Water Science and Technology最新文献

This study evaluates the performance of the Internal Circulation eXperience (ICX) reactor in treating high-strength paper mill wastewater in the south of Vietnam. The ICX reactor effectively managed organic concentrations (sCOD) of up to 11,800 mg/L. Results indicate a volumetric loading rate (VLR) of 26.8 kg/m³ × day, achieving processing efficiency exceeding 81% while consistently maintaining volatile fatty acids (VFA) below 300 mg/L. The study employed Monod and Stover-Kincannon kinetic modeling, revealing dynamic parameters including K_s = 56.81 kg/m³, Y = 0.121 kgVSS/kgsCOD, K_d = 0.0242 1/day, μ_max = 0.372 1/day, U_max = 151 kg/m³ × day, and K_B = 175.92 kg/m³ × day, underscoring the ICX reactor's superior efficiency compared to alternative technologies. Notably, the reactor's heightened sensitivity to VFA levels necessitates influent concentrations below 1,400 mg/L for effective sludge treatment. Furthermore, the influence of calcium on treatment efficiency requires post-treatment alkalinity maintenance below 19 meq/L to stabilize MLVSS/MLSS concentration. Biogas production ranged from 0.6 to 0.7 Nm³ biogas/kg sCOD; however, calcium impact diminished this ratio, reducing overall treatment efficiency and biogas production. The study contributes valuable insights into anaerobic treatment processes for complex industrial wastewaters, emphasizing the significance of controlling VFA, calcium, and alkalinity for optimal system performance.

To achieve the purpose of treating waste by waste, in this study, a nitrogen-doped Fe/Mn bimetallic biochar material (FeMn@N-BC) was prepared from chicken manure for persulfate activation to degrade Bisphenol A (BPA). The FeMn@N-BC was characterized by scanning electron microscopy (SEM), X-ray diffract meter (XRD), fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectrometer (XPS) and found that N doping can form larger specific surface area. Catalytic degradation experiments showed that Fe/Mn bimetal doping not only accelerated the electron cycling rate on the catalyst surface, but also makes the biochar magnetic and easy to separate, thus reducing environmental pollution. Comparative experiments was concluded that the highest degradation efficiency of BPA was achieved when the mass ratios of urea and chicken manure, Fe/Mn were 3:1 and 2:1, respectively, and the pyrolysis temperature was 800 °C, which can almost degrade all the BPA in 60 min. FeMn@N-BC/PS system with high catalytic efficiency and low consumables is promising for reuse of waste resources and the remediation of wastewater.

The study investigates the effect of the oxidant calcium oxide (CaO) on the codigestion of excess sludge (ES) and plant waste (PW) under mesophilic anaerobic conditions to enhance methane production. The findings indicate that CaO significantly elevated methane yield in the codigestion system, with an optimum CaO addition of 6% resulting in a maximum methane production of 461 mL/g volatile solids, which is approximately 1.3 times that of the control group. Mechanistic exploration revealed that CaO facilitated the disintegration of organic matter, enhanced the release of soluble chemical oxygen demand, and increased the concentrations of soluble proteins and polysaccharides within the codigestion substrate. The presence of CaO was conducive to the generation and biological transformation of volatile fatty acids, with a notable accumulation of acetic acid, a smaller carboxylic acid within the VFAs. The proportion of acetate in the CaO-amended group increased to 32.6-36.9%. Enzymatic analysis disclosed that CaO enhanced the activity of hydrolytic and acidogenic enzymes associated with the ES and PW codigestion process but suppressed the activity of coenzyme F420. Moreover, CaO augmented the nutrient load in the fermentation liquid. The study provides an alternative scheme for the efficient resource utilization of ES and PW.

Groundwater and soil contamination by aromatic amines (AAs), used in the production of polymers, plastics, and pesticides, often results from improper waste disposal and accidental leaks. These compounds are resistant to anaerobic degradation; however, micro-aeration can enhance this process by promoting microbial interactions. In batch assays, anaerobic degradation of aniline (0.14 mM), a model AA, was tested under three micro-aeration conditions: T30, T15, and T10 (30, 15, and 10 min of micro-aeration every 2 h, respectively). Aniline degradation occurred in all conditions, producing both aerobic (catechol) and anaerobic (benzoic acid) byproducts. The main genera involved in T30 and T15 were Comamonas, Clostridium, Longilinea, Petrimonas, Phenylobacterium, Pseudoxanthomonas, and Thiobacillus. In contrast, in T10 were Pseudomonas, Delftia, Leucobacter, and Thermomonas. While T30 and T15 promoted microbial cooperation for anaerobic degradation and facultative respiration, T10 resulted in a competitive environment due to dominance and oxygen scarcity. Despite aniline degradation in 9.4 h under T10, this condition was toxic to Allium cepa seeds and exhibited cytogenotoxic effects. Therefore, T15 emerged as the optimal condition, effectively promoting anaerobic degradation without accumulating toxic byproducts. Intermittent micro-aeration emerges as a promising strategy for enhancing the anaerobic degradation of AA-contaminated effluents.

The aim of this study is to assess groundwater pollution in the city of Taza, Morocco. This was accomplished through hydrochemical and biological investigations, focusing on analyzing the physicochemical and bacteriological parameters of groundwater. Water samples were collected from wells and sources within Taza City on a monthly basis during the spring and summer of 2023. These samples were subjected to analysis to identify physicochemical and bacteriological characteristics. The findings revealed multiple contaminations, primarily stemming from two sources: significant microbial pollution observed in 100% of samples due to runoff percolation and discharge of domestic and industrial wastewater, and varying degrees of chemical pollution observed across all samples. The results underscored deviations from national standards, notably in parameters such as dissolved oxygen, nitrate, and nitrite concentrations. These parameters exhibited values either lower or higher than the established norm.

