41 results on '"Hamisi, Rajabu"'
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2. Optimization of on-site wastewater treatment efficiency and recovery based on nutrient mobility and adsorption kinetics modelling using HYDRUS-2D coupled with PHREEQC
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Hamisi, Rajabu, Renman, Agnieszka, Renman, Gunno, Wörman, Anders, and Thunvik, Roger
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- 2024
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3. Treatment efficiency and recovery in sand filters for on-site wastewater treatment: Column studies and reactive modelling
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Hamisi, Rajabu, Renman, Agnieszka, Renman, Gunno, Wörman, Anders, and Thunvik, Roger
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- 2024
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4. The natural magnesite efficacy on arsenic extraction from water and alkaline influence on metal release in water
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Irunde, Regina, Ligate, Fanuel J., Ijumulana, Julian, Ahmad, Arslan, Maity, Jyoti Prakash, Hamisi, Rajabu, Philip, Joseph Y.N., Kilulya, Kessy Fidel, Karltun, Erik, Mtamba, Joseph, Bhattacharya, Prosun, and Mtalo, Felix
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- 2023
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5. Optimization of fluoride removal using calcined bauxite: Adsorption isotherms and kinetics
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Kimambo, Vivian, Ligate, Fanuel Josephat, Ijumulana, Julian, Maity, Jyoti Prakash, Jong, Ron, Ahmad, Arslan, Hamisi, Rajabu, Mtamba, Joseph, Mtalo, Felix, and Bhattacharya, Prosun
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- 2023
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6. Geogenic contaminants and groundwater quality around Lake Victoria goldfields in northwestern Tanzania
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Ligate, Fanuel, Lucca, Enrico, Ijumulana, Julian, Irunde, Regina, Kimambo, Vivian, Mtamba, Joseph, Ahmad, Arslan, Hamisi, Rajabu, Maity, Jyoti Prakash, Mtalo, Felix, and Bhattacharya, Prosun
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- 2022
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7. Long-term phosphorus sorption and leaching in sand filters for onsite treatment systems
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Hamisi, Rajabu, Renman, Agnieszka, Renman, Gunno, Wörman, Anders, and Thunvik, Roger
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- 2022
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8. Performance of a tidal flow constructed wetland used for post-treatment of on-site wastewater in cold climate
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Hamisi, Rajabu, Renman, Agnieszka, Renman, Gunno, Wörman, Anders, and Thunvik, Roger
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- 2022
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9. Spatial modeling of the occurrences of geogenic fluoride in groundwater systems in Tanzania : Implications for the provision of safe drinking water
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Ijumulana, Julian, Ligate, Fanuel Josephat, Bhattacharya, Prosun, Ahmad, Arslan, Zhang, Chaosheng, Tomasek, Ines, Irunde, Regina, Kimambo, Vivian, Hamisi, Rajabu, Mtalo, Felix, Ijumulana, Julian, Ligate, Fanuel Josephat, Bhattacharya, Prosun, Ahmad, Arslan, Zhang, Chaosheng, Tomasek, Ines, Irunde, Regina, Kimambo, Vivian, Hamisi, Rajabu, and Mtalo, Felix
- Abstract
Inadequate data and spatial dependence in the observations during geochemical studies are among the disturbing conditions when estimating environmental factors contributing to the local variability in the pollutants of interest. Usually, spatial dependence occurs due to the researcher 's imperfection on the natural scale of occurrence which affects the sampling strategy. As a consequence, observations on the study variable are significantly correlated in space. In this study, the machine learning approach was developed and used to study the environmental factors controlling the local variability in fluoride concentrations in drinking water sources of northern Tanzania within the East African Rift Valley. The approach constituted the use of geographical information systems (GIS) technology, exploratory spatial data analysis (ESDA) methods, and spatial regression modeling at a local level. The environmental variables used to study the local variation in fluoride concentration include topography, tectonic processes, water exchanges between hydrogeological layers during lateral movement, mineralization processes (EC), and water pH. The study was based on 20 local spatial regimes determined using GIS based on water sources density in the four hydrogeological environments. Specifically, the nonparametric (one-way Kruskal-Wallis sum ranks test and Multiple Comparisons Dunn Test), spatial statistics (Global Moran 's I statistic), ordinary least squares (OLS) regression, and spatial lag models were used to quantify the effects of topography, tectonic processes, water exchange between hydrogeological environments and water physiochemical parameters (pH and EC) on the spatial variability of fluoride concentrations in drinking water sources at a local scale. In order of significance, the local spatial variation in fluoride concentration is influenced by the EC, topography, tectonic processes, pH, and water exchange between hydrogeological layers during water movement. The resul, QC 20240715
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- 2024
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10. Optimisation of On-Site Wastewater Treatment Efficiency and Recovery Based on Nutrient Mobility and Adsorption Kinetics Modelling Using Hydrus-2d Coupled with Phreeqc
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Hamisi, Rajabu, primary, Renman, Agnieszka, additional, Renman, Gunno, additional, Wörman, Anders, additional, and Thunvik, Roger, additional
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- 2024
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11. Knowledge of cardiovascular risk factors among caretakers of outpatients attending a tertiary cardiovascular center in Tanzania: a cross-sectional survey
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Pallangyo, Pedro, Misidai, Nsajigwa, Komba, Makrina, Mkojera, Zabella, Swai, Happiness J., Hemed, Naairah R., Mayala, Henry, Bhalia, Smita, Millinga, Jalack, Mollel, Upendo W., Kusima, Happiness L., Chavala, Ester, Joram, Ziada, Abdallah, Halifa, Hamisi, Rajabu, and Janabi, Mohamed
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- 2020
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12. Chapter 13 - Fluoride as a global groundwater contaminant
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Kumar, Rakesh, Ali, Shakir, Sandanayake, Sandun, Islam, Md. Aminul, Ijumulana, Julian, Maity, Jyoti Prakash, Vithanage, Meththika, Armienta, Maria Aurora, Sharma, Prabhakar, Hamisi, Rajabu, Kimambo, Vivian, and Bhattacharya, Prosun
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- 2024
