Cleaner Water最新文献

Carbon-based adsorbents with abundant resources, environmental friendliness, and sufficient adsorption sites have broad application prospects for efficient removal of Chromium (Cr(VI)) in aquatic environment. Pursuing a heavy metal adsorption material and advancing it from the laboratory to the actual water environment are of great importance. Herein, we developed a general synthesis strategy for large-scale preparation of N-doped microporous-dominated carbon-based adsorbents (NC-s) via a direct pyrolysis process of ethylene diamine tetraacetic acid tetrasodium. The NC-s samples had abundant microporous, different nitrogen configurations and large specific surface area (503 m² g⁻¹). Due to these advantages, the NC sample prepared at 800 °C (NC-800) possessed high adsorption capacity toward Cr(VI) (167.3 mg g⁻¹) toward Cr(VI), fast adsorption process (180 min), and good reusability. Through specific experiments and density functional theory (DFT) calculations, we proposed that the adsorption mechanism of NC-s samples was primarily determined by the ion exchange/electrostatic attraction-reduction-complexation synergy, and the mechanism included adsorption-reduction of Cr(VI) and immobilization of Cr(III). Graphitic-N and pyridinic-N adsorbed Cr(VI) in solution mainly by electrostatic attraction, while pyrrolic-N mainly reduced the toxicity primarily by reducing Cr(VI) to Cr(III). These insights prove that the nitrogen-doped porous carbon-based adsorbents prepared in this study can effectively reduce Cr(VI) pollution in water environment.

Universal access to safely managed drinking water (SMDW) is important for human health, well-being, and development. It is reflected in Sustainable Development Goal (SDG) 6. In rural areas of low- and middle-income countries, 1.9 billion people lack access to SMDW. Multiple water source use and seasonal source switching may negate health and development gains from SMDW. Hence, achieving SDG 6 requires a better understanding of how these factors relate to household service levels. We explored this using data from 37,105 household surveys and 6395 household drinking water samples collected from rural areas of 14 low- and middle-income countries (Ethiopia, Ghana, Honduras, India, Kenya, Malawi, Mali, Mozambique, Niger, Rwanda, Tanzania, Uganda, Zambia, Zimbabwe). A different primary water source was used in the rainy and dry seasons by 10% of households; seasonal source switching was most common in Kenyan households (29%) and least common in Zambian households (3%). Twenty-three percent of households used a secondary water source, and 37% of these secondary sources were unimproved (e.g., unprotected dug wells and surface water). Sixty-nine percent of household water samples contained E. coli. In 11 of 14 countries studied, fecally contaminated water was the water service parameter preventing households from having SMDW free from fecal contamination at the point of use. Overall, 7% of households had access to SMDW free from contamination at the point of use. Our results confirm that the WHO/UNICEF Joint Monitoring Programme for Water Supply, Sanitation, and Hygiene (JMP) substantively overstate the population benefiting from safely managed drinking water, and their reporting statistics should be interpreted with caution. Seasonal source switching and secondary water source use have an important influence in some countries and should be accounted for in monitoring and programming activities.

Pressure on freshwater resources is tremendously increasing due to large-scale global population explosion, socio-economic development, climate change and infrastructural development worldwide. The study area faces severe water crisis, groundwater fluoride contamination, and high drought frequency. Thus, the principal objectives are i) to assess the recent surface and subsurface water dynamics in this plateau fringe using satellite datasets on Google Earth Engine (GEE) and ii) to demarcate the suitable sites for dam construction to manage the severe water crisis and substitute drinking water sources. Satellite datasets such as Sentinel 2 and Gravity Recovery and Climate Experiment (GRACE) have been used to access the surface and groundwater dynamics. Numerous criteria or influencing factors including geology, geomorphology, lineament, elevation, slope, rainfall, land use/land cover, soil, stream density, normalized vegetation index (NDVI), and distance from the river have been considered to demarcate the suitable sites for new dam site suitability. In this study, four advanced machine learning models namely support vector machine (SVM), random forest (RF), logistic regression (LR) and gradient boosting (XGBoost) have been applied to recommend suitable sites for dam construction. Average surface water changes from 157.375 km² (2012–2016) to 156.185 km²(2017–2022). Estimated water thickness (EWT) values vary from 28.58 cm to −27.07 cm (2002–2017). In case of soil moisture (SM), the lowest value (2.4 cm) was in June 2009, and the highest (21.51 cm) was in September 2003. After the deduction of SM from EWS, it specifies that maximum groundwater storage (9.48 cm) occurred in July 2004 whereas a minimum (-30.21 cm) in March 2016. Dam site suitability results denote that 10% of areas come under the very high suitable for surface and subsurface dam construction. The area under curve (AUC) values of SVM, RF, LR, and XGBoost are 0.94, 0.95, 0.91, and 0.92 respectively. Therefore, the RF model has comparatively higher values regarding model performance. The output of this research will be advantageous to define suitable places for new dam construction and sustainable water resource management in semi-arid environment.

