Potential Use of Water Guard as a Disinfectant for Domestic Water Use

Water Guard which consists of 0.75% sodium hypochlorite (chlorine-based water disinfectant solution) has been identified as an alternative method for treatment of domestic drinking water. The aim of this study was to investigate the effectiveness of Water Guard in disinfecting drinking water from different sources drawn from Kinondoni district, Dar es Salaam as well as to establish appropriate dosage that can be used during the treatment. Results showed that, a dose of 4.0mL per 20 litrer of water guard is sufficient for disinfectionof urban water sources. The above prescribed doses provide 100% disinfection efficiency with residue chlorine of less than 0.3mg/l. Water with turbidity values of 30-35 NTU, chlorine dosage of 8mL/20 litres is recommended and this gives residue chlorine of 0.3 – 0.5 mg/L. From this study, it can be concluded that, Water guard is effective against pathogen and that there is an increase of residue chlorine as the dosage increases irrespective of from which source the water was drawn. Also the safety of water is obtained even where the residual chlorine is less that 0.1mg/l. However, there are health implications associated with theuse of Water Guard which need further researc

Metalevel algorithms for variant satisfiability

Variant satisfiability is a theory-generic algorithm to decide quantifier-free satisfiability in an initial algebra when its corresponding theory has the finite variant property and its constructors satisfy a compactness condition. This paper: (i) gives a precise definition of several meta-level sub-algorithms needed for variant satisfiability; (ii) proves them correct; and (iii) presents a reflective implementation in Maude 2.7 of variant satisfiability using these sub-algorithms.NSF CNS 13-19109Ope

Health worker motivation in the context of HIV care and treatment challenges in Mbeya Region, Tanzania: A qualitative study

Health worker motivation can potentially affect the provision of health services. The HIV pandemic has placed additional strain on health service provision through the extra burden of increased testing and counselling, treating opportunistic infections and providing antiretroviral treatment. The aim of this paper is to explore the challenges generated by HIV care and treatment and their impact on health worker motivation in Mbeya Region, Tanzania. Thirty in-depth interviews were conducted with health workers across the range of health care professions in health facilities in two high HIV-prevalence districts of Mbeya Region, Tanzania. A qualitative framework analysis was adopted for data analysis. The negative impact of HIV-related challenges on health worker motivation was confirmed by this study. Training seminars and workshops related to HIV contributed to the shortage of health workers in the facilities. Lower status workers were frequently excluded from training and were more severely affected by the consequent increase in workload as seminars were usually attended by higher status professionals who controlled access. Constant and consistent complaints by clients have undermined health workers' expectations of trust and recognition. Health workers were forced to take responsibility for dealing with problems arising from organisational inefficiencies within the health system. HIV-related challenges undermine motivation among health workers in Mbeya, Tanzania with the burden falling most heavily on lower status workers. Strained relations between health workers and the community they serve, further undermine motivation of health workers

Dar es Salaam Water Supply Problems and Possible Solutions: Reflections

Dar es Salaam is the largest and most rapidly growing city, (with a growth rate of about 7% per annum) in Tanzania with an estimated population of over 2.8 million people. Like all Regional Headquarters Water Supplies and 'Water Supply to Dar es Salaam City residents is inadequate. Since 1982 water demand has exceeded total water production capacity of the three plants namely Mtoni; Upper Ruvu and Lower Ruvu. In 1989 the estimated water demand was about 289,760 m3fday while total estimated water production was about 239,560 m3/day. giving a deficit of 50,000 m3/day. Estimated production from the three plants is Mtoni 4,520 m3/day, Upper Ruvu 54,340 m3/day and lower 180,800 m3/day (Ministry of Water, 1989). The location of the plants and the main pipeline network is as shown of Figure 1 below. The problems of water supply can be those of quantity and invariably those of quality. There is not a doubt that the supplied quantity has been exceeded by the demand. In future this demand will be beyond what the present sources can ever supply. There is therefore a need to develop other augmentation systems through short term and long term plans. Under short term solutions shallow wells, boreholes and rain water harvesting should be considered. Long term solutions should include development of the Kizinga and Mzinga reservoirs which would release up to 1,000 m3/day. The development of the proposed Kidunda reservoir upstream of the present Ruvu intakes will enhance the supply up to 2.2 million m3/day which surpasses the year 2020 demand of about 1,000,000 m3/day. The quality of water from deep boreholes is usually of acceptable levels in terms of physical, chemical and bacteriological parameters. In some cases the quality does not meet the Tanzania Standard, therefore calls for treatment. Saline water intrusion is another problem to be tackled especially for ground water exploitation along the coastal belt. Shallow wells which are invariably from shallow aquifers are prone to pollution. It is therefore to be expected that their waters will need treatment. Often shallow wells do not produce water which meets the international standards in terms of chloride, nitrate and pathogenic organisms quality. This paper is an attempt to highlight the water problems facing the Dar es Salaam residents and propose possible solutions to the same. The paper points out the possible short and long term solutions

