反渗透膜应用于钢厂废水回用膜污染研究

以钢厂实际运行中污染的反渗透膜为研究对象,采用SEM、能谱分析(EDS)等方法对膜面污染物成分和碱洗所带出的污染物进行了分析。结果表明,反渗透膜表面的污染物主要为有机磷酸铝、钙、镁等元素组成的无机化合物和有机污染物。     

Performance of landfill leachate treatment system with disc-tube reverse osmosis units

Reverse osmosis system with the disc-tube module (DT-RO) was applied to treat landfill leachate on full scale at the Changshengqiao Sanitary Landfill, Chongqing City, China. In the first six-mouth operation phase, the treatment performance of DT-RO system had been excellent and stable. The removal rate of chemical oxygen demand (COD), total organic carbon (TOC), electrical conductivity (EC), and ammonia nitrogen (NH₃-N) reached 99.2–99.7%, 99.2%, 99.6%, and over 98%, respectively. The rejection of Ca²⁺, Ba²⁺, and Mg²⁺ was over 99.9%, respectively. Suspended solid (SS) was not detected in product water. Effective methods had been adopted to control membrane fouling, of which chemical cleaning is of utmost importance to guarantee the long smooth operation of the DT-RO system. The DT-RO system is cleaned in turns with Cleaner A and Cleaner C. At present, the 1st stage cleaning cycle by Cleaner A and Cleaner C is conducted every 100 and 500 h, respectively, depending on raw the water quality.     

Design of nanofibre interlayer supported forward osmosis composite membranes and its evaluation in fouling study with cleaning

• A fine fibre (40–60 nm diameter) interlayer (~1 µm thickness) was electrospun. • Fine fibre interlayer promoted formation of defect-free dense polyamide layer. • FO membrane with dual-layer substrate had less organic fouling potential. • High reverse salt flux accelerated organic fouling on FO membrane. Nanofibre-supported forward osmosis (FO) membranes have gained popularity owing to their low structural parameters and high water flux. However, the nanofibrous membranes are less stable in long-term use, and their fouling behaviours with foulants in both feed solution (FS) and draw solution (DS) is less studied. This study developed a nanofibrous thin-film composite (TFC) FO membrane by designing a tiered dual-layer nanofibrous substrate to enhance membrane stability during long-term usage and cleaning. Various characterisation methods were used to study the effect of the electrospun nanofibre interlayer and drying time, which is the interval after removing the M-phenylenediamine (MPD) solution and before reacting with trimesoyl chloride (TMC) solution, on the intrinsic separation FO performance. The separation performance of the dual-layer nanofibrous FO membranes was examined using model foulants (sodium alginate and bovine serum albumin) in both the FS and DS. The dual-layer nanofibrous substrate was superior to the single-layer nanofibrous substrate and showed a flux of 30.2 L/m²/h (LMH) when using 1.5 mol/L NaCl against deionised (DI) water in the active layer facing draw solution (AL-DS) mode. In the fouling test, the water flux was effectively improved without sacrificing the water/solute selectivity under the condition that foulants existed in both the FS and DS. In addition, the dual-layer nanofibrous TFC FO membrane was more robust during the fouling test and cleaning.     

Comparing Contaminant Removal Costs for Aquifer Recharge with Wastewater with Water Supply Benefits

The use of waters of impaired quality has been suggested as a means to expand available water resources supply for water‐limited communities. An ongoing concern is the safety of supplies that use wastewater because of the potential for introduction of emerging contaminants such as pharmaceuticals into drinking water supplies. Prior research into contaminants of emerging concerns (CECs) have included a variety of methods, but the only consistent removal is with reverse osmosis (RO) membranes, ultraviolet light (UV), and advanced oxidation processes (AOP). However, few of these prior studies have measurable quantities of these contaminants in the influent wastewater, so determining actual removal percentages is difficult. This project was designed to evaluate the removal of CECs to verify that a 3‐log removal of common constituents was realized. Spike testing was used to compare to prior research and to evaluate whether the project costs were competitive with other forms of reuse or other water supplies. The combination of RO/UV/AOP was effective at obtaining a 3‐log removal of CECs, but the RO and UV/AOP processes alone were not capable of removing all substances. However, despite the extensive treatment, the proposed process was both competitive cost‐wise and met the water quality goals.     

三醋酸纤维(CTA)正渗透膜活性层朝向对正渗透过程的影响

本文通过在线实时监测研究了三醋酸纤维(CTA)正渗透膜的活性层在朝向料液(AL-FS)和汲取液(AL-DS)两种模式下的正渗透水通量、反向溶质通量、特性反向溶质通量等因素及其变化规律。在实验室条件下模拟了三醋酸纤维膜(CTA)对于不同浓度苦咸水的处理,当苦咸水浓度为2000ppmNaCl、5000ppmNaCl、8000ppmNaCl时,CTA膜活性层朝向对脱盐率几乎没有影响,AL-FS模式和AL-DS模式的脱盐率分别为96.49%和96.13%、97.40%和96.38%、98.04%和96.81%。研究结果对于进一步开发CTA正渗透系统和实用化具有重要意义。     

Ozonation as an efficient pretreatment method to alleviate reverse osmosis membrane fouling caused by complexes of humic acid and calcium ion