The presence of small-sized (<5 mm) plastic particles, called microplastics (MPs), in the environment, including aquatic bodies, air, soil, and bodies of living beings, is a cause of significant concern to the entire world. These MPs can contaminate drinking water sources, move up the food chain, and release toxic substances that could pose a threat to human health. Therefore, there is an urgent need to develop methods for removing MPs from the environment to protect present and future generations. The coagulation-flocculation sedimentation (CFS) process (using synthetic chemicals) has emerged as a fundamental method for treating MPs in water because of its economy, high efficiency, and ease of use. However, the xenobiotic nature of such compounds, coupled with their adverse health effects, calls for the development of sustainable solutions. This is the first study to report the effectiveness of plant-based natural coagulants in removing MPs from water and their comparison against synthetic coagulants. Two natural coagulants, Benincasa hispida (BH) and Moringa oleifera (MO), were investigated and have shown comparable MP removal efficiencies to commonly used synthetic coagulant: alum. The CFS approach resulted in 83.73 ± 1.41% (100 mg L^–1 dosage) and 86.99 ± 1.41% (150 mg L^–1 dosage) MP removal efficiencies for BH and MO, respectively, while alum resulted in 86.58 ± 1.22% removal (50 mg L^–1 dosage). Further, FTIR analysis has revealed that these MPs are composed of high-density polyethylene (HDPE), and SEM imaging has shown their shapes as spherical, rod-like and irregular. The results of the present study show that plant-based natural materials can be used for MP removal, thus yielding a sustainable and cost-effective process.

Conventional drinking water treatment facilities employ coagulants, typically alum and ferric sulfate to remove turbidity and improve the clarity of the water. While alum for example, is naturally occurring and has no known health hazards when used in the right amount for water treatment, there is growing concern about the sustainability and environmental impacts of these inorganic coagulants. To explore a cost-effective, sustainable, and eco-friendly alternative, we investigated the shell of calabash fruit (Crescentia cujete) as a plant-based natural and eco-friendly coagulant. Although the plant has been extensively studied for its medicinal purposes this is the first report of its potential use as a coagulant in water treatment. Using Jar Test experiments and statistical analysis, we found that the coagulant obtained from Crescentia cujete was able to reduce the turbidity of the water by 84.3% at an optimal dosage of only 1.0 g/L. Zeta potential and particle size diameter were determined using Zetasizer Nano ZS (Malvern Instruments Ltd., UK) and found to be −3.42 mV and 2.55 × 10⁴ d.nm respectively. The plant sample was further characterized via FT-IR analyses and was found to be largely composed of hemicellulosic materials, which likely contributed to the effectiveness of the coagulant.

The study assessed the physicochemical and biological properties of selected groundwater sources in the Southeastern part of the Western Region, to assess the impact on water quality and health risk. The Piper Trilinear plot was used to categorize the water samples into water types based on the dominant anion and cation concentrations. Statistical analysis (One way ANOVA and two sample t-test) was used to determine the sources of variation in the data at 95% confidence interval. The Water Quality Index (WQI) and Hazard Quotient (HQ) were used to estimate the water quality and health risk respectively. TDS and turbidity were above the acceptable WHO guidelines in 16.7% of the samples with a mildly acidic pH in 83.3% of the water samples. Also, 91.7% of the water samples were contaminated with total coliform (TC) and 25% with e-coli. Generally, the groundwater samples were dominated by Ca²⁺ and HCO^3- ion water types. The variations between parameters were found not significant for all the parameters (p>0.05). Water samples in the North are of good quality with a mean WQI of 96, but of poor quality in the South with a mean WQI of 144.6. HQ values for all the samples were less than 0.1, suggesting less harmful impacts of the heavy metal concentrations on human health. Overall, the results showed the presence of heavy metals in the groundwater sources sampled, however in quantities with low health risks either through oral or dermal channels. Groundwater within the communities is good for domestic purposes but needs treatment for drinking. To improve upon the study, it is recommended that further studies consider a higher number of samples and include other accessible groundwater stations where possible.

