sludge ages (16, 14 and 12 days). The modified ASM2 may be applicable to a wide range of situations where PAOs and GAOs can compete. This modification may well provide a better understanding about GAO behaviour.
This paper presents laboratory scale experimentation carried out to study enhanced biological pho... more This paper presents laboratory scale experimentation carried out to study enhanced biological phosphorus removal at high phosphorus concentrations in a sequencing batch reactor. Four series of data obtained in a sequencing batch reactor are examined in light of the Activated Sludge Model No. 2. This model was calibrated using data from the first and second series working at low phosphorus concentrations. The Activated Sludge Model No. 2 successfully characterised the enhanced biological phosphorus removal performance of the sequencing batch reactor at low phosphorus concentrations. The calibrated model was then used to adjust experimental results of the other series working at high phosphorus concentration. Differences between model predictions and experimental data could be explained by redissolution in the anaerobic phase and precipitation in the aerobic phase of calcium phosphates not taken into account by the model. This hypothesis can be justified by the conditions of pH and phosphorus concentration prevailing in the experiments and it was confirmed by the results of another experiment in which precipitated phosphorus profile was measured during the cycle.
PURPOSE The establishment of a positive HIV serologic status of an individual could have been an ... more PURPOSE The establishment of a positive HIV serologic status of an individual could have been an inhibitory factor to prevent risk behaviours in people living with HIV/AIDS. We conducted a cross-sectional study in order to assess the prevalence and predictors of risk behaviors among HIV-positive people in Douala-Cameroon. METHODS We used pre-checked questionnaires to systematically collect data from four HIV Treatment centers in Douala. This was done to some of them during the distribution of drugs, and to others during their classical rendezvous, between the months of May and July 2012. The Chi-Square and Student t-test were used forcross tabulation of variables; multiple regression analysis was performed to identify predictors of risky sexual behaviours. RESULTS Of the 330 persons interviewed. Sixty percent were reported to have had sexual intercourse after the diagnosis of HIV. We obtained 37% HIV-positive partners and 63% had HIV-negative partners or partners with unknown status...
Proceedings of the Water Environment Federation, 2004
This paper compares two methods for designing compensators for dual actuated motion systems [3] .... more This paper compares two methods for designing compensators for dual actuated motion systems [3] . Usually H , control is used, including p-synthesis. This method gives very little insight in the controller design proces. The methods compared in this article treat the design of the controller as the design of two SISO controllers, which leads to much more insight. In this paper both methods are explained and illustrated by an example of a servo-positioning system using two actuators.
Obesity is a worldwide public health problem, and its burden has been poorly explored in Cameroon... more Obesity is a worldwide public health problem, and its burden has been poorly explored in Cameroon, especially in work place. We therefore carried out in April 2010, an analytic cross-sectional study aiming to determine the prevalence of obesity, associated risk factors and health risk in six randomly selected enterprises based in Douala. Among the 552 participants, 383 (69.4%) were males. Most of the workers (55.4%) were aged less than 35 years old. There was 191 (34.60%) office staff as against 361 (65.40%) labourers. In each participant, blood pressures, and fasting blood glucose were recorded, as well as obesity indexes comprising body mass index and waist circumference. They were calculated and data analyzed using SPSS 16 and Win Pepi 11.8. The prevalence of obesity in workers was 23.4%, and was more pronounced in women than in men (36.1% vs 17.8%; P < 0.005). The workers aged > or = 45 years old exhibited highest obesity rate than other age group (P = 0.03). Importantly, ...
The aim of this work is to present an overview about an experimental study for biological nitroge... more The aim of this work is to present an overview about an experimental study for biological nitrogen removal implemented in a pilot-scale plant, located in the Universidad Del Norte in Barranquilla, Colombia. This plant was studied in two different periods. The first period, which was carried out in 90 days, was dedicated to study the influence of the daily variations on the influent and effluent wastewater, and prove some control routines for nitrogen removal. In the second period, which was carried out in 120 days, the removal process was optimized with the addition of acetic acid as an external carbon source, and the implementation of the final control strategy was performed based on the results of the previous period.
This paper presents laboratory scale experimentation carried out to study enhanced biological pho... more This paper presents laboratory scale experimentation carried out to study enhanced biological phosphorus removal at high phosphorus concentrations in a sequencing batch reactor. Four series of data obtained in a sequencing batch reactor are examined in light of the Activated Sludge Model No. 2. This model was calibrated using data from the first and second series working at low phosphorus concentrations. The Activated Sludge Model No. 2 successfully characterised the enhanced biological phosphorus removal performance of the sequencing batch reactor at low phosphorus concentrations. The calibrated model was then used to adjust experimental results of the other series working at high phosphorus concentration. Differences between model predictions and experimental data could be explained by redissolution in the anaerobic phase and precipitation in the aerobic phase of calcium phosphates not taken into account by the model. This hypothesis can be justified by the conditions of pH and phosphorus concentration prevailing in the experiments and it was confirmed by the results of another experiment in which precipitated phosphorus profile was measured during the cycle.
Introduction : La multiplication des thérapeutiques, le caractère chronique et souvent asymptomat... more Introduction : La multiplication des thérapeutiques, le caractère chronique et souvent asymptomatique de la maladie poussent souvent à la mauvaise observance thérapeutique chez le diabétique. L'objectif de cette étude était d'évaluer l'influence du niveau socio-économique et du niveau d'instruction sur l'observance thérapeutique chez le diabétique de type 2. Patients et méthodes : Il s'agit d'une étude prospective qui a intéressée 61 diabétiques de type 2, âgés en moyenne de 63 ans, ayant une durée moyenne du diabète de 17,7 ans et traités par antidiabétiques oraux (ADO) et insuline. Tous les patients ont répondu à un questionnaire concernant la qualité de l'observance de leur traitement depuis la dernière consultation en précisant les causes de mauvaise observance. Le niveau intellectuel et le niveau socio-économique étaient évalués par l'interrogatoire. Résultats : Depuis la dernière consultation, 42 % des patients n'avaient interrompu aucune fois leur traitement, 15 % avaient interrompu les ADO et l'insuline, 20 % l'insuline seulement et 23 % les ADO seulement. Les principales causes de l'arrêt du traitement étaient l'oubli (28 % des cas) et la non disponibilité au dispensaire local (22 % des cas). Les patients mal observants étaient plus âgés (pþ= 0,04), avaient un taux d'analphabétisme plus élevé (pþ= 0,03). Le niveau socio-économique (p = 0,6) n'avaient pas d'influence sur la qualité de l'observance thérapeutique. Conclusion : L'évaluation de la qualité de la prise médicamenteuse est nécessaire chez le diabétique à chaque consultation. L'éducation thérapeutique doit tenir compte du niveau intellectuel du patient diabétique.
... E! rel-isa de aguas iesieízraies se PFL&#x27;SI.Ï&#x27;IÍI&#x27;J vaina un FUCIJ... more ... E! rel-isa de aguas iesieízraies se PFL&#x27;SI.Ï&#x27;IÍI&#x27;J vaina un FUCIJFSU nidrici) disponible ¡{ni-I&#x27;ll combatir ia escasez deagua y ... en di-ferentes países muestra que es posible desarrollar empresas que gestionen in-tegradamente el reuso de aguas resi-duales (Moscoso j., 1993). ...
This paper presents a very useful software tool to design, simulate and optimise wastewater treat... more This paper presents a very useful software tool to design, simulate and optimise wastewater treatment plants. The program is called DESASS (DEsign and Simulation of Activated Sludge Systems) and has been developed by CALAGUA research group. The mathematical model implemented is the Biological Nutrient Removal Model No.1 (BNRM1) which allows simulating the most important physical, chemical and biological processes taking place in treatment plants. DESASS calculates the performance under steady or transient state of whole treatment schemes including primary settlers, volatile fatty acid generation systems by primary sludge fermentation, activated sludge systems for biological organic matter and nutrient removal, chemical phosphorus precipitation, secondary settlers, gravity thickeners and sludge digesters (aerobic and anaerobic). Biological conversions occurring in settlers and thickeners (primary sludge fermentation, denitrification) are also taken into account, i.e. they are considered as reactive elements. DESASS also includes pH calculation coupled to biological processes in all the elements, so pH effect on biological processes can be directly simulated. Furthermore, the effect of sidestreams on nutrient removal efficiency can be estimated because the performance of the whole plant can be simulated.
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Papers by J. Manga