Water is not enough. Nowadays, numerous chemicals are used for fire extinction. After use, however, these may unintentionally enter sewerage systems. In order to safely treat firefighting wastewater (FFWW), knowledge of the potential effects of these chemicals on biological treatment processes is essential. This study characterized and mimicked the composition of FFWW containing two powders, three foams and one foam degrader. Nitrogen (162-370 mg NH4(+)-N L(-1)) and phosphorus (173-320 mg PO4(3-)-P L(-1)) concentrations exceeded discharge limits, whereas chemical and biological oxygen demand, suspended solids and detergent concentrations remained sufficiently low. Adequate nutrient removal could be obtained through FeCl3 addition and nitrification/denitrification with acetate as substrate. In batch tests, residual nitrifying activities of 84, 81, 89, 95 and 93% were observed in the presence of powders, foams, foam degrader, synthetic and real FFWW, respectively. All categories showed higher denitrification rates than the control. Although the powders at first seemed to inhibit anammox activity at 82%, after pH correction anammox was fully feasible, allowing nitrogen removal through oxygen-limited nitrification/denitrification (OLAND). Detailed cost calculations indicated that OLAND could save 11% of capital and 68% of operational costs compared to nitrification/denitrification, identifying OLAND as the most recommendable process for nitrogen removal from firefighting wastewaters.

为解决传统剥色工艺复杂、剥色时间长、剥色过程能耗大等问题,设计并采用二氧化硫脲与过硫酸钠联合组成的还原-氧化剥色体系对活性蓝KN-R染色棉织物进行剥色,分析了剥色液中剥色剂质量浓度、碱剂质量浓度、剥色时间以及温度对剥色效果和棉织物强力的影响,探究了剥色剂对染色棉织物进行剥色的剥色机制。得到的二氧化硫脲体系最佳剥色工艺条件为:二氧化硫脲质量浓度2 g/L,氢氧化钠质量浓度6 g/L,剥色时间20 min,剥色温度60 ℃。过硫酸钠体系最佳剥色工艺条件为:过硫酸钠质量浓度6 g/L,氢氧化钠浓度质量4 g/L,剥色时间20 min,剥色温度60 ℃。在最佳剥色工艺条件下对活性蓝KN-R染色棉织物剥色率达到96.05%,强力保留率也维持在90%以上。相比于传统剥色工艺,二氧化硫脲-过硫酸钠剥色体系对染色棉织物进行剥色的剥色率较高,织物强力损伤较小,所需剥色剂用量少,剥色时间短,剥色温度低,是一种高效、节能的剥色方法。

<p id="p00005"><strong>Objective</strong> The annual production of waste textiles is enormous, and the existing treatment routes such as chemical incineration and physical landfill are commonly employed to deal with waste textiles. These methods not only severely pollute the environment but also result in significant resource waste. Therefore, recycling waste textiles is crucial for conserving resources and reducing pollution. Color stripping is a prerequisite for recycling the colored waste textiles. However, conventional color stripping processes are characterized by high energy consumption, low efficiency, and operational complexity. This research aims to develop an environmentally friendly color stripping process that is both low in energy consumption and easy to operate as an alternative to the conventional color stripping methods. </p> <p id="p00113"><strong>Method</strong> A reduction-oxidation stripping system, employing thiourea dioxide (TD) as the reducing agent and sodium persulfate (Na₂S₂O₈) as the oxidizing agent, was used to strip the dyed cotton fabrics colored with Reactive Blue KN-R. The influences of stripping agent concentration, alkali concentration, stripping time, and temperature on the color stripping rate and the strength retention rate of the fabric were investigated. After stripping, the <i>K/S</i> values of the fabrics were measured using spectrophotometers to determine the color stripping rate. The strength retention rate was measured using an electronic fabric strength tester. All samples were measured three to five times to obtain an average value. </p> <p id="p00112"><strong>Results</strong> In the reductive color stripping process, the concentration of NaOH significantly affected the removal of dye molecules. When the concentration of NaOH was increased from 1 g/L to 6 g/L, the stripping rate increased from 73.09% to 86.95%. Excessive dosage of TD resulted in slight decreases in both color stripping rate and strength retention rate, indicating that excessive TD concentration is not conducive to colorant removal. The color stripping rate increased with time but showed minimal improvement beyond 20 min. Higher temperatures improved the color stripping rate but also caused a notable decrease in strength retention rate. When the temperature of the stripping system reached 70 ℃, after stripping for 20 minutes, the fabric strength retention rate dropped below 90%. In the oxidative stripping process, the stripping rate was higher than 90.00% with the dosage of NaOH being more than 1 g/L. A gradually increasing tendency was also obtained as the concentration of the oxidant Na₂S₂O₈ being increased from 1 g/L to 6 g/L. Similarly, the color stripping rate was increased within 20 minutes and stabilized afterward. Higher temperature also increased the color stripping rate but damaged the cotton fabrics, reducing the strength retention rate. After TD reduction stripping and Na₂S₂O₈ oxidation stripping, the fabric color changed from blue to purple and eventually to white. Additionally, the sequential reduction-oxidation stripping system effectively stripped fabrics dyed with other reactive dyes. For fabrics dyed with Reactive Red M-3BE, Reactive Red X-3B, Reactive Blue KN-G, and Reactive Blue M-BE, the initial reductive color stripping rates were 91%, 93%, 64%, and 78%, respectively. The subsequent oxidative stripping further improved the rates to 97%, 98%, 83%, and 96%, respectively.</p> <p id="p00111"><strong>Conclusion</strong> The sequential stripping system of TD reduction and Na₂S₂O₈ oxidation can serve as an alternative to conventional color stripping methods. For the cotton fabrics dyed with Reactive Blue KN-R, the stripping rate can reach 96% under low-temperature conditions, while the strength retention rate remains above 90%. The optimized TD reductive stripping process includes a thiourea dioxide concentration of 2 g/L, NaOH concentration of 6 g/L, stripping time of 20 minutes, and stripping temperature of 60 ℃. The optimized Na₂S₂O₈ oxidative stripping process includes a sodium persulfate concentration of 6 g/L, NaOH concentration of 4 g/L, stripping time of 20 minutes, and stripping temperature of 60 ℃. Compared to traditional color stripping processes, the new method causes less fabric damage, uses fewer stripping agents, requires shorter stripping times, and operates at lower temperatures. Moreover, the sequential reduction-oxidation stripping system is applicable to a wide range of reactive dyes.</p>

