Reverse osmosis membrane composition, structure and performance modification by bisulphite, iron(III), bromide and chlorite exposure

Reverse osmosis (RO) membrane exposure to bisulphite, chlorite, bromide and iron(III) was assessed in terms of membrane composition, structure and performance. Membrane composition was determined by Rutherford backscattering spectrometry (RBS) and membrane performance was assessed by water and chloride permeation, using a modified version of the solution-diffusion model. Iron(III) dosage in presence of bisulphite led to an autooxidation of the latter, probably generating free radicals which damaged the membrane. It comprised a significant raise in chloride passage (chloride permeation coefficient increased 5.3–5.1 fold compared to the virgin membrane under the conditions studied) rapidly. No major differences in terms of water permeability and membrane composition were observed. Nevertheless, an increase in the size of the network pores, and a raise in the fraction of aggregate pores of the polyamide (PA) layer were identified, but no amide bond cleavage was observed. These structural changes were therefore, in accordance with the transport properties observed.Peer ReviewedPostprint (author's final draft

Particle Image Velocimetry (PIV) measurements in a water film, application to a tire rolling through a puddle

International audienceA measurement method based on Particle Image Velocimetry with refraction of the laser sheet at a win-dow/water interface is proposed for the measurement of the velocity field of a water flow formed by a tire moving inside a water puddle. This study focuses of the feasibility and repeatability of this optical measurement method. The characterization of the optical properties of the measurement technique defines the integration effect in height of the measurement method. The analysis of the overall features of the flow is focused on two main zones in front and around the tire. The flow inside the first zone is defined by a characteristic velocity of the water displaced in an area located in front of the tire ; in the second zone a characteristic velocity representative of the flow in the vicinity of the shoulder of the tire is also defined. Correlations of both characteristic velocities with the car speed and water film height are established. New and worn tires were tested in this work

Understanding reverse osmosis polyamide active layer macrostructure and performance through indirect microscopic observation of film growth

Given the random nature of reverse osmosis polyamide macrostructure, it is difficult to understand the relationship between its structure and its separation characteristics. Many have addressed this subject and a few have reached significant conclusions to date. Acknowledging that membrane chemistry is the most important lever in controlling performance and not structure, to truly understand which features of the polyamide film can be manipulated to affect performance, there may be value in understanding its formation mechanism. Building upon a basic grasp of this mechanism, it may be possible to fine tune membrane performance through structure manipulation. While direct observation of polyamide film growth is not yet possible on a microscopic scale, new methods have been developed for indirect observation of the process. These methods, pseudo-stop-motion imaging and reactive post-polymerization potting, have provided valuable insight on the formation mechanism. The pseudo-stop-motion imaging technique was developed to view the polyamide structure on a microscopic scale at discrete points in time during the interfacial polymerization, from the first appearance of polyamide material on the support surface to the end of the polymerization. Essentially watching the process occur diminished the need for complex modeling to produce a basic growth hypothesis. Furthermore, the method can be used for any type of polyamide, and is limited only by the resolution of electron microscopy. Reactive post-polymerization potting is a technique developed to understand the structure of polyamide in its as-formed state. Historical microscopy has been performed on dried membranes, but not on films immediately following polymerization. The resulting structures are strikingly different from those observed in the literature via SEM and TEM, and when taken in context with the growth mechanism proposed from pseudo-stop-motion imaging, it further supports a mechanism of polyp inflation rather than continuous film formation. Well-controlled pilot-scale polyamide casting has been performed to corroborate the proposed mechanistic theory, and the theory will be framed within the broader context of polyamide membrane development

Підготовка питної води для населення міста Дніпродзержинська

Наведена динаміка зміни якості води у Дніпродзержинському водосховищі в період 2005–2008 років, а також виконаний більш глибокий аналіз середньорічних показників якості води за 2008 рік. Визначені вузькі місця в схемі підготовки питної води на Аульському водозаборі. Розроблені заходи для покращення перемішування коагулянту з водою, а також виготовлена у масштабі пілотної установки удосконалена реакційна камера.The dynamics of the change of the quality of water in Dniprodzerzhinsk water-storage reservoir is presented during the period of 2005–2008 years and the richer analysis of the average annual rates of the quality of water for the 2008 year is done. The bottlenecks in the scheme of the drinking-water preparation in Auli intake are determined. Measures for improvement of interfusion of coagulant with water are worked out and the improved reaction chamber is made at scales of pilot facility

Оптимизация современных технологий деминерализации морской воды для нужд электроэнергетики

Статья посвящена разработке экономически оптимальной технологии деминерализации морской воды для нужд электроэнергетики. Показана экономическая целесообразность применения двухстадийной обратноосмотической технологии с использованием мембран среднего и низкого давления для деминерализации воды Черного моря. Предложенная энергоэффективная технология получения питьевой воды из морской не требует постреминерализации.Economical effectiveness of seawater desalination process for power producing industry is considered in the article. It is shown that double-stage reverse osmosis utilizing low and middle pressure membranes is the most preferable for demineralization of Black Sea water. Energy effective membrane technology for drinking water producing is suggested, which is cost-effective due to needless of remineralization stage