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13. Bauxite : a prospective mineral for arsenic elicitation from water and acidity influence
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Irunde, Regina, Ligate, Fanuel Josephat, Ijumulana, Julian, Hamisi, Rajabu, Maity, Jyoti P., Kumar, Rakesh, Mtalo, Felix, Bhattacharya, Prosun, Irunde, Regina, Ligate, Fanuel Josephat, Ijumulana, Julian, Hamisi, Rajabu, Maity, Jyoti P., Kumar, Rakesh, Mtalo, Felix, and Bhattacharya, Prosun
- Abstract
The study evaluates the performance of bauxite for arsenic (As) elucidation from water. The raw, calcined, and alkaline ferric-bauxite composite was applied in batch experiments to evaluate the influence of dosage, initial As concentrations, contact time, and pH. The X-ray diffraction studies revealed significant content of gibbsite (Al(OH)3 in the bauxite. Visual MINTEQ simulation indicated As removal increases with an increase in dosage, the pH range between acidic and near neutral favors maximum removal. The 100 g/L calcined bauxite at pH 7.4 removed 99.9% As to below 0.001 mg/L after 20 minutes from an initial concentration of 1 mg/L. The raw 100 g/L bauxite at pH 6 removed 99.86% As to below 0.003 mg/L after 1 hour from an initial As concentration of 1 mg/L. The alkaline ferric-bauxite composite used for treatment of 2 mg/L As raised pH from pH 4 to 12, and removal efficiency declined to 31% after 4 hours. Aluminium (Al) was sensitive to pH, and about 435 mg/L was released in water at pH 12. Despite the decrease in specific surface area during calcination at 500 °C, the As removal was more improved for the calcined bauxite. The removal capacity was high, up to 6 mg/g, when less dosage of 0.5 g/L bauxite was used. The kinetic reaction process using 5 g/L reaction obeys pseudo-secondorder with R2 of 0.99 while its removal isotherm obeys Langmuir with R2 of 0.98 and is confirmed favorable., QC 20231127
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- 2023
14. Fluoride as a global groundwater contaminant
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Kumar, Rakesh, Ali, Shakir, Sandanayake, Sandun, Islam, Md Aminul, Ijumulana, Julian, Maity, Jyoti Prakash, Vithanage, Meththika, Armienta, Maria Aurora, Sharma, Prabhakar, Hamisi, Rajabu, Kimambo, Vivian, Bhattacharya, Prosun, Kumar, Rakesh, Ali, Shakir, Sandanayake, Sandun, Islam, Md Aminul, Ijumulana, Julian, Maity, Jyoti Prakash, Vithanage, Meththika, Armienta, Maria Aurora, Sharma, Prabhakar, Hamisi, Rajabu, Kimambo, Vivian, and Bhattacharya, Prosun
- Abstract
Fluoride is essential for the human body and a global groundwater contaminant (the recommended WHO limit is 1.5mg/L). The mobilization and genesis of fluoride depend on fluoride-bearing rocks (e.g., fluorite, fluor-apatite, biotite, etc.) that are a part of the natural geogenic process, which later contaminate the groundwater. More specifically, the dissolution process (via infiltration), lateral water flow, ion exchange, climatic factors, and chemical weathering of “rocks and minerals” are highly responsible for the release of elevated concentrations of fluoride in groundwater. The intake of fluoride-contaminated groundwater and anthropogenically produced daily usable products (e.g., dental products, foods, etc.) causes physiological and metabolic disturbances in animals and humans. However, this fluoride can be removed effectively from water by technology-enhanced processes (e.g., reverse osmosis, nano-filtration, coagulation, adsorption, electrochemical, membrane distillation, ion exchange, and precipitation). This, in turn, means that climate-dependent contamination, mobilization mechanism, and bioaccumulation will be essential for selecting efficient, cost-effective green technologies. Adequate information should be provided to overcome people’s wrong perceptions concerning fluoride-related issues, especially in lower socioeconomic groups. Policy interventions are required to improve the quality of life in the developing world, where there is a lack of awareness about health issues. Extensive research in this field can identify fluoride “hot spots” (through regular monitoring) and removal technique(s) utilizing public-private sector collaboration., Part of ISBN 9780323904001, 9780323906852QC 20240703
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- 2023
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15. Bauxite Prospective Mineral for Arsenic Elicitation from Water and Acidity Influence
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Irunde, Regina, primary, Ligate, Fanuel Josephat, additional, Ijumulana, Julian, additional, Hamisi, Rajabu, additional, Maity, Jyoti Prakash, additional, Kumar, Rakesh, additional, Bhattacharya, Prosun, additional, and Mtalo, Felix, additional
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- 2023
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16. Geogenic contaminants and groundwater quality around Lake Victoria goldfields in northwestern Tanzania
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Ligate, Fanuel Josephat, Lucca, Enrico, Ijumulana, Julian, Irunde, Regina, Kimambo, Vivian, Mtamba, Joseph, Ahmad, Arslan, Hamisi, Rajabu, Maity, Jyoti Prakash, Mtalo, Felix, Bhattacharya, Prosun, Ligate, Fanuel Josephat, Lucca, Enrico, Ijumulana, Julian, Irunde, Regina, Kimambo, Vivian, Mtamba, Joseph, Ahmad, Arslan, Hamisi, Rajabu, Maity, Jyoti Prakash, Mtalo, Felix, and Bhattacharya, Prosun
- Abstract
Geogenic contamination of groundwater is frequently associated with gold mining activities and related to drinking water quality problems worldwide. In Tanzania, elevated levels of trace elements (TEs) have been reported in drinking water sources within the Lake Victoria Basin, posing a serious health risk to communities. The present study aims to assess the groundwater quality with a focus on the concentration levels of geogenic contaminants in groundwater around the Lake Victoria goldfields in Geita and Mara districts. The water samples were collected from community drinking water sources and were analysed for physiochemical parameters (pH, EC, Eh), major ions, and trace elements. The analysed major ions included Na+, K+, Ca2+, Mg2+, SO42-, HCO3- and Cl- whereas the trace elements were As, Al, Li, Ba, B, Ti, V, U, Zr, Sr, Si, Mn Mo, Fe, Ni, Zn, Cr, Pb, Cd, and V. The present study revealed that the concentration levels of the major ions were mostly within the World Health Organization (WHO) drinking water standards in the following order of their relative abundance; for cations, Ca2+-Na+ >Mg2+ >K+ and for anions was HCO3- > SO42- > NO3-, Cl- > PO43-. Statistical and geochemical modelling software such as 31 Studio', IBM SPSS, geochemical workbench, visual MINTEQ were used to understand the groundwater chemistry and evaluate its suitability for drinking purpose. The concentration of As in groundwater sources varies between below detection limit (bdl) and 300 mu g/L, with highest levels in streams followed by shallow wells and boreholes. In approximately 48% of the analysed samples, As concentration exceeded the WHO drinking water guideline and Tanzania Bureau of Standards (TBS) guideline for drinking water value of 10 mu g/L. The concentration of the analyzed TEs and mean values of physicochemical parameters were below the guideline limits based on WHO and TBS standards. The Canadian Council of Ministries of the Environment Water Quality Index (CCME, QC 20221118
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- 2022
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17. Integrating digitalization of the decadal understanding on the hydrogeochemistry of geogenic arsenic and societal aspects for Sustainable Arsenic Mitigation in Bangladesh
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Bhattacharya, Prosun, primary, Ahmed, Kazi Matin, additional, Akter, Nargis, additional, Alam, Md. Jahid, additional, Hamisi, Rajabu, additional, von Brömssen, Mattias, additional, Khan, Eheteshamul Russel, additional, Sharma, Sanjeev, additional, and Rahman, Md. Saifur, additional
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- 2022
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18. Contributors
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Abbasi, Sepide, Adhya, T.K., Ahmad, Muhammad Nauman, Ali, Shakir, Antoniadis, Vasileios, Aqsa, Armienta, Maria Aurora, Bari, A.S.M. Fazle, Basta, Nicholas T., Betts, Aaron R., Bhattacharya, Prosun, Biswas, Ashis, Biswas, Bhaba, Boim, Alexys Giorgia Friol, Cavanagh, Joanne E., Chandima Wekumbura, W.G., Chen, Zueng-Sang, Deb, Amal Kanti, Dhillon, Karaj S., Fan, Wanyi, Ferreira, Amanda D., Ferreira, Tiago O., Filippini, Tommaso, Gooneratne, Ravi, Halim, Md Abdul, Hamisi, Rajabu, Haynes, Richard J., Hettiarachchi, Ganga M., Hseu, Zeng-Yei, Huang, Tai-Hsiang, Ijumulana, Julian, Islam, Md. Aminul, Kimambo, Vivian, Kumar, Rakesh, Lai, Yun-Jie, Lake, Loryssa, Lee, Yi-Ting, Liu, Yanju, Luo, Yongming, Maity, Jyoti Prakash, Maki, Benjamin, Mayer, Manfred M., Michalke, Bernhard, Mukhtar, Maria, Naidu, Ravi, Nawaz, Nabia, Nóbrega, Gabriel N., Otero, Xosé L., Pattnaik, R., Queiroz, Hermano M., Rahman, Md. Aminur, Rahman, Mohammad Mahmudur, Rahman, Zeeshanur, Riaz, Muhammad, Rinklebe, Jörg, Robinson, Brett, Saleeb, Nadir, Sandanayake, Sandun, Sanderson, Peter, Scheckel, Kirk G., Selvakumar, Rajendran, Shaheen, Sabry M., Sharma, Prabhakar, Singh, Bal Ram, Sun, Yafei, Tu, Chen, Vinceti, Marco, Vithanage, Meththika, Wang, Jianxu, Wu, Caixin, Yang, Shuai, Ying, Samantha C., and Zaman, Kh Ashraf Uz
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- 2024
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19. Performance of an On-Site Wastewater Treatment System Using Reactive Filter Media and a Sequencing Batch Constructed Wetland
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Hamisi, Rajabu, Renman, Agnieszka, and Renman, Gunno
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lcsh:GE1-350 ,biofiltration ,lcsh:Environmental effects of industries and plants ,Other Environmental Engineering ,lcsh:TJ807-830 ,lcsh:Renewable energy sources ,Polonite ,sand ,nitrogen ,add-on unit ,lcsh:TD194-195 ,package treatment plant ,Annan naturresursteknik ,phosphorus ,lcsh:Environmental sciences - Abstract
Many on-site wastewater treatment systems, such as soil treatment systems, are not sustainable in terms of purification efficiency, nutrient recycling potential, and economics. In this case study, a sequencing batch constructed wetland (SBCW) was designed and added after a package treatment plant (PTP) using reactive filter media for phosphorus (P) removal and recycling. The treatment performance of the entire system in the start-up phase and its possible applicability in rural areas were investigated. Raw and treated effluents were sampled during a period of 25 weeks and analyzed for nitrogen, phosphorus, BOD7, and bacteria. Field measurements were made of wastewater flow, electrical conductivity, oxygen, and temperature. The entire system removed total-P and total inorganic nitrogen (TIN) by 83% and 22%, respectively. High salt concentration and very low wastewater temperature were possible reasons for these unexpectedly low P and TIN removal efficiencies. In contrast, removal rates of bacteria (Escherichia coli, enterococci) and organic matter (as BOD) were high, due to filtration in the alkaline medium Polonite®, (Ecofiltration Nordic AB, Stockholm, Sweden) and the fine sand used as SBCW substrate. High pH in effluent from the PTP was efficiently reduced to below pH 9 in the SBCW, meeting recommendations by environmental authorities in Sweden. We concluded that treating cold on-site wastewater can impair treatment performance and that technical measures are needed to improve SBCW performance.
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- 2019
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20. Filtration System For On-Site Wastewater Treatment : Experiences From Modelling and Experimental Investigations
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Hamisi, Rajabu
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Environmental Engineering ,Naturresursteknik - Abstract
Many on-site wastewater treatment systems in Sweden are not sustainable in terms of treatment efficiency, nutrient recycling and economics. Achieving reliable and sustainable systems to meet on-site wastewater treatment demands requires comprehensive field investigations of the performance of novel technologies. This thesis investigated the performance of a new leading-edge technology for on-site wastewater treatment in a real field environment in northwest of Baltic Proper Sea, Sweden. The system integrates septic tank treatment technology with a package treatment plant (PTP) and a sequencing batch subsurface flow constructed wetland (SBCW). The investigation combined three approaches: field monitoring, laboratory-scale column experiments and process-based modelling, to provide a better understanding of system performance, predict contaminant retention and test system response to various environmental factors, design scenarios and operational conditions. The overall results indicated that the entire system is efficient in removing total phosphorus (83%), biological oxygen demand (BOD7, 99%) and Escherichia coli bacteria (89%). It is less efficient in total inorganic nitrogen removal (22%). Mean concentration of phosphorus (0.96 mg/L) and pH (8.8) in effluent from the entire system were found to be below the Swedish threshold values for on-site wastewater discharge. This indicates that the system could be reliable and sustainable technology for on-site wastewater treatment in cold climate conditions. A complementary three-dimensional (3D) model developed using COMSOL Multiphysics® software proved to be a useful and rapid tool for predicting the behaviour of complex hydraulic dynamics. It provided valuable insights into the spatial and temporal variability in sorption processes caused by changes in different wastewater treatment system design parameters, environmental factors and modes of operation. Through process-based modelling, a reactive filter material with longer lifetime and a SBCW design that improved the sustainability of on-site wastewater treatment system were successfully identified. It was concluded that long-term performance of reactive filter materials in PTP systems can be achieved when the system is loaded intermittently with low influent contaminant concentrations (
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- 2019
