Reverse Osmosis Technology Research Articles

Electrochemical treatment of concentrate from reverse osmosis of sanitary landfill leachate

Conventional sanitary landfill leachate treatment has recently been complemented and, in some cases, completely replaced by reverse osmosis technology. Despite the good quality of treated water, the efficiency of the process is low and a large volume of reverse osmosis concentrate has to be either discharged or further treated. In this study, the use of anodic oxidation combined with electro-Fenton processes to treat the concentrate obtained in the reverse osmosis of sanitary landfill leachate was evaluated. The anodic oxidation pretreatment was performed in a pilot plant using an electrochemical cell with boron-doped diamond electrodes. In the electro-Fenton experiments, a boron-doped diamond anode and carbon-felt cathode were used, and the influence of the initial pH and iron concentration were studied. For the experimental conditions, the electro-Fenton assays performed at an initial pH of 3 had higher organic load removal levels, whereas the best nitrogen removal was attained when the electrochemical process was performed at the natural pH of 8.8. The increase in the iron concentration had an adverse impact on treatment under natural pH conditions, but it enhanced the nitrogen removal in the electro-Fenton assays performed at an initial pH of 3. The combined anodic oxidation and electro-Fenton process is useful for treating the reverse osmosis concentrate because it is effective at removing the organic load and nitrogen-containing species. Additionally, this process potentiates the increase in the biodegradability index of the treated effluent.

Co-production of frugal innovation: Case of low cost reverse osmosis water filters in India

The increased role of market actors in the provision of drinking water has implied a greater salience to issues of affordability. With its emphasis of increasing affordability without compromising on quality, the idea of frugal innovation holds out particular promise in resource constrained environments. In this paper, we study the case of low cost household water filters using reverse osmosis (RO) technology in the Indian city of Ahmedabad. Using mixed methods, we find the citizen to be an active participant – a co-producer – in the frugal innovation process that allows small scale, local entrepreneurs to customize their products and services to the needs and price expectations of their customers. This co-production process, that has been facilitated by the proximity of the user with the local entrepreneur, has not only reduced private costs borne by users but also been as successful as their more expensive counterparts in meeting the diverse needs of end users. Further, we find that the context facilitating such service co-production is characterized by institutional co-production, with actions of both the state and citizen creating the demand for innovation around more affordable, private solutions. While there is much to celebrate in the value created by the frugal innovation, we believe the implications of the contested and unregulated water filter technology suggest reasons for caution.

The Economics of Reverse Osmosis Desalination Projects

Desalination applications based on reverse osmosis (RO) technology today comprise over 50% of the capacity of all desalination systems worldwide and represent 75-85% of new desalination projects being implemented. The major reason for the shift in desalination projects to RO technology is the high energy efficiency of the RO process. There are three major application categories of large capacity, RO-based desalination projects: brackish RO; advanced municipal wastewater reclamation; and seawater RO. In the two first categories (brackish RO and wastewater reclamation), the systems’ configuration and equipment components are well defined. Therefore, project costs and operating expenses are fairly predictable. In seawater RO desalination systems, the RO process configuration is also very similar; however, some variability exists regarding the configuration of seawater water delivery and feed water pretreatment. The rest of the system’s components and system operation methods are very uniform. However, an evaluation of published cost data of medium- to large-scale water RO desalination projects illustrates significant variability in costs of desalination systems. This paper will analyze current economic conditions of seawater desalination, and highlight the limitations and possibilities of additional improvements of the economics of the SWRO desalination process.

Integration of monopolar and bipolar electrodialysis for valorization of seawater reverse osmosis desalination brines: Production of strong acid and base

Water scarcity in the Mediterranean basin has been solved by using seawater desalination reverse osmosis technology (SWD-RO). This technology produces brine which is discharged back into the sea resulting in an environmental impact on marine ecosystems. Under the circular economy approach, the aim of this work is to recover resources from NaCl-rich brine (~60–70g/L), e.g. in the form of NaOH and HCl, by integration of two ion exchange-based membrane technologies and quantify the electrical energy consumption. Electrodialysis (ED) incorporating monovalent selective cation exchange membranes as divalent ions purification and concentration of the NaCl present in the SWD-RO brine, was integrated with bipolar membrane ED (EDBM) to produce NaOH and HCl. Current densities of 0.30–0.40kA/m2 at two temperature ranges simulating different seawater temperature regimes (15–18°C and 22–28°C) were tested and a pure NaCl solution was used as starting concentrate stream. NaCl-rich brines with 100 or 200g NaCl/L were obtained by ED and then introduced in the EDBM stack producing HCl and NaOH up to 2M, depending on the initial concentrations. A minimum energy consumption of 1.7kWh/kg NaOH was calculated when working by EDBM with initial concentrations of 104g NaCl/L and 0.24M HCl and NaOH.

