Search

The highly-efficient treatment of coal mine water with low energy consumption contributes to much safer and more efficient coal mining. At present, mine water processing at underground is still limited for its small treatment water yield, large land coverage and high operation cost in ground treatment, high drainage costs when mine water is discharged into the surface water system. In this light, this study puts forward the "deep ground-underground-surface ground" linkage system for mine water treatment and utilization. The treated mine water is partially used for mining production and residential usage, while the rest is subject to deep reinjection or drainage. This paper first introduces the operational mechanism behind this system, and then evaluates its validity in terms of water quality, water quantity, hydrogeology, underground structure, and feasibility of recharge engineering. This study then reviews existing mine water treatment methods for varying water qualities and the "underground-surface" joint treatment system; Also, a summary is drawn regarding the selection of aquifer for reinjection purposes, reinjection construction operations, reinjection tests, simulation of reinjection water quality, and analysis of reinjection safety.

This review examines the technological bottlenecks, potential solutions, and future development directions in the treatment and resource utilization of semi-coking wastewater (SCOW) in China. By comprehensively investigating the semi-coking industry and analyzing wastewater treatment research hotspots and existing projects, this study systematically explores the current status and challenges of each treatment unit, emphasizing the necessity for innovative wastewater treatment technologies that offer high efficiency, engineering feasibility, environmental friendliness, and effective resource recovery. This review highlights prospects and recommendations, including the development of novel extractants for phenol and ammonia recovery, a deeper understanding of biological enhancement mechanisms, exogenous bio-enhancement materials, and the creation of cost-effective advanced oxidation process (AOP)-based combined processes. Additionally, it underscores the potential for repurposing SCOW as a valuable resource through appropriate treatment, whether recycling for production or other applications. [ABSTRACT FROM AUTHOR]

Per- and polyfluoroalkyl substances (PFASs) are bioaccumulative and widely distributed persistent organic pollutants (POPs). Understanding the distribution of and ecological risks posed by PFASs is critical, particularly for PFAS emissions and accumulation from a common urban pollution source. The transformation characteristics and ecological risks of PFASs from a typical aging municipal landfill leachate were systematically monitored and assessed over five years in this study. The results showed that the total PFAS concentrations (ΣPFASs) in the rivers were between 26.4 and 464.3 ng/L, whereas in sediment, ΣPFASs ranged from 9.5 to 58.5 ng/g (w/w). The presence of perfluorooctanoic acid (PFOA) was the most prominent PFAS in both water (39.4–152.3 ng/L) and sediment (1.1–56.1 ng/g). In a five-year monitoring study, the concentration of PFASs in the aging landfill decreased by 23.3%, with higher mean concentrations observed during summer (307.6 ng/L) compared to winter (250.4 ng/L). As for the pollution distribution, the suspended particulate matter–water partition coefficient (log Kd) of carboxylic acid (PFCAs) and perfluoroalkane sulfonic acids (PFSAs) ranged from 1.53 to 2.65, and from 1.77 to 2.82, respectively. PFSAs and long-chain PFCAs exhibited a greater propensity for sediment association compared to short-chain PFCAs. An ecological risk assessment of four typical PFASs, PFOA, perfluorooctane sulfonate (PFOS), perfluorobutanoic acid (PFBA), and perfluorobutane sulfonic acid (PFBS), utilizing the hazard quotient method revealed that the rivers surrounding the typical aging landfill exhibited a low contamination risk for PFOA, while no ecological risks were associated with the other three FPASs. This study contributes to an enhanced comprehension of the occurrence, distribution, and risk of PFASs in the rivers in rivers and sediment surrounding a typical aging landfill site in China, thereby providing crucial reference information for ensuring water quality safety. [ABSTRACT FROM AUTHOR]