21. Modelling Phosphorus Sorption Kinetics and the Longevity of Reactive Filter Materials Used for On-Site Wastewater Treatment
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Hamisi, Rajabu, primary, Renman, Gunno, additional, Renman, Agnieszka, additional, and Wörman, Anders, additional
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- 2019
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22. Modelling phosphorus sorption kinetics and the longevity of reactive filter materials used for on-sitewastewater treatment
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Hamisi, Rajabu, Renman, Gunno, Renman, Agnieszka, Wörman, Anders, Hamisi, Rajabu, Renman, Gunno, Renman, Agnieszka, and Wörman, Anders
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Use of reactive filter media (RFM) is an emerging technology in small-scale wastewater treatment to improve phosphorus (P) removal and filter material longevity for making this technology sustainable. In this study, long-term sorption kinetics and the spatial dynamics of sorbed P distribution were simulated in replaceable P-filter bags filled with 700 L of reactive material and used in real on-site treatment systems. The input data for model calibration were obtained in laboratory trials with Filtralite P®, Polonite® and Top16. The P concentration breakthrough threshold value was set at an effluent/influent (C/C 0 ) ratio of 1 and simulations were performed with P concentrations varying from 1 to 25 mg L -1 . The simulation results showed that influent P concentration was important for the breakthrough and longevity, and that Polonite performed best, followed by Top16 and Filtralite P. A 100-day break in simulated intermittent flow allowed the materials to recover, which for Polonite involved slight retardation of P saturation. The simulated spatial distribution of P accumulated in the filter bags showed large differences between the filter materials. The modelling insights from this study can be applied in design and operation of on-site treatment systems using reactive filter materials., QC 20190815
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- 2019
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23. Modelling phosphorus dynamics in constructed wetlands upgraded with reactive filter media
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Hamisi, Rajabu
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COMSOL ,Sorption Process ,Reactive Solute Transport ,Constructed Wetland ,Water Engineering ,Vattenteknik ,Modelling - Abstract
Developing low-cost and effective technologies to upgrade phosphorus (P) removal from the catchment runoffs and rural wastewater treatment facilities is one of the main research agendas to save the Baltic Sea from eutrophication. In Sweden, the construction of the constructed wetlands has been one of the environmental objectives for wastewater quality improvement in the small communities. However, the insufficiently understanding of the mechanisms underlying the process of phosphorus mobility and sorption in the constructed wetlands has limited design of the effective constructed wetlands. To provide the better understanding of sorption process in the catchment and constructed wetland system, this thesis used the GIS-based Soil and Water Assessment Tool (SWAT) to predict phosphorus mobility and identify the critical diffusing sources of phosphorus loss in the Oxunda catchment (Paper I). Then, the study developed the three-dimensional numerical Reactive TRAnsPort Model (RETRAP - 3D) in the COMSOL Multiphysics® for evaluating the long - term sorption processes and removal efficiencies of the porous reactive media for upgrading the performance of constructed wetlands (Paper II and III). The latter model coupled many physics equations to solve process of water flow, reaction kinetics and solute transport in the porous reactive adsorbent media for application in the constructed wetlands. The data from the field measurements and column experiments have been used to demonstrate the model simulation accuracy to capture the process of phosphorus sorption in the real environment. Modeling results ranked the phosphorus removal efficiency of the adsorbent media as follows: Polonite® (88 %), Filtralite P® (85%), BFS (62%), Wollastonite (57 %). The satisfactory agreement which obtained between the simulated outputs and measured data confirmed that the SWAT and RETRAP-3D are useful tools for describing various processes in the complicated system. However, further study is required to generate and validate more experimental data to evaluate the sensitivity of local parameters. This reserch project was finacially supported by Lars Erik Lundberg scholarship foundation for projectnumber (2015/34 and 2016/12), ÅkeochGreta Lissheds Stiftelsen for project number (2015-00026), J.Gust. Richert Stiftelsen and Ecopool researchproject for smart and sustainable environment. QC 20170523
- Published
- 2017
24. Simulations of water balance conditions and cli-mate variability for Sustainable Agriculture and Energy in the Lower Rufiji Basin
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Hamisi, Rajabu
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Adaptation ,Agriculture ,Climate Change ,CoupModel ,Hydropower ,SWAT ,Water Balance ,Civil Engineering ,Samhällsbyggnadsteknik - Abstract
This study provides a long-term understanding of the impact of climate varia-bility and land use on seasonal water balance conditions for sustainable agricul-ture development, hydropower generation and ecosystem stability in the Lower Rufiji Basin. The severity of soil drought, extreme flooding and salinity intru-sion in the lower Rufiji floodplains are currently increasing smallholder poverty and enhance the sensitivity on the natural wetlands for shifting farming and livestock pastures. The CoupModel and SWAT hydrological model were ap-plied to assess and compare the impact of climate variability on the water bal-ance. The monthly river discharge was used for calibrating and validating the runoff at the Stiegler's Gorge. The simulated results for water balance compo-nents at Stiegler's Gorge showed 55% of accumulated precipitation is lost through evapotranspiration and 42 % is river runoffs for downstream agricul-ture and ecosystem services. The evaluation of the models simulation perfor-mance and posterior distribution of parameter behavioral value indicates the (GLUE) calibration method in the CoupModel agreed satisfactory with the Bayesian calibration (BC). The minimal variance in the Bayesian Calibration posterior parameter distribution was observed in the parameter for regulating water uptake from (CritThresholDry) and soil moisture availability for soil evaporation(PsiRs_ip). The SWAT simulation showed that south of the central floodplains has high risk of soil drought. The overall assessment implies that drought and river runoff dynamics in the LRB is affected by upstream land use activities. The strategies for building smallholder resilience towards climate change and land use impact requires collective and coordinated water manage-ment actions powered by individual, institutional, financial and technological adaptation.
