Methods to reliably estimate faecal sludge quantities and qualities for the design of treatment technologies and management solutions.

Sanitation access in urban areas of low-income countries is provided through unstandardized onsite technologies containing accumulated faecal sludge. The demand for infrastructure to manage faecal sludge is increasing, however, no reliable method exists to estimate total accumulated quantities and qualities (Q&Q) This proposed approach averages out complexities to estimate conditions at a centralized to semi-centralized scale required for management and treatment technology solutions, as opposed to previous approaches evaluating what happens in individual containments. Empirical data, demographic data, and questionnaires were used in Kampala, Uganda to estimate total faecal sludge accumulation in the city, resulting in 270 L/cap∙year for pit latrines and 280 L/cap∙year for septic tanks. Septic tank sludge was more dilute than pit latrine sludge, however, public toilet was not a distinguishing factor. Non-household sources of sludge represent a significant fraction of the total and have different characteristics than household-level sludge. Income level, water connection, black water only, solid waste, number of users, containment volume, emptying frequency, and truck size were predictors of sludge quality. Empirical relationships such as a COD:TS of 1.09 ±â€¯0.56 could be used for more resource efficient sampling campaigns. Based on this approach, spatially available demographic, technical and environmental (SPA-DET) data and statistical relationships between parameters could be used to predict Q&Q of faecal sludge.

Long-term variations of water quality in the Inner Murchison Bay, Lake Victoria.

The water quality in the Inner Murchison Bay (IMB) located in Uganda on the northern shores of Lake Victoria is affected by a complex mixture of processes and driving factors including pollution, river inflows, lake water levels, wetland management and flora and fauna populations. This study attempts to explain long-term variations of the IMB water quality and to provide a plausible water quality model. Because intermittent monitoring around the Bay hinders accurate determination of pollution, concentrations at the extreme northern shores (hotspots) are considered indicative of the pollutant loading into the bay. Delft3D-Flow was applied to study the Bay hydrodynamics and coupled with the Delwaq module to investigate water quality processes related to oxygen: organic and nutrient components i.e. dissolved oxygen (DO), biological oxygen demand (BOD) and ammonium (NH4+). It is found that the IMB water quality deteriorated exponentially in the period 2001-2014 due to increased pollution and the high residence time of water. The worst water quality was in 2010 when diffuse pollution intensified due to the lining of more drainage channels within Kampala City in addition to the declining wetland effect. The water quality towards the Outer Murchison Bay (OMB) deteriorated over time with dilution accounting for 40-60% of pollutant reduction. Although the effect of lake level variations is negligible compared to pollution into the IMB, increased lake levels after 2011 improved DO levels and mixing and hence BOD levels in the IMB.

Are pit latrines in urban areas of Sub-Saharan Africa performing? A review of usage, filling, insects and odour nuisances.

BACKGROUND: A pit latrine is the most basic form of improved sanitation which is currently used by a number of people around the globe. In spite of the wide spread use, known successes and advantages associated with pit latrines, they have received little attention in form of research and development. This review focuses on the usage and performance (filling, smell and insect nuisance) of pit latrines in urban areas of sub-Saharan Africa (SSA) and proposes approaches for their improvements and sustainability. METHODS: Current pit latrine usage within urban SSA was calculated from Joint Monitoring Programme (JMP) water and sanitation country-files. We conducted a literature search and review of documents on pit latrine usage, filling, smell and insect nuisances in urban areas of SSA. Findings of the review are presented and discussed in this paper. RESULTS AND DISCUSSION: Pit latrines are in use by more than half the urban population in SSA and especially among low income earners. An additional 36 million people in urban areas of SSA have adopted the pit latrine since 2007. However, their performance is unsatisfactory. Available literature shows that contributions have been made to address shortfalls related to pit latrine use in terms of science and technological innovations. However, further research is still needed. CONCLUSION: Any technology and process management innovations to pit latrines should involve scientifically guided approaches. In addition, development, dissemination and enforcement of minimum pit latrine design standards are important while the importance of hygienic latrines should also be emphasized.

