Optimum arrangement of two-stage plug and concentrate recycling RO systems using thermodynamic and exergy analysis

2019 ◽  
Vol 30 (6) ◽  
pp. 3323-3348
Author(s):  
Abbas Naeimi ◽  
Mohammad Hossein Ahmadi ◽  
Milad Sadeghzadeh ◽  
Alibakhsh Kasaeian
Keyword(s):  
Reverse Osmosis ◽  
Water Pressure ◽  
Optimization Method ◽  
Feed Water ◽  
Two Stage ◽  
Content Type ◽  
Optimum Arrangement ◽  
North Of Iran ◽  
Optimization Parameters ◽  
Seawater Reverse Osmosis

Purpose This paper aims to determine the optimum arrangement of a reverse osmosis system in two methods of plug and concentrate recycling. Design/methodology/approach To compare the optimum conditions of these two methods, a seawater reverse osmosis system was considered to produce fresh water at a rate of 4,000 m3/d for Mahyarkala city, located in north of Iran, for a period of 20 years. Using genetic algorithms and two-objective optimization method, the reverse osmosis system was designed. Findings The results showed that exergy efficiency in optimum condition for concentrate recycling and plug methods was 82.6 and 92.4 per cent, respectively. The optimizations results showed that concentrate recycling method, despite a 36 per cent reduction in the initial cost and a 2 per cent increase in maintenance expenses, provides 6 per cent higher recovery and 19.7 per cent less permeate concentration than two-stage plug method. Originality/value Optimization parameters include feed water pressure, the rate of water return from the brine for concentrate recycling system, type of SW membrane, feedwater flow rate and numbers of elements in each pressure vessel (PV). These parameters were also compared to each other in terms of recovery (R) and freshwater unit production cost. In addition, the exergy of all elements was analyzed by selecting the optimal mode of each system.

Enhancing boron rejection in seawater reverse osmosis facilities

2008 ◽  
Vol 8 (5) ◽  
pp. 519-525 ◽  
Author(s):  
R. P. Huehmer ◽  
F. Wang ◽  
J. Lozier ◽  
L. Henthorne
Keyword(s):  
Reverse Osmosis ◽  
World Health ◽  
Feed Water ◽  
Natural Seawater ◽  
Potential Health ◽  
Pass System ◽  
Wide Range ◽  
Seawater Reverse Osmosis ◽  
Health Organization ◽  
High Rejection

Linked to potential health problems and toxicity to crops, boron is present in seawater at concentrations of ranging from 4 to 7 mg/L, and not readily removed by reverse osmosis technology. Commercially available seawater reverse osmosis (SWRO) membranes possess a wide range of rejection characteristics for boron in seawater under ambient temperature and pH, ranging from approximately 50% for low-energy membranes to greater than 90% for the newest high rejection membranes. This level of rejection is typically insufficient to reduce boron concentrations in natural seawater to less than recommended levels. Current World Health Organization (WHO) drinking water concentrations for boron are limited to 0.5-mg/L. Two techniques utilized to mitigate boron concentrations are (1) increasing the dissociation of boric acid by increasing pH prior to SWRO; and, (2) utilizing a second pass reverse osmosis system, potentially coupled with pH adjustment. Utilizing these techniques, the authors tested commercially available SWRO membranes from three different manufacturers utilizing feed water alkalization, coupled with a second pass system. Utilizing feed water alkalization alone, the authors found that all three SWRO membranes were able to produce permeate complying with WHO regulations. Using second pass RO, a boron concentration of less than 0.5 mg/L was achieved for feed pH greater than 6, and less than 0.1-mg/L for pH of 10.

scholarly journals Composition and Variability of Biofouling Organisms in Seawater Reverse Osmosis Desalination Plants

2011 ◽  
Vol 77 (13) ◽  
pp. 4390-4398 ◽  
Author(s):  
Minglu Zhang ◽  
Sunny Jiang ◽  
Dian Tanuwidjaja ◽  
Nikolay Voutchkov ◽  
Eric M. V. Hoek ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Reverse Osmosis ◽  
Clone Library ◽  
Bacterial Communities ◽  
Rrna Gene ◽  
Sequencing Analysis ◽  
Content Type ◽  
Seawater Reverse Osmosis ◽  
Desalination Plants

