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.

Seasonal variations and shared latrine cleaning practices in the slums of Kampala city, Uganda.

BACKGROUND: The effect of seasons on health outcomes is a reflection on the status of public health and the state of development in a given society. Evidence shows that in Sub-Saharan Africa, most infectious diseases flourish during the wet months of the year; while human activities in a context of constrained choices in life exacerbate the effects of seasons on human health. The paper argues that, the wet season and when human activities are at their peak, sanitation is most dire poor slum populations. METHODS: A shared latrine cleaning observation was undertaken over a period of 6 months in the slums of Kampala city. Data was collected through facility observations, user group meetings, Focus group discussions and, key informant interviews. The photos of the observed sanitation facilities were taken and assessed for facility cleanliness or dirt. Shared latrine pictures, observations, Focus Group Discussion, community meetings and key informant interviews were analysed and subjected to an analysis over the wet, dry and human activity cycles before a facility was categorised as either 'dirty' or 'clean'. RESULTS: Human activity cycles also referred to as socio-economic seasons were, school days, holidays, weekends and market days. These have been called 'impure' seasons, while the 'pure' seasons were the wet and dry months: improved and unimproved facilities were negatively affected by the wet seasons and the peak seasons of human activity. Wet seasons were associated with, mud and stagnant water, flooding pits and a repugnant smell from the latrine cubicle which made cleaning difficult. During the dry season, latrines became relatively cleaner than during the wet season. The presence of many child(ren) users during school days as well as the influx of market goers for the roadside weekly markets compromised the cleaning outcomes for these shared sanitation facilities. CONCLUSION: Shared latrine cleaning in slums is impacted by seasonal variations related to weather conditions and human activity. The wet seasons made the already bad sanitation situation worse. The seasonal fluctuations in the state of shared slum sanitation relate to a wider malaise in the population and an implied capacity deficit among urban authorities. Poor sanitation in slums is part of a broader urban mismanagement conundrum pointing towards the urgent need for multiple interventions aimed at improving the general urban living conditions well beyond sanitation.

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.

Gender variations in access, choice to use and cleaning of shared latrines; experiences from Kampala Slums, Uganda.

BACKGROUND: Sanitation is one of the most intimate issues that affect women, especially in slums of developing countries. There are few studies that have paid attention to the gender variations in access, choice to use and cleaning of shared latrines in slums. METHODS: This paper draws on qualitative data from a cross sectional study conducted between 2012 and 2013 in six slums of Kampala City, Uganda. The study involved both women and men. Data were collected from 12 Focus Group Discussions (FGDs), 15 Key informant interviews; community transects and photographs of shared latrines. RESULTS: Location of a shared latrine facility, distance, filthy, narrow and irregular paths; the time when a facility is visited (day or night), privacy and steep inclines were gender 'filters' to accessing shared latrines. A full latrine pit was more likely to inhibit access to and choice of a facility for women than men. Results indicate that the available coping mechanisms turned out to be gendered, with fewer options available for women than men. On the whole, women sought for privacy, easy reach, self-respect and esteem, cleanliness and privacy than men. While men like women also wanted clean facilities for use; they (men) were not keen on cleaning these facilities. The cleaning of shared latrines was seen by both women and men as a role for women. CONCLUSION: The presence of sanitation facilities as the first step in the access, choice, use, and cleaning by both women and men has distinct motivations and limitations along gender lines. The study confirms that the use and cleaning of latrines is regulated by gender in daily living. Using a latrine for women was much more than relieving oneself: it involved security, intimacy and health concerns.

Descending the sanitation ladder in urban Uganda: evidence from Kampala Slums.

BACKGROUND: While the sanitation ladder is useful in analysing progressive improvements in sanitation, studies in Uganda have not indicated the sanitation barriers faced by the urban poor. There are various challenges in shared latrine use, cleaning and maintenance. Results from Kampala city indicate that, failure to clean and maintain sanitation infrastructure can lead to a reversal of the potential benefits that come with various sanitation facilities. METHODS: A cross sectional qualitative study was conducted between March and May 2013. Data were collected through 18 focus group discussions (FGDs) held separately; one with women, men and youth respectively. We also used pictorial methods; in addition, 16 key informant interviews were conducted. Data were analysed using content thematic approach. Relevant quotations per thematic area were identified and have been used in the presentation of the results. RESULTS: Whether a shared sanitation facility was improved or not, it was abandoned once it was not properly used and cleaned. The problem of using shared latrines began with the lack of proper latrine training when people do not know how to squat on the latrine hole. The constrained access and security concerns, obscure paths that were filthy especially at night, lack of light in the latrine cubicle, raised latrines sometimes up to two metres above the ground, coupled with lack of cleaning and emptying the shared facilities only made a bad situation worse. In this way, open defecation gradually substituted use of the available sanitation facilities. This paper argues that, filthy latrines have the same net effect as crude open defection. CONCLUSION: Whereas most sanitation campaigns are geared towards provision of improved sanitation infrastructure, these findings show that mere provision of infrastructure (improved or not) without adequate emphasis on proper use, cleaning and maintenance triggers an involuntary descent off the sanitation ladder. Understanding this reversal movement is critical in sustainable sanitation services and should be a concern for all actors.

