The relationship between water pressure variations and drinking-water quality in small water supplies: A case of Mukono District, Uganda

The supply of a safe and adequate quantity of water is essential for human health and socioeconomic development. Physiochemical and microbiological quality of water supplied in piped distribution systems can be affected by long water residence times and travel distances. This may be due to low pressure, reservoir storage and insufficient disinfection in the system among other causes. As such, large schemes usually have mechanisms of improving the quality of water along supply and/or distribution networks at reservoir and other points. In contrast, small, piped water supply schemes rarely have the infrastructure and resources to monitor and provide treatment to the water in distribution. The objective of this study was to assess the variation of water quality and water pressure along the supply network in small, piped water systems. The study used mixed methods of quantitative water quality and pressure assessments, alongside stakeholder interviews, to investigate the variability of water pressure and specific water quality parameters across the distribution network, and reliability of supply in two different small water supply schemes in the study area of Mukono, Uganda. Results showed water pressure in small, piped water supply networks have minimal influence on variation of selected water quality parameters in smaller (< 4000 m travel distances) and well operated and maintained systems. A pressure drop from 82.2 m to 22.5 m changed Turbidity by < 1, Apparent Color by < x10 and Total Dissolved Solids by < x102. Proper management of supply systems to ensure optimal residual and continuous pressure can safeguard the quality of water in the distribution systems of small piped water networks against intrusion of contaminants. Good management practice that utilizes historical operational data with continuous capacity development and training support on water quality and pressure fluctuations can significantly improve system performance to meet acceptable standards

Application of black soldier fly larvae in decentralized treatment of faecal sludge from pit latrines in informal settlements in Kampala city

Introduction: Faecal sludge management (FSM) in urban areas of low-and middle-income countries (LMICs) is not properly implemented due to inaccessibility of sanitation facilities and high faecal sludge (FS) emptying costs, amongst others. Unlike in solid waste and fresh human excreta, use of black soldier fly larvae (BSFL) in treatment of FS from pit latrines - which are the most common sanitation facilities in urban areas of LMICs - has not yet been explored. Moreover, the optimal conditions for efficient FS degradation, such as moisture content, feeding rate and larval density are not yet well known. Against this backdrop, the overarching aim of this study was to determine the effectiveness of BSFL in treating FS under different conditions of moisture content, feeding rate and larval density. Also, the quality of residue left after treatment was assessed.Methods: FS samples were collected from lined and unlined pit latrines in Bwaise I parish in Kampala, Uganda and experiments were set up to feed 10-day old larvae.Results and Discussion: The optimum feeding rate, larval density and moisture content were found to be 50 mg/larvae/day, 1.33 larvae/cm2 and 60%, respectively. The reduction efficiency at optimum conditions were 72% and 66% for FS from lined and unlined pit latrines, respectively. It was further noted that BSFL can feed on FS from pit latrines without dewatering it, hence there is no need for a dewatering unit. The properties of the residue left after treatment were within the allowable limit for use as compost except for helminth egg concentration. Thus, in informal urban settlements, BSFL can be applied for effective treatment of FS from pit latrines while generating good quality residue thereby providing an additional value chain in FSM

The association of water carriage, water supply and sanitation usage with maternal and child health. A combined analysis of 49 Multiple Indicator Cluster Surveys from 41 countries

Background  Millions of people carry water home from off-plot sources each day and lack improved sanitation. Research on the health outcomes associated with water fetching is limited, and with usage of improved sanitation is inconclusive.  Objectives  To analyse the association of water fetching, unimproved water supplies, and usage of improved sanitation facilities with indicators of women’s and children’s health.  Methods  49 Multiple Indicator Cluster Surveys from 41 countries were merged, creating a data set of 2,740,855 people from 539,915 households. Multilevel, multivariable analyses were conducted, using logistic regression for binary outcomes, negative binomial regression for count data and ordinary linear regression for linear data. We adjusted for confounding factors and accounted for clustering at survey, cluster and household level.  Results  Compared to households in which no-one collects water, water fetching by any household member is associated with reduced odds of a woman giving birth in a health care facility (OR 0.88 to 0.90). Adults collecting water is associated with increased relative risk of childhood death (RR 1.04 to 1.05), children collecting water is associated with increased odds of diarrheal disease (OR 1.10 to 1.13) and women or girls collecting water is associated with reduced uptake of antenatal care (β-0.04 to -0.06) and increased odds of leaving a child under five alone for one or more hours, one or more days per week (OR 1.07 to 1.16). Unimproved water supply is associated with childhood diarhhoea (OR 1.05), but not child deaths, or growth scores. When the percentage of people using improved sanitation is more than 80% an association with reduced childhood death and stunting was observed, and when more than 60%, usage of improved sanitation was associated with reduction of diarhhoea and acute undernutrition.  Conclusion  Fetching water is associated with poorer maternal and child health outcomes, depending on who collects water. The percentage of people using improved sanitation seems to be more important than type of toilet facility, and must be high to observe an association with reduced child deaths and diarhhoea. Water access on premises, and near universal usage of improved sanitation, is associated with improvements to maternal and child health

