Water Science and Technology最新文献

Ionic liquids are regarded as green solvents mainly due to their non-volatile and easy regeneration and recycling properties. However, ionic liquids have negative effects on the environment and human health, especially alkyl imidazole ionic liquids are more toxic than traditional organic solutions. Studies on the toxicology, ecotoxicology, and degradation of ionic liquids are rarely found in the literature. Here, we prepared the cheap La and Ce-codoped TiO₂@PAM (polyacrylamide) composite microspheres with a simple procedure for the first time to degrade three kinds of imidazole ionic liquids with high efficiency. The experimental results show that the composite La (0.25%) and Ce (0.15%)-codoped TiO₂@PAM composite microspheres with calcination temperature of 450 °C had a high photocatalytic activity for 1-butyl-3-methyl imidazolium hexafluorophosphate, 1-hexyl-3-methyl imidazolium hexafluorophosphate, and 1-octyl-3-methyl imidazolium hexafluorophosphate with the concentration of 10 mg/L. The photocatalysis degradation extent of the three ionic liquids is 97.4, 91.2, and 88.5% at 90 min. This work opened a new route for the simple preparation of cheap composite microspheres in the photocatalytic degradation of ionic liquids with a high efficiency.

This study introduces ensemble empirical mode decomposition (EEMD) coupled with the autoregressive integrated moving average (ARIMA) model for drought prediction. In the realm of drought forecasting, we assess the EEMD-ARIMA model against the traditional ARIMA approach, using monthly precipitation data from January 1970 to December 2019 in Herat province, Afghanistan. Our evaluation spans various timescales of standardized precipitation index (SPI) 3, SPI 6, SPI 9, and SPI 12. Statistical indicators like root-mean-square error, mean absolute error (MAE), mean absolute percentage error (MAPE), and R² are employed. To comprehend data features thoroughly, each SPI series initially computed from the original monthly precipitation time series. Subsequently, each SPI undergoes decomposition using EEMD, resulting in intrinsic mode functions (IMFs) and one residual series. The next step involves forecasting each IMF component and residual using the corresponding ARIMA model. To create an ensemble forecast for the initial SPI series, the predicted outcomes of the modeled IMFs and residual series are finally added. Results indicate that EEMD-ARIMA significantly enhances drought forecasting accuracy compared to conventional ARIMA model.

Antimony, extensively used in energy applications, poses toxicity and contamination concerns, especially in anaerobic environments where its impact on microbial activity is poorly understood. Emerging remedies, like biochar, show promise in soil and water treatment. This study investigates biochar's influence on methanogenic activity under Sb(V) and Sb(III) stress using anaerobic sludge as inoculum and lactate as the carbon source. Sb(III) and Sb(V) were introduced at varied concentrations (5-80 mg/L), with or without biochar, monitoring changes in biogas production, pH, Sb, and lactate levels over time. Experiments with Sb(V) also involved calculating mass balance and electron distribution. Results showcased the following significant enhancements: biochar notably improved COD removal and biogas production in Sb(III) spiked conditions, up to 5-fold and 2-fold increases, respectively. Sb(III) removal reached up to 99% with biochar, while in high Sb(V) concentrations, biochar reduced the adverse effect on biogas production by 96%. Adsorption capacities favored biomass (60.96 mg Sb(III)/gVSS, and 22.4 mg Sb(V)/gVSS) over biochar (3.33 mg Sb(III)/g, and 1.61 mg Sb(V)/g) for both Sb species. This study underscores biochar's potential to mitigate metalloid impact on methanogenic activity while aiding Sb removal from liquid phase, suggesting promising implications for remediation and methane production enhancement strategies.

In the pursuit of a treatment approach that is both cost-effective and environmental-friendly, the applicability of microscreen (MS) techniques coupled with a primary sedimentation tank (PST) as a physical advanced primary treatment (APT) to enhance the removal of particulate organic carbon (POC) from municipal wastewater was investigated. A pilot unit, including a modified MS, adjustable to different meshes (including 20 and 15 μm) was operated continuously downstream to the PST at the Büsnau wastewater treatment plant in Stuttgart, Germany, and monitored for more than half a year. A strategy involving time-dependent backwashing and recirculation of MS permeate was employed to remove as much POC as possible from primarily treated wastewater, thereby extending the application of the MS. The optimal configuration, PST + 15-μm MS, achieved maximum removal efficiencies of 90% for turbidity, 90% for total suspended solids (TSS), and 80% for total chemical oxygen demand (TCOD). These results are significant, as comparable removal levels for these parameters were conventionally achieved using less eco-friendly methods such as physiochemical APT, including coagulation-flocculation with iron or aluminum salts followed by microscreening or sedimentation. However, this study's findings ascertained that solo physical APT applications could produce equivalent effluent quality with a much smaller footprint while keeping the advanced primary treated wastewater suitable for biological treatment.

