Discover Water最新文献

Sulfolane is a worldwide water-soluble pollutant, which typically migrates rapidly in impacted aquifers, with risks to water bodies and drinking water wells. Sulfolane migration may be delayed in sites co-polluted by hydrocarbons, which move more slowly and in which sulfolane partitions. However, when bacteria such as Pseudomonas aeruginosa aerobically biodegrade hydrocarbons and sulfolane, they generate biosurfactants (such as rhamnolipids). These enclose sulfolane within micelles and droplets, as seen by optical microscopy, and hamper its partitioning into hydrocarbons, as shown by Fourier transform infrared spectroscopy. Therefore, biosurfactants have the potential to accelerate sulfolane migration in groundwater, compared to scenarios where biosurfactant-producing bacteria are absent. These findings will aid safe management of impacted sites, where aerobic bacterial bioremediation is used for pollutant clean-up. When aerobic bacterial activity is promoted to enable pollutant biodegradation, sulfolane migration may accelerate before clean-up is complete, begging for careful monitoring of pollutant plumes.

Graphical abstract:

Water insecurity, driven by urbanization, population growth, land use and climate change, poses a global challenge. This study examines water supply and demand trends in the Mbagathi-Stony Athi sub-catchments, highlighting urbanization's impact in a semi-arid context. Using GIS, and the WEAP model, various scenarios were simulated. Results show annual rainfall increased insignificantly (p = 0.61) from 1981 to 2019. By 2063, rainfall is projected to rise by 12.43% (RCP 4.5) and 21.02% (RCP 8.5). Mean temperature increased by 0.88 °C (1981-2019) and is projected to rise by 1.70 °C (RCP 4.5) and 1.75 °C (RCP 8.5) by 2063. Land use analysis (2000-2019) showed a 53.67% increase in built-up areas and a 99.32% decline in wetlands. Between 2000 and 2019, the annual supply, demand, and unmet demand increased by 171.64%, 147.56%, and 73%, respectively. Land use changes between 2000 and 2019, particularly the increase in shrublands and decline in bare land, contributed to a 25.51% decrease in surface runoff and a 3.55% rise in total annual evapotranspiration. Future projections indicate surface runoff decreases of up to 4.47% under RCP 4.5 and increases of 9.38% under RCP 8.5. Potential evapotranspiration is projected to rise by 23.39% (reference), 16.44% (RCP 4.5), and 11.19% (RCP 8.5). Water demand will increase across all scenarios, peaking at 184% under high urbanization, while unmet demand will rise by up to 162.47% under irrigation expansion. Water scarcity is expected to worsen due to climate change, population growth, and land use shifts. These findings inform sustainable water resource management in development corridors.

Greywater reuse in households and off-grid applications is growing in response to water scarcity. Effective treatment technologies must balance water quality, efficiency, and low energy or chemical inputs. This study presents a low-energy, non-biological greywater treatment system using foam fractionation and in situ electrochlorination, leveraging ambient chloride in greywater. Designed for handwashing stations and household reuse, the system treats up to 450 L day^- 1 using < 1 kWh day^- 1 of energy with no chemical dosing. Among six screened physical-chemical processes, foam fractionation was the only method achieving > 80% COD removal with high water recovery. Smaller diffuser pore sizes and lower air flowrates improved COD removal by increasing bubble surface area, though at the cost of water recovery. Pulsed aeration improved water recovery by ~ 20% with minimal COD performance loss. Surfactant behavior, correlated with the critical micelle concentration (CMC), strongly influenced foam stability and COD removal. Both free and combined chlorine residuals were successfully generated via in situ electrochlorination, using only the chloride ions naturally present in greywater. In situ electrochlorination following foam treatment generated up to 0.53 mg L^- 1 of residual chlorine. Foam fractionation with small-pore diffusers removed surfactants and other compounds that inhibit chlorine generation, such as CAPB, SDS, and anions, improving disinfection outcomes. The system achieved > 70% COD removal and > 80% water recovery. This integrated, chemical-free system provides a promising solution for decentralized greywater reuse. With further optimization, it may consistently achieve < 50 mg L^- 1 COD and adequate disinfection, supporting sustainable hygiene in low-resource settings.

Supplementary information: The online version contains supplementary material available at 10.1007/s43832-025-00295-x.