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- 2013
25. Applications of Process Base Models for Sustainable Water Utilizations in a Competing Demands and Climate Variability : A Case of the Lower Rufiji, Tanzania
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Hamisi, Rajabu, Balfors, Berit, Thunvik, Roger, Jansson, Per-Erik, Hamerlynck, O, Duvail, S, Hamisi, Rajabu, Balfors, Berit, Thunvik, Roger, Jansson, Per-Erik, Hamerlynck, O, and Duvail, S
- Abstract
QC 20140128
- Published
- 2013
26. A new modelling approach for phosphorus mobility and retention processes in the Oxundaån catchment, Sweden
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Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, and Thunvik, Roger
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Sediment erosion ,Constructed wetlands ,Phosphorus retentions ,Adaptive management ,Watershed modelling ,Water Engineering ,Vattenteknik - Abstract
Eutrophication is the most significant threat towater quality in the entire Baltic Sea region. Its causes are nutrientover-enrichment from diffuse and point sources. Thematic strategies forsustainable mitigation of phosphorus loss from sewage drainage systems andrunoffs from arable land require a holistic approach to identify the criticalpolluting sources and implement relevant policy for adaptive water qualitymanagement. The use of constructed wetlands constitutes one such strategy thatcan mitigate phosphorus loss. However, insufficient understanding about phosphorusmobility and retention in catchments significantly hinders efforts to identifysuitable sites for constructed wetlands and implement alternative, adaptive andeffective management actions. This study aims to evaluate the long-termphosphorus mobility and retention in the Oxudaån catchment in Sweden, andthereby propose suitable sites to localize constructed wetlands. The Soil andWater Assessment watershed model was applied to map and quantify the phosphorusloading from diffuse and point sources under the scenarios of land usemanagement practices. Simulation results have demonstrated the positivecorrelation between the phosphorus concentration with the surface runoffs andnegative correlation with the pH. Overall, Oxundaån catchment indicates a decreasingtrend of phosphorus loading in the Verkaån and Oxundaån riverine of around 2.1% and 1.3 % per year, respectively. The present study suggests the suitablesites for localizing constructed wetlands in the south-west and north-east ofOxundaån lake based on the factor of low slope topography and soilpermeability. The simulation results from the SWAT model offer evidence thatcan guide the localization and choice of management interventions to achieve asustainable mitigation of phosphorus loss. This study concludes that, while singlemanagement actions can help solve the problem of eutrophication, a moreeffective and sustainable mitigation of eutrophication will require the integrationof multiple adaptive land use management approaches. QC 20170529
27. Modelling phosphorus recovery by reactive adsorbent in a vertical subsurface flow constructed wetland
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Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, Thunvik, Roger, Welin, Anders, and Larm, Thomas
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COMSOL ,Constructed wetlands ,Residence Time ,Phosphorus ,Reactive Media ,Water Engineering ,Vattenteknik - Abstract
Phosphorus removal efficiencies by four low - costsreactive adsorbent media were evaluated in the long - time period using thethree - dimensional model of the vertical subsurface flow constructed wetlandsin the COMSOL Multiphysics® software. Evaluations were made for Polonite,Filtralite P, Sorbulite and Wollastonite adsorbent media with the aims ofpredicting their long - term sorption capacity and describing the phenomena ofsorption mechanisms when applied in the vertical subsurface flow constructedwetlands for wastewater purification. The 3D model of the vertical flowconstructed wetlands were dimensioned to Swedish EPA guidelines for small scalewastewater treatment, and calibrated at saturated media using the breakthroughdata derived from the column experiments of similar adsorbent mediaapplication, and the local sensitivity analysis were performed for waterquality and hydraulic loading parameters. It was observed that the breakthroughcurves developed by model were significantly correlated to the experimentaldata. The overall findings showed that Polonite® could be the potentialreactive adsorbent for phosphorus removal in the VF-CWs application, and itsremoval efficiency was discovered to last for 5 years. The large variation ofmedia sorption capacities discovered to be affected more by factor of pH andhydraulic loading rates than the particle size. High degree of predictionaccuracy which is demonstrated by this model suggest that the proposed model isa useful tool for predicting pollutants removal in various reactive porousmedia. QC 20170529
28. Simulating the hydraulic dynamics and treatment performance of a sequencing batch flow constructed wetland
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Hamisi, Rajabu, Renman, Gunno, Renman, Agnieszka, Wörman, Anders, Hamisi, Rajabu, Renman, Gunno, Renman, Agnieszka, and Wörman, Anders
- Abstract
In a six-month field trial, the performance of a full-scale sequencing batch flow constructed wetland (SBCW) treating on-site wastewater was determined. The filling and draining periods lasted 5-9 days, depending on wastewater production by users (two households). The results indicated that the SBCW system efficiently removed ammonium-nitrogen (NH4-N, 76%) and Escherichia coli (89%). However, draining by pumping increased preferential water flow and considerably limited removal of dissolved phosphorus (PO4-P) in the filter bed. Analysis of water samples from nine points and three vertical levels of the wetland bed showed that pumping aerated the bed, resulting in removal of NH4-N being highest in the top 0-0.2 m layer (43%) intermediate in the 0.2-0.4 m layer (32%), and lowest in the deep (0.4-0.6 m) layer (4%). Complementary modeling using COMSOL Multiphysics software to predict the hydraulic dynamics for three different SBCW designs indicated that the drainage system of the present SBCW should be re-designed to increase contact time and aeration, for improved phosphorus and nitrogen removal., QC 20190903
29. Phosphorus sorption and leaching in sand filters used for onsite wastewater treatment - a column experiment
- Author
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Hamisi, Rajabu, Renman, Gunno, Renman, Agnieszka, Wörman, Anders, Hamisi, Rajabu, Renman, Gunno, Renman, Agnieszka, and Wörman, Anders
- Abstract
The sorption capacities of filter sands used for onsite wastewater treatment and their associated risks of phosphorus (P) leakage on contact with rainwater were investigated in column experiments and modelling studies. Columns packed with sand were exposed to real domestic wastewater of different characteristics and hydraulic loading modes. The wastewater fed into the columns was effluent collected from three different treatment units in the field: a septic tank (ST), biofiltration tank (BF) and Polonite® filter bag (PO). The risk of P leaching to groundwater and surface water was also assessed, by exposing the same sand columns to artificial rainwater. The results indicated that sand columns can exhibit different adsorption capacities for Total-P, phosphate-P and total suspended solids, depending on the characteristics of influent wastewater. The adsorption capacity increased in the order ST > BF > PO, based on availability of organic matter to form biofilm. Effluent from Pol columns was significantly clearer, indicating lower organics content, than effluent from ST and BF columns. The modelled breakthrough curves for Total-P desorption agreed satisfactorily with the measured values, but further model improvement is needed., QC 20190903
30. Modelling phosphorus recovery by reactive adsorbent in a vertical subsurface flow constructed wetland
- Author
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Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, Thunvik, Roger, Welin, Anders, Larm, Thomas, Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, Thunvik, Roger, Welin, Anders, and Larm, Thomas