Excessive fluoride in mine water has become a major concern because it can cause detrimental effects to human health. Nevertheless, the removal efficiency of traditional adsorbents is far from satisfactory. Herein, La and Fe bimetallic supported zeolite was synthesized by co-precipitation method, for efficient defluoridation. The defluoridation performance of La-Fe zeolite was studied by a batch adsorption experiment and dynamic adsorption column test. Results indicated that the removal efficiency of F− was 99.04% under the optimal conditions (4 h, adsorbent dosage 8.0 g/L, agitation rate 200 rpm/min, temperature 298K and pH = 6 ± 1) that were determined through the batch adsorption experiments. CO32− and HCO3− can inhibit the defluorination effect of La-Fe zeolite. The adsorption of fluoride ions on La-Fe zeolite can be well described by the Langmuir adsorption model, and the maximum fluoride ion adsorption capacity is 2.64 mg/g. The test of dynamic adsorption column shows that the adsorption efficiency of F− by La-Fe zeolite on was higher than 85% for continuous adsorption of 9 h, indicating that La-Fe zeolite has good practical applications. The mechanism analysis indicated that the adsorption of fluoride ion by La-Fe modified zeolite involves both ion exchange and complexation, which belongs to the physicochemical process. [ABSTRACT FROM AUTHOR]

Acrylic manufacturing wastewater is characterized by high toxicity, poor biodegradability, high chemical oxygen demand (COD) and ammonia nitrogen. Herein, we exploited traditional Fenton technology to treat acrylic fiber manufacturing wastewater. The impacts of key operating variables including the initial concentration of H2O2 (CH2O2), the initial concentration of Fe2+ (DFe2+), and solution pH (pH) on the COD removal rate (RCOD) were explored and the treatment process was optimized by Response Surface Methodology (RSM). The results indicated that the optimum parameters are determined as pH 3.0, 7.44 mmol/L of Fe2+ and 60.90 mmol/L of H2O2 during Fenton process. For the actual acrylic manufacturing wastewater treatment shows that the removal rates for COD, TOC, NH4+-N and TN are 61.45%~66.51%, 67.82%~70.99%, 55.67%~60.97% and 56.45%~61.03%, respectively. It can meet the textile dyeing and finishing industry water pollutant discharge standard (GB4287-2012). During the Fenton reaction, the effective degradation and removal of organic matter is mainly achieved by HO• oxidation, supplemented by flocculation and sedimentation of Fe3+ complexes. This study will provide useful implications in the process parameters for the practical application of Fenton method in acrylic acid production wastewater. [ABSTRACT FROM AUTHOR]

Studied were the adsorption-desorption and degradation of two widely used neonicotinoid insecticides clothianidin and thiamethoxam in three different agricultural soils in the state of Mississippi. The adsorptions of both the neonicotinoids fit a linear isotherm model. In different soils at different depths with different moisture contents, the adsorption distribution coefficients of clothianidin and thiamethoxam were found to be 0.62 to 1.94 and 0.59–2.03 L kg −1 , respectively. These distribution coefficients showed strong positive correlations with organic carbon content and pH of the soils. The desorptions of clothianidin and thiamethoxam also followed a linear isotherm, but were irreversible in respect to their adsorption isotherms. The desorption distribution coefficients ranged from 0.14 to 0.62 L kg −1 , increased with the decrease of organic carbon content. The degradations of clothianidin and thiamethoxam in the soils were found to be slow with half-lives ranged from 90 to 280 and 65 to 170 d for clothianidin and thiamethoxam respectively. The degradation rates increased with the increase of the organic carbon content in the soils. The moisture content in the soils had a positive effect on the degradation rates. The Groundwater Ubiquity Scores calculated from the adsorption distribution coefficient, organic content, and half-life suggest that clothianidin and thiamethoxam have moderate to high potential to leach to groundwater. [ABSTRACT FROM AUTHOR]

