Treatment and reuse of dyeing effluents by potassium ferrate

The use of potassium ferrate, K₂FeO₄, an environmentally-friendly chemical reagent containing iron in the + 6 oxidation state, has been investigated as a new approach for dyeing wastewater purification.The performance of this product, alone or in combination with a cationic organic polymer and/or power ultrasound, was compared to the traditional biological activated sludge process and a tertiary treatment featuring ozonation.Experimental tests showed that, thanks to its unique properties (high redox potential and simultaneous generation of ferric coagulating species), potassium ferrate can be successfully used in dyeing wastewater treatment. In fact, treatment with ferrate at the optimal dose of 70 mg/L as Fe(VI) was found to allow a high removal efficiency of relevant parameters such as turbidity, total suspended solids and chemical oxygen demand (COD).Whilst potassium ferrate alone had a minor effect on colour, the combination of ferrate with the organic polymer allowed a good decolourisation: this suggested the eventual application of this combined process for reuse of dyeing wastewater, resulting in environmental and economic benefits. The possibility of reusing the purified effluent in textile processes that do not require softened water was demonstrated through dyeing tests.     

Design of continuous ion exchange process for the wastewater treatment

A generic design procedure for the continuous ion exchange process is proposed. The procedure is based on the optimized arrangement of parallel batch columns. The continuity of the process is achieved by proper shifting of the inlet conditions. The method for the optimization of the process variables is presented.The concept is demonstrated on the example of ammonia removal from wastewaters. Two flowsheet schemes are considered utilizing fresh or recycled regenerating agent.The superiority of the optimized process over the periodic operation is demonstrated.     

Chemical cleaning of reverse osmosis membranes used for treating wastewater from a rolling mill process

An analysis of fouling material and the effects of chemical cleaning were examined for a reverse osmosis (RO) membrane, which was used for the treatment of wastewater from a rolling mill process in the steel industry. The bulk foulant accumulated in the membrane module consisted mainly of CaSO₄·2H₂O, and the organic contaminants were contained at a very low level. The test pieces obtained from the exhausted RO membrane module (spiral-wound type) were used to examine chemical cleaning with the following solutions: acid and alkaline solutions with EDTA added, 50% methanol, and 10% ethyleneglycol monobutyrate (EGMB). Although a major component of the fouling material was calcium salt, the acid or alkaline solution containing EDTA did not promote the effective recovery of the water flux. On the other hand, cleaning with 50% methanol or 10% EGME solution increased the water flux significantly. The atomic force microscopy images of the membrane surface indicated that relatively large particles accumulated at the surface of the fouled membranes, and the large particles remained even after acid or alkaline cleaning. In the case of EGMB cleaning after alkaline cleaning, large particles did not remain, and uniform and fine particles were observed. The results that calcium salt, a major fouling material, was not removed effectively with the acid and alkaline solution may be due to trace organic materials in the fouling layer that act as a binder for inorganic fouling materials.     

膜生物反应器在废水处理中的应用

膜生物反应器 (MembraneBio -Reactor ,MBR)是一种传统活性污泥法的改进技术 ,它应用于给水和废水处理的研究发展过程。介绍了膜生物反应器的发展状况、结构形式、优点和应用领域。     

