Roger NJILA | Université Laval (original) (raw)
Papers by Roger NJILA
Groundwater for sustainable development, Apr 1, 2024
The Yato physicochemical water purification station is located in Dibombari District Council in t... more The Yato physicochemical water purification station is located in Dibombari District Council in the Littoral-Cameroon region. It is one of the largest drinking water production stations in the Central African sub-region. This work aims to evaluate, through the quantification of the concentrations of Trace Metal Elements (TMEs), the polluting status of the sludge from this drinking water production station and their impacts on the soil. To achieve this objective, mixed samples of sludge from sludge treatment ponds (taken according to the technique described in GIDS-A003 point 6 as explained in the Solid and pasty waste sampling strategy of Code of Good Practice No. 2) and samples of sludge from primary settling basins (taken in transparent bottles in polyethylene terephthalate of 1.5L) were analysed. Likewise, three soil wells were carried out and soil samples were taken on two levels of alteration then sent to the laboratory where physicochemical and TME analyses were carried out. The characteristics of the samples that were analysed are: particle size, texture (sand, silt, clay), physiochemistry (pH, electrical conductivity, temperature, phosphorus, nitrogen) and TME (chromium, copper, zinc, manganese). The results obtained show that the polluting status of the sludge from the Yato station is proven because their pollution index by heavy metals is greater than 1. The pollution index greater than 1 in the sludge from the treatment basins is due to the strong concentrations of TME originating from the accumulation of waste of all kinds in this location. Overall, TME concentrations in soils decrease for the most part from the surface towards depth. All the TMEs studied (Zn, Mn, Cu, Cr) are present in all horizons. There is multiple contamination of sludge by TMEs because their pollution index is greater than 1 (IP>1). Although the sludge pollution indices are greater than 1, those of the different horizons are much lower than 1. Thus, since the TMEs decrease with depth, the subsurface horizons would be less affected by the pollutants contained in the station sludge. marking a real pollution of the surface layers.
The Yato physicochemical water purification station is located in the commune of Dibombari in the... more The Yato physicochemical water purification station is located in the commune of Dibombari in the Littoral-Cameroon region. It is one of the largest drinking water production stations in the Central African sub-region. This work aims to evaluate the agronomic power of the sludge from this drinking water production station. To achieve this objective, mixed samples of sludge from sludge treatment basins (taken according to the technique described in GIDS-A003 point 6 as explained in the Solid and pasty waste sampling strategy of the Code of Good Practice No. 2). and primary settling basins (collected in transparent 1.5L polyethylene terephthalate bottles) were analyzed. Likewise, three soil samples (marsh, Point 1 and Point 2) were taken and then sent to the laboratory where physicochemical analyzes were carried out. The characteristics of the samples that were analyzed are: particle size, texture (sand, silt, clay) and physicochemistry (organic matter, CEC, sum of exchangeable bases, calcium, nitrogen, potassium and magnesium). The results obtained show that the soils exposed to contamination from the sludge of the station have better agronomic properties both on a physical level with a stable structure favorable to plant growth and good aeration unlike the soils far from the station which presented a high risk. degradation; that on the chemical level with an optimal cationic balance, a high reserve of exchangeable bases, a strong CEC but average limitations in assimilable phosphorus and pH unlike the soil far from the station which presented an insufficiency of potassium which did not facilitate a balance cationic, a low CEC but a pH above 5.5 which is the value recommended in agronomy. Biochemically, organic matter is above 2% in all soils, a mineralization rate less than 20 favoring the rapid mineralization of carbon and a release of nitrogen available to the plant. These results obtained allow us to conclude that the sludge from the Yato station can be used in agronomy as an organic fertilizer in order to correct the soil structure, the CEC, the cationic balances and also provide the soil with a good base reserve. However, treating this sludge with lime could regulate the pH of the soil and reduce the mobility of heavy metals in the soil.