Mapping out the solid waste generation and collection models: The case of Kampala City.

This paper presents a mapping of the waste collection systems in Kampala city, using geographical information system (GIS) ArcGIS mapping software. It discusses the existing models of waste collection to the final disposal destinations. It was found that food and yard wastes constitute 92.7% of the waste generated in Kampala. Recyclables and other special wastes constitute only 7.3% of the total waste, mainly because of the increased level of reuse and recycling activities. The generation rate of solid wastes was on average, 582, 169, 105, and 90 tons/day from poor areas, upscale wealthier areas, business centers, and market areas respectively. This tonnage of waste was collected, transported, and disposed of at the city landfill. The study found that in total, residential areas of poor people generate more waste than other categories stated earlier, mainly because of their large populations. In total, there were 133 unofficial temporary storage sites acknowledged by Kampala Capital City Authority (KCCA) but not formally designated, 59 illegal dump sites, and 35 officially recognized temporary waste storage locations. This paper presents large-scale data that can help with understanding the collection models and their influence on solid waste management in Kampala city, which could be used for similar cities in developing countries.

Microbial and chemical contamination of water, sediment and soil in the Nakivubo wetland area in Kampala, Uganda.

The reuse of domestic and industrial wastewater in urban settings of the developing world may harm the health of people through direct contact or via contaminated urban agricultural products and drinking water. We assessed chemical and microbial pollutants in 23 sentinel sites along the wastewater and faecal sludge management and reuse chain of Kampala, Uganda. Water samples were examined for bacteria (thermotolerant coliforms (TTCs), Escherichia coli and Salmonella spp.) and helminth eggs. Physico-chemical parameters were determined. Water, sediment and soil samples and edible plants (yams and sugar cane) were tested for heavy metals. Water samples derived from the Nakivubo wetland showed mean concentrations of TTCs of 2.9 × 10(5) colony-forming units (CFU)/100 mL. Mean E. coli was 9.9 × 10(4) CFU/100 mL. Hookworm eggs were found in 13.5% of the water samples. Mean concentrations of iron (Fe), copper (Cu) and cadmium (Cd) were 21.5, 3.3 and 0.14 mg/L, respectively. In soil samples, we found a mean lead (Pb) concentration of 132.7 mg/L. In yams, concentrations of Cd, chromium (Cr) and Pb were 4.4, 4.0 and 0.2 mg/L, while the respective concentrations in sugar cane were 8.4, 4.3 and 0.2 mg/L. TTCs and E. coli in the water, Pb in soil, and Cd, Cr and Pb in the plants were above national thresholds. We conclude that there is considerable environmental pollution in the Nakivubo wetland and the Lake Victoria ecosystem in Kampala. Our findings have important public health implications, and we suggest that a system of sentinel surveillance is being implemented that, in turn, can guide adequate responses.

Exposure to multiple pesticides and neurobehavioral outcomes among smallholder farmers in Uganda.