Real-time state estimation of a distributed electrical power system under conditions of deregulation

Thesis (DTech (Electrical Engineering))--Cape Peninsula University of Technology, 2010.Static state estimation is a mathematical procedure in which physical measurements from sub-stations and physical model are combined in an optimal way. That is, the measurements obtained from the sub-stations are used with the physical model and the states of the power system are selected or calculated such that the states match the measurements in some best way. The states of a power system are the bus voltage magnitude and voltage angle of each bus of the system. Static state estimation is an increasingly common part of electrical power utility energy management systems (EMS). It plays a critical part in a day-to-day operation of a power system utility. The system measurements obtained from static estimation are used for realtime operations like optimal power flow calculations and contingency analysis. Proper system operations with regards to avoidance of insecure conditions includes situational awareness, therefore, the static estimator plays an important role in power system security. A further motivation: in increasingly electrical power deregulation, more economic operations mean savings for customers and electrical power provider alike. Economic benefit might be realized if system operators have a more accurate situational awareness of the system through improved power system state estimator. The objective of the study was to develop method, algorithm and MATLAB program for solution of power system state estimation using parallel processing techniques. In achieving the objective, the study has concentrated on development of an approximate Tanzanian power system network model comprising of 30 buses and used as a case study; decomposing the bus admittance matrix of the model into 3 interconnected sub-systems; development of mathematical model for real and reactive power injections, real and reactive power flows in the transmission lines and tie-lines connecting the sub-systems; development of measurement data model for voltage magnitude, real and reactive power injections, real and reactive power flows; formulating of a constrained weighted least absolute value state estimation problem; development of decomposition-coordination method and algorithm; and formulating algorithm and MATLAB program for solving the constrained state estimation problem using parallel processing technique

Groundwater management by using mathematical modeling: case of the Makutupora groundwater basin in dodoma Tanzania

The ever-growing dependency on groundwater sources for both agriculture and domestic water uses has called for studies to ensure aquifer sustainability. The computer code Visual MODFLOW was employed in the study. The study intended at developing a groundwater management model for Makutupora groundwater basin through mathematical modeling. The model was calibrated using a set of observed dynamic water levels, aquifer parameters until the best fit between the observed and simulated heads was obtained. The model was then verified using parameters that gave the least Root Mean Square Error (RMSE). The developed model was then used to simulate the dynamic water table elevations for the next twenty years under the different management scenarios and pumping policies from the year 2000 to 2020. The model revealed that a pumping scenario that considers a 10 % of rainfall as recharge could ensure aquifer sustainability for the planned period. (Botswana Journal of Technology: 2003 12(1): 19-24

Modelling Nitrogen Transformation in Horizontal Subsurface Flow Constructed Wetlands Planted with Phragmites Mauritianus

A mathematical model was developed to permit dynamic simulation of nitrogen interaction in a pilot horizontal subsurface flow constructed wetland receiving effluents from primary facultative pond. The system was planted with Phragmites mauritianus, which was provided with root zone depth of 75 cm. The root zone was packed with gravel of 6 to 25 mm diameter in uniform proportions. Stella II software was used to simulate nitrogen transformation processes. The results show that the most influential nitrogen transformation processes were nitrification, denitrification, plant uptake, decomposition and accretion of organic nitrogen. Volatilisation played a negligible role in reducing nitrogen at the typically neutral pH levels found in subsurface wetland systems. Denitrification process, which ensures the permanent removal of nitrogen, accounted for 0.219 g/m2.d, which was only 15.0% of incoming nitrogen load (1.458 gN/m2.d). Harvesting of plants removed 0.195 gN/m2.d (13.4%) from the system. Accretion of organic nitrogen was a major pathway accounting for 0.279 g/m2.d, which is 19.2% of all the influent nitrogen. The accumulation of ammonia nitrogen was found to be high compared to other water phase state variables (organic nitrogen and nitrate nitrogen). Journal of Civil Engineering Research and Practice Vol.1(2) 2004: 1-1