Water Practice & Technology
Groundwater is a major resource for drinking water, especially in developing countries, where it ... more Groundwater is a major resource for drinking water, especially in developing countries, where it is less expensive to treat than surface water. Today, the resource is highly susceptible to pollution, particularly as a result of human activity. This review was based on a literature review and critical analysis of models for estimating the groundwater vulnerability. The results show that the deepest porous aquifers are the least susceptible to pollution, whereas those in karstic and fissured environments are susceptible, whatever their depth. Pollution usually arises from human activity. Critical analysis of the literature shows that existing methods are developed in specific environmental contexts. Given the variability of factors in space and time, these methods do not take the intrinsic realities of all natural settings into account adequately and are not perfectly applicable in all environments. This highlights the need to develop appropriate models for each environment, such as t...
Water Practice & Technology
Natural coagulants can be an alternative solution to minimise the environmental pollution and hea... more Natural coagulants can be an alternative solution to minimise the environmental pollution and health risks caused by the use of chemical coagulants. The main objective of this research was to evaluate the performance of groundnut extract for turbidity removal from water. For this, the active coagulant agents were extracted from the deshelled nuts and used in a series of water treatment tests performed at low, medium, and high turbidity levels using synthetic turbid water. The groundnut extract showed good coagulative abilities, close to those of Al2(SO4)3. The best performance was obtained at medium turbidity (150 NTU), where the extract removed 89% of the turbidity using a 500 mg/L dosage. However, it was not as efficient as Al2(SO4)3, whose coagulation was better at every turbidity level. The use of the groundnut extract does not modify the water's pH significantly and the floc size decreases as turbidity increases, although they are bigger than those produced by Al2(SO4)3. It...
Groundwater for sustainable development, Jun 1, 2024
Water Practice & Technology
The purpose of this work was to show that the change in land use impacts the quality of free grou... more The purpose of this work was to show that the change in land use impacts the quality of free groundwater and therefore the health of the population in the city of Bafoussam. Land use was dominated by housing (about 42%) followed by agricultural areas (33%) and green space. The socio-economic diagnosis by the guided survey showed that 62.5% of the population consumes CAMWATER water with malaria as the dominant water-related disease. The collection of water samples analysed by the colorimetric and photometric assay has allowed us to obtain a dominant water facies of the chloride and sulphate–calcium–magnesium type. The mapping of areas potentially vulnerable to pollution by ArcGIS 10.8 software presents the low-lying areas, downstream of agricultural sites, close to industries and neighbourhoods with strong urban disorder as the most vulnerable to pollution and therefore retained as actors of diffuse groundwater pollution in the city of Bafoussam. Thus, the change in land use and the ...
Water Practice and Technology
The work presented here aims to carry out a physical characterisation of soils to understand thei... more The work presented here aims to carry out a physical characterisation of soils to understand their hydrodynamic behaviour and estimate the susceptibility of each group of soils to microbiological pollution. The field work associated with the laboratory work consisted of monitoring the hydrodynamic behaviour of previously identified and selected well waters, measuring the permeabilities of the soil samples and analysing the bacteriological parameters of the sampled well waters. At the end of this work, the piezometric data show a dominant SE-NW and ENE-OSW flow direction. The water levels vary significantly between the wet and dry seasons. The granulometric analysis of the soils reveals CU>3 showing a spread out granulometry with very low permeabilities of the order of 1.58×10−7 m/s and moderately high permeabilities of the order of 1.86×10−5 m/s. The microbiological data show pollution of human origin with a high bacterial load in the rainy season represented by a maximum of 240 ...