Evaluation of forward osmosis membrane performance by using wastewater treatment plant effluents as feed solution

AbstractCurrently, there is a growing emphasis on seawater desalination and wastewater reuse around the world. Reverse osmosis (RO) is typically used for both seawater desalination and wastewater reuse. As an alternative technology of RO, forward osmosis–reverse osmosis (FO–RO) hybrid system has recently attracted attention. To select suitable membrane and feed water for this process, the performance of forward osmosis (FO) membrane according to the types of membrane and feed water quality was evaluated in this study, including three types of FO membrane (membrane I/II/III) and three types of feed water (1st/2nd/3rd wastewater treatment plant effluents, WWTP Efs). Despite high structural parameter, membrane II showed the highest water permeability (5.37 LMH/bar) with highest water flux (around 27.1 LMH) using draw solution of 0.5 M NaCl (feed solution: 5 mM NaCl). In fouling test, there was severe water flux decline when 1st WWTP Ef was used as feed solution compared to the case when 2nd/3rd WWTP Efs was ...

Pilot study on arsenic removal from groundwater using a small-scale reverse osmosis system—Towards sustainable drinking water production

Arsenic contamination of groundwater is posing a serious challenge to drinking water supplies on a global scale. In India and Bangladesh, arsenic has caused the most serious public health issue in the world for nearly two decades. The aim of this work was to study an arsenic removal system based on reverse osmosis at pilot scale treating two different water sources from two different locations in the State of Bihar, India. For this purpose two villages, Bind Toli and Ramnagar in the Patna District were selected, both located very close to the river Ganga. The trials were conducted with aerated and non-aerated groundwater. It is the first time that the arsenic removal efficiency for aerated and non-aerated groundwater by reverse osmosis technology in combination with an energy-saving recovery system have been studied. As the principle of reverse osmosis requires a relatively high pressure, its energy demand is naturally high. By using an energy recovery system, this demand can be lowered, leading to an energy demand per liter permeate of 3–4Wh/L only. Due to high iron levels in the groundwater and as a consequence the precipitation of ferric (hydr)oxides, it was necessary to develop a granular media filter for the trials under aeration in order to protect the membrane from clogging. Two different materials, first locally available sand, and second commercially available anthracite were tested in the granular media filter. For the trials with aerated groundwater, total arsenic removal efficiency at both locations was around 99% and the arsenic concentration in permeate was in compliance with the WHO and National Indian Standard of 10μg/L. However, trials under anoxic conditions with non-aerated groundwater could not comply with this standard. Additionally a possible safe discharge of the reverse osmosis concentrate into an abandoned well was studied. It was observed that re-injection of reject water underground may offer a safe disposal option. However, long-term hydrogeological studies need to be conducted for confirmation.

Going big with forward osmosis

The frontier of water treatment technologies is being defined by hybrid processes and thoughtful design integration within treatment trains. The use of increasingly sophisticated process trains is driven by the need to treat dramatically impaired water supplies while maintaining low cost, high utilization, and high operational flexibility. Integrating forward osmosis (FO) technology is one notable, emerging opportunity to realize substantial advantages in cost and performance compared to the use of either conventional membrane processes or thermal technologies. Reverse osmosis technology remains ideally suited to desalinate low fouling streams to moderate levels of recovery. Spray dryers or crystallizers employing mechanical or thermal vapor compression cycles are still best used to convert saturated or organic rich liquors to solid products. But what of the multitude of waters, especially industrial streams, that are too saline or high in foulants to be well treated by reverse osmosis and are not of high enough value to warrant direct crystallization? The traditional answer defaults to a 90 + year old technology in the thermal brine concentrator. Today, Oasys Water is offering an alternative solution by using thermolytic draw solutions to enable FO processes that challenge traditional treatment paradigms in diverse commercial applications.