A membrane-aerated biofilm reactor (MABR) combines membrane technology with biofilm processes and has unique advantages in the treatment of organic wastewater and volatile wastewater. The common membranes for MABR systems usually have relatively uneven pore structures and low bubble point pressure, resulting in unsatisfactory O₂ utilization and wastewater treatment efficiency. In this work, polydimethylsiloxane (PDMS) and UiO-66 (a Zr-based metal organic framework) were coated on the surface of a commercial polypropylene (PP) hollow fiber membrane to prepare oxygen-rich MABR membranes and modules, which showed an attractive O₂ utilization rate and wastewater treatment efficiency. The bubble points of the PDMS and PDMS-UiO-66 membranes were significantly higher than those of the PP membranes, and the PDMS-UiO-66 membranes had better oxygen enrichment capacity and biological affinity. The optimal PDMS-UiO-66 membrane modules had an O₂ permeance of 31.65 GPU (1 GPU = 3.35 × 10^-10 mol m^-2 s^-1 Pa^-1), with O₂/N₂ selectivity of 2.21. The membrane hanging effect and processing capacity for domestic sewage were greatly improved. This study may provide insights and guidelines to fabricate porous mixed matrix membranes and modules in the industry for MABR. The developed products are expected to be applied in the actual separation process.

The sustainable management of groundwater resources in developing countries is often challenging due to limited measurement and monitoring infrastructure to collect data necessary for decision support. To make a contribution towards addressing these challenges, this study investigated the use of Internet of Things (IoT) technology and low-cost sensors to collect the required groundwater-level data and develop a model to map the recharge potential with stormwater. The study focused on two stormwater ponds located in a highly urbanised area in Cape Town, South Africa. A combination of Geographic Information System and analytic hierarchy process was integrated to generate a groundwater recharge potential zone map of the study area. The IoT-based data were used to develop and calibrate a numerical groundwater model in MODFLOW. The study determined that retrofitted stormwater ponds are potential groundwater augmentation zones and can provide opportunity for stormwater recharge in urban areas. Overall, this study highlights the potential of IoT to collect hydrogeological data with low-cost sensors. Data can be collected at high temporal resolution, and the spatial scale can be increased due to availability of low-cost sensors.

Quinoline inevitably remains in the effluent of coking wastewater treatment plants due to its bio-refractory nature, which might cause unfavorable effects on human and ecological environments. In this study, MnCe_xO_y was consciously synthesized by α-MnO₂ doped with Ce³⁺ (Ce:Mn = 1:10) and employed as the ozonation catalyst for quinoline degradation. After that, the removal efficiency and mechanism of quinoline were systematically analyzed by characterizing the physicochemical properties of MnCe_xO_y, investigating free radicals and monitoring the solution pH. Results indicated that the removal rate of quinoline was greatly improved by the prepared MnCe_xO_y catalyst. Specifically, the removal efficiencies of quinoline could be 93.73, 62.57 and 43.76%, corresponding to MnCe_xO_y, α-MnO₂ and single ozonation systems, respectively. The radical scavenging tests demonstrated that ^•OH and ^•O₂^- were the dominant reactive oxygen species in the MnCe_xO_y ozonation system. Meanwhile, the contribution levels of ^•OH and ^•O₂^- to quinoline degradation were about 42 and 35%, respectively. The abundant surface hydroxyl groups and oxygen vacancies of the MnCe_xO_y catalyst were two important factors for decomposing molecular O₃ into more ^•OH and ^•O₂^-. This study could provide scientific support for the application of the MnCe_xO_y/O₃ system in degrading quinoline in bio-treated coking wastewater.

The scouring process near spur dikes poses a threat to riverbank stability, making it crucial for river engineering to accurately calculate the maximum scour depth. However, determining the maximum scour depth has been challenging due to the intricacy of scour phenomena surrounding these structures. This research introduces a reliable ensemble data-driven model by hybridizing random tree (RT) using additive regression (AR), bagging (B), and random subspace (RSS) for predicting scour depths around spur dikes. A database of 154 experimental observations was collected from literature, with 103 and 51 observations used for training and testing subsets, respectively. A dimensionless analysis was performed on the collected dataset, selecting four variables as input variables (v/v_s, y/l, l/d₅₀, and Fd₅₀) and d_s/l as response variables. The performance comparison demonstrates that B_AR_RT has a better coefficient of determination (R²) of 0.9693, root mean square error (RMSE) of 0.1305, and Nash-Sutcliffe efficiency (NSE) of 0.9692. Finally, a comparison of the best hybrid model has been done with previous studies, and sensitivity analysis is performed to determine the most influential parameter for predicting the scour depth around spur dikes.

The volume capture ratio of annual rainfall (VCRAR) of low-impact development measures is significantly influenced by its operating characteristics, particularly for residential stormwater detention tanks (SWDTs). The multi-objective operation strategy of SWDTs, encompassing toilet flushing (TF), green space irrigation (GSI), combined TF and GSI (TF-GSI), and peak flow reduction (PFR) rate, were compared using a case study in Beijing based on the stormwater management model. The findings indicate that the VCRAR for TF, GSI, and TF-GSI rainwater harvesting targets was 89.05, 77.16, and 91.21%, respectively. The operating scheme and return periods have a significant impact on the PFR rate's effectiveness. When the return period was lower than 10 years, the SWDT does not reach its maximum storage capacity, and the PFR rate was increased with increasing the return period: the PFR rate was 71.47% when the design return period was 10 years. It will also produce the phenomena of water inrush, and the overflow volume will grow rapidly when the SWDT reaches its maximum storage capacity. Hence, the operation of SWDTs may be integrated with real-time control to optimize the VCRAR for rainwater reuse and flood migration, thereby enhancing the volume utilization efficiency of SWDTs.