Department of Agricultural Engineering, Faculty of Agronomy and Agricultural Sciences/ University... more Department of Agricultural Engineering, Faculty of Agronomy and Agricultural Sciences/ University of Dschang, Cameroon ABSTRACT: In developing countries drainage systems are most often designed without taking into consideration the reality of solid domestic wastes and soil sediments that regular fill the limited number of drains in a drainage system. Soil sediments from erosion are usually conveyed by runoff into the drains however the poor land use practices accelerate the process of erosion. On the other hand, because of the poor waste management most of the waste produced by households are left uncollected and end up in the drainage system. The Abiergué drainage basin was used to assess the impact of solid domestic wastes and soil sediments on the design of drainage system in developing countries. Models were designed to take into consideration this aspect. However, the initial model used computed values of runoff obtained from precipitation and runoff coefficient. As such a new ...
ISPRS Int. J. Geo Inf., 2021
In this paper, we propose a decentralized semantic reasoning approach for modeling vague spatial ... more In this paper, we propose a decentralized semantic reasoning approach for modeling vague spatial objects from sensor network data describing vague shape phenomena, such as forest fire, air pollution, traffic noise, etc. This is a challenging problem as it necessitates appropriate aggregation of sensor data and their update with respect to the evolution of the state of the phenomena to be represented. Sensor data are generally poorly provided in terms of semantic information. Hence, the proposed approach starts with building a knowledge base integrating sensor and domain ontologies and then uses fuzzy rules to extract three-valued spatial qualitative information expressing the relative position of each sensor with respect to the monitored phenomenon’s extent. The observed phenomena are modeled using a fuzzy-crisp type spatial object made of a kernel and a conjecture part, which is a more realistic spatial representation for such vague shape environmental phenomena. The second step of...
Sensors
Sensor networks (SN) are increasingly used for the observation and monitoring of spatiotemporal p... more Sensor networks (SN) are increasingly used for the observation and monitoring of spatiotemporal phenomena and their dynamics such as pollution, noise and forest fires. In multisensory systems, a sensor node may be equipped with different sensing units to observe and detect several spatiotemporal phenomena at the same time. Simultaneous detection of different phenomena can be used to infer their spatial interactions over space and time. For this purpose, decentralized spatial computing approaches have shown their potential for effective reasoning on spatial phenomena within a sensor network. However, in most cases, spatial extents of continuous dynamic phenomena are uncertain, and their relations and interactions cannot be inferred by the existing approaches at the sensor node level. To address this limitation, in this paper, we propose and develop a decentralized fuzzy rule-based spatial reasoning approach to depict the spatial relations that hold between two evolving spatial phenom...
Http Www Afriquescience Info, Mar 1, 2015
Environmental Geochemistry and Health
Groundwater quality of the Banana Plain (Mbanga, Njombe, Penja—Cameroon) was assessed for its sui... more Groundwater quality of the Banana Plain (Mbanga, Njombe, Penja—Cameroon) was assessed for its suitability for drinking, domestic, and agricultural uses. A total of 67 groundwater samples were collected from open wells, springs, and boreholes. Samples were analyzed for physicochemical properties, major ions, and dissolved silica. In 95% of groundwater samples, calcium is the dominant cation, while sodium dominates in 5% of the samples. Eighty percent of the samples have HCO3 as major anion, and in 20%, NO3 is the major anion. Main water types in the study area are CaHCO3, CaMgHCO3, CaNaHCO3, and CaNaNO3ClHCO3. CO2-driven weathering of silicate minerals followed by cation exchange seemingly controls largely the concentrations of major ions in the groundwaters of this area. Nitrate, sulfate, and chloride concentrations strongly express the impact of anthropogenic activities (agriculture and domestic activities) on groundwater quality. Sixty-four percent of the waters have nitrate concentrations higher than the drinking water limit. Also limiting groundwater use for potable and domestic purposes are contents of Ca2+, Mg2+ and HCO3− and total hardness (TH) that exceed World Health Organization (WHO) standards. Irrigational suitability of groundwaters in the study area was also evaluated, and results show that all the samples are fit for irrigation. Groundwater quality in the Banana Plain is impeded by natural geology and anthropogenic activities, and proper groundwater management strategies are necessary to protect sustainably this valuable resource.
