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Research paper thumbnail of Evaluation of Radiological Risk Hazards in Sediments and Selected Streams Around Kalulushi and Kitwe Towns

Research paper thumbnail of Evaluation of Radiological Risk Hazards in Sediments and Selected Streams Around Kalulushi and Kitwe Towns

Research Square (Research Square), Jun 19, 2024

Mining operations in the uraniferous Copperbelt Province of the Katanga Basin have raised signifi... more Mining operations in the uraniferous Copperbelt Province of the Katanga Basin have raised significant environmental and health concerns, primarily due to the generation of waste during copper and cobalt extraction processes. Kitwe town heavily relies on the Kafue River for its domestic water supply. However, there has been a lack of studies measuring the levels of natural radionuclides in several tributaries of the Kafue River, namely, the Fikondo Stream, Mindolo Stream, Kitwe Stream, and Mwambashi River. This study utilized gamma-ray spectrometry to assess the presence of radionuclides, specifically radium-226, thorium-232, and potassium-40, in sediments and water near Kitwe and Kalulushi in the Copperbelt Province. The results indicated varying concentrations of 226 Ra, 232 Th, and 40 K in sediments and water, ranging from 51.8 to 104.6 Bq/kg and 1.7 to 28.5 Bq/l, respectively, in sediments, and 43.1 to 72.2 Bq/kg and 0 to 1.3 Bq/l, respectively, in water. These concentrations were compared to permissible limits set by the UNSCEAR and WHO. The study revealed that all three primordial radionuclides exhibited greater activity in sediment samples than in water samples, except for specific instances. The activity of 226 Ra exceeded the WHO limits in most cases, while 232 Th and 40 K were generally greater in all stream samples. To assess the radiological hazard posed by natural radioactivity, various parameters, such as the radius equivalent, absorbed dose rate, absorbed equivalent dose, internal hazard index, external hazard index, and excess lifetime cancer risk, were calculated for the study sites and materials.

Research paper thumbnail of Optimal path planning in a real-world radioactive environment: A comparative study of A-star and Dijkstra algorithms

Nuclear engineering and design, Apr 1, 2024

Research paper thumbnail of Characterization of biosolids and evaluating the effectiveness of plastic-covered sun drying beds as a biosolids stabilization method in Lusaka, Zambia

International Journal of Recycling of Organic Waste in Agriculture, 2014

Introduction The Lusaka Water and Sewerage Company (LWSC) produces *800-1,000 kg of treated sewag... more Introduction The Lusaka Water and Sewerage Company (LWSC) produces *800-1,000 kg of treated sewage sludge per day at its Manchinchi wastewater treatment plant (WWTP). The biosolids are used for land application purposes although the contaminant and pathogen composition and quality of the biosolids have been unknown until this study. Zambia does not have legal standards and guidelines for biosolids management or application. The Manchinchi plant in Lusaka suffers from constant breakdowns such that the effectiveness of the plant to produce quality grade biosolids for land application use is questionable. In peri-urban areas, the problem of poor sanitation is being addressed using different technologies including urine diversion ecosan toilets. The effectiveness of ecosan toilets to stabilize faecal sludge has not been assessed in Zambia. The purpose of this study was to stabilize and characterize the biosolids from Manchinchi plant and ecosan toilets. Stabilization was done by use of drying beds and irradiation. The parametres that were used for characterization were microbiological, parasitological and heavy metals. Results Biosolids from the Manchinchi WWTP sun drying bed, ecosan toilets and from an experimental plasticcovered drying bed were found to contain different pathogenic microorganisms and contaminant levels. A radiation dose and time-related declining trend in pathogens loads in biosolids were observed. By the third week, no viable Ascaris eggs were detected. Based on controlled conditions, the biosolids quality was found to be within the internationally acceptable standards for restricted use. Conclusions Both the untreated LWSC biosolids and ecosan sludge contained pathogen levels with the potential to cause environmental and public health hazards if used for agriculture purposes. Under plastic-covered drying beds, viable Ascaris eggs were not detected by the fourth week of treatment and the biosolids were stabilized to levels equivalent to Class C of the Australian standards for restricted land application. Covered drying beds can be considered as cost effective stabilization treatment technology for biosolids in developing countries. The technology has potential benefits for improving public health and reducing environmental pollution in Zambia, especially during the rainy season when biosolids are directly discharged into the environment.