Survey of MBR market: Trends and perspectives in China

Membrane bioreactor (MBR) has gained considerable attention for wastewater treatment and reuse in China in the last two decades. Comparing with the global MBR market, which has an average annual growth rate of 10.9%, the average annual growth rate in China is nearly 100% in recent years. In the past 10 years, publications on MBR researches and applications for wastewater treatment have increased sharply. Over three hundred MBR plants have been successfully applied into practice for different wastewater treatments, such as municipal wastewater, bathing wastewater, restaurant wastewater, landfill leachate, hospital wastewater, petrochemical wastewater and high-concentration industrial wastewater. These plants have capacities ranging from 10 to 100,000 m³/d, among which over 12 MBR plants have capacities exceeding 10,000 m³/d. The largest MBR plant, i.e. Beijing Kunyu River WWPT, which has a capacity of 100,000 m³/d for municipal wastewater treatment and reuse, was constructed in Beijing by Origin Water Technology Co., Ltd. The largest MBR plant for industrial wastewater treatment was located in Tianjin and installed by Motimo Membrane Inc., which has a capacity of 30,000 m³/d. The largest MBR application for industrial sectors was petrochemical wastewater treatment, and over ten MBR plants each exceed a capacity of 5000 m³/d. In South-east China, the constructed MBRs are mostly involved in the high-strength industrial wastewater treatment while in North China MBRs mainly focused on municipal wastewater treatment and reuse.For an MBR commercial application in China, MBR plants were constructed by a lot of home-grown companies such as Tianjin Motimo Membrane Technology Co., Ltd., Beijing Origin Water Technology Co., Ltd. and Omexell Environmental Engineering Co., Ltd. and overseas-funded companies like Zenon-GE and CNC-Simens. Origin Water occupies the majority of the MBR market in China, whereas CNC-Simens and Zenon-GE have a larger number of installations in other parts of China. MBR unit key suppliers in China are Zenon (Canada), Mitsubishi-Rayon (Japan), Toray (Japan), Kubota (Japan), Norit (Netherlands), Motimo (China) etc.Due to more stringent regulations and wastewater reuse strategies, it is expected that a significant increase in MBR plant capacity and a widening of application areas will occur in the future.     

A continuous process for dye removal from liquid effluents using carbonised wool waste

Industrial dyeworks are often conspicuous due to discoloration of rivers and streams into which they discharge waste materials. The adsorption process put forward for the treatment of such effluent makes use of wool-carbonising waste made up of carbonised keratinic fibres and a hydrolysed vegetable material rich in ionic groups. This agro-industrial by-product showed a remarkable capacity for fixing surfactants, metallic cations and dyes. The current pilot project studied the removal of Maxilon Red from aqueous solutions by adsorption of the dye into the vegetable part of waste from the carbonising process. The operation was carried out continuously in a series of mixers. An examination of the hydrodynamic behaviour of a particular type of extractor established operating conditions favouring efficient removal of dyes from the effluent. A maximum dye removal rate of around 98% was possible.     

Viability study of different reverse osmosis membranes for application in the tertiary treatment of wastes from the tanning industry

The tanning industry uses large quantities of water and produces a correspondingly large amount of wastewater with high levels of salts and organic materials. Before these wastewaters can be eliminated, they must be submitted to a suitable depuration treatment. However, conventional treatments such as those used for urban wastewater are not able to reduce the salt content sufficiently and new methods need to be studied in the light of new technologies. In this aspect, membrane technology is increasingly used as a separation technique in chemical and environmental engineering, including desalination, selective separation and wastewater treatment. In this paper, we describe a comparative study of six different reverse osmosis membranes, which were tested for their ability to reduce the salt content in the tertiary treatment after the elimination of chromium salts and organic matter of an effluent from a pilot plant for treating industrial wastewater from the tanning industry to reach the legal levels established for their safe disposal. The membranes were checked using a 3×10⁻³ m² flat cell, where the concentrated streams were recirculated to the feed reservoir.     

膜蒸馏和膜吸收技术现状及发展

膜蒸馏和膜吸收是一种以蒸汽压差为推动力的新型高效的膜分离技术,作者介绍了膜蒸馏和膜吸收技术发展现状,机理及优缺点,并对其在有机废水处理中的应用及今后发展方向进行了论述。     

利用蒸馏与中和方式处理顺酐洗锅废水

利用顺丁烯二酸酐生产过程中副产的蒸汽对产生的洗锅废水进行蒸馏、中和处理,降低了洗锅废水中污染物浓度,使废水达到可进一步处理的工艺要求。     

渗透模式影响纳米涂层修饰陶瓷微滤膜分离性能的研究

研究了膜分离技术处理含油废水存在因油滴变形引起的膜堵塞问题。为减少膜污染,使用在市场上销售氧化铝微滤膜孔道表面制备纳米ZrO2涂层,利用纳米涂层改变微滤膜的表面亲水憎油性,具有良好的效果。考虑其工业应用条件,重点研究了循环模式（模拟大量废水处理）和浓缩模式（模拟少量废水处理）对膜渗透通量的影响。结果表明：循环模式下料液的油浓度为恒定的,纳米涂层能有效提高微滤膜的渗透通量。膜面流速的增加在一定程度上能提高膜渗透通量,但超过一定程度后,增加不明显。当膜面流速为7m／s时,修饰陶瓷膜的最大渗透通量为280L／（m^2·h）,油截留率为96．4％。在浓缩模式下,料液的油浓度随渗透液的排出呈指数性增加,随着油浓度的增加,渗透通量持续衰减,油截留率持续上升。当油浓度达到一定程度后,修饰陶瓷微滤膜不能有效地实现稳定含油废水的油水分离。     

Membrane choice for wastewater treatment using external cross flow tubular membrane filtration

Systematic investigations of activated sludge separation were conducted using membrane filtration. To accomplish this, different organic tubular membranes with different separation limits and diameters were examined. Furthermore, from the results obtained in the initial tests, an appropriate membrane was chosen for a long-term test. The investigations determined that for biomass separation by the tubular membranes in the tested system, neither the membrane material nor the separation limit within a range of 1 μm to 20,000 Da had a significant influence on the filtration characteristics. It was recognized that the application of a tubular membrane with a diameter of less than 8 mm is problematic, because high flow velocities were needed to prevent blockage of the membrane. When the flow velocity was in the range of 1 to 4 m/s, a linear relation between flux and velocity was found. This showed the potential for controlling the membrane filtration process and externally influencing the permeate rate. An average retention of TOC was about 75%. The retention of TOC was not significantly influenced by the nominal pore sizes of the membranes (except for the membrane WFNX 0505) which were tested here. The ultrafiltration membrane WFS 0120 (Stork) was prominent in the long-term test due to its very high flux, germfree permeate with a MWCO (molecular weight cut-off) of 100,000 Da, and was not blocked with a diameter of 14.4 mm, also at lower flow velocities. The results of the long-term test supported the hypothesis that a meaningful application of such a module concept is possible in a filtration plant for the preparation of samples or for the rejection of the biomass in small sewage treatment plants.     

Microbial Fuel Cell Membrane Bioreactor in Wastewater Treatment,Electricity Generation and Fouling Mitigation

Membrane bioreactors (MBR) have gained much attention due to their ability to achieve higher treatment efficiency. However, high external energy consumption in aeration for membrane fouling mitigation has been limiting their application. Microbial fuel cells (MFC) can ideally extract energy from wastewater in the form of electricity and reduce membrane fouling. Thus, the use of MFC-MBR is rapidly expanding. However, the MFC-MBR design and operation is not fully mature and further research is needed to optimize the process efficiency and enhance the applicability. This review gives an overview of recent studies on the performances of MFC-MBR systems, regarding the design and configuration of the integrated system, irrespective of whether optimization was done or not in the operating system.     

膜法水处理技术在油田上的应用

微滤、超滤、反渗透和电渗析法的特点及其在在国内外油田水处理上的应用,膜法水处理技术将成为油田水处理的一个主要发展方向。     

High strength wastewater treatment in a jet loop membrane bioreactor: kinetics and performance evaluation

Treatment of wastewater containing high organic matter was investigated by means of a jet loop bioreactor combined with a membrane process. Volume of jet loop bioreactor and area of membrane filtration unit were 23 l and 155 cm² respectively. It was found that jet loop reactor had high mass transfer coefficient (K_La) varying from 58.8 to 486 h^-1 depending on the water flow rate (i.e. power input) and air flow rate. Oxygen transfer efficiency and oxygenation capacity of the reactor varied from 12 to 22.5% and from 0.2 to 1.8 , respectively. The efficiency of jet loop membrane bioreactor was found to be approximately 97% for a volumetric organic load of 2- over a period of 10 weeks. The reactor was not disturbed from the organic loads up to , but the treatment efficiency decreased to about 60% at higher organic loads. This decrease was due to insufficient oxygen transfer rate. The relationship between the effluent substrate concentration and the specific oxygen uptake rate (SOUR) values was determined. Applied food/microorganism (F/M) ratio was varied between 2.5 and . Critical sludge age of the system () was evaluated to be 7.2 h. Sludge with unsatisfactory settling characteristics formed at high F/M values under turbulent conditions. Therefore, membrane process was used for solid-liquid separation and effluent solid concentration was approximately zero. Specific cake resistances (α) changed with F/M ratio. It was found that permeate fluxes were significantly effected with F/M ratio much more than mixed liquor suspended solids (MLSS). Average flux was for pore sized cellulose acetate membrane. It was concluded that the jet loop membrane bioreactor has distinctive advantages such as the ability to treat high strength wastewater, low area requirements and easy operation.     