Efficient cathode regeneration is a significant challenge in the electrochemical water softening process. This work explores the use of an electroless plating Ni-P-PTFE electrode with low surface energy for this purpose. The Ni-P-PTFE electrode demonstrates improved self-cleaning performance at high current densities. By combining the low surface energy of the electrode with fluid flushing shear force, the precipitation rate on the Ni-P-PTFE electrode remains stable at approximately 18 g/m²·h over extended periods of operation. Additionally, the cleaning efficiency of the Ni-P-PTFE electrode surpasses that of stainless steel by 66.34%. The Ni-P-PTFE electrode can maintain a larger active area and a longer operational lifespan is attributed to its self-cleaning performance derived from low surface energy. Furthermore, the loose scale layers on the electrode surface are easily removed during electrochemical water softening processes, presenting a novel approach to cathode surface design.

Urban flooding intensifies with escalating urbanization. This study focuses on Xiong'er river as the study area and couples a 1D/2D urban flooding model using InfoWorks ICM (Integrated Catchment Modeling). Ten scenarios are set respectively with a rainfall return period of 5a 10a, 20a, 50a, and 100a, alongside rainfall durations of 1 and 24 h. Subsequently, the H-V (hazard-vulnerability) method was applied to evaluate urban flooding risk. Three indicators were selected for each of hazard factors and vulnerability factors. The relative weight values of each indicator factor were calculated using the AHP method. The result shows that (1) flood depth, rate, and duration escalate with longer rainfall return periods, yet decrease as the duration of rainfall increases; (2) as the rainfall return period lengthens, the proportion of node overflow rises, whereas it diminishes with longer rainfall durations, leading to an overall overloaded state in the pipeline network; and (3) the distribution in the research area is mainly low-risk areas, with very few extremely high-risk. Medium to high-risk areas are mainly distributed on both sides of the river, in densely built and low-lying urban areas. This study demonstrates that the model can accurately simulate urban flooding and provide insights for flood analyses in comparable regions.

The depth-dependent dynamics of dissolved organic matter (DOM) structure and humification in an artificial lake limits the understanding of lake eutrophication and carbon cycling. Using fluorescence regional integration (FRI) and parallel factor analysis (PARAFAC) models to analyze the 3D fluorescence spectroscopy dataset, we revealed the depth-dependent structure and vertical distribution of DOM in the estuarine and center regions of Lake Hongfeng. The percentage fluorescence response (P_i,n) showed humic acid is an important part of DOM in Lake Hongfeng. Fluorescence results show that the fulvic-like and protein-like materials in HF1-DOM located at the estuarine position showed greater variation in the middle stage, probably due to human influence and sediment suspension. Fluorescence index (P_I+II+IV,n/P_III+V,n and FI_C4/FI_C3) can be used to indicate the degree of humification of DOM in artificial lakes. Results of each index show that the estuary is more affected by human activities, and the humification degree is significantly lower than that of the center of the lake. The evaluation index system of the humification degree of artificial lake established in this study can effectively predict the eutrophication state of the typical area of artificial lake and deeply understand the possible important influence of human activities on the carbon cycle of lake.

Palladium is now frequently utilized in fuel cells, electroplating, electronics, and catalysis. Due to their rarity and high cost, precious metal recovery has taken on a significant role. The extraction method frequently utilized in polymer inclusion membranes (PIMs) is both efficient and simple since it has been demonstrated that precious metal adsorption on the membrane significantly controls the mechanism of chemical adsorption. In this study, polyvinyl chloride (PVC) as a polymer, A336 as a plasticizer, and trioctylamine (TOA) as a carrier were used to produce a PIM by evaporation. After the production of PIMs, palladium extract was studied. The stripping phase, palladium concentration in the feed phase, and components of the membrane were changed to determine the optimum condition with better extraction ability. When 0.5 M of HCl was used, higher kinetic parameter results and higher than 85% extraction efficiency were achieved compared to other concen- trations. When the EDX results were examined, 3.3% palladium was retained on the membrane surface. When the palladium concentration was selected at 2.5 ppm, higher kinetic parameters were observed, and the extraction efficiency was over 90%. The best membrane was the PIM containing 40% PVC-40% A336-20% TOA.

The composition of waste-activated sludge (WAS) is complex, containing a large amount of harmful substances, which pose a threat to the environment and human health. The reduction and resource utilization of sludge has become a development demand in sludge treatment and disposal. Based on the technical bottlenecks in the practical application of direct anaerobic digestion technology, this study adopted two different thermal and thermal-alkali hydrolysis technologies to pretreat sludge. A pilot-scale experiment was conducted to investigate the experimental conditions, parameters, and effects of two hydrolysis technologies. This study showed that the optimal hydrolysis temperature was 70 °C, the hydrolysis effect and pH can reach equilibrium with the hydrolysis retention time was 4-8 h, and the optimal alkali concentration range was 0.0125-0.015 kg NaOH/kg dry-sludge. Thermal-alkali combination treatment greatly improved the performance of methane production, the addition of NaOH increased methane yield by 31.2% than that of 70 °C thermal hydrolysis. The average energy consumption is 75 kWh/m³ 80% water-content sludge during the experiment. This study provides a better pretreatment strategy for exploring efficient anaerobic digestion treatment technologies suitable for southern characteristic sewage sludge.