- Abstract
Phosphorus removal efficiencies by four low - costsreactive adsorbent media were evaluated in the long - time period using thethree - dimensional model of the vertical subsurface flow constructed wetlandsin the COMSOL Multiphysics® software. Evaluations were made for Polonite,Filtralite P, Sorbulite and Wollastonite adsorbent media with the aims ofpredicting their long - term sorption capacity and describing the phenomena ofsorption mechanisms when applied in the vertical subsurface flow constructedwetlands for wastewater purification. The 3D model of the vertical flowconstructed wetlands were dimensioned to Swedish EPA guidelines for small scalewastewater treatment, and calibrated at saturated media using the breakthroughdata derived from the column experiments of similar adsorbent mediaapplication, and the local sensitivity analysis were performed for waterquality and hydraulic loading parameters. It was observed that the breakthroughcurves developed by model were significantly correlated to the experimentaldata. The overall findings showed that Polonite® could be the potentialreactive adsorbent for phosphorus removal in the VF-CWs application, and itsremoval efficiency was discovered to last for 5 years. The large variation ofmedia sorption capacities discovered to be affected more by factor of pH andhydraulic loading rates than the particle size. High degree of predictionaccuracy which is demonstrated by this model suggest that the proposed model isa useful tool for predicting pollutants removal in various reactive porousmedia., QC 20170529
31. Reactive transport modelling of long-term phosphorus dynamic in the compact constructed wetland using COMSOL Multiphysics
- Author
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Hamisi, Rajabu, Renman, Gunno, Herrmann, Inga, Thunvik, Roger, Hamisi, Rajabu, Renman, Gunno, Herrmann, Inga, and Thunvik, Roger
- Abstract
A three-dimensional reactive transport model (RETRAP-3D) was developed by this study in the COMSOL Multiphysics®software to evaluate the long-term sorption capacity and mechanisms of dissolved reactive phosphorus removal in reactive adsorbent. The model coupledphysics interfaces for water flow, transport of reactive species, reaction kinetics for chemical compositions and biofilm development. Simulations were conducted for Polonite®, Filtralite P®, and Blast Furnace Slag mediaat fully saturated media, equilibrium miscible solution and isothermal heat transfer conditions. The model was validated using column experimental data ofsimilar media for application in constructed filter beds. The general modelling results showed good agreement with the measured breakthrough data. The most significant DIP retention capacity (P < 0.02) and longest residence time(1250 days) has been found for Polonite® and the most insignificant DIP retention for blast furnace slag (P > 0.54). The DIP removal was significantly correlated to factors of pH change, media characteristics, hydraulic dosage and retention times. These results demonstrate the reliability of the model as aflexible tool to predict the long-term performance of filter media and better understand processes within the system under various operational, weather and wastewater conditions., QC 20170529
32. A new modelling approach for phosphorus mobility and retention processes in the Oxundaån catchment, Sweden
- Author
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Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, Thunvik, Roger, Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, and Thunvik, Roger
- Abstract
Eutrophication is the most significant threat towater quality in the entire Baltic Sea region. Its causes are nutrientover-enrichment from diffuse and point sources. Thematic strategies forsustainable mitigation of phosphorus loss from sewage drainage systems andrunoffs from arable land require a holistic approach to identify the criticalpolluting sources and implement relevant policy for adaptive water qualitymanagement. The use of constructed wetlands constitutes one such strategy thatcan mitigate phosphorus loss. However, insufficient understanding about phosphorusmobility and retention in catchments significantly hinders efforts to identifysuitable sites for constructed wetlands and implement alternative, adaptive andeffective management actions. This study aims to evaluate the long-termphosphorus mobility and retention in the Oxudaån catchment in Sweden, andthereby propose suitable sites to localize constructed wetlands. The Soil andWater Assessment watershed model was applied to map and quantify the phosphorusloading from diffuse and point sources under the scenarios of land usemanagement practices. Simulation results have demonstrated the positivecorrelation between the phosphorus concentration with the surface runoffs andnegative correlation with the pH. Overall, Oxundaån catchment indicates a decreasingtrend of phosphorus loading in the Verkaån and Oxundaån riverine of around 2.1% and 1.3 % per year, respectively. The present study suggests the suitablesites for localizing constructed wetlands in the south-west and north-east ofOxundaån lake based on the factor of low slope topography and soilpermeability. The simulation results from the SWAT model offer evidence thatcan guide the localization and choice of management interventions to achieve asustainable mitigation of phosphorus loss. This study concludes that, while singlemanagement actions can help solve the problem of eutrophication, a moreeffective and sustainable mitigation of eutrophication will requ, QC 20170529
33. Modelling phosphorus recovery by reactive adsorbent in a vertical subsurface flow constructed wetland
- Author
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Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, Thunvik, Roger, Welin, Anders, Larm, Thomas, Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, Thunvik, Roger, Welin, Anders, and Larm, Thomas
- Abstract
Phosphorus removal efficiencies by four low - costsreactive adsorbent media were evaluated in the long - time period using thethree - dimensional model of the vertical subsurface flow constructed wetlandsin the COMSOL Multiphysics® software. Evaluations were made for Polonite,Filtralite P, Sorbulite and Wollastonite adsorbent media with the aims ofpredicting their long - term sorption capacity and describing the phenomena ofsorption mechanisms when applied in the vertical subsurface flow constructedwetlands for wastewater purification. The 3D model of the vertical flowconstructed wetlands were dimensioned to Swedish EPA guidelines for small scalewastewater treatment, and calibrated at saturated media using the breakthroughdata derived from the column experiments of similar adsorbent mediaapplication, and the local sensitivity analysis were performed for waterquality and hydraulic loading parameters. It was observed that the breakthroughcurves developed by model were significantly correlated to the experimentaldata. The overall findings showed that Polonite® could be the potentialreactive adsorbent for phosphorus removal in the VF-CWs application, and itsremoval efficiency was discovered to last for 5 years. The large variation ofmedia sorption capacities discovered to be affected more by factor of pH andhydraulic loading rates than the particle size. High degree of predictionaccuracy which is demonstrated by this model suggest that the proposed model isa useful tool for predicting pollutants removal in various reactive porousmedia., QC 20170529
34. A new modelling approach for phosphorus mobility and retention processes in the Oxundaån catchment, Sweden
- Author
-
Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, Thunvik, Roger, Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, and Thunvik, Roger
- Abstract
