International Journal of Environmental Science and Technology最新文献

This study investigated the production of renewable activated carbon derived from residual ashes generated during the boiler combustion process for the treatment of food industry wastewater. The chemical modification of ashes into activated carbon was optimized using potassium hydroxide, phosphoric acid, and nitric acid. The results indicated that the adsorbent synthesized with phosphoric acid exhibited the best performance in removing indigo carmine dye, achieving 98% removal rate when using the adsorbent at a concentration of 0.5 g L⁻¹, with an average particle diameter of 0.088 mm. The surface area increased from 120.3 to 605.1 m² g⁻¹ with phosphoric acid activation, resulting in a high-quality adsorbent with a capacity for reuse up to four times. The Redlich–Peterson isotherm model provided the best fit for experimental data on indigo carmine dye adsorption, with a maximum adsorption capacity of approximately 100 mg g⁻¹ according to the Langmuir model. In the treatment of food industry wastewater (cheese whey), the adsorbent reduced the lactose content (32.45%), turbidity (62.92%), BOD₅ (90.48%), and COD (93.07%). The removal of these adsorbates from cheese whey effluent reduced the organic load of cheese whey, enabling the water reuse within the food industry. In conclusion, activated carbon produced from residual ashes can be considered as a sustainable alternative for treating food industry effluents, advocating water reuse.

In this study, a novel draw solution based on trisodium dicarboxymethyl alaninate and citric acid was evaluated for its potential to be utilized in forward osmosis water desalination systems. The effect of various operation parameters (including draw solution concentration, feed stream salination, and operation temperature) on desalination efficiency of the forward osmosis system utilizing such novel draw solutions was investigated, utilizing a bench-scale cross/tangential flow membrane testing system. In addition, images of membranes’ surfaces produced by scanning electron microscopes were also studied to determine the nature of fouling resulting from prolonged operations, and the effectiveness of applied cleaning procedures. Compared to the more well-established trisodium citrate-based draw solution, the novel draw solution exhibited higher water flux against deionized water, while also offering low reverse solute flux and good regeneration capability through low-pressure reverse osmosis. In particular, experiment results showed that at the initial concentration of 250 g L⁻¹, the forward osmosis system utilizing such novel draw solution could achieve specific water fluxes of up to 9.23 L m⁻² h⁻¹ against deionized water, and up to 4.95 L m⁻² h⁻¹ against feed streams of 20‰ salinity. Additionally, such system also has relatively low operational loss, with specific reverse solute flux and reverse osmosis recovery rate of 0.22 g L⁻¹ and 98.65%, respectively. Overall, the novel draw solution was proven to be effective for water desalination applications, while also being relatively cheap, readily-available in large quantities, low in toxicity, and relatively eco-friendly.

Graphical Abstract

The accurate prediction of significant wave height is essential for coastal and offshore engineering, and is especially important for producing renewable ocean wave energy. However, H_s is traditionally predicted using empirical or numerical models, which lack accuracy, are computationally demanding, or require extensive datasets. Due to chaotic nature, it is very challenging for empirical or numerical models to precisely predict H_s. This study developed and tested several standalone machine learning models for H_s prediction and explored hybrid versions of these models based on additive regression to further improve model accuracy. Half-hourly H_s data along with common variables measured at ocean buoys were collected from four sations (i.e., Mooloolaba, Gladstone, Caloundra and Brisbane) along the coastline of Queensland, Australia and used to develop the ML models. The ML models were tested for their ability to accurately predict H_s at Mooloolaba station and were transferred to the three other stations to prove their spatial generalization capabilities. Overall, the results demonstrate that the ML models, and especially their hybrid versions, can accurately predict H_s at Mooloolaba as well as for other stations. Thus, the proposed models may serve as promising tools for improving ocean wave energy production.

The removal of nitrogen in wastewater treatment systems is temperature-sensitive, with lower temperatures inhibiting the activity of nitrogen-removing bacteria. To mitigate this during cold seasons, a combined approach of bioaugmentation and mud-film symbiosis technology was applied to domestic wastewater secondary effluent. Biological agents A (nitrifying bacteria) and B (denitrifying bacteria) were introduced at 6–8 °C, with a 7-day incremental dosing regimen. The outcomes revealed significant enhancements in Total Nitrogen, NH_3–N, NO₃–N removal rates, and simultaneous nitrification–denitrification (SND) efficiency by 30.73%, 37.55%, 32.25%, and 43.69%, respectively, compared to untreated low-temperature conditions.

High-throughput sequencing analysis demonstrated an increased abundance of nitrifying and denitrifying microbial communities, including Nitromonas, Nitrobacterium, Truepera, Dechloromonas, and Unclassified Aeromycetes, in the floating biofilm and activated sludge. This augmentation of nitrogen removal capacity underscores the importance of bioaugmentation in strengthening the SND process, ensuring effective nitrogen removal in cold winter conditions for wastewater treatment systems. The findings provide valuable insights into enhancing nitrogen removal efficiency in wastewater treatment during cold periods.

This review deals with the applicability of polymeric sorbents in removing spilled free oil from water surfaces. The theoretical framework covers the sorption ability of polymeric materials in general, respecting their size and morphology; however, the main focus is on polyolefins, primarily various grades of polyethylene (PE) and polypropylene (PP), including PE and PP waste. The core motivation associated with recycling polyethylene LDPE is the low interest in plastic convertors and the limited marketability of these commodities. The scientific focus in this area is on the development of new products having at least two general features: i) a specific application that does not require high mechanical performance, and ii) the material has a unique functionality that is not significantly influenced by using a recyclate against the use of the pristine polymer. Recycled polyolefins fully satisfied these requirements. This review pays special attention to the theoretical aspects of polymeric sorbents. Specific features of sorbents are analyzed depending on their geometry and morphology, involving powders, membranes/mats, and 3D foams (sponges)/gels. The wettability and sorption mechanisms regarding the chemical composition of materials, their surface topology, and internal porosity are discussed in detail. The presented manuscript emphasizes the close connection between materials’ behavior and properties, which is crucial for efficient oil/water separation and the theoretical modeling of adsorption and absorption processes. The focus on the physical aspects of materials from a theoretical point of view is highlighted, enabling a complex understanding of the oil/water separation processes.