Frank Kansiime

Natural wetlands are critical water quality regulators, especially in developing tropical countries. The Lubigi wetland is a large urban wetland in Kampala, the largest city in Uganda in Africa. We studied whether stormwater discharge and wastewater effluent from a nearby stormwater channel and a sewage treatment plant in the western part of the city were cleaned as they flowed through the wetland. Despite the significant pollution, the wetland removed ammonium-nitrogen, orthophosphate, and particulate nutrients during both seasons, achieving removal rates ranging from 50 to 60% for orthophosphate but only 20–40% for ammonium-nitrogen. Overall, seasonal differences in loads and retention rates of nutrient and organic matter inputs were minimal. Interestingly, the wetland mostly released nitrate and nitrite during water passage through the wetland, most likely due to the mineralization of organic nitrogen and agricultural run-off during rainy events in the wet season. However, the limited capacity of the sewage treatment plant and untreated stormwater discharge from the Nsooba main channel reduced the wetland’s ability to clean water. The insufficient carrying capacity of the treatment plant and the release of untreated sewage into the wetland significantly impact the self-purification capacity of the Lubigi wetland. Thus, the concept of Nature-Based Solutions is ineffective if the wetland systems are overloaded.

Aquaculture generates substantial amount of residual feeds and faecal matter that accumulate in the culture environment and pollute effluent-receiving water, diminishing its ecological functioning. To devise means of treating nutrient-rich aquaculture wastewater, the efficiency of integrated papyrus-bivalve mesocosms in removing nutrients was evaluated. The mesocosms were fed on water (6600 L) from one brood-stock pond and allowed to settle for 2 weeks. Physico-chemical parameters, including nutrient level in influent and effluent of mesocosms, were analysed fortnightly using standard methods. The integrated papyrus-bivalve mesocosms had the highest removal of 69.5, 52.9, and 70.5% for total nitrogen (TN), total phosphorus (TP), and total dissolved solids (TDS), respectively, from the aquaculture wastewater. The removal efficiency of TN and TDS by the mesocosms followed the order: integrated papyrus-bivalve ˃ papyrus ˃ bivalves ˃ control, and removal efficiency for TP followed a similar trend, albeit integrated papyrus-bivalve≈papyrus. The nutrient retention (g/DMm²) in papyrus biomass was 24.09 and 2.93 in integrated papyrus-bivalve mesocosm and 20.77 and 3.81 in papyrus mesocosms for nitrogen and phosphorus, respectively. Meanwhile, the nutrient retention in bivalve biomass was 3.06 and 0.44 in integrated papyrus-bivalve and 1.95 and 0.34 in bivalve mesocosm, for nitrogen and phosphorus, respectively. The study confirms the synergistic functionality of papyrus and bivalves in treating aquaculture wastewater. Papyrus and bivalves in the mesocosms contributed to the bioremediation of wastewater through physical and biochemical processes, including filtration, nutrient uptake, and attachment surfaces for microorganisms. Therefore, we recommend integrated papyrus-bivalve bioremediation technology to fish farmers and policy makers.

Indiscriminate expansion of agricultural activities into wetlands affects the sustainability of wetland-dependent livelihoods. Systems research is an important tool for identifying and dealing with the underlying drivers of wetland degradation; however, there is limited research employing system tools in Sub-Saharan Africa. This research employed causal loop diagrams and system archetypes to characterize common wetland resource systems in Sub-Saharan Africa, using the wetland agricultural system of Uganda as a case study. Mental models of wetland users were indirectly elicited by interviewing 66 wetland users. Causal loop diagrams were generated to illustrate the multiple, interdependent feedback linkages within the system. The case study wetland is mainly used for farming (40%), vegetation harvesting (26%), and fishing (24%), while other activities like hunting and grazing are carried out by 10% of wetland users. A reinforcing feedback loop was dominant, illustrating how initial encroachment on the wetland to meet livelihood needs can accelerate further encroachment. Based on the dominant loop and current interventions, we characterized the system using three archetypes: tragedy of the commons, shifting the burden, and fixes that fail. A two-pronged approach was proposed, where solutions for decelerating wetland degradation, like restoration activities, can be implemented in the short term while planning long-term measures that take into account the need for alternative livelihoods for wetland-dependent communities and targeting a paradigm shift through continuous sensitization of stakeholders on the benefits of sustainable wetland management.

Socio-institutional factors are poorly addressed in the risk assessment of groundwater contamination. This paper contributes to the development of a socio-institutional assessment framework based on a case study of contamination by on-site sanitation (OSS) in an informal settlement of Bwaise (Kampala, Uganda). We conducted a snapshot survey of the recent extent of groundwater contamination by OSS using microbial and hydro-chemical indicators. Through transition arenas and key informant interviews, we investigated the socio-institutional drivers of the contamination. Overall, 14 out of the 17 sampled groundwater sources tested positive for Escherichia coli during the wet season. Nitrate concentrations at four sources exceeded the World Health Organization guideline value (50 mg/L), attributed to OSS. Despite the high contamination, the community highly valued groundwater as an alternative to the intermittent municipal water supply. We deduced six drivers of groundwater contamination, including land-use management, user attributes, governance, infrastructure management, groundwater valuation, and the operating environment (“LUGIVE”). Qualitative indicators for each of the drivers were also construed, and their interlinkages presented in a causal loop diagram, representing a socio-institutional assessment framework. The framework can help policymakers and the community to analyze various socio-institutional control levers to reduce the risk of groundwater contamination by OSS in informal settlements.

The impact of different vegetation communities on soil organic carbon (SOC) in a tropical freshwater wetland in Uganda was investigated. SOC content, density and storage potential were determined u...

Sanitation infrastructure are not able to cope with the increasing population in low-income countries, which leaves populations exposed to faecal contamination from multiple pathways. This study evaluated public health risk (using SaniPath) in a low-income community during the dry season, to identify the dominant exposure pathways, and compare this data to existing data for the rainy season, questioning the assumption that risk of faecal contamination is higher in the rainy season. SaniPath was used to collect and assess exposure and environmental data, and to generate risk profiles for each pathway. In the dry season the highest exposure frequency was for bathing and street food, exposure frequency generally increased, and seasonal variation was found in five pathways. The highest hazards in the dry season were through contact with drains, soil, and street food. Seasonal variation was found in the contamination of open drains and street food, with higher levels of Escherichia coli (E. coli) in the dry season. Open drains were identified as the most dominant risk pathway in both seasons, but risk was higher in the dry season. This highlights the complex nature of seasonal variation of faecal risk, and questions the assumption that risk is higher in the rainy season.

High urbanization in Sub-Saharan Africa (SSA) has resulted in increased peri-urban groundwater contamination by on-site sanitation. The World Health Organization introduced Water Safety Plans (WSP) towards the elimination of contamination risks to water supply systems; however, their application to peri-urban groundwater sources has been limited. Focusing on Uganda, Ghana, and Tanzania, this paper reviews limitations of the existing water regime in addressing peri-urban groundwater contamination through WSPs and normative attributes of Transition Management (TM) towards a sustainable solution. Microbial and nutrient contamination remain prevalent hazards in peri-urban SSA, arising from on-site sanitation within a water regime following Integrated Water Resources Management (IWRM) principles. Limitations to implementation of WSPs for peri-urban groundwater protection include policy diversity, with low focus on groundwater; institutional incoherence; highly techno-centric management tools; and limited regard for socio-cultural and urban-poor aspects. In contrast, TM postulates a prescriptive approach promoted by community-led frontrunners, with flexible and multi-domain actors, experimenting through socio-technical tools towards a shared vision. Thus, a unified risk-based management framework, harnessing attributes of TM and IWRM, is proposed towards improved WSP implementation. The framework could assist peri-urban communities and policymakers in formulating sustainable strategies to reduce groundwater contamination, thereby contributing to improved access to safe water.