Humic acids (HA) didn’t cause obvious reverse osmosis (RO) membrane fouling in 45 h. Osmotic pressure (NaCl) affected slightly the RO membrane fouling behavior of HA. Ca²⁺ promoted aggregation of HA molecules and thus aggravated RO membrane fouling. Ozonation eliminated the effect of Ca²⁺ on the RO membrane fouling behavior of HA. The change of the structure of HA was related to its membrane fouling behavior. Humic acid has been considered as one of the most significant sources in feed water causing organic fouling of reverse osmosis (RO) membranes, but the relationship between the fouling behavior of humic acid and the change of its molecular structure has not been well developed yet. In this study, the RO membrane fouling behavior of humic acid was studied systematically with ozonation as a pretreatment method to control RO membrane fouling. Furthermore, the effect of ozone on the structure of humic acid was also explored to reveal the mechanisms. Humic acid alone (10–90 mg/L, in deionized water) was found not to cause obvious RO membrane fouling in 45-h operation. However, the presence of Ca²⁺ aggravated significantly the RO membrane fouling caused by humic acid, with significant flux reduction and denser fouling layer on RO membrane, as it was observed by scanning electron microscope (SEM) and atomic force microscope (AFM). However, after the pretreatment by ozone, the influence of Ca²⁺ was almost eliminated. Further analysis revealed that the addition of Ca²⁺ increased the particle size of humic acid solution significantly, while ozonation reduced the SUVA₂₅₄, particle size and molecular weight of the complexes of humic acid and Ca²⁺ (HA-Ca²⁺ complexes). According to these results and literature, the bridge effect of Ca²⁺ aggregating humic acid molecules and the cleavage effect of ozone breaking HA-Ca²⁺ complexes were summarized. The change of the structure of humic acid under the effect of Ca²⁺ and ozone is closely related to the change of its membrane fouling behavior.     

污水再生处理微滤-反渗透工艺经济分析

近年来,微滤-反渗透(MF-RO)工艺在污水再生处理领域中的应用越来越受到关注,但其设备投资和运行成本较高,需要建立科学、高效的运行管理机制和投入产出机制,以提高其经济效益。系统研究了北京市某再生水厂微滤-反渗透(MF-RO)工艺的设备投资及运行费用等情况。再生水成本主要由设备折旧费和运行成本组成,其中运行成本所占比例较高,而在运行成本中所占比例最高的是膜更换费、电费和药剂费。目前该厂再生水销水量约为7 000 m3/d,运行负荷率仅为33.33%,导致再生水成本较高,总成本约达5.29元/m3,其中设备折旧费为0.83元/m3,运行成本约为4.46元/m3。因此提高运行负荷率,即提高销水量,是降低再生水成本的关键。     

Removal of PFOS, PFOA and other perfluoroalkyl acids at water reclamation plants in South East Queensland Australia

This paper examines the fate of perfluorinated sulfonates (PFSAs) and carboxylic acids (PFCAs) in two water reclamation plants in Australia. Both facilities take treated water directly from WWTPs and treat it further to produce high quality recycled water. The first plant utilizes adsorption and filtration methods alongside ozonation, whilst the second uses membrane processes and advanced oxidation to produce purified recycled water. At both facilities perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorohexanoic acid (PFHxA) and perfluorooctanoic acid (PFOA) were the most frequently detected PFCs. Concentrations of PFOS and PFOA in influent (WWTP effluent) ranged up to 3.7 and 16 ng L⁻¹ respectively, and were reduced to 0.7 and 12 ng L⁻¹ in the finished water of the ozonation plant. Throughout this facility, concentrations of most of the detected perfluoroalkyl compounds (PFCs) remained relatively unchanged with each successive treatment step. PFOS was an exception to this, with some removal following coagulation and dissolved air flotation/sand filtration (DAFF). At the second plant, influent concentrations of PFOS and PFOA ranged up to 39 and 29 ng L⁻¹. All PFCs present were removed from the finished water by reverse osmosis (RO) to concentrations below detection and reporting limits (0.4-1.5 ng L⁻¹). At both plants the observed concentrations were in the low parts per trillion range, well below provisional health based drinking water guidelines suggested for PFOS and PFOA.     

微絮凝-反渗透耦合过程深度处理邻苯二甲酸二辛酯化工废水

高浓度DOP有机化工废水生物毒性强,采用常规处理手段难完全降解,对环境存在较高危害性.采用微絮凝-反渗透耦合过程对DOP化工厂二级生化出水进行深度处理研究,考察了絮凝预处理的最佳条件,比较了BW30和CPA2两种反渗透复合膜对该实际废水的处理性能,并利用电子扫描电镜分析了废水处理过程中膜表面结构的变化.结果表明:絮凝预...     

印染废水回用处理的设计实例

采用"厌氧水解—缺氧—好氧—二次沉淀—超滤—反渗透"组合工艺进行印染废水的处理回用。运行结果表明,在平均进水COD和色度分别为508 mg/L和1695倍的情况下,COD和色度的总去除率分别为94.2%和98.8%,硬度不超过10 mg/L,铁、锰离子未检出,各项指标均达到HJ 471—2009《纺织染整工业废水治理工程技术规范》中的回用标准。GC-MS分析结果显示,二沉池出水中主要有机物成分复杂,超滤出水中有机物浓度有一定降低,反渗透出水中酸类全部被去除、苯胺类和烷烃类含量明显降低。从染色的白位沾色、手感、颜色和亮度等指标分析,回用水的染色效果远优于工业水。污水处理工程总投资约1×10~7元,设计规模4 500 m~3/d,回用水规模2 500 m~3/d,回用率55%,回用运行成本1.80元/m~3。