Zero discharge process for dyeing wastewater treatment

The feasibility of a novel zero discharge process for dyeing wastewater depth treatment after biochemical processes was investigated in this study. The novel process was integrated with reverse osmosis (RO) technology, electrochemical oxidation (EO) and bipolar membrane electrodialysis (BMED). The fresh water generated from the RO and BMED processes and the mixed acid and base solutions regenerated from BMED could be reused as resources. No pollutants or wastewater were discharged into the environment during dyeing wastewater depth treatment. The effects of operation parameters, such as recovery ratio, specific current and input power on RO/EO/BMED performance were explored and discussed. The experimental results indicated that the recovery ratio of wastewater by this RO/EO/BMED process reached 97%, as compared with 70% achieved by RO or nanofiltration (NF); more than 83% of the total dissolved solids (TDS) in wastewater were desalinized and converted into mixed acid and base solutions. The total operating power requirement was 24.6 kWh to treat one cubic meter of wastewater, 0.97 tons fresh water and 1.31kg mixed acid (0.12mol/L) and 2.16kg base (0.18mol/L) were produced. This work has demonstrated proof of concept for the RO/EO/BMED process; further optimization remains to be carried out.

REMEDIAL STUDY OF IRON INDUSTRY EFFLUENTS USING REVERSE OSMOSIS TECHNOLOGY.

Reverse osmosis (RO) system has been effectively applied on a large scale throughout the world for the treatment of effluent and the polluted water. The Arab countries and some other affluent countries have the credit of successfully running such large scale plants without minding for the cost factor involved in such projects. Here the polluted effluent is treated using RO technology in order to remove the pollutants. The investigator has taken an attempt has been made to find out in the impact of Iron Industry Effluent and also to know about the quality of Iron Industry effluents after the treatment of using R O plant. Reverse osmosis has been successfully applied on a large scale for the treatment of effluent and the polluted water. In the present study the Iron Industry effluent are treated using RO plant and treatment can be recommended to all Iron Industries. The same reverse osmosis method can also be applied to other industry effluent.

Recycling of warp size materials and comparison of yarn mechanical properties sized with recycled materials and virgin materials

Warp sizing is an established method for improving the weaveability of textile yarns by coating or impregnating warp yarns with a polymer that improves the efficiency of the weaving operation. Despite its high cost, polyvinyl alcohol (PVA) normally shows better adhesion to fibers than other sizing agents like starch which makes it an essential constituent of size liquor recipe. However PVA desized effluent is a major chemical oxygen demand contributor to a textile plant’s primary oxygenation treatment of water operation and being biologically inert and presents a major threat to the environment. Therefore, the recovery and recycling of PVA will not only be cost-effective but will also be eco-friendly. The aim of this research work is to recycle the warp size materials and to study the comparison of yarn mechanical properties sized with recycled materials to the properties of yarn sized with conventional sizing. Ultrafiltration reverse osmosis technology is used for the recovery and recycling of PVA size material. For this purpose, Ne 16/1 and Ne 21/1 carded 100% cotton yarns were used and sized with both conventional sizing recipe and by 50% recycled PVA together with 50% fresh sizing recipe. It was found that yarn sized through recycled PVA sizing recipe has almost the same (slightly lower) mechanical properties such as tensile strength, elongation and abrasion resistance as compared to yarn sized through conventional sizing recipe.

PV-Li-ion-micropump membrane systems for portable personal desalination

This research presents a technical simulation of theoretically portable desalination systems utilising low-energy and lightweight components that are either commercially available or currently in development. The commercially available components are small-scale flexible and portable photovoltaic (PV) modules, Li-ion battery-converter units, and high pressure low voltage brushless DC motor-powered micropumps. The theoretical and conventional small-scale desalination membranes are compared against each other: low-pressure reverse osmosis (RO), nanofilters, graphene, graphene oxide, and graphyne technology. The systems were designed with the identical PV-Li-ion specifications and simulation data to quantify the energy available to power the theoretical energy demand for desalinating a saline water at 30,000–40,000 ppm total dissolved solid (TDS) to reliably supply the minimum target of 3.5 L d−1 of freshwater for one theoretical year. The results demonstrate that modern portable commercially available PV-battery systems and new generations of energy-efficient membranes under development have the potential to enable users to sustainably procure daily drinking water needs from saline/contaminated water resources, with the system exhibiting a net reduction in weight than carrying water itself.