Sanitation facilities in Kampala slums, Uganda: users' satisfaction and determinant factors.

Access to improved sanitation is a key preventive measure against sanitary-related gastro-enteric diseases such as diarrhoea. We assessed the access to sanitation facilities and users' satisfaction in 50 randomly selected slums of Kampala through a cross-sectional survey conducted in 2010. A total of 1500 household respondents were interviewed. Sixty-eight per cent of the respondents used shared toilets, 20% private, 11% public toilets and less than 1% reported using flying toilets or practising open defecation. More than half of the respondents (51.7%) were not satisfied with their sanitation facilities. Determinants for satisfaction with the facilities used included the nature and type of toilet facilities used, their cleanliness, and the number of families sharing them. The study findings showed that slum dwellers had high access to sanitation facilities. However, most of them were shared and majority of the respondents were not satisfied with their facilities, primarily due to cleanliness and over demand.

Ecological sanitation coverage and factors affecting its uptake in Kabale municipality, western Uganda.

Ecological sanitation (Ecosan) is a relatively new concept being promoted in many developing countries to improve sanitation coverage and recycle nutrients in excreta for agricultural production. We conducted a cross-sectional study in Kabale municipality, western Uganda to determine the coverage of Ecosan and factors affecting its uptake. A total of 806 respondents were interviewed, randomly selected from 32 of 77 (42%) villages in Kabale municipality. We held six focus group discussions and 10 key informant interviews. Ecosan coverage was found to be 20% (163/806). The factors that were significantly associated with Ecosan coverage included education, occupation, religion and age. Our study found a relatively high Ecosan coverage in Kabale municipality compared to the targeted national coverage of 15% by 2018. Policy-makers and organizations in Ecosan development ought to take into consideration the influence of education and socio-economic factors for successful uptake of ecological sanitation.

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.

Attitudes of food consumers at universities towards recycling human urine as crop fertiliser: A multinational survey dataset.

We present here a data set generated from a multinational survey on opinions of university community members on the prospect of consuming food grown with human urine as fertiliser and about their urine recycling perceptions in general. The data set comprises answers from 3,763 university community members (students, faculty/researchers, and staff) from 20 universities in 16 countries and includes demographic variables (age bracket, gender, type of settlement of origin, academic discipline, and role in the university). Questions were designed based on Ajzen's theory of planned behaviour to elicit information about three components of behavioural intention-attitudes, subjective norms, and perceived behavioural control. Survey questions covered perceived risks and benefits (attitudes), perceptions of colleagues (injunctive social norm) and willingness to consume food grown with cow urine/faeces (descriptive social norm), and willingness to pay a price premium for food grown with human urine as fertiliser (perceived behavioural control). We also included a question about acceptable urine recycling and disposal options and assessed general environmental outlook via the 15-item revised New Ecological Paradigm (NEP) scale. Data were collected through a standardised survey instrument translated into the relevant languages and then administered via an online form. Invitations to the survey were sent by email to university mailing lists or to a systematic sample of the university directory. Only a few studies on attitudes towards using human urine as fertiliser have been conducted previously. The data described here, which we analysed in "Willingness among food consumers at universities to recycle human urine as crop fertiliser: Evidence from a multinational survey" [1], may be used to further understand potential barriers to acceptance of new sanitation systems based on wastewater source separation and urine recycling and can help inform the design of future sociological studies.

Willingness among food consumers to recycle human urine as crop fertiliser: Evidence from a multinational survey.

Source-separating sanitation systems offer the possibility of recycling nutrients present in wastewater as crop fertilisers. Thereby, they can reduce agriculture's impacts on global sources, sinks, and cycles for nitrogen and phosphorous, as well as their associated environmental costs. However, it has been broadly assumed that people would be reluctant to perform the new sanitation behaviours that are necessary for implementing such systems in practice. Yet, few studies have tried to systematically gather evidence in support of this assumption. To address this gap, we surveyed 3763 people at 20 universities in 16 countries using a standardised questionnaire. We identified and systematically assessed cross-cultural and country-level explanatory factors that were strongly associated with people's willingness to consume food grown using human urine as fertiliser. Overall, 68% of the respondents favoured recycling human urine, 59% stated a willingness to eat urine-fertilised food, and only 11% believed that urine posed health risks that could not be mitigated by treatment. Most people did not expect to pay less for urine-fertilised food, but only 15% were willing to pay a price premium. Consumer perceptions were found to differ greatly by country and the strongest predictive factors for acceptance overall were cognitive factors (perceptions of risks and benefits) and social norms. Increasing awareness and building trust among consumers about the effectiveness of new sanitation systems via cognitive and normative messaging can help increase acceptance. Based on our findings, we believe that in many countries, acceptance by food consumers will not be the major social barrier to closing the loop on human urine. That a potential market exists for urine-fertilised food, however, needs to be communicated to other stakeholders in the sanitation service chain.

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.

Comparative Analysis of Pesticide Use Determinants Among Smallholder Farmers From Costa Rica and Uganda.

Pesticides are used globally in agriculture and pose a threat to the health of farmers, communities, and the environment. Smallholder farmers in low- and middle-income countries have generally a low socio-economic status and educational level. Consequently, they are particularly vulnerable to negative impacts of pesticides on their health, yields, or land. In a Knowledge, Attitude, and Practices study, we compared the pest management practices between a market-oriented farming system in Zarcero County, Costa Rica, and a subsistence-based farming system in Wakiso District, Uganda. We conducted a cross-sectional survey among smallholder farmers from Costa Rica (n = 300) in 2016 and from Uganda (n = 302) in 2017. We enrolled conventional and organic farmers, but also farmers with mixed practices and non-applicators of any pest management strategy. We found that the majority of pesticides used in both case studies are classified as highly hazardous by the World Health Organization. While more than 90% of smallholder farmers from both countries were aware of the negative health effects of pesticide exposure, <11% in Costa Rica and <2% in Uganda reported using personal protective equipment every time they handled or applied pesticides. Hygiene and other safe use practices were not adopted by all farmers (<61%), especially among farmers applying more hazardous pesticides. Conventional farmers from Costa Rica (14%) and Uganda (19%) reported disposing pesticide residuals into rivers. Using a logistic regression we found that organic farmers were more likely to having been trained on safe pesticide use practices. Using a robust regression, we observed that smallholder household income was primarily driven by education and not directly by the use of synthetic pesticides. Our results suggest that negative effects of pesticides can be managed over the whole life cycle, from purchase, via storage and application to residual and waste management by fostering professionalization of farmers. We advise future safe use and handling interventions to consider the pesticide use-related socioeconomic and demographic findings highlighted in this paper.

Inactivation of bacteria and viruses in human urine depending on temperature and dilution rate.

Source separation and reuse of human urine can decrease the environmental pollution of recipient waters and reduce the need for artificial mineral fertilisers. However, the reuse of urine introduces another pathogen transmission route that needs to be managed. The inactivation of enteric pathogens and model organisms (Salmonella enterica subspecies 1 serovar Typhimurium (S. typhimurium), Enterococcus faecalis, bacteriophages S. typhimurium 28B, MS2 and Phi x 174) by urine storage was studied at dilutions (urine:water) 1:0, 1:1 and 1:3 at temperatures 4, 14, 24 and 34 degrees C. A threshold concentration of ammonia was found at approximately 40 mM NH(3) (e.g. 2.1 g NH(3)-NL(-1) and pH 8.9 at 24 degrees C), below which all studied organisms, except Salmonella, persisted considerably longer irrespective of treatment temperature, showing that urine dilution rate is of great importance for pathogen inactivation. For Salmonella spp. no threshold level was found in these studies (15 mM NH(3) lowest concentration studied). At temperatures below 20 degrees C, bacteriophage reduction was very slow. Therefore, urine stored at temperatures below 20 degrees C carries a high risk of containing viable viruses. The study indicated that the current recommended storage time for urine of 6 months at 20 degrees C or higher is safe for unrestricted use and could probably be shortened, especially for undiluted urine.

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.