Evolution of water quality in rainwater harvesting systems during long-term storage in non-rainy seasons

Assessing the Influence of Hand-Dug Well Features and Management on Water Quality

Underground water quality can be affected by natural or human-made influences. This study investigates how the management and characteristics of hand-dug wells impact water quality in 3 suburbs of Kumasi, Ghana, using a combination of qualitative and quantitative research methods. Descriptive analysis, including frequency and percentages, depicted the demographic profiles of respondents. Box plot diagrams illustrated the distribution of physicochemical parameters (Total Dissolved Solid [TDS], Electrical Conductivity [EC], Turbidity, Dissolved Oxygen [DO], and Temperature). Factor analysis evaluated dominant factors among these parameters. Cluster analysis (hierarchical clustering) utilized sampling points as variables to establish spatial variations in water physicochemical parameters. Cramer's V correlation test explored relationships between demographic variables and individual perceptions of water management. One-way ANOVA verified significant mean differences among the physicochemical parameters. Logistic regression models assessed the influence of selected well features (e.g., cover and apron) on TDS, pH, Temperature, Turbidity, and DO. The findings revealed that proximity to human settlements affects water quality, and increasing turbidity is associated with unmaintained covers, significantly impacting water quality (P < .05). Over 80% of wells were located within 10 to 30 m of pollution sources, with 65.63% situated in lower ground and 87.5% being unmaintained. Other significant contamination sources included plastic bucket/rope usage (87.50%), defective linings (75%), and apron fissures (59.37%). Presence of E. coli, Total coliform, and Faecal coliform rendered the wells unpotable. Factor analysis attributed 90.85% of time-based and spatial differences to organic particle decomposition factors. However, Cramer's V correlation analysis found establishing association between demographic factor associations with individual perceptions of hand-dug well management difficult. It is encouraged to promote hand-dug well construction and maintenance standards to ensure that wells are properly built and protected from contamination sources.

Identifying potential uses for green roof discharge based on its physical-chemical-microbiological quality

Green roofs are promising tools in sustainable urban planning, offering benefits such as stormwater management, energy savings, aesthetic appeal, and recreational spaces. They play a crucial role in creating sustainable and resilient cities, providing both environmental and economic advantages. Despite these benefits, concerns persist about their impact on water quality, especially for non-potable use, as conflicting results are found in the literature. This study presents a comparative analysis of the quantity and quality of water drained from an extensive green roof against an adjacent conventional rooftop made of fiber-cement tiles in subtropical Brazil. Over a 14-month period, the water drained from both roofs was evaluated based on physical (turbidity, apparent color, true color, electrical conductivity, total solids, total dissolved solids, suspended solids), chemical (pH, phosphate, total nitrogen, nitrate, nitrite, chlorides, sulfates, and BOD), microbiological (total coliforms and E. coli), and metal (copper, iron, zinc, lead, and chrome) concentration parameters. The discharge from the green roof was 40% lower than its counterpart measured at the control roof, while the water quality from both roofs was quite similar. However, the green roof acted as source of chlorides, electrical conductivity, color, BOD, total hardness, E. coli, phosphate, sulfate, and turbidity. On the other side, the green roof neutralized the slightly acidic character of rainwater, showcasing its potential to mitigate the effects of acid rain. The study's results underscored that the water discharged from the green roof generally aligned with non-potable standards mandated by both Brazilian and international regulations. However, the findings emphasized the imperative need for pre-treatment of the green roof discharge before its utilization, specifically adjusting parameters like turbidity, BOD, total coliforms, and E. coli, which were identified as crucial to ensure water safety and compliance with non-potable use standards.

Advancing rainwater treatment technologies for irrigation of urban agriculture: A pathway toward innovation

Urban agriculture (UA) has emerged for local food security since the 1960s. However, the access to sufficient and safe irrigation water remains a significant constraint. Municipal water supply, though commonly used in UA practices, proves unsustainable due to high costs, intensive energy consumption, and limited availability in many vacant urban spaces. In contrast, rainwater harvesting (RWH) exhibits a potential as a non-traditional water supply for urban farming. This article aims to provide insights into the advantages and challenges associated with RWH for UA irrigation, analyze existing low-cost RWH treatment technologies, and identify a visionary way toward innovative, new-generation RWH treatment processes in UA practices. Despite a promising water source, harvested rainwater is challenged for crop irrigation owing to the presence of various contaminants (e.g., waterborne pathogens, potentially toxic metals and metalloids, and synthetic organic chemicals). While established RWH treatment processes (e.g., first flush diversion, sedimentation, solar disinfection, chlorination, UV irradiation, granular filtration, and bio-sand filtration) can remove certain pollutants, they cannot offer viable treatment solutions for UA irrigation due to different technical, economic, and social restrictions. Particularly, their capacity to reliably remove contaminants of emerging concern in runoff remains limited or uncertain. Consequently, it is essential to develop next-generation RWH treatment technologies tailored specifically for UA irrigation. To this end, three fundamental principles are recommended. First, the focus should be on technically viable, low-cost, simple-operation, and easy-maintenance treatment technologies capable of simultaneously addressing traditional and emerging runoff contaminants, while minimizing the production of undesirable treatment byproducts. Second, advancing the understanding of the water, soil, and crop interactions enables the development of "right" RWH treatment processes for irrigation of "right" crops at a "right" place. Last, crop nutrients, if possible, are retained in rainwater to reduce the nutrient demand for crop production. The insights and perspectives have far-reaching implications for water conservation, stormwater management, and the integration of water, food, and energy systems within the urban environment.