In the Apulia region (Southern Italy), the issue of water scarcity is escalating, making wastewater reclamation and reuse crucial options for promoting sustainable development. Despite substantial financial investments, the practical adoption of wastewater reuse for agricultural irrigation remains constrained. Using a quantitative SWOT framework, we analyzed market, social, and product-related factors impacting water reuse. A questionnaire with 23 out of 30 expert stakeholders, including researchers, public administration officials, utility members, farmers, and engineers, was used to evaluate the significance of each aspect identified in the SWOT analysis. The key drivers of a wastewater-reuse-based economy include improved water availability during drought, a commitment to the circular economy, and existing successful agricultural reuse projects. Conversely, identified obstacles encompass the lack of storage basins for storing wastewater between seasons to synchronize production with crop water needs, inadequate political dedication to oversee groundwater withdrawals, difficulties in controlling investments, and bureaucratic demands arising from stringent regulation. Underpinned by the recently enacted EU Water Reuse Regulation, the reuse of wastewater is crucial for addressing water scarcity, mitigating aquifer over-exploitation, and achieving objectives related to the circular economy. However, moving forward, an updated governance framework integrating continuous monitoring, active stakeholder engagement, and investments in intermediate storage facilities is imperative for effective and sustainable wastewater reuse. This research provides novel empirical evidence and expands upon existing studies on barriers and opportunities related to reclaimed water in a Mediterranean context and regions facing similar challenges. The findings can serve as a valuable reference for future research in this field.

Tanneries are known to be one of the most polluting industries due to the generation of harmful contaminants at various stages, from the beam house to finishing. Each day, significant quantities of tannery wastewater containing contaminants like chromium salts are released into open areas, farmlands, rivers and other corpses of water. This practice poses a severe threat to the environment health, leading to extensive soil and water pollution. In this study, a biological material (scales of fish Catla catla) is employed as an adsorbent for biosorption of contaminants from tannery effluent. Every day a considerable amount of fish scales is generated and thrown away from the local fish market, which burdens the environment and causes environmental pollution. The primary emphasis of this study is to reduce wastewater pollution and the environmental burden of fish waste disposal. Two adsorbents were prepared by treating the dried fish scales with NaOH and Orthophosphoric acid to enhance the adsorbent properties by creating pores and roughness of the surface. Then, it was characterized using FTIR, SEM, and TGA analyses. After characterization, adsorbents were subjected to the adsorption of a standard chromium solution to detect the ideal adsorbent dose, contact time, and pH conditions of adsorption. The study's findings showed that during adsorption, the maximum uptake capacity of acid-treated adsorbent is found at pH 4 with an adsorbent dose of 20 g/L for a 60-minute contact time. That base-treated adsorbent is obtained at pH 2.50 with an adsorbent amount of 20 g/L for 4 hours of contact time. Then, the adsorbents were used to treat tannery effluents, and it was discovered that they successfully removed pollutants like chromic oxide, total suspended solids (TSD), total dissolved solids (TDS), BOD, COD, and others. The results indicated that the acid-treated adsorbent achieved optimal removal percentages for chromic oxide, BOD₅, COD, TDS, and TSS at 72.82%, 42.85%, 56.12%, 13.37%, and 35%, respectively. Thus, the study concluded that acid and base-washed fish scale adsorbents are affordable and straightforward to use adsorbents for removing pollutants from tannery effluent.

A set of 4 soil column duplicates was irrigated with treated wastewater to study the possible leaching of nitrate, salt, and Escherichia coli to groundwater. The reclaimed water was a municipal secondary effluent, stored for 5 days to attenuate microbial contamination. It had nitrate concentration of 36.1±4.9 mgN/L, electrical conductivity of 1.6±0.1 mS/cm, and E. coli content between 36 and 918 MPN/100 mL (median value of 194 MPN/100 mL). Soil column tests were carried out over a period of 80 days, considering both the cultivation of a typical Mediterranean crop (pepper) and the edge case of non-cultivated soil. Nitrate and salt were up-taken by crops for around 90% and 50%, respectively, while they leached through non-cultivated soil according to linear relationships, with nitrate moving faster than salts. Due to its natural decay, E. coli never reached 66 cm depth. Crop irrigation with reclaimed water can be managed so as not to cause significant leaching of E. coli and nitrate, even though it may result in a small leaching of salt. Replacing groundwater with reclaimed water as an irrigation source should be considered as a possible action to protect aquifers, and especially those suffering from saline contamination, from the effects of overexploitation and overfertilization practices.