ABSTRACTSeawater reverse osmosis (SWRO) membrane biofouling remains a common challenge in the desalination industry, but the marine bacterial community that causes membrane fouling is poorly understood. Microbial communities at different stages of treatment processes (intake, cartridge filtration, and SWRO) of a desalination pilot plant were examined by both culture-based and culture-independent approaches. Bacterial isolates were identified to match the generaShewanella,Alteromonas,Vibrio, andCellulophagabased on 16S rRNA gene sequencing analysis. The 16S rRNA gene clone library of the SWRO membrane biofilm showed that a filamentous bacterium,Leucothrix mucor, which belongs to the gammaproteobacteria, accounted for nearly 30% of the clone library, while the rest of the microorganisms (61.2% of the total clones) were related to the alphaproteobacteria. 16S rRNA gene terminal restriction fragment length polymorphism (T-RFLP) analysis indicated that bacteria colonizing the SWRO membrane represented a subportion of microbes in the source seawater; however, they were quite different from those colonizing the cartridge filter. The examination of five SWRO membranes from desalination plants located in different parts of the world showed that although the bacterial communities from the membranes were not identical to each other, some dominant bacteria were commonly observed. In contrast, bacterial communities in source seawater were significantly different based on location and season. Microbial profiles from 14 cartridge filters collected from different plants also revealed spatial trends.

scholarly journals Aggravated biofouling caused by chlorine disinfection in a pilot-scale reverse osmosis treatment system of municipal wastewater

2021 ◽  
Author(s):  
Li-Wei Luo ◽  
Yin-Hu Wu ◽  
Yun-Hong Wang ◽  
Xin Tong ◽  
Yuan Bai ◽  
...  
Keyword(s):  
Reverse Osmosis ◽  
Relative Abundance ◽  
Membrane Fouling ◽  
Municipal Wastewater ◽  
Water Pressure ◽  
Pilot Scale ◽  
Resistant Bacteria ◽  
Feed Water ◽  
Chlorine Disinfection ◽  
Key Species

Abstract The reverse osmosis (RO) system is widely applied to produce reclaimed water for high-standard industrial use. Chlorine disinfection is the main biofouling control method in the RO systems for wastewater reclamation. However, researchers reported the adverse effects of chlorine disinfection which aggravated biofouling in laboratory-scale RO systems. In this study, four parallel 4-inch spiral wound RO membranes were used to study the effect of chlorine on biofouling in a pilot-scale RO system. The free chlorine dosages in four experimental groups were 0, 1, 2 and 5 mg/L, respectively. After continuous chlorination and dechlorination, the feed water entered the RO system. It was found that chlorine pretreatment caused a 1.9–36.7% increase in relative feed water pressure of the RO system, suggesting that chlorine aggravated the membrane fouling in the pilot-scale RO system. The microbial community structures of living bacteria in the feed water of the RO system were determined by the PMA (propidium monoazide)-PCR method and showed that the relative abundance of chlorine-resistant bacteria (CRB) was significantly increased after disinfection. Nine major genera which maintained higher relative abundance in experimental groups with high chlorine dosage were considered as possible key species causing membrane fouling, including Pedobacter, Clostridium and Bradyrhizobium.

System development and testing of wind-powered reverse osmosis desalination for remote Pacific islands

2002 ◽  
Vol 2 (2) ◽  
pp. 123-129
Author(s):  
C.C.K. Liu ◽  
R. Migita ◽  
J.-W. Park
Keyword(s):  
Wind Speed ◽  
Wind Power ◽  
Reverse Osmosis ◽  
Pacific Islands ◽  
System Development ◽  
Water Pressure ◽  
Small Island ◽  
Feed Water ◽  
Average Wind Speed ◽  
Short Supply

Reverse osmosis (RO) is one of the most feasible methods of desalination to produce a supplemental freshwater supply. Because traditional RO desalination is energy-intensive, it is not a viable solution for remote Pacific islands where electricity is also in short supply. The utilization of wind power holds promise as a solution to this problem, as most of these remote islands are subject to constant trade winds. RO desalination of brackish groundwater, which is available in many of these islands, requires low feed water pressure that can be delivered by wind power at a moderate wind speed. Testing of a prototype wind-powered RO desalination system constructed on Coconut Island, a small island off the windward coast of Oahu, Hawaii, indicated that at an average wind speed of 8.5 m/s, a freshwater flow of over 4000 L/d can be produced. This volume is sufficient to meet the freshwater needs of a typical remote island community.

Kristal® 2000 PVDF hollow fiber UF membrane in the pretreatment for seawater desalination

2012 ◽  
Vol 7 (4) ◽  
Author(s):  
Zanguo Peng ◽  
Zhaoxuan Zhang ◽  
Pandurangan Mohan ◽  
Kasinathan Manimaran ◽  
Dongfei Li
Keyword(s):  
Water Quality ◽  
Pilot Study ◽  
Reverse Osmosis ◽  
Hollow Fiber ◽  
Large Scale ◽  
Operating Costs ◽  
Feed Water ◽  
Seawater Desalination ◽  
Seawater Reverse Osmosis ◽  
Uf Membranes

Membrane technology has emerged as a dominant solution to seawater desalination due to its superior advantages such as stable output water quality, lower energy consumption, ease of operation and smaