This study focused on designing a drinking water systems sustainability index for Integrated Water Resources Management in low-income countries. Water Supply Systems Sustainability Index (WSSI), a field assessment tool, was designed for rapid appraisal of drinking water systems in selected urban, peri-urban and rural Nigerian communities. The systems were classified into Highly Sustainable, Sustainable, Averagely Sustainable, and Unsustainable WSSI categories. Sanitary Risk Score (SRS) was assigned, classifying drinking water systems into Very High, High, Intermediate (Medium) and Low-Risk categories. WSSI results revealed that for urban systems, 90 are Highly Sustainable, 27 are Sustainable and 12 are Averagely Sustainable. For peri-urban systems, 13 are Highly Sustainable, 7 Sustainable and 1 Averagely Sustainable. Only urban hand-dug wells are in the Very High-Risk category. Public water supplies occurred only in the Low-Risk (17) and Intermediate-Risk (6) categories. Urban and rural boreholes had better quality than peri-urban boreholes. WSSI and SRS correlation result indicated strong positive correlation for urban hand-dug wells' (R2 = 0.5688, at p < 0.05) and weak positive correlation between peri-urban hand-dug wells' (R2 = 0.1847, at p < 0.05) and urban boreholes' WSSI and SRS (R2 = 0.2032, at p < 0.05). Findings showed that drinking water systems are, generally, sustainable and WSSI could be incorporated into community-level water supply assessment.
Water security, as a sustainable development goal, ensures that sustainable water supply is consistently available to every individual. A water supply systems assessment matrix was designed as a tool for assessing water supply systems (WSS) in low-income countries; with selected urban, peri-urban, and rural Nigerian communities as case studies. Sustainability of the WSS was assessed through established criteria against five sustainability factors. Sanitary surveys were conducted to evaluate the risks associated with the WSS using Sanitary Inspection Forms through which the Sanitary Risk Scores (SRS) were derived. For sustainability, the WSS were ranked as Very High, High, Medium and Low Sustainability, and for SRS as Very High, High, Intermediate and Low Risk. A Sustainability and Risk Assessment Matrix (SRAM) was designed using sustainability evaluation and risk assessment for the WSS. The WSS in the rural areas are more ‘Secure’ than those in urban and peri-urban towns, and boreholes are more ‘Secure’ than hand-dug wells, but none of the public water point is scored ‘Secure’. The paper concludes that SRAM provides a cost-effective method of classification and may serve as a pre-water quality and source sustainability assessment tool, especially in low-income countries, as part of the measures to achieve water security.
The risk assessment of drinking-water supply systems in Ogun State, Nigeria, was carried out using the failure mode effects and criticality analysis (FMECA) approach.The FMECA is a systemic process that identifies potentials failure modes within a system and was chosen for its causes and effect approach to assessing risks. The objective of the study was to assess drinking-water supply systems and identify water supply systems' risks from source to point-of-use. Three major water supply sources were selected for assessment: hand-dug wells, boreholes and public water supply sources. The sources were assessed by identifying the potential failure modes that exist within the water supply sources and the consequence of the identified risks on relevant stakeholders. The sources were divided into modules. The risk in each module was determined by multiplying failure rate (likelihood) and consequences of failure of the module. Risk reduction options include repair and maintenance measures, information dissemination on the procedures to reduce the identified risks and preventive and regulatory approaches. The resulting risks were characterized using FMECA risk matrix of each water source and classified into high, medium and low risks. Well cover and lining were the most risk-prone modules for hand-dug wells (high and medium risks). Broken well cover and lining serve as pathways to contaminants into the well. Casing and screen modules posed the highest risk for boreholes, recording high to medium risk. Cracked casing and broken screen provide access for contamination into boreholes. The module with the greatest risk for public water supply source was the point-of-abstraction/use module. Unsanitary containers and poor storage conditions is believed to be responsible for recontamination of the treated water Climate variability, environmental and anthropogenic influences were observed to be responsible for most of the identified risks. The study highlights that consumer participation is vital in ensuring the availability of safe drinking-water, stressing consumer education as the most important channel. The study recommends the use of FMECA to ensure implementing preventive and regulatory measures by water monitoring agencies and for water resources planning and policy making.
The study examined the water supply situation in Abeokuta, with emphasis on the quality of water distributed by the Ogun State Water Corporation from the treatment plant of the Abeokuta Water Scheme. Water samples were collected from standpipes (taps) across the city randomly selected using the stratified random sampling method and was analysed for physical and chemical parameters: pH, total dissolved solids (TDS), electrical conductivity (EC), total alkalinity, total hardness, calcium, magnesium, potassium, sodium, nitrate, bicarbonate, sulphate and chloride. The result of the physical and chemical parameters was subjected to statistical analyses using the multivariate t-test. The result of the treated water was further compared with the result of the analyses of raw water obtained from the source of water used in the treatment plant.
Low-cost and easily accessible sludge treatment technologies are necessary in low- and middle-income countries. This study aimed to evaluate the use of Moringa oleifera seed powder (MO) as a natural sludge conditioner for supernatant quality improvement prior to thickening as a result of gravity settling. The zone settling rate (ZSR) and sludge volume index (SVI) were used to evaluate the gravity settling capacity. Supernatant clarification was evaluated in terms of the capacity to remove turbidity, apparent colour, Escherichia coli, and organic matter associated with zeta potential evolution. The effects on the values of pH and electrical conductivity were also evaluated. Finally, the effects on the toxicity (chronic and acute) of the supernatant effluent were examined. A significant supernatant quality improvement was observed with the addition of MO. The ZSR (0.16 cm/min) and SVI (53 mL/g) results showed that the sludge had good sedimentability, and the addition of MO maintained these characteristics in a statistical manner. Increasing the MO dosage increased the zeta potential of the supernatant, resulting in an optimal dosage of 1.2 g/L, with a removal of 90% turbidity, 70% apparent colour, 99% E. coli, and 40% organic matter. The pH and electrical conductivity values did not change with increasing MO dosage, which is a competitive advantage of MO addition compared to iron and aluminium salt addition. A reduction in the ability to remove organic matter was observed at higher dosages of the natural coagulant due to the presence of residual MO in the final effluent. The optimal MO dosage of 1.2 g/L did not affect the acute or chronic toxicity of the supernatant. These results emphasized that M. oleifera seed powder can improve the supernatant quality and can potentially be a low-cost and easily accessible conditioner for wastewater sludge thickening.
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