Eutrophication is the most significant threat towater quality in the entire Baltic Sea region. Its causes are nutrientover-enrichment from diffuse and point sources. Thematic strategies forsustainable mitigation of phosphorus loss from sewage drainage systems andrunoffs from arable land require a holistic approach to identify the criticalpolluting sources and implement relevant policy for adaptive water qualitymanagement. The use of constructed wetlands constitutes one such strategy thatcan mitigate phosphorus loss. However, insufficient understanding about phosphorusmobility and retention in catchments significantly hinders efforts to identifysuitable sites for constructed wetlands and implement alternative, adaptive andeffective management actions. This study aims to evaluate the long-termphosphorus mobility and retention in the Oxudaån catchment in Sweden, andthereby propose suitable sites to localize constructed wetlands. The Soil andWater Assessment watershed model was applied to map and quantify the phosphorusloading from diffuse and point sources under the scenarios of land usemanagement practices. Simulation results have demonstrated the positivecorrelation between the phosphorus concentration with the surface runoffs andnegative correlation with the pH. Overall, Oxundaån catchment indicates a decreasingtrend of phosphorus loading in the Verkaån and Oxundaån riverine of around 2.1% and 1.3 % per year, respectively. The present study suggests the suitablesites for localizing constructed wetlands in the south-west and north-east ofOxundaån lake based on the factor of low slope topography and soilpermeability. The simulation results from the SWAT model offer evidence thatcan guide the localization and choice of management interventions to achieve asustainable mitigation of phosphorus loss. This study concludes that, while singlemanagement actions can help solve the problem of eutrophication, a moreeffective and sustainable mitigation of eutrophication will requ, QC 20170529
35. Spatial modeling of the occurrences of geogenic fluoride in groundwater systems and implications for the provision of safe drinking water in Tanzania
- Author
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Ijumulana, J., Ligate, Fanuel Josephat, Bhattacharya, Prosun, Ahmad, Arslan, Zhang, Chaosheng, Tomašek, Ines, Irunde, R., Kimambo, Vivian, Hamisi, Rajabu, Mtalo, Felix, Ijumulana, J., Ligate, Fanuel Josephat, Bhattacharya, Prosun, Ahmad, Arslan, Zhang, Chaosheng, Tomašek, Ines, Irunde, R., Kimambo, Vivian, Hamisi, Rajabu, and Mtalo, Felix
- Abstract
Inadequate data and spatial dependence in the observations during geochemical studies are among the disturbing conditions when estimating environmental factors contributing to the local variability in the pollutants of interest. Usually, spatial dependence occurs due to the researcher’s imperfection on the natural scale of occurrence which affects the sampling strategy. As a consequence, observations on the study variable are significantly correlated in space. In this study, the machine learning approach was developed and used to study the environmental factors controlling the local variability in fluoride concentration in drinking water sources of northern Tanzania within the East African Rift Valley. The approach constituted use of the geographical information systems (GIS) technology, exploratory spatial data analysis methods, and spatial modeling at a local level. The environmental variables used to study the local variation in fluoride concentration include topography, tectonic processes, water exchanges between hydrogeological layers during lateral movement, the mineralization processes (EC), and pH. The study was based on 20 local spatial regimes determined using GIS based on water sources density in the four hydrogeological environments. The non-parametric (one-way Kruskal-Wallis sum ranks test and Multiple Comparisons Dunn Test), spatial statistics (Global Moran's I statistic), ordinary least squares (OLS) regression and spatial lag models were used to quantify the effects of topography, tectonic processes, water exchange between hydrogeological environments and waterphysiochemical parameters (pH and EC) on the spatial variability of fluoride concentrations in drinking water sources at a local scale. In the order of significance, the local spatial variation in fluoride concentration is influenced by the EC, topography, tectonic processes, pH and water exchange between hydrogeological layers during water movement. The results presented in this paper are cruc, QC 20220121
36. Modelling phosphorus recovery by reactive adsorbent in a vertical subsurface flow constructed wetland
- Author
-
Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, Thunvik, Roger, Welin, Anders, Larm, Thomas, Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, Thunvik, Roger, Welin, Anders, and Larm, Thomas
- Abstract
Phosphorus removal efficiencies by four low - costsreactive adsorbent media were evaluated in the long - time period using thethree - dimensional model of the vertical subsurface flow constructed wetlandsin the COMSOL Multiphysics® software. Evaluations were made for Polonite,Filtralite P, Sorbulite and Wollastonite adsorbent media with the aims ofpredicting their long - term sorption capacity and describing the phenomena ofsorption mechanisms when applied in the vertical subsurface flow constructedwetlands for wastewater purification. The 3D model of the vertical flowconstructed wetlands were dimensioned to Swedish EPA guidelines for small scalewastewater treatment, and calibrated at saturated media using the breakthroughdata derived from the column experiments of similar adsorbent mediaapplication, and the local sensitivity analysis were performed for waterquality and hydraulic loading parameters. It was observed that the breakthroughcurves developed by model were significantly correlated to the experimentaldata. The overall findings showed that Polonite® could be the potentialreactive adsorbent for phosphorus removal in the VF-CWs application, and itsremoval efficiency was discovered to last for 5 years. The large variation ofmedia sorption capacities discovered to be affected more by factor of pH andhydraulic loading rates than the particle size. High degree of predictionaccuracy which is demonstrated by this model suggest that the proposed model isa useful tool for predicting pollutants removal in various reactive porousmedia., QC 20170529
37. A new modelling approach for phosphorus mobility and retention processes in the Oxundaån catchment, Sweden
- Author
-
Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, Thunvik, Roger, Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, and Thunvik, Roger
- Abstract
Eutrophication is the most significant threat towater quality in the entire Baltic Sea region. Its causes are nutrientover-enrichment from diffuse and point sources. Thematic strategies forsustainable mitigation of phosphorus loss from sewage drainage systems andrunoffs from arable land require a holistic approach to identify the criticalpolluting sources and implement relevant policy for adaptive water qualitymanagement. The use of constructed wetlands constitutes one such strategy thatcan mitigate phosphorus loss. However, insufficient understanding about phosphorusmobility and retention in catchments significantly hinders efforts to identifysuitable sites for constructed wetlands and implement alternative, adaptive andeffective management actions. This study aims to evaluate the long-termphosphorus mobility and retention in the Oxudaån catchment in Sweden, andthereby propose suitable sites to localize constructed wetlands. The Soil andWater Assessment watershed model was applied to map and quantify the phosphorusloading from diffuse and point sources under the scenarios of land usemanagement practices. Simulation results have demonstrated the positivecorrelation between the phosphorus concentration with the surface runoffs andnegative correlation with the pH. Overall, Oxundaån catchment indicates a decreasingtrend of phosphorus loading in the Verkaån and Oxundaån riverine of around 2.1% and 1.3 % per year, respectively. The present study suggests the suitablesites for localizing constructed wetlands in the south-west and north-east ofOxundaån lake based on the factor of low slope topography and soilpermeability. The simulation results from the SWAT model offer evidence thatcan guide the localization and choice of management interventions to achieve asustainable mitigation of phosphorus loss. This study concludes that, while singlemanagement actions can help solve the problem of eutrophication, a moreeffective and sustainable mitigation of eutrophication will requ, QC 20170529
38. Modelling phosphorus recovery by reactive adsorbent in a vertical subsurface flow constructed wetland