Groundwater for sustainable development, Apr 1, 2024
The Yato physicochemical water purification station is located in Dibombari District Council in t... more The Yato physicochemical water purification station is located in Dibombari District Council in the Littoral-Cameroon region. It is one of the largest drinking water production stations in the Central African sub-region. This work aims to evaluate, through the quantification of the concentrations of Trace Metal Elements (TMEs), the polluting status of the sludge from this drinking water production station and their impacts on the soil. To achieve this objective, mixed samples of sludge from sludge treatment ponds (taken according to the technique described in GIDS-A003 point 6 as explained in the Solid and pasty waste sampling strategy of Code of Good Practice No. 2) and samples of sludge from primary settling basins (taken in transparent bottles in polyethylene terephthalate of 1.5L) were analysed. Likewise, three soil wells were carried out and soil samples were taken on two levels of alteration then sent to the laboratory where physicochemical and TME analyses were carried out. The characteristics of the samples that were analysed are: particle size, texture (sand, silt, clay), physiochemistry (pH, electrical conductivity, temperature, phosphorus, nitrogen) and TME (chromium, copper, zinc, manganese). The results obtained show that the polluting status of the sludge from the Yato station is proven because their pollution index by heavy metals is greater than 1. The pollution index greater than 1 in the sludge from the treatment basins is due to the strong concentrations of TME originating from the accumulation of waste of all kinds in this location. Overall, TME concentrations in soils decrease for the most part from the surface towards depth. All the TMEs studied (Zn, Mn, Cu, Cr) are present in all horizons. There is multiple contamination of sludge by TMEs because their pollution index is greater than 1 (IP>1). Although the sludge pollution indices are greater than 1, those of the different horizons are much lower than 1. Thus, since the TMEs decrease with depth, the subsurface horizons would be less affected by the pollutants contained in the station sludge. marking a real pollution of the surface layers.
The Yato physicochemical water purification station is located in the commune of Dibombari in the... more The Yato physicochemical water purification station is located in the commune of Dibombari in the Littoral-Cameroon region. It is one of the largest drinking water production stations in the Central African sub-region. This work aims to evaluate the agronomic power of the sludge from this drinking water production station. To achieve this objective, mixed samples of sludge from sludge treatment basins (taken according to the technique described in GIDS-A003 point 6 as explained in the Solid and pasty waste sampling strategy of the Code of Good Practice No. 2). and primary settling basins (collected in transparent 1.5L polyethylene terephthalate bottles) were analyzed. Likewise, three soil samples (marsh, Point 1 and Point 2) were taken and then sent to the laboratory where physicochemical analyzes were carried out. The characteristics of the samples that were analyzed are: particle size, texture (sand, silt, clay) and physicochemistry (organic matter, CEC, sum of exchangeable bases, calcium, nitrogen, potassium and magnesium). The results obtained show that the soils exposed to contamination from the sludge of the station have better agronomic properties both on a physical level with a stable structure favorable to plant growth and good aeration unlike the soils far from the station which presented a high risk. degradation; that on the chemical level with an optimal cationic balance, a high reserve of exchangeable bases, a strong CEC but average limitations in assimilable phosphorus and pH unlike the soil far from the station which presented an insufficiency of potassium which did not facilitate a balance cationic, a low CEC but a pH above 5.5 which is the value recommended in agronomy. Biochemically, organic matter is above 2% in all soils, a mineralization rate less than 20 favoring the rapid mineralization of carbon and a release of nitrogen available to the plant. These results obtained allow us to conclude that the sludge from the Yato station can be used in agronomy as an organic fertilizer in order to correct the soil structure, the CEC, the cationic balances and also provide the soil with a good base reserve. However, treating this sludge with lime could regulate the pH of the soil and reduce the mobility of heavy metals in the soil.