Energy-water-environment nexus underpinning future desalination sustainability

Energy-water-environment nexus is very important to attain COP21 goal, maintaining environment temperature increase below 2 °C, but unfortunately two third share of CO2 emission has already been used and the remaining will be exhausted by 2050. A number of technological developments in power and desalination sectors improved their efficiencies to save energy and carbon emission but still they are operating at 35% and 10% of their thermodynamic limits. Research in desalination processes contributing to fuel World population for their improved living standard and to reduce specific energy consumption and to protect environment. Recently developed highly efficient nature-inspired membranes (aquaporin & graphene) and trend in thermally driven cycle's hybridization could potentially lower then energy requirement for water purification. This paper presents a state of art review on energy, water and environment interconnection and future energy efficient desalination possibilities to save energy and protect environment

THE COST OF DIRECT AND INDIRECT POTABLE WATER REUSE IN A MEDIUM SIZED INLAND COMMUNITY

In the face of increasing population, development pressures, and climate change, many regions around the world face freshwater shortages. Planned potable water reuse can improve sustainability and reliability of water supplies by providing drinking water from wastewater. Most potable reuse research has focused on large coastal communities with relatively high mean household incomes. However, the US Department of Interior predicts that “hot spots” of conflict over water in the arid West are “highly likely” in numerous small-to-medium-sized inland communities with low-to-moderate household income levels. Potable reuse options may be different for larger, wealthier coastal communities as compared to small-to-medium-sized inland ones, not only in terms of the technologies used, but also in the communities’ knowledge of, attitudes toward, and ability to pay for the required technologies. Significant knowledge gaps exist regarding these issues for the arid, inland context, making it difficult for inland water managers to understand the feasibility of potable reuse for their communities. This research aims to inform decision-making about planned potable reuse in small-to-medium-sized, arid inland communities by estimating the total present worth of several indirect and direct potable reuse treatment scenarios that are appropriate for the inland context. The Albuquerque Bernalillo County Water Utility Authority in Albuquerque, NM, was used as a case study. Each of the indirect and direct potable reuse scenarios was examined with two different options for advanced treatment: reverse osmosis and ozone/biological activated carbon, both of which were preceded by microfiltration and followed by ultraviolet disinfection. The results showed that the present worth for indirect potable reuse was substantially higher than that for direct potable reuse primarily because of additional pumping and piping requirements. The type of advanced treatment included in an indirect or direct potable reuse scenario had a significant impact the scenario’s overall present worth, with options including reverse osmosis being more expensive than those including ozone/biological activated carbon. Costs aside, any scenario must also be acceptable to regulators and the public and approvable from a water rights perspective

Fresh water generation from aquifer-pressured carbon storage: Feasibility of treating saline formation waters

AbstractBrines up to 85,000 ppm total dissolved solids produced during Carbon Capture and Storage (CCS) operations in saline formations may be used as the feedstock for desalination and water treatment technologies via reverse osmosis (RO). The aquifer pressure resulting from the injection of carbon dioxide can provide all or part of the inlet pressure for the desalination system. Residual brine from such a process could be reinjected into the formation at net volume reduction, such that the volume of fresh water extracted is comparable to the volume of CO2 injected into the formation. Such a process could provide additional CO2 storage capacity in the aquifer, reduce operational risks (e.g., fracturing, seismicity, leaking) by relieving overpressure in the formation, and provide a source of low-cost fresh water to offset costs or operational water needs equal to about half the water usage of a typical coal ICGG power plant. We call the combined processes of brine removal, treatment, and pressure management active reservoir management. We have examined a range of saline formation water compositions propose a general categorization for the feasibility of the process based total dissolved solids (TDS): •10,000–40,000 mg/L TDS: Standard RO with ≥50% recovery•40,000–85,000 mg/L TDS: Standard RO with ≥10% recovery; higher recovery possible using 1500 psi RO membranes and/or multi-stage incremental desalination likely including NF (nanofiltration)•85,000–300,000 mg/L TDS: Multi-stage process using process design that may differ significantly from seawater systems•>300,000 mg/L TDS brines: Not likely to be treatable Brines in the 10,000–85,000 mg/L TDS range appear to be abundant (geographically and with depth) and could be targeted in planning CCS operations. Costs for desalination of fluids from saline aquifers are in the range of $400–1000/acre foot of permeate when storage aquifer pressures exceed 1200 psi. This is about half of conventional seawater desalination costs of$1000–1400/acre foot. Costs increase by 30 to 50% when pressure must be added at the surface. The primary reason for the cost reduction in pressurized aquifers relative to seawater is the lack of need for energy to drive the high-pressure pumps. An additional cost savings has to do with less pre-treatment than is customary for ocean waters full of biological activity and their degradation products. An innovative parallel low-recovery approach is proposed that would be particularly effective for saline formation waters in the 40,000–85,000 mg/L TDS range