Power ultrasonic freezing for membrane concentrate treatment

用于膜浓缩物处理的功率超声冷冻

• 批准号: RGPIN-2014-06573
• 负责人: Gao, Wa
• 金额: $ 1.46万
• 依托单位: Lakehead University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567899
• 关键词: Power; ultrasonic; freezing; membrane; concentrate

Application of membrane technologies has increased dramatically in recent years due to increasing demand for drinking water and decreasing unpolluted source water. Membrane filtration, especially, reverse osmosis (RO) and nanofiltration (NF) are the leading technologies for treatment of nontraditional source water such as seawater, brackish groundwater and reclaimed wastewater for potable and nonpotable uses. However, membrane filtration operations generate large volumes of wastewater/liquid waste, including reject-brine, backwash water and membrane cleaning solutions. The product water recovery, for instance, is only 30-40% for some RO/NF membrane based desalination plants. With continued installation of membrane plants, disposal of the concentrate is becoming a major factor affecting the viability of many membrane projects. Currently, most concentrate generated from the membrane filtration operations is discharged into surface water or sanitary sewers without any treatment (except some type of pH adjustment for cleaning wastes). Salts, metals and organic contaminants contained in the feed water become concentrated during membrane filtration processes, along with chemicals and reaction byproducts from pretreatment. Discharging the membrane concentrate of desalination plants into seawater has been considered a safe option but recent studies have shown that the dilution of the concentrate by seawater may be lower than expected. Continue to discharge large volumes of untreated membrane concentrate may result in serious adverse impacts on the aquatic environment. Treatment of membrane concentrate is becoming necessary and volume minimization, even zero-liquid discharge may be soon required for some operations. However, little effort has been made so far to develop practical treatment technologies for environmentally friendly management of membrane concentrate. This research proposal presents an innovative method for membrane treatment and volume reduction. Freeze concentration is a physical process that involves the fractional crystallization of water and subsequent removal of ice. When freeze concentration is used to purify water or liquid waste, impurities are separated from ice crystals and concentrated in the unfrozen liquid. The advantages of freeze concentration treatment include no addition of chemicals, high treatment efficiency, high capacity of waste volume reduction, low corrosion of the treatment facility, and recovery of a pure water stream from the original liquid waste. Power ultrasonic freezing is a promising technology that may significantly improve efficiency of freezing processes. The primary objective of the proposed study is to develop a power ultrasonic freeze concentration (PUFC) process/unit that can be used in new or the existing OR/NF desalination or water/wastewater treatment plants for membrane concentrate treatment. The significance of the proposed research lies in its potential not only to provide an effective technology for membrane concentrate treatment but also to improve the product water recovery rate for the RO/NF membrane filtration plants by generating a pure water stream from the ice formed from membrane concentrate. This research will also advance our knowledge of the effect of ultrasound waves on chemical, physical and/or biological characteristics of freezing materials, ice nucleation and impurity incorporation/rejection in water-ice (solid) interface. The membrane based seawater desalination industry, in-land water and wastewater treatment plants, as well as all freezing related industrial processes such as refrigeration, pharmaceutical, chemical and food processing will greatly benefit from this research.

近年来，由于饮用水需求的增加和未污染水源的减少，膜技术的应用急剧增加。膜过滤，特别是反渗透（RO）和纳滤（NF）是处理非传统水源水的领先技术，如海水，微咸水地下水和再生水用于饮用和非饮用用途。然而，膜过滤操作会产生大量废水/液体废物，包括废弃盐水、反冲洗水和膜清洁溶液。例如，对于一些基于RO/NF膜的脱盐工厂，产品水回收率仅为30-40%。随着膜设备的不断安装，浓缩物的处置正在成为影响许多膜项目可行性的主要因素。目前，膜过滤操作产生的大多数浓缩物未经任何处理就排入地表水或卫生下水道（除了某些类型的pH值调节以清洁废物）。给水中所含的盐、金属和有机污染物在膜过滤过程中与来自预处理的化学品和反应副产物一起沿着浓缩。将海水淡化厂的膜浓缩液排入海水被认为是一种安全的选择，但最近的研究表明，海水对浓缩液的稀释可能低于预期。继续排放大量未经处理的膜浓缩物可能会对水生环境造成严重的不利影响。膜浓缩液的处理变得越来越必要，并且体积最小化，甚至对于某些操作可能很快需要零液体排放。然而，迄今为止，几乎没有努力开发用于膜浓缩物的环境友好管理的实用处理技术。这项研究提出了一种膜处理和体积减少的创新方法。 冷冻浓缩是一个物理过程，涉及水的分级结晶和随后的除冰。当冷冻浓缩用于净化水或液体废物时，杂质从冰晶中分离并浓缩在未冻结的液体中。冷冻浓缩处理的优点包括不添加化学品、处理效率高、废物体积减少能力高、处理设施的腐蚀低、以及从原始液体废物中回收纯水流。功率超声冷冻是一种很有前途的技术，可以显着提高冷冻过程的效率。拟议研究的主要目标是开发一种功率超声冷冻浓缩（PUFC）工艺/装置，可用于新的或现有的OR/NF脱盐或水/废水处理厂膜浓缩液处理。拟议的研究的意义在于它的潜力，不仅提供了一种有效的技术，膜浓缩液处理，但也提高产品水回收率的RO/NF膜过滤厂通过产生纯净水流从膜浓缩液形成的冰。这项研究也将推进我们的知识超声波对冷冻材料的化学，物理和/或生物特性，冰成核和杂质的掺入/排斥在水-冰（固体）界面。基于膜的海水淡化工业，陆地水和废水处理厂，以及所有与冷冻相关的工业过程，如制冷，制药，化学和食品加工将大大受益于这项研究。