Contributions of Human Activities and Climatic Variability to Changes in River Rwizi Flows in Uganda, East Africa

This study employed Soil and Water Assessment Tool (SWAT) to analyze the impacts of climate variability and human activities on River Rwizi flows. Changes in land use and land cover (LULC) types from 1997 to 2019 were characterized using remotely sensed images retrieved from Landsat ETM/TM satellites. SWAT was calibrated and validated over the periods 2002–2008 and 2009–2013, respectively. Correlation between rainfall and river flow was analyzed. By keeping the optimal values of model parameters fixed while varying the LULC maps, differences in the modeled flows were taken to reflect the impacts of LULC changes on rainfall–runoff generation. Impacts due to human activities included contributions from changes in LULC types and the rates of water abstracted from the river as a percentage of the observed flow. Climate variability was considered in terms of changes in climatic variables such as rainfall and evapotranspiration, among others. Variability of rainfall was analyzed with respect to changes in large-scale ocean-atmosphere conditions. From 2000 to 2014, the portion of River Rwizi catchment area covered by cropland increased from 23.0% to 51.6%, grassland reduced from 63.3% to 37.8%, and wetland decreased from 8.1% to 4.7%. Nash–Sutcliffe Efficiency values for calibration and validation were 0.60 and 0.71, respectively. Contributions of human activities to monthly river flow changes varied from 2.3% to 23.5%. Impacts of human activities on the river flow were on average found to be larger during the dry (14.7%) than wet (5.8%) season. Using rainfall, 20.9% of the total river flow variance was explained. However, climate variability contributed 73% of the river flow changes. Rainfall was positively and negatively correlated with Indian Ocean Dipole (IOD) and Niño 3, respectively. The largest percentages of the total rainfall variance explained by IOD and Niño 3 were 12.7% and 9.8%, respectively. The magnitude of the correlation between rainfall and IOD decreased with increasing lag in time. These findings are relevant for developing River Rwizi catchment management plans

Abating eutrophication on urban lakes: a case study of Kabaka's Lake, Uganda

Eutrophication of water bodies is a challenge in many urban areas. This study measured and modelled quantitatively the pollutant nutrient load of an urban lake (80,596 m2), and assessed both external (constructed wetland) and internal (dredging) eutrophication extenuation measures. For the past 25 years, there has been redistribution (p < 0.005) of the lake's catchment land use, with built-up area increasing by 78.5%, and a reduction in vegetated (37.2%) and water surface (1.8%) areas. A 92.2% reduction in the lakes receiving wetland footprint (p = 0.000003) was noted, with increased nutrient load. The lake's light attenuation was found to be dominated by algae, limited by nitrogen and classified under the oligotrophic class (Trophic State Index < 40), with a threat of eutrophication in an estimated 25 years. Scenario analyses show that the construction of a wetland in the remaining 0.54 hectares of natural wetland will reduce total phosphorus by 35% and total nitrate by 45% (p = 0.05), whereas dredging the lake could reduce them by 80% each (p = 0.0005). Watershed management is the only sustainable solution to control nutrient flow into the lake and enable self-cleansing, factoring in the design of the receiving wetland and groundwater sources. HIGHLIGHTS Quantitative measurement and modelling pollutant nutrient load of an urban lake.; Redistribution of lake catchment area lid to reduced lake footprint and increased nutrient load.; Lake's light attenuation is dominated by algae and limited by nitrogen.; Lake classified under the oligotrophic class of lakes (Trophic State Index < 40); Dredging significantly increases lake storage capacity and allows for thermal self-purification.

Additional file 1: Table S1. of Are pit latrines in urban areas of Sub-Saharan Africa performing? A review of usage, filling, insects and odour nuisances

Summary of success and failure attributes of different sanitation technologies used in Sub-Saharan Africa. Table S2. Summary data on pit latrine use in urban areas of Sub-Saharan Africa. Table S3. Comparison of 2015 and 2007 pit latrine coverage figures. (DOC 157 kb