Studies on Feasibility of Reverse Osmosis (Membrane) Technology for Treatment of Tannery Wastewater

Tanneries reusing wastewater by combination of conventional and advanced Reverse Osmosis (RO) treatment technologies were assessed for technical and economic viabilities. Conventional treatment methods such as neutralization, clari-flocculation and biological processes are followed to clean the effluents before feeding to RO membrane modules. The characteristics of untreated composite effluents such as pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), total dissolved solids (TDS), and total chromium were in the range of 4.00-4.60, 680-3600 mg/L, 1698-7546 mg/L, 980-1480 mg/L, 4200-14500 mg/L, and 26.4-190 mg/L, respectively. Inorganic ions like Ca2+, Na+, Cl– and SO42– were found more in the wastewaters. Conventional treatments significantly removed the organic pollutants however failed to remove dissolved inorganic salts. Membrane technology removed the salts as well as remaining organic pollutants and the product water is reused in the process. The studied tanneries (5 numbers) have achieved 93-98%, 92-99% and 91-96% removal of TDS, sodium and chloride, respectively. Seventy to eighty five percentage of wastewater was recovered and recycled in the industrial processes. The rejects are subject to either solar evaporation system or Multiple Effect Evaporation (MEE) technology. The resulting salts are collected in polythene bags and disposed into scientifically managed secured land fill (SLF) site. The cost of wastewater treatment for operation and maintenances of RO including the pre-treatments (conventional methods) is INR 100-110 m-3.

An Air Operated Domestic Brackish Water Reverse Osmosis Plant: Economically Sustainable Solution for Safe Drinking Water Supply for Chronic Kidney Disease of Unknown Etiology Affected Areas in Sri Lanka

Chronic Kidney Disease with unknown etiology (CKDu) is one of the crucial health issues in North Central, Uva, North Western, North, Central, and Eastern Provinces of Sri Lanka and incapacitates the kidney function. The main source for the CKDu has not yet been identified, though many scientists believed that the number of certain drinking water quality parameters is changed due to the contamination of water sources by agricultural activities. Hence, the government of Sri Lanka introduces electrically driven Brackish Water Reverse Osmosis (BWRO) plants with a capacity of 10 tones/day to supply safe drinking water for the impacted community though it is an energy-intensive process. Concurrently, a smaller version of an electrically driven BWRO plant was introduced to the rural farming community for their domestic use. However, it was not practically worked out due to various reasons such as high cost, unavailability of electrical power supply for those villages. In this study, an economical air operated domestic use BWRO plant with zero-emission was designed. This anticipated system significantly reduces the government expenditures to subsidize the water purification cost by 50% of the existing expenses. Besides, simple payback time was found to be 2.5 years, and the benefit-cost ratio to be more than 1. Evaluating the performance with the conventional values, it comprehends with more sustainable and economically viable system compared to the existing method of water purification.

Design and Operation of Small-Scale Photovoltaic-Driven Reverse Osmosis (PV-RO) Desalination Plant for Water Supply in Rural Areas

The alarming water and energy crisis in many regions of the world can be eased by combining renewable energy with desalination technologies. The ADIRA project funded by the EU looked for demonstrating the feasibility of water desalination in areas around the Mediterranean by installing a number of autonomous desalination systems (ADS) which are able to convert brackish or seawater into potable water for the needs of small communities. Within the activities of the ADIRA project a reverse osmosis unit powered by photovoltaic electricity was installed in a village in the northern part of Jordan with a capacity of 0.5 m3/day. The system was composed of a softener, reverse osmosis unit, PV panels (432 Wp) and storage batteries. Residential type “OSMONICS” membrane (TFM-100) was utilized in the RO unit. Field tests were performed on brackish water (1700 mg/L total dissolved solids (TDS)). This paper sheds the light on the process flow diagram, sizing of the system main components and presents some of the results obtained.

Pilot Scale Biological Treatment as Pre-Treatment for Reverse Osmosis

Treatment of pharmaceutical wastewaters is a challenging task owing to their complexity and pollution load, variability in strength of waste streams accompanied with shock loads. Since no single treatment system is a viable option, integration of existing systems with advanced physical/chemical processes has been gaining attention for treatment of pharmaceutical wastewater. In the present study, two biological treatment methods were evaluated for their efficiency as pre-treatment system for RO which are sequencing batch reactor and membrane bioreactor. Efficiency of biological treatments tested SBR and MBR was pre-sented in terms of percentage removal of physico-chemical parameters. Total dissolved solids removal by SBR was 31.82% while MBR showed 29.25% reduction. Chemical oxygen demand removal by SBR was 69.54% while MBR showed 30.35% removal. Efficiency of combined treatments SBR-RO and MBR-RO was presented in terms of removal of total dissolved solids, COD and ammonia. TDS removal was the highest in the combination of SBR-RO with 95.94% removal, while MBR-RO combination resulted in 87.29% removal. Chemical oxygen demand was achieved maximum with the combination of MBR-RO 92.33% while competitive results were achieved with the combination SBR-RO also with 88.62% removal. Removal of ammonia was maximum with the combination SBR-RO 87.5%, while competitive results were obtained with MBR-RO 85.51%. From the results, it can be understood that SBR was efficient in removing ammonia, total dissolved solids and was equally competent in removing chemical oxygen demand. This study concludes that combined treatment of SBR-RO proves to be promising in treating pharmaceutical wastewaters.

Membrane Engineering for Green Process Engineering

Green process engineering, which is based on the principles of the process intensification strategy, can provide an important contribution toward achieving industrial sustainable development. Green process engineering refers to innovative equipment and process methods that are expected to bring about substan- tial improvements in chemical and any other manufacturing and processing aspects. It includes decreasing production costs, equipment size, energy consumption, and waste generation, and improving remote con- trol, information fluxes, and process flexibility. Membrane-based technology assists in the pursuit of these principles, and the potential of membrane operations has been widely recognized in the last few years. This work starts by presenting an overview of the membrane operations that are utilized in water treatment and in the production of energy and raw materials. Next, it describes the potential advantages of innovative membrane-based integrated systems. A case study on an integrated membrane system （IMS） for seawa- ter desalination coupled with raw materials production is presented. The aim of this work is to show how membrane systems can contribute to the realization of the goals of zero liquid discharge （ZLD）, total raw materials utilization, and low energy consumption.

Experimental Investigation on Saline Water Purification Using Reverse Osmosis by a Novus Biomimetic Membrane

A substantial amount of Earth’s water is inadequate for human consumption while local demand is outstripping traditional supplies in many world regions;thereby,brackish and seawater treatment has become a prerequisite.This investigation suggested a complete design of an RO-based desalination filter with a multilayer biomimetic membrane.The study demonstrated a comprehensive method for experimentally fabricating a proprietary biomaterial-based multilayer nano-porous membrane.This analysis revealed that Silk Nano-Fibril(SNF)and Hydroxyapatite(HAP)extracted from Bombyx Mori silkworm cocoons may be utilized to manufacture highly methodical multilayer membranes by incorporating protein-self-assembly and in-situ-bio-mineralization.Membrane’s aquaporin layer containing lipid-bilayers has rapid water permeability and high efficacy at eliminating salt ions and contaminants.The 4µm thick SNF/HAP membrane showed a considerable decrease in salinity,with a salt rejection of 93.33%.The proposed membrane had a saline water permeability of 6.58 LMH/bar,almost 61.09%higher than conventional TFC membranes.Hydrophobic barrier and spiral-wrapped filter architecture of the membrane enable low fouling and self-cleaning properties.The schematic filter design and biomimetic fabrication of the SNF/HAP membrane have formulated a conceptual framework that might direct to the broad-scale,low-cost RO water purification filters,increasing the efficiency of water desalination and boosting the effectiveness of water treatment technologies to reduce potable water scarcity.

Highly hydrophobic oil−water separation membrane: reutilization of waste reverse osmosis membrane

The increasing applications of seawater desalination technology have led to the wide usage of polyamide reverse osmosis membranes,resulting in a large number of wasted reverse osmosis membranes.In this work,the base nonwoven layer of the wasted reverse osmosis membrane was successfully modified into the hydrophobic membrane via surface deposition strategy including TiO_(2) and 1H,1H,2H,2H-perfluorooctyltrichlorosilane(PFOTS),respectively.Various techniques were applied to characterize the obtained membranes,which were then used to separate the oil–water system.The optimally modified membrane displayed good hydrophobicity with a contact angle of 135.2°±0.3°,and its oil–water separation performance was as high as 97.8%.After 20 recycle tests,the oil–water separation performance remained more than 96%,which was attributed to the film adhesion of the anchored TiO_(2) and PFOTS layer on the surface.This work might provide a new avenue for recycling the wasted reverse osmosis membrane used in oily wastewater purification.

太阳能真空膜蒸馏和肥料汲取液正渗透处理反渗透浓水的节能性和经济性分析

针对太阳能真空膜蒸馏(Solar vacuum membrane distillation,SVMD)和肥料汲取液正渗透(Fertilizer draw forward osmosis,FDFO)系统处理反渗透(Reverse osmosis,RO)浓水的试验研究较多,而对其能耗和经济性分析的较少.通过对试验规模和工业规模条件下2种系统的膜通量、能耗和成本进行对比分析,结果表明,在试验规模条件下,将RO浓水浓缩4倍,无辅助热源SVMD系统的膜通量为2.46 kg/(m^(2)·h),比能耗为110.6 kWh/m^(3),单位水生产成本为96.6元/m^(3);有辅助热源SVMD系统的膜通量为3.75 kg/(m^(2)·h),比能耗为230.7 kWh/m^(3),单位产水成本为13.4元/m^(3);FDFO系统的膜通量为3.62 kg/(m^(2)·h),比能耗为20.44 kWh/m^(3),单位产水成本为26.8元/m^(3).在工业化规模条件下,设计产水量均为240 m^(3)/d时,SVMD系统比能耗为12.8 kWh/m^(3),单位产水成本为10.8元/m^(3);FDFO系统比能耗为12 kWh/m^(3),单位产水成本为9.38元/m^(3).可见生产规模越大,不同系统的产水成本越小,差别也越小.

膜阻垢剂及其阻垢机理研究新进展

由于水资源紧缺的问题,反渗透膜处理技术发展迅速。膜阻垢剂因能减缓膜组件的结垢、提高水净化效率,因而被广泛应用于反渗透膜处理技术。常见的膜阻垢剂有磷酸盐类、阴离子聚合物类、阳离子聚合物类以及绿色阻垢剂等,一般认为它们可以通过螯合、分散、晶格畸变等作用或阈值效应阻碍或缓解垢的形成。树枝状聚合物膜阻垢剂具有优异的阻垢性能,与其结构相似的球形聚电解质刷作为一种刷状聚合物膜阻垢剂也在膜处理领域中崭露头角。深入研究新型膜阻垢剂的阻垢机理可为设计开发针对性强、经济环保的高效阻垢产品奠定理论基础。

苦咸水淡化处理研究进展

在我国一些干旱缺水地区,苦咸水是该地区仅有的可利用的水资源,因此苦咸水淡化成为了解决干旱地区域缺水的重要途径。为更系统的了解目前苦咸水淡化处理工艺及其流程,本文综述了近年来国内外苦咸水淡化处理技术和工艺流程,系统地总结了各处理方法的优缺点,并对未来苦咸水淡化技术的研究方向进行展望。