Reverse osmosis applications: Prospect and challenges

Reverse osmosis (RO) is a pressure driven membrane process which has been widely applied and recognized as the leading technology of desalination process. Improvement in RO technology including advanced membrane material, module and process design, and energy recovery has led to cost reduction which in turn gaining interest to its commercial applications. RO is now being used in various applications including selective separation, purification, and concentration processes. In food industry, RO is applied for concentration of fruits and vegetable juices, pre-concentration of milk and whey, and dealcoholization of alcoholic beverage. For area which has large source of natural humic water or peat water, RO can be applied to produce clean water for community water supply. RO was also investigated for organic mixture separation and CO2 regeneration from essential oil extraction using supercritical fluid. The application of RO as a final step of wastewater treatment for water reuse and valuable component recovery seems to be promising in wastewater reclamation. In this paper, the applications of RO, its advantages, and limitations are discussed. In addition, challenges and perspective of RO membranes are pointed out.

Fouling characteristics of reverse osmosis membranes at different positions of a full-scale plant for municipal wastewater reclamation

Membrane fouling is an important shortcoming limiting the efficiency and wide application of reverse osmosis (RO) technology. In this paper, RO membranes in a full-scale municipal wastewater reclamation plant were autopsied. From the lead to tail position RO membranes in RO system, both of organic and inorganic matters on membranes reduced gradually. The higher ion products in RO concentrate didn't result in more serious inorganic scaling on the last position RO membranes, which was contrast with some other researches. Fe, Ca and Mg were major inorganic elements. Fe had a relatively low concentration in RO influent but the highest content on membranes. However, there was no specific pretreatment in terms of Fe removal. Ca and Mg scaling was controlled by the antiscalants injected. Organic fouling (75.0–84.5% of dry weights) was major problem on RO membranes due to the large amount of dissolved organic matters in secondary effluent as raw water. Hydrophilic acid (HIA, 48.0% of total DOC), hydrophobic acid (HOA, 23.6%) and hydrophobic neutral (HON, 19.0%) fraction was largest among the six fractions in RO influent, while HON (38.2–51.1%) and HOA (22.1–26.1%) tended to accumulate on membranes in higher quantities. Monitoring HON and HOA might help to forecast organic fouling.

The integration of desalination plants and mineral production

A noticeable increase in the number of seawater reverse osmosis (SWRO) desalination plants has been observed during the last decade. This is due to the low energy consumed by reverse osmosis technology and the high freshwater recovery when compared to other desalination technologies. The desalination of seawater is the main source of freshwater in Kuwait. However, SWRO desalination plants generate huge volumes of concentrated brine, which is considered a potential source of mineral content. Some of these minerals are expensive and scarce on earth. The recovery of these minerals from brine can help in increasing the freshwater recovery, reducing the overall cost of desalinated water, offering a new source of raw materials, and decreasing the environmental impact from discharging brine to the sea. This study gives an overview of the different technologies used for the treatment of SWRO brine and explores the benefit to recover and reuse valuable potential minerals in brine. The study is motivated by the strong need to establish a local industry in Kuwait based on the extraction of potential valuable minerals from SWRO brine. Such industries can be combined with desalination plants to form a complex cogeneration of plants that accommodate desalination and power plants.

Analysis and simulation of reverse osmosis technology with non-conventional energy sources

The aim of this doctoral thesis was to study the technical viability of reverse osmosis systems actuation by means of non-conventional energetic sources in a variety of scenarios.This project carri...

Membrane Distillation and Reverse Electrodialysis for Near-Zero Liquid Discharge and low energy seawater desalination

With a total capacity of 70 million cubic meters per day, seawater desalination industry represents the most affordable source of drinking water for many people living in arid areas of the world. Seawater Reverse Osmosis (SWRO) technology, driven by the impressive development in membrane materials, modules and process design, currently shows an overall energy consumption of 3–4kWh per m3 of desalted water, substantially lower than thermal systems; however, the theoretical energy demand to produce 1m3 of potable water from 2m3 of seawater (50% recovery factor) is 1.1kWh. In order to move towards this goal, the possibility to recover the energy content of discharged concentrates assumes a strategic relevance. In this work, an innovative approach combining Direct Contact Membrane Distillation (DCMD) and Reverse Electrodialysis (RE) is tested for simultaneous water and energy production from SWRO brine, thus implementing the concept of low energy and Near-Zero Liquid Discharge in seawater desalination. DCMD operated on 1M NaCl RO retentate fed at 40–50°C resulted in a Volume Reduction Factor (VRF) up to 83.6% with transmembrane flux in the range of 1.2–2.4kg/m2h. The performance of RE stack fed with DCMD brine (4–5.4M) and seawater (0.5M) was investigated at different temperatures (10–45°C) and flow velocities (0.7–1.1cm/s). Experimental data show the possibility to obtain an Open Circuit Voltage (OCV) in the range of 1.5–2.3V and a gross power density of 0.9–2.4W/mMP2 (membrane pair). In general, optimization is required to find best operating conditions for the proposed system.