BACKGROUND: Multiple epidemiological studies have shown that exposure to single pesticide active ingredients or chemical groups is associated with adverse neurobehavioral outcomes in farmers. In agriculture, exposure to multiple pesticide active ingredients is the rule, rather than exception. Therefore, occupational studies on neurobehavioral effects of pesticides should account for potential co-exposure confounding. METHODS: We conducted a cross-sectional study of 288 Ugandan smallholder farmers between September and December 2017. We collected data on self-reported use of pesticide products during the 12 months prior to survey and estimated yearly exposure-intensity scores for 14 pesticide active ingredients using a semi-quantitative exposure algorithm. We administered 11 neurobehavioral tests to assess five neurobehavioral domains. We implemented a Bayesian Model-Averaging (BMA) approach to examine the association between exposure to multiple pesticides and neurobehavioral outcomes, while accounting for multiple testing. We applied two levels of inference to determine (1) which neurobehavioral outcomes were associated with overall pesticide exposure (marginal inclusion probability (MIP) for covariate-only models <0.5) and (2) which specific pesticide active ingredients were associated with these outcomes (MIP for models where active ingredient was included >0.5). RESULTS: Seventy-two percent of farmers reported use of pesticide products that contained at least one of 14 active ingredients, while the applicators used in median three different active ingredients (interquartile range (IQR) 4) in the 12 months prior to the study. The most widely used active ingredients were glyphosate (79%), cypermethrin (60%), and mancozeb (55%). We found that overall pesticide exposure was associated with impaired visual memory (Benton Visual Retention Test (BVRT)), language (semantic verbal fluency test), perceptual-motor function (Finger tapping test), and complex attention problems (Trail making A test and digit symbol test). However, when we looked at the associations for individual active ingredients, we only observed a positive association between glyphosate exposure and impaired visual memory (-0.103 [95% Bayesian Credible Interval (BCI)] [-0.24, 0] units in BVRT scores per interquartile range (IQR) increase in annual exposure to glyphosate, relative to a median [IQR] of 6 [3] units in BVRT across the entire study population). CONCLUSIONS: We found that overall pesticide exposure was associated with several neurobehavioral outcome variables. However, when we examined individual pesticide active ingredients, we observed predominantly null associations, except for a positive association between glyphosate exposure and impaired visual memory. Additional epidemiologic studies are needed to evaluate glyphosate's neurotoxicity, while accounting for co-pollutant confounding.

Pharmaceutical pollution of water resources in Nakivubo wetlands and Lake Victoria, Kampala, Uganda.

This study investigated the occurrence and removal in wastewater and water bodies in Nakivubo wetland area and Inner Murchison Bay, Lake Victoria, of common prescription and non-prescription pharmaceutically-active substances (PhACs) sold in Kampala city, Uganda. A questionnaire was sent to 20 pharmacies in Kampala, to identify the most commonly sold PhACs in the city. During two sampling campaigns, samples were collected from Bugolobi wastewater treatment plant (WWTP) influent and effluent and surface water samples from Nakivubo channel, Nakivubo wetland and Inner Murchison Bay. The concentrations of 28 PhACs, organic matter, solids and nutrients in water samples were analysed. Ciprofloxacin (antibiotic), cetirizine (anti-allergy), metformin (anti-diabetes), metronidazole (antibiotic) and omeprazole (gastric therapy) were reported by pharmacies to be the PhACs most commonly sold in the study area. Chemical analysis of water samples revealed that trimethoprim (antibiotic) and sulfamethoxazole (antibiotic) were the dominant PhACs in water from all sites except Lake Victoria. Other PhACs such as atenolol (anti-hypertensive), carbamazepine (anti-epileptic) and diclofenac (anti-inflammatory) were also found at all study sites except Lake Victoria. ∑PhACs in effluent from Bugolobi WWTP (13000-37,600 ng L-1) was higher than in the corresponding influent (4000-28,000 ng L-1), indicating poor removal of PhACs within the WWTP. ∑PhACs decreased by a factor of 2-6 between Bugolobi WWTP effluent and Nakivubo channel (5700 ng L-1), due to dilution and sorption to channel sediment, and by a factor of 1-3 between the Nakivubo channel and Nakivubo wetland (3900-5400 ng L-1), due to sorption to sediment and uptake by plants in the wetland. No detectable levels of PhACs were found in water from Lake Victoria. Overall, this investigation demonstrated that PhACs in wastewater enter Nakivubo water system. Thus, Bugolobi WWTP needs to be upgraded to improve PhACs removal from wastewater. Considering the high occurrence of antibiotics in the water system in Kampala, development and spread of antimicrobial resistance within the area should also be investigated.

Per- and polyfluoroalkyl substances (PFASs) in water, soil and plants in wetlands and agricultural areas in Kampala, Uganda.