基于自由基和非自由基途径的高级氧化技术等替代化学处理技术在水处理中越来越受到重视,特别是基于铁的双金属类芬顿反应和基于硫酸根自由基的高级氧化工艺在处理有机污染物中得到了广泛的应用。包括铁在内的过渡金属在有机污染环境的修复中被广泛用作过硫酸盐活化剂,铁与其他金属形成双金属结构可以调节催化剂的电子结构和活性位点,因此铁基双金属催化剂通常表现出更高的稳定性、催化活性、回收利用性。根据国内外研究现状,综述了近年来铁基双金属催化剂的制备方法、活化机理以及降解应用,讨论了影响铁基双金属催化剂稳定性及其活化过硫酸盐体系降解率的主要因素,最后对该体系降解有机废水的发展趋势和研究方向作出了展望。

Alternative chemical treatment methods, including radical- and non-radical-based advanced oxidation processes, have drawn increasing attention in water treatment. In particular, the Fenton-like bimetallic reaction centered on iron and sulfate radical-based oxidation are widely applied to remove organic contaminants. Transition metals, including iron, serve as common persulfate activators in remediating organic pollution, and forming bimetallic complexes between iron and other metals fine-tunes the catalyst's electronic structure and active sites. Consequently, iron-based bimetallic catalysts frequently exhibit enhanced stability, catalytic potency, and recyclability. Drawing on current domestic and international research, this paper reviews recent developments in the fabrication, activation mechanism, and applications of iron-supported bimetallic catalysts for pollutant degradation. Key factors affecting the catalyst's stability and the activation efficiency of peroxodisulfate-based systems are also discussed, along with possible future directions for organic wastewater treatment using these catalysts.

采用聚乙烯醇（PVA）为包埋剂，制备了以火山渣为填充剂、过氧化钙（CaO₂）为氧源的缓释氧剂，旨在为黑臭水体治理提供一种高效可行的方式。通过清水实验和黑臭水体实验，研究了缓释氧剂的释氧性能及其在污染物去除方面的作用。结果表明，相较粉末状过氧化钙，缓释氧剂的释氧得到有效控制，且对pH的影响相对减弱。在2 L的黑臭水体中投加6.08 g缓释氧剂后，DO峰值达5.16 mg/L，且19 d内仍维持在2 mg/L以上，COD由145.99 mg/L降至28.6 mg/L，总磷去除率达95%以上。表明缓释氧剂能显著改善黑臭水体上覆水的溶氧状态，且对COD和总磷的去除有积极的促进作用。