Design of a small mobile PV-driven RO water desalination plant to be deployed at the northwest coast of Egypt

Water desalination projects based on reverse osmosis (RO) technology are being introduced in Egypt to combat drinking water shortage in remote areas. RO desalination is a pressure-driven process. This paper focuses on the design of an integrated brackish water and seawater RO desalination and solar photovoltaic (PV) technology. A small Mobile PV-driven RO desalination plant prototype without batteries is designed and tested. Solar-driven RO desalination can potentially break the dependence of conventional desalination on fossil fuels, reduce operational costs, and improve environmental sustainability. Moreover, the innovative features incorporated in the newly designed PV–RO plant prototype are focusing on improving the cost effectiveness of producing drinkable water in remote areas. This is achieved by maximizing energy yield through an integrated automatic single axis PV tracking system with programmed tilting angle adjustment. An autonomous cleaning system for PV modules is adopted for maximizing energy generation efficiency. RO plant components are selected so as to produce 4–5 m3/d of potable water. A basic criterion in the design of this PV-RO prototype is to produce a minimum amount of fresh water by running the plant during peak sun hours. Mobility of the system will provide potable water to isolated villages and population as well as ability to provide good drinking water to different number of people from any source that is not drinkable.

Biochemical Methane Potential Test forBiogas Production from Tannery Ro Reject

Most CETPs use Reverse Osmosis technology in their tertiary treatment. The major problem in this technology is the disposal of RO concentrate. The present disposal methods for the RO reject are energy intensive. This paper focuses on the concept of generating biogas from RO reject by codigesting it with secondary treatment plant sludge. Biochemical methane potential test were conducted for different ratios of RO reject and secondary treatment sludge, to examine the optimum ratio for biofuel generation. From the results obtained it was observed that the mixture containing one part of seed sludge and two part of RO reject were the optimum ratio.

Synthesis, characterization and permeation performance of cellulose acetate/polyethylene glycol-600 membranes loaded with silver particles for ultra low pressure reverse osmosis

In order to tap the seemingly boundless problem of water scarcity, reverse osmosis (RO), has been formulated as a significant solution. However, RO technology, suffers by a major challenge of biofouling, which results in reduced production capacity and increased operation costs. Thus, there is an urgent demand to fabricate an appropriate disinfection membrane surface with maximum permeation performance. In this work, cellulose acetate/poly ethylene glycol membranes impregnated with silver particles were prepared by 2-stage phase inversion protocol. The Modified membranes were characterized for their compositional analysis, surface roughness, surface morphology, permeation properties, membrane hydraulic resistance and antibacterial activity. The presence of functional group was determined by FTIR spectra. The asymmetric surface morphology of membranes was elucidated from the scanning electron microscope. The varying nature of nodules and interstices spaces was observed in the images obtained by the atomic forced microscopy. The progressive decreased was observed in the surface roughness of membranes. The modification has significantly increased the flux and salt rejection capacity of membranes. All modified membranes exhibited remarkable antibacterial properties against gram negative Escherichia Coli. The synthesis of cellulose acetate membrane, doped with polyethylene glycol and modified with silver, provides a convenient way for the development of self-sterilized membranes.

Synthesis of reverse osmosis desalination network under boron specifications

Recent regulations regarding water quality motivated research in reverse osmosis (RO) technology for water desalination especially under boron restrictions. Boron control in the permeate products by reverse osmosis technology comprises several mitigation options which impose capital and operation costs. In our study, we investigate the design of RO system under the design concept of split partial second pass reverse osmosis (SPSPRO) in order to allow extraction of permeate streams along the RO pressure vessels. The design approach is based on superstructure optimization which allows the identification of optimal process layout and optimal operation conditions of the process units. pH adjustment of the network streams is also included in the model to control boron species distribution during the separation process. A mixed integer nonlinear program (MINLP) model is subsequently formulated based on the superstructure representation. The mathematical programming formulation is demonstrated on a case study to show the application of the mathematical programming model. The results show lower treatment cost through the proposed mathematical programming model.