Application of Seeded Membrane Distillation Crystallization for Zero Liquid Discharge

Zero liquid discharge (ZLD) is a crucial requirement in industrial operations concerned with water scarcity and environmental protection. This study investigates the feasibility of using membrane distillation combined with crystallization (MDC) as a potential solution for ZLD. High-saline NaCl solutions were used to evaluate the performance of a seeded MDC system, which demonstrated excellent recovery rates for both water (over 95 %) and salt (over 95.5 %). The presence of seeding crystals in the MDC system was found to inhibit membrane wetting. The MDC system achieved an average thermal efficiency of 61.5 %, showcasing its potential for long-term processes. These results indicate that introducing seed crystals to the membrane's feed side enhances the MDC system's viability as a promising solution for ZLD. Additionally, the MDC system offers the prospect of high water and salt recovery, making it a sustainable approach to wastewater treatment and water reclamation.     

Spiral-wound membrane reverse osmosis and the treatment of industrial effluents

Reverse osmosis (RO) is increasingly used as a separation technique in chemical and environmental engineering where desalination, selective separation and wastewater treatment are well established examples. Treatment by RO reduces high levels of dissolved salts but has certain limitations when used for the removal of organic compounds from effluents of the chemical industry. The spiral-wound membrane element is the most widely used membrane device because it has a high membrane surface area to volume ratio, it is easy to replace and can be manufactured from a wide variety of materials. This work forms part of a wider research project aimed at recovering products and reducing the concentration of pollutants in wastewater by using membrane process. The synthetic effluent stream that was treated contained an organic product (acrylnitrile) and four inorganic species (sulphate, ammonium, cyanide and sodium). It was found that the pH value ofthe solution plays an important role in the ionization of the different species and, subsequently, in their retention. The object of this study was to reduce the concentration of pollutants to the levels of mentioned regulations concerning discharges, using a pilot plant with a spiral-wound membrane element (0.56 m² surface area) and a polyamide membrane, which was previously selected. The RO measurements were carried out in a closed-loop controlled-pressure system, with the solution being constantly fed through the spiral-wound membrane. The rejection percentage of sulphate ion was high in the two treatments assayed, regardless ofthe operational pH and sequence of steps followed. The degree to which NH₄⁺ and CN⁻ were eliminated was strongly dependent on the pH of the feed stream. Ammonium ion, too, was strongly eliminated regardless ofthe sequence ofthe steps, while the best results with CN⁻ were obtained when the first step had a nearly neutral pH and the second a pH of 11.0. Acrylnitrile showed low rejection percentages in all the steps carried out.     

含油废水处理技术的研究与应用现状

综述了含油废水的来源、危害与分类,并对重力法、气浮法、电化学法、吸附法、超声波法和生物法等传统的含油废水处理方法的原理、优缺点及改进作了较详细的论述。分析了石油工业含油废水的特征并对现有工艺应用现状作了概述。根据目前研究现状预测了含油废水处理方法的发展趋势。     

乳状液膜法处理粘胶纤维厂的含锌废水

针对粘胶纤维厂排放的含锌废水，对乳状液膜的制备条件、乳状液与废水的混合分离工艺和交流高电压破乳器设计方法进行了较为详细的理论和实验研究。结果表明，在最佳操作条件下，经一级液膜分离，废水中锌离子浓度可降至５ｐｐｍ以下。     

SheII 煤气化废水处理及回用

Shell 煤气化工艺过程产生的废水具有高 SS、高 CODCr 以及污染物成分复杂的特点，其中主要的污染物有氰化物、 NH3-N、硫化物以及苯酚等。通过预处理（曝气-絮凝沉降)、深度氧化以及双膜处理的工艺对 Shell 煤气化废水进行处理，考察了各工艺段的最佳运行条件。试验结果表明，在最优运行条件下，该处理工艺出水达到GB 8978-1996《污水综合排放标准》的要求，同时通过阻垢及缓蚀试验结果确定，工艺出水达到 GB 50050-2007《工业循环冷却水处理设计规范》中工业循环水用水标准的要求，可以回用至循环冷却水系统。     

弱酸床处理循环冷却水系统防垢试验研究

从调节循环冷却水的水化学工况入手，防止以弱酸床处理水作为循环冷却水补充水系统的结垢与腐蚀。实验室及现场运行试验结果表明，该方法行之有效。