A slow oxygen-releasing agent is prepared by using polyvinyl alcohol (PVA) as an embedding agent,scoria as a filling agent and CaO₂ as an oxygen source,aiming at providing an efficient and feasible way to treat black and odorous water.The oxygen-releasing performance of slow oxygen-releasing agent and its role in the removal of pollutants are evaluated through experiments on clear water and black odorous water,respectively.It is indicated that the oxygen release rate of slow oxygen-releasing agent is controlled effectively compared with powdered calcium peroxide,and the effect on pH value weakens relatively.After adding 6.08 g of slow oxygen-release agent into 2 L of black odorous water,the highest concentration of dissolved oxygen reaches 5.16 mg&#183;L^-1 and maintains above 2 mg&#183;L^-1 in 19 days,the concentration of <i>COD</i> decreases from 145.99 mg&#183;L^-1 to 28.6 mg&#183;L^-1 and the maximum removal rate of total phosphorus exceeds 95%.It indicates that this slow oxygen-releasing agent can significantly improve the dissolved oxygen state of the overlying water in the black odorous water and promote the removals of <i>COD</i> and total phosphorus.

以典型内分泌干扰物双酚A(BPA)为目标污染物,研究了高铁酸钾[Fe(Ⅵ)]对其的去除效果及机理。通过高效液相色谱仪、离子色谱仪等手段考察了pH、Fe(Ⅵ)投加量和共存离子等因素对BPA去除效果的影响。结果表明,在pH为8.0、Fe(Ⅵ)与BPA浓度比为30:1时,反应10 min后BPA的降解率达到81.5%。Cl^-、SO^2-₄、NO^-₃、HCO^-₃等共存阴离子未影响 Fe(Ⅵ)体系的氧化能力,但Ca²⁺和Mg²⁺因加速了Fe(Ⅵ)自分解而抑制了BPA降解。通过淬灭实验对体系中的活性氧物种进行识别,Fe(Ⅵ)及其高价铁氧中间体Fe(Ⅴ)/Fe(Ⅳ)在氧化BPA中起主导作用。在实际水体(自来水、市政二级出水和地下水)中,Fe(Ⅵ)氧化体系对BPA的降解未受到明显影响,证实其具有较高的环境适应性。

The removal effect and mechanism of potassium ferrate (Fe(Ⅵ)) on bisphenol A (BPA),a typical endocrine disruptor chemical substance,are studied.The effects of pH value,Fe(Ⅵ) dosage,and coexisting ions on the removal efficiency of BPA are investigated through using high-performance liquid chromatography (HPLC),ion chromatography,and other measurements.The results show that the degradation rate of BPA reaches 81.5% after 10 minutes of reaction at a pH of 8.0 and a Fe(Ⅵ) to BPA concentration ratio of 30:1.The co-existed anions including Cl^-,SO^2-₄,NO^-₃ and HCO^-₃ exert negligible effect on the oxidation ability of Fe(Ⅵ) system,while Ca²⁺ and Mg²⁺ both accelerate the self-decomposition of Fe(Ⅵ) and therefore suppress the degradation of BPA.The reactive oxygen species in the system are identified through quenching experiments,and Fe(Ⅵ) and its intermediate high valence product Fe(Ⅴ)/Fe(Ⅳ) play a dominant role in the oxidation of BPA.In some real water bodies (tap water,municipal secondary effluent,and groundwater),no obvious negative effects on degradation of BPA by Fe(Ⅵ) oxidation system have been observed,indicating a high adaptability.

Despite the importance of phosphorus as a nutrient for humans and its role in ecological sustainability, its high abundance, resulting in large part from human activities, causes eutrophication that negatively affects the environment and public health. Here, we present the use of ferrate(VI) as an alternative agent for removing phosphorus from aqueous media. We address the mechanism of phosphate removal as a function of the Fe/P mass ratio and the pH value of the solution. The isoelectric point of γ-Fe2O3 nanoparticles, formed as dominant Fe(VI) decomposition products, was identified to play a crucial role in predicting their efficiency in removing of phosphates. Importantly, it was found that the removal efficiency dramatically changes if Fe(VI) is added before (ex-situ conditions) or after (in-situ conditions) the introduction of phosphates into water. Removal under in-situ conditions showed remarkable sorption capacity of 143.4 mg P per gram of ferric precipitates due to better accessibility of active surface sites on in-situ formed ferric oxides/oxyhydroxides. At pH = 6.0-7.0, complete removal of phosphates was observed at a relatively low Fe/P mass ratio (5:1). The results show that phosphates are removed from water solely by sorption on the surface of γ-Fe2O3/γ-FeOOH core/shell nanoparticles. The advantages of Fe(VI) utilization include its environmentally friendly nature, the possibility of easy separation of the final product from water by a magnetic field or by natural settling, and the capacity for successful phosphate elimination at pH values near the neutral range and at low Fe/P mass ratios.Copyright © 2016 Elsevier Ltd. All rights reserved.