双膜法工艺在矿井水深度处理中的应用实例

高矿化度煤矿矿井水往往具有盐含量高、硬度和碱度高的特征,处理工艺复杂,难度较高。陕西某煤矿矿井水深度处理回用工程设计进水量为7200 m^(3)/d,产水量为4800 m^(3)/d(25℃),系统回收率为65%,采用超滤(UF)+反渗透(RO)双膜法工艺,产水回用于井下生产。该工程通过定量投加复合阻垢剂取代传统的药剂软化工艺,节约了投资成本和运行成本。运行数据表明:矿井水原水(经过格栅+预沉调节池+磁加载沉淀处理后)温度约为27℃,溶解性总固体质量浓度为3700~4000 mg/L,硬度在450~500 mg/L;产水TDS质量浓度在70 mg/L左右,硬度质量浓度≤6.0 mg/L,氯离子质量浓度<35 mg/L,硫酸根质量浓度<5.5 mg/L,脱盐率为98%,系统回收率为71.4%,运行稳定可靠。

反渗透浓水回收利用的探索研究

反渗透水处理伴随产生了大量的浓水,为了避免污染问题,分别从反渗透水处理装置的原理、反渗透浓水回收利用方案和相关注意事项出发,提出了反渗透浓水回收利用的工艺改造思路,进而使得水资源的利用率提高,最终为实现零排放奠定基础。

内循环脱氮反应器处理炼化反渗透浓水的工程应用

在内循环(Internal circulation,IC)厌氧反应器结构基础上,设计了IC脱氮反应器,并研究了其在炼化反渗透浓水处理中的工程应用。结果表明,IC脱氮反应器启动快、运行稳定。在进水TN为18.7~39.0 mg/L,平均26.6 mg/L条件下,经IC脱氮反应器处理后出水TN为1.89~14.0 mg/L,平均4.65 mg/L,显著低于《陕西省黄河流域污水综合排放标准》(DB 61/224—2018)表1中B标准对于TN≤15 mg/L的排放要求;出水悬浮物质量浓度低,平均为18.6 mg/L;后续内循环曝气生物滤池出水COD平均为35.4 mg/L,可稳定控制在50 mg/L以下,综合处理效果好。同时,该设备占地面积小,工艺简单,水处理直接成本为1.36元/m3,具有显著的经济效益。

以富CO_(2)吸收液为汲取液的沼液中水正渗透回收特性研究

针对沼气工程存在的沼液量大难处理问题及沼气提纯的需求,提出将正渗透技术与沼气CO_(2)化学吸收分离耦合,探究了沼气CO_(2)化学吸收中的富CO_(2)吸收液作为正渗透汲取液从沼液中回收水及浓缩沼液的可行性,并以沼液浓缩过程中的水通量、沼液浓缩倍数、沼液氨氮截留率与吸收剂反向传质通量为指标,考察了汲取液种类、汲取液浓度与其他操作参数对正渗透水回收性能的影响。结果表明,富CO_(2)吸收液作为汲取液从沼液中回收水并浓缩沼液具有可行性,且随着汲取液浓度、流量和温度的增加,沼液中水向汲取液的传质通量增加,沼液浓缩倍数也相应增加,但沼液中氨氮截留率下降,同时汲取液中的吸收剂溶质向沼液的反向传质通量也增加。当采用浓度2.5mol/L、CO_(2)负荷0.5mol/mol的富CO_(2)甘氨酸钾溶液作为汲取液,汲取液温度为70℃、流速为150mL/min、沼液室温及流速为150mL/min时,采用正渗透技术从沼液中回收水的初始通量达8.05L/(m^(2)·h),经过4h运行后,沼液浓缩倍数为1.18,氨氮截留率为84.13%,反向吸收剂通量仅为2.94g/(m^(2)·h)。