Occurrence and concentrations of 26 per- and polyfluoroalkyl substances (PFASs) were evaluated in wastewater, surface water, soil and crop plants (yam (Dioscorea spp.), maize (Zea mays) and sugarcane (Saccharum officinarum)) in Nakivubo wetland and Lake Victoria at Kampala, Uganda. ∑PFAS concentrations in effluent from Bugolobi wastewater treatment plant (WWTP) were higher (5.6-9.1ngL-1) than in the corresponding influent (3.4-5.1ngL-1), indicating poor removal of PFASs within the WWTP. ∑PFAS concentrations decreased by a factor of approximately five between Nakivubo channel (8.5-12ngL-1) and Lake Victoria (1.0-2.5ngL-1), due to dilution, sorption to sediment and uptake by plants in the wetland. ∑PFAS concentrations were within the range 1700-7900pgg-1 dry weight (dw) in soil and 160pgg-1 dw (maize cobs) to 380pgg-1 dw (sugarcane stems) in plants. The dominant PFASs were perfluorohexanesulfonate (PFHxS) in wastewater, perfluorooctanoate (PFOA) in surface water, perfluorooctanesulfonate (PFOS) in soil and perfluoroheptanoate (PFHpA) and PFOA in different plant tissues, reflecting PFAS-specific partitioning behaviour in different matrices. Soil-water partitioning coefficient (log Kd) in wetland soil under yam was lowest for short-chain PFHxA (1.9-2.3Lkg-1) and increased with increasing chain length to 2.8-3.1Lkg-1 for perfluoroundecanoate (PFUnDA) and 2.8-3.1Lkg-1 for perfluoroctanesulfonate (PFOS). The log Koc values ranged between 2.2 and 3.6Lkg-1, with the highest log Koc estimated for long-chain perfluorocarbon PFASs (i.e. PFUnDA 3.2-3.5Lkg-1 and PFOS 3.2-3.6Lkg-1). The concentration ratio (CR) between plants and soil was <1 for all PFASs and plant species, with the highest CR estimated for PFHpA (0.65-0.67) in sugarcane stem and PFBS (0.53-0.59) in yam root. Overall, this investigation demonstrated PFASs entry into the terrestrial food chain and drinking water resources in Kampala, Uganda. Source identification, assessment of impacts on human health and the environment, and better wastewater treatment technologies are needed.

Enhancing faecal sludge dewaterability and end-use by conditioning with sawdust and charcoal dust.

Faecal sludge (FS) treatment in urban slums of low-income countries of sub-Saharan Africa is poor or non-existent. FS contains over 90% water and therefore dewatering it within slums decreases transport costs, facilitates local treatment and end-use. This study was designed to enhance the dewatering efficiency of FS, using two locally available physical conditioners (sawdust and charcoal dust), each applied at dosages of 0%, 25%, 50%, 75%, 100% and 125% TS. The optimum dosage for both conditioners occurred at 50% and 75% for cake moisture content and capillary suction time, respectively. The dewatering rate improved by 14.3% and 15.8%, whereas dewatering extent (% cake solids) improved by 22.9% and 35.7%, for sawdust and charcoal dust, respectively. The dewatering in FS conditioned with sawdust and charcoal dust was mainly governed by absorption and permeation (porosity), respectively. The FS calorific value improved (from 11.4 MJ kg-1) by 42% and 49% with 50% TS dosage of sawdust and charcoal dust, respectively. The FS structure also became porous after dewatering which hastens the subsequent drying and/or composting processes. Due to comparable performance in dewatering, sawdust or charcoal dust, whichever is locally available, is recommended to treat FS in low-income urban slum settlements.

Health risk assessment along the wastewater and faecal sludge management and reuse chain of Kampala, Uganda: a visualization.

Reuse of wastewater in agriculture is a common feature in the developing world. While this strategy might contribute to the livelihood of farming communities, there are health risks associated with the management and reuse of wastewater and faecal sludge. We visualise here an assessment of health risks along the major wastewater channel in Kampala, Uganda. The visualization brings to bear the context of wastewater reuse activities in the Nakivubo wetlands and emphasises interconnections to disease transmission pathways. The contextual features are complemented with findings from environmental sampling and a cross-sectional epidemiological survey in selected exposure groups. Our documentation can serve as a case study for a step-by-step implementation of risk assessment and management as described in the World Health Organization's 2006 guidelines for the safe use of wastewater, greywater and excreta in light of the forthcoming sanitation safety planning approach.