In this study, microbial induce carbonate precipitation (MICP) was introduced to immobilize chromium (Cr) in stainless steel pickling sludge (SSPS). Two methods were utilized to conduct the MICP process — Bacteria lysis liquor (BLL)-based MICP and bacteria-based MICP. BLL was obtained by breaking the cell walls with ultrasonic treatment. The urea hydrolyzation test illustrated that the BLL was better than bacteria solution. Both the treatments of bacteria lysis liquor-based MICP and bacteria-based MICP process can effectively entrap the Cr into mineral lattices, that reduce the potential environmental risk of SSPS. With 30 g/L urea and 7 days' treatment, BLL-based MICP presented better immobilization performance than bacteria-based MICP by lowering the bacteria concentration (OD 600) from 0.8 to 0.7. The excellent biosorption of BLL contributed to Cr removal. Nevertheless, the addition of calcium (Ca) significantly enhanced the immobilization performance of bacteria-based MICP process rather than BLL-based MICP process. pH-dependent leaching tests illustrated the leaching of Cr followed an amphoteric pattern, while the leaching of Ni and Ca followed the cation pattern. Geochemical modeling revealed that the leaching of Cr from bio-mineralized products was solubility-controlled by Cr(OH) 3 and Cr 2 O 3. [Display omitted] • Bacteria lysis liquor-based MICP presented better immobilization performances. • The addition of Ca improved the immobilization of Cr in bacteria-based MICP process. • Cr from bio-mineralized products showed strong pH-dependent leaching behavior. • Cr presented as Cr 2 O 3 and Cr(OH) 3 in the bio-mineralization products. [ABSTRACT FROM AUTHOR]

[Display omitted] • Both atomic H∗ and ∙OH were responsible for 2,4-DCP removal with Fe–P-CA cathode. • The release of iron ions with Fe–P-CA cathode was inhibited. • Hydrogen evolution potential with Fe–P-CA cathode was significantly decreased. [ABSTRACT FROM AUTHOR]

With the rapid economy and population growth, wastewater containing sulfate originated from industrial and human activities have gradually become a potential threat to the ecological security. As dominant microorganism responsible for treating high-sulfate wastewater, the sulfate-reducing bacteria (SRB) not only utilizes sulfate as the terminal electron acceptors, but also resists various harsh environments, so it was applied to a broader range of wastewater treatment. Based on previous studies, this study provides a comprehensive review of the metabolic mechanism and functional organisms of SRB. Further, the influence mechanism of environmental factors on the metabolic activity of SRB was analyzed from the perspective of pH, temperature, COD/SO 4 2− ratio, electron donors, oxidation reduction potential, hydraulic retention time, concomitant ions, and syntrophic/competitive effect. Additionally, applications and enhancing strategies for SRB were discussed based on above mechanism of action. Lastly, existing challenges and future development directions in environmental engineering applications are proposed. Future analysis should focus on functional genes and enzymes in assimilation sulfate reduction, research of SRB with complete oxidation capacity, the establishment of mathematical models simulating the metabolic activity and efficiency of SRB, the development of novel carbon sources fit for SRB, the potential value of heavy metals and S 0 recovery in sulfate reduction, and exploration of interaction mechanism between organohalides-respiring bacteria (OHRB) and SRB. [Display omitted] • The metabolic mechanism of SRB were summarized through metabolic pathways, functional organisms and key genes. • Eight key influencing factors affecting the metabolic activity of SRB were summarized. • SRB-mediated wastewater treatment technology is crucial in the process of water pollution control. • Further challenges and directions for SRB applications in environmental engineering are presented. [ABSTRACT FROM AUTHOR]

The pickling sludge produced from rolling process contains a large amount of Fe, Ca, Al as well as other metals. If these metals can be extracted and used, it will promote the recycling of pickling sludge. Herein, we proposed a two-step extraction method to extract Fe ions out from the pickling sludge, and then the extracted Fe was oxidized by H 2 O 2 and prepared into Fe-containing coagulant in the presence of Na 2 HPO 4 as stabilizer. The three main factors that affect the color removal efficiency and COD removal efficiency are identified as P:Fe ratio, H 2 O 2 adding amount, and curing time. Results show that the optimal preparation conditions are: P:Fe = 0.05, H 2 O 2 amount = 115%, and the curing time = 6 d, at which the color and COD removal efficiency reached 96.25% and 65.91%, respectively. The assessment of toxicity of the PPFC indicated that the content of harmful substances meets the thresholds in Chinese national standard GB141591-2016. The findings in this study are expected to provide new implications in treating different kinds of Fe-containing sludge. [Display omitted] • A two-stage extraction was developed for Fe extraction from pickling sludge. • P-doped polyferric chloride coagulant (PPFC) was prepared. • PPFC is no-toxic and effective coagulant for color and COD removal. [ABSTRACT FROM AUTHOR]