臭氧催化/超滤组合工艺去除石化反渗透浓水中有机物

由于石化反渗透浓水含盐量高且存在难降解有机物,不利于水资源的回收利用。采用臭氧催化/超滤组合工艺去除反渗透浓水中的有机物,通过分析臭氧催化氧化预处理实验中影响因素并考察超滤膜比通量变化规律并结合膜污染动力学模型揭示膜污染机理。研究结果表明:当臭氧催化氧化预处理条件为臭氧浓度17 mg/L、催化剂投加量体积比40%、紫外光强0.7 mW/cm^(2)、反应时间40 min,臭氧催化氧化预处理效果最佳;探讨孔径、流速、温度对膜比通量及膜污染影响,得出最佳运行条件为孔径20 nm、流速4.2 L/min、温度40℃且孔径越大、温度越低、流速越小,膜比通量越小,膜污染越严重;基于三维荧光光谱(3D-EEM)及水质分析,臭氧催化/超滤组合工艺能高效去除石化反渗透浓水中有机物。本研究构建的组合工艺可为石化反渗透浓水中的有机物去除提供参考。

电渗析浓缩钢铁工业浓盐水试验研究

以泰山钢铁反渗透浓水为对象进行电渗析(ED)浓缩中试研究。结果表明:ED对钢铁工业浓盐水具有较为理想的浓缩效果,能够实现浓盐水电导率的高倍浓缩,浓缩倍数为5~10倍。ED淡水电导率均<3000μs/cm;ED对浓盐水的浓缩效果受水中不同离子种类的影响;ED对COD的浓缩效果不明显,具有一定的抗有机物污染能力;试验期间ED能耗为2.3~2.4 kWh/t,浓水系统回收率≥85%,能够低能耗、高效率地实现浓盐水浓缩减量,为进一步实施废水零排放提供了可行性方向。

反渗透浓盐水零排放与改进设计

某除盐水站采用反渗透膜工艺处理回用水,稳定产出一级除盐水和一级浓盐水。为进一步浓缩处理浓盐水,提高钢铁工艺全流程废水的回收率和综合利用率,继续采用二级反渗透系统处理一级浓盐水,分离得到二级除盐水和二级浓盐水。二级除盐水循环补充到钢铁工艺流程或工业水管网,二级浓盐水则进入高含盐水管网。针对高含盐管网用水需求量不稳定的情况,结合该站现有的中水处理设备设施,进行改进设计,优化管路,统筹各级水源串级使用,落实废水资源化利用和浓盐水零排放。

新型压力驱动高倍膜浓缩技术在废水零排放处理中的应用研究

采用高倍膜浓缩技术对燃煤电厂脱硫废水零排放系统反渗透浓水进行深度浓缩处理中试试验研究。通过168 h连续运行测试,验证了高倍膜浓缩技术在6~7 MPa的运行压力下将浓盐水浓缩至100 g/L以上的可行性。现场连续运行测试结果表明,高倍膜浓缩工艺具有浓缩极限高、操作压力低、系统运行稳定的特点,可用于废水零排放反渗透浓水的减量化处理。

电厂高盐水回用工程实例

以浙江某电厂高盐水回用工程为实例,介绍了“高效反应器-流砂过滤器-超滤-弱酸阳床-反渗透”工艺在高盐水回用中的应用。结果表明:高盐水回用系统产水的电导率在250μS/cm以下,硬度为0,COD在7 mg/L以下,活性二氧化硅在4 mg/L以下。超滤水回收率在90%以上,一段反渗透水回收率在64%以上,脱盐率在98%以上,二段反渗透水回收率在55%以上,脱盐率在97%以上。且出水水质优良且稳定,可用作循环水补水,给该电厂带来良好的经济效益、环境效益和社会效益。

海涂水库水源水厂全流程工程设计

浙江沿海某地水资源匮乏,在沿海滩涂建设了海涂水库进行水资源开发利用,海涂水库水具有p H和碱度较高、氯化物高、有机物超标、冬季水温低等特点。文章就以海涂水库为水源的城市工业水厂工程设计进行了阐述。水厂设计供水规模为10万m^(3)/d,采用管道混合+折板絮凝+平流沉淀+超滤+反渗透+后矿化的处理工艺,滤池及超滤反冲洗水经沉淀后回用,反渗透浓水排海处置,污泥经机械浓缩脱水至80%后外运处置。工程已竣工运行3年,出水水质指标稳定达标,总体达到了预期的工程效果。