Research paper thumbnail of Evaluation of Radiological Risk Hazards in Sediments and Selected Streams Around Kalulushi and Kitwe Towns

Research paper thumbnail of Evaluation of Radiological Risk Hazards in Sediments and Selected Streams Around Kalulushi and Kitwe Towns

Research Square (Research Square), Jun 19, 2024

Mining operations in the uraniferous Copperbelt Province of the Katanga Basin have raised signifi... more Mining operations in the uraniferous Copperbelt Province of the Katanga Basin have raised significant environmental and health concerns, primarily due to the generation of waste during copper and cobalt extraction processes. Kitwe town heavily relies on the Kafue River for its domestic water supply. However, there has been a lack of studies measuring the levels of natural radionuclides in several tributaries of the Kafue River, namely, the Fikondo Stream, Mindolo Stream, Kitwe Stream, and Mwambashi River. This study utilized gamma-ray spectrometry to assess the presence of radionuclides, specifically radium-226, thorium-232, and potassium-40, in sediments and water near Kitwe and Kalulushi in the Copperbelt Province. The results indicated varying concentrations of 226 Ra, 232 Th, and 40 K in sediments and water, ranging from 51.8 to 104.6 Bq/kg and 1.7 to 28.5 Bq/l, respectively, in sediments, and 43.1 to 72.2 Bq/kg and 0 to 1.3 Bq/l, respectively, in water. These concentrations were compared to permissible limits set by the UNSCEAR and WHO. The study revealed that all three primordial radionuclides exhibited greater activity in sediment samples than in water samples, except for specific instances. The activity of 226 Ra exceeded the WHO limits in most cases, while 232 Th and 40 K were generally greater in all stream samples. To assess the radiological hazard posed by natural radioactivity, various parameters, such as the radius equivalent, absorbed dose rate, absorbed equivalent dose, internal hazard index, external hazard index, and excess lifetime cancer risk, were calculated for the study sites and materials.

Research paper thumbnail of Optimal path planning in a real-world radioactive environment: A comparative study of A-star and Dijkstra algorithms

Nuclear engineering and design, Apr 1, 2024

Research paper thumbnail of Characterization of biosolids and evaluating the effectiveness of plastic-covered sun drying beds as a biosolids stabilization method in Lusaka, Zambia

International Journal of Recycling of Organic Waste in Agriculture, 2014

Introduction The Lusaka Water and Sewerage Company (LWSC) produces *800-1,000 kg of treated sewag... more Introduction The Lusaka Water and Sewerage Company (LWSC) produces *800-1,000 kg of treated sewage sludge per day at its Manchinchi wastewater treatment plant (WWTP). The biosolids are used for land application purposes although the contaminant and pathogen composition and quality of the biosolids have been unknown until this study. Zambia does not have legal standards and guidelines for biosolids management or application. The Manchinchi plant in Lusaka suffers from constant breakdowns such that the effectiveness of the plant to produce quality grade biosolids for land application use is questionable. In peri-urban areas, the problem of poor sanitation is being addressed using different technologies including urine diversion ecosan toilets. The effectiveness of ecosan toilets to stabilize faecal sludge has not been assessed in Zambia. The purpose of this study was to stabilize and characterize the biosolids from Manchinchi plant and ecosan toilets. Stabilization was done by use of drying beds and irradiation. The parametres that were used for characterization were microbiological, parasitological and heavy metals. Results Biosolids from the Manchinchi WWTP sun drying bed, ecosan toilets and from an experimental plasticcovered drying bed were found to contain different pathogenic microorganisms and contaminant levels. A radiation dose and time-related declining trend in pathogens loads in biosolids were observed. By the third week, no viable Ascaris eggs were detected. Based on controlled conditions, the biosolids quality was found to be within the internationally acceptable standards for restricted use. Conclusions Both the untreated LWSC biosolids and ecosan sludge contained pathogen levels with the potential to cause environmental and public health hazards if used for agriculture purposes. Under plastic-covered drying beds, viable Ascaris eggs were not detected by the fourth week of treatment and the biosolids were stabilized to levels equivalent to Class C of the Australian standards for restricted land application. Covered drying beds can be considered as cost effective stabilization treatment technology for biosolids in developing countries. The technology has potential benefits for improving public health and reducing environmental pollution in Zambia, especially during the rainy season when biosolids are directly discharged into the environment.