- Author
-
Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, Thunvik, Roger, Welin, Anders, Larm, Thomas, Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, Thunvik, Roger, Welin, Anders, and Larm, Thomas
- Abstract
Phosphorus removal efficiencies by four low - costsreactive adsorbent media were evaluated in the long - time period using thethree - dimensional model of the vertical subsurface flow constructed wetlandsin the COMSOL Multiphysics® software. Evaluations were made for Polonite,Filtralite P, Sorbulite and Wollastonite adsorbent media with the aims ofpredicting their long - term sorption capacity and describing the phenomena ofsorption mechanisms when applied in the vertical subsurface flow constructedwetlands for wastewater purification. The 3D model of the vertical flowconstructed wetlands were dimensioned to Swedish EPA guidelines for small scalewastewater treatment, and calibrated at saturated media using the breakthroughdata derived from the column experiments of similar adsorbent mediaapplication, and the local sensitivity analysis were performed for waterquality and hydraulic loading parameters. It was observed that the breakthroughcurves developed by model were significantly correlated to the experimentaldata. The overall findings showed that Polonite® could be the potentialreactive adsorbent for phosphorus removal in the VF-CWs application, and itsremoval efficiency was discovered to last for 5 years. The large variation ofmedia sorption capacities discovered to be affected more by factor of pH andhydraulic loading rates than the particle size. High degree of predictionaccuracy which is demonstrated by this model suggest that the proposed model isa useful tool for predicting pollutants removal in various reactive porousmedia., QC 20170529
39. A new modelling approach for phosphorus mobility and retention processes in the Oxundaån catchment, Sweden
- Author
-
Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, Thunvik, Roger, Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, and Thunvik, Roger
- Abstract
Eutrophication is the most significant threat towater quality in the entire Baltic Sea region. Its causes are nutrientover-enrichment from diffuse and point sources. Thematic strategies forsustainable mitigation of phosphorus loss from sewage drainage systems andrunoffs from arable land require a holistic approach to identify the criticalpolluting sources and implement relevant policy for adaptive water qualitymanagement. The use of constructed wetlands constitutes one such strategy thatcan mitigate phosphorus loss. However, insufficient understanding about phosphorusmobility and retention in catchments significantly hinders efforts to identifysuitable sites for constructed wetlands and implement alternative, adaptive andeffective management actions. This study aims to evaluate the long-termphosphorus mobility and retention in the Oxudaån catchment in Sweden, andthereby propose suitable sites to localize constructed wetlands. The Soil andWater Assessment watershed model was applied to map and quantify the phosphorusloading from diffuse and point sources under the scenarios of land usemanagement practices. Simulation results have demonstrated the positivecorrelation between the phosphorus concentration with the surface runoffs andnegative correlation with the pH. Overall, Oxundaån catchment indicates a decreasingtrend of phosphorus loading in the Verkaån and Oxundaån riverine of around 2.1% and 1.3 % per year, respectively. The present study suggests the suitablesites for localizing constructed wetlands in the south-west and north-east ofOxundaån lake based on the factor of low slope topography and soilpermeability. The simulation results from the SWAT model offer evidence thatcan guide the localization and choice of management interventions to achieve asustainable mitigation of phosphorus loss. This study concludes that, while singlemanagement actions can help solve the problem of eutrophication, a moreeffective and sustainable mitigation of eutrophication will requ, QC 20170529
40. A new modelling approach for phosphorus mobility and retention processes in the Oxundaån catchment, Sweden
- Author
-
Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, Thunvik, Roger, Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, and Thunvik, Roger
- Abstract
Eutrophication is the most significant threat towater quality in the entire Baltic Sea region. Its causes are nutrientover-enrichment from diffuse and point sources. Thematic strategies forsustainable mitigation of phosphorus loss from sewage drainage systems andrunoffs from arable land require a holistic approach to identify the criticalpolluting sources and implement relevant policy for adaptive water qualitymanagement. The use of constructed wetlands constitutes one such strategy thatcan mitigate phosphorus loss. However, insufficient understanding about phosphorusmobility and retention in catchments significantly hinders efforts to identifysuitable sites for constructed wetlands and implement alternative, adaptive andeffective management actions. This study aims to evaluate the long-termphosphorus mobility and retention in the Oxudaån catchment in Sweden, andthereby propose suitable sites to localize constructed wetlands. The Soil andWater Assessment watershed model was applied to map and quantify the phosphorusloading from diffuse and point sources under the scenarios of land usemanagement practices. Simulation results have demonstrated the positivecorrelation between the phosphorus concentration with the surface runoffs andnegative correlation with the pH. Overall, Oxundaån catchment indicates a decreasingtrend of phosphorus loading in the Verkaån and Oxundaån riverine of around 2.1% and 1.3 % per year, respectively. The present study suggests the suitablesites for localizing constructed wetlands in the south-west and north-east ofOxundaån lake based on the factor of low slope topography and soilpermeability. The simulation results from the SWAT model offer evidence thatcan guide the localization and choice of management interventions to achieve asustainable mitigation of phosphorus loss. This study concludes that, while singlemanagement actions can help solve the problem of eutrophication, a moreeffective and sustainable mitigation of eutrophication will requ, QC 20170529
41. Modelling phosphorus recovery by reactive adsorbent in a vertical subsurface flow constructed wetland
- Author
-
Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, Thunvik, Roger, Welin, Anders, Larm, Thomas, Hamisi, Rajabu, Renman, Gunno, Brokking Balfors, Berit, Thunvik, Roger, Welin, Anders, and Larm, Thomas
- Abstract
Phosphorus removal efficiencies by four low - costsreactive adsorbent media were evaluated in the long - time period using thethree - dimensional model of the vertical subsurface flow constructed wetlandsin the COMSOL Multiphysics® software. Evaluations were made for Polonite,Filtralite P, Sorbulite and Wollastonite adsorbent media with the aims ofpredicting their long - term sorption capacity and describing the phenomena ofsorption mechanisms when applied in the vertical subsurface flow constructedwetlands for wastewater purification. The 3D model of the vertical flowconstructed wetlands were dimensioned to Swedish EPA guidelines for small scalewastewater treatment, and calibrated at saturated media using the breakthroughdata derived from the column experiments of similar adsorbent mediaapplication, and the local sensitivity analysis were performed for waterquality and hydraulic loading parameters. It was observed that the breakthroughcurves developed by model were significantly correlated to the experimentaldata. The overall findings showed that Polonite® could be the potentialreactive adsorbent for phosphorus removal in the VF-CWs application, and itsremoval efficiency was discovered to last for 5 years. The large variation ofmedia sorption capacities discovered to be affected more by factor of pH andhydraulic loading rates than the particle size. High degree of predictionaccuracy which is demonstrated by this model suggest that the proposed model isa useful tool for predicting pollutants removal in various reactive porousmedia., QC 20170529
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