Water Practice & Technology
Groundwater is a major resource for drinking water, especially in developing countries, where it ... more Groundwater is a major resource for drinking water, especially in developing countries, where it is less expensive to treat than surface water. Today, the resource is highly susceptible to pollution, particularly as a result of human activity. This review was based on a literature review and critical analysis of models for estimating the groundwater vulnerability. The results show that the deepest porous aquifers are the least susceptible to pollution, whereas those in karstic and fissured environments are susceptible, whatever their depth. Pollution usually arises from human activity. Critical analysis of the literature shows that existing methods are developed in specific environmental contexts. Given the variability of factors in space and time, these methods do not take the intrinsic realities of all natural settings into account adequately and are not perfectly applicable in all environments. This highlights the need to develop appropriate models for each environment, such as t...
Water Practice & Technology
Natural coagulants can be an alternative solution to minimise the environmental pollution and hea... more Natural coagulants can be an alternative solution to minimise the environmental pollution and health risks caused by the use of chemical coagulants. The main objective of this research was to evaluate the performance of groundnut extract for turbidity removal from water. For this, the active coagulant agents were extracted from the deshelled nuts and used in a series of water treatment tests performed at low, medium, and high turbidity levels using synthetic turbid water. The groundnut extract showed good coagulative abilities, close to those of Al2(SO4)3. The best performance was obtained at medium turbidity (150 NTU), where the extract removed 89% of the turbidity using a 500 mg/L dosage. However, it was not as efficient as Al2(SO4)3, whose coagulation was better at every turbidity level. The use of the groundnut extract does not modify the water's pH significantly and the floc size decreases as turbidity increases, although they are bigger than those produced by Al2(SO4)3. It...
Groundwater for sustainable development, Jun 1, 2024
Water Practice & Technology
The purpose of this work was to show that the change in land use impacts the quality of free grou... more The purpose of this work was to show that the change in land use impacts the quality of free groundwater and therefore the health of the population in the city of Bafoussam. Land use was dominated by housing (about 42%) followed by agricultural areas (33%) and green space. The socio-economic diagnosis by the guided survey showed that 62.5% of the population consumes CAMWATER water with malaria as the dominant water-related disease. The collection of water samples analysed by the colorimetric and photometric assay has allowed us to obtain a dominant water facies of the chloride and sulphate–calcium–magnesium type. The mapping of areas potentially vulnerable to pollution by ArcGIS 10.8 software presents the low-lying areas, downstream of agricultural sites, close to industries and neighbourhoods with strong urban disorder as the most vulnerable to pollution and therefore retained as actors of diffuse groundwater pollution in the city of Bafoussam. Thus, the change in land use and the ...
Water Practice and Technology
The work presented here aims to carry out a physical characterisation of soils to understand thei... more The work presented here aims to carry out a physical characterisation of soils to understand their hydrodynamic behaviour and estimate the susceptibility of each group of soils to microbiological pollution. The field work associated with the laboratory work consisted of monitoring the hydrodynamic behaviour of previously identified and selected well waters, measuring the permeabilities of the soil samples and analysing the bacteriological parameters of the sampled well waters. At the end of this work, the piezometric data show a dominant SE-NW and ENE-OSW flow direction. The water levels vary significantly between the wet and dry seasons. The granulometric analysis of the soils reveals CU>3 showing a spread out granulometry with very low permeabilities of the order of 1.58×10−7 m/s and moderately high permeabilities of the order of 1.86×10−5 m/s. The microbiological data show pollution of human origin with a high bacterial load in the rainy season represented by a maximum of 240 ...
Department of Agricultural Engineering, Faculty of Agronomy and Agricultural Sciences/ University... more Department of Agricultural Engineering, Faculty of Agronomy and Agricultural Sciences/ University of Dschang, Cameroon ABSTRACT: In developing countries drainage systems are most often designed without taking into consideration the reality of solid domestic wastes and soil sediments that regular fill the limited number of drains in a drainage system. Soil sediments from erosion are usually conveyed by runoff into the drains however the poor land use practices accelerate the process of erosion. On the other hand, because of the poor waste management most of the waste produced by households are left uncollected and end up in the drainage system. The Abiergué drainage basin was used to assess the impact of solid domestic wastes and soil sediments on the design of drainage system in developing countries. Models were designed to take into consideration this aspect. However, the initial model used computed values of runoff obtained from precipitation and runoff coefficient. As such a new ...
ISPRS Int. J. Geo Inf., 2021
In this paper, we propose a decentralized semantic reasoning approach for modeling vague spatial ... more In this paper, we propose a decentralized semantic reasoning approach for modeling vague spatial objects from sensor network data describing vague shape phenomena, such as forest fire, air pollution, traffic noise, etc. This is a challenging problem as it necessitates appropriate aggregation of sensor data and their update with respect to the evolution of the state of the phenomena to be represented. Sensor data are generally poorly provided in terms of semantic information. Hence, the proposed approach starts with building a knowledge base integrating sensor and domain ontologies and then uses fuzzy rules to extract three-valued spatial qualitative information expressing the relative position of each sensor with respect to the monitored phenomenon’s extent. The observed phenomena are modeled using a fuzzy-crisp type spatial object made of a kernel and a conjecture part, which is a more realistic spatial representation for such vague shape environmental phenomena. The second step of...
Sensors
Sensor networks (SN) are increasingly used for the observation and monitoring of spatiotemporal p... more Sensor networks (SN) are increasingly used for the observation and monitoring of spatiotemporal phenomena and their dynamics such as pollution, noise and forest fires. In multisensory systems, a sensor node may be equipped with different sensing units to observe and detect several spatiotemporal phenomena at the same time. Simultaneous detection of different phenomena can be used to infer their spatial interactions over space and time. For this purpose, decentralized spatial computing approaches have shown their potential for effective reasoning on spatial phenomena within a sensor network. However, in most cases, spatial extents of continuous dynamic phenomena are uncertain, and their relations and interactions cannot be inferred by the existing approaches at the sensor node level. To address this limitation, in this paper, we propose and develop a decentralized fuzzy rule-based spatial reasoning approach to depict the spatial relations that hold between two evolving spatial phenom...
Http Www Afriquescience Info, Mar 1, 2015
Environmental Geochemistry and Health
Groundwater quality of the Banana Plain (Mbanga, Njombe, Penja—Cameroon) was assessed for its sui... more Groundwater quality of the Banana Plain (Mbanga, Njombe, Penja—Cameroon) was assessed for its suitability for drinking, domestic, and agricultural uses. A total of 67 groundwater samples were collected from open wells, springs, and boreholes. Samples were analyzed for physicochemical properties, major ions, and dissolved silica. In 95% of groundwater samples, calcium is the dominant cation, while sodium dominates in 5% of the samples. Eighty percent of the samples have HCO3 as major anion, and in 20%, NO3 is the major anion. Main water types in the study area are CaHCO3, CaMgHCO3, CaNaHCO3, and CaNaNO3ClHCO3. CO2-driven weathering of silicate minerals followed by cation exchange seemingly controls largely the concentrations of major ions in the groundwaters of this area. Nitrate, sulfate, and chloride concentrations strongly express the impact of anthropogenic activities (agriculture and domestic activities) on groundwater quality. Sixty-four percent of the waters have nitrate concentrations higher than the drinking water limit. Also limiting groundwater use for potable and domestic purposes are contents of Ca2+, Mg2+ and HCO3− and total hardness (TH) that exceed World Health Organization (WHO) standards. Irrigational suitability of groundwaters in the study area was also evaluated, and results show that all the samples are fit for irrigation. Groundwater quality in the Banana Plain is impeded by natural geology and anthropogenic activities, and proper groundwater management strategies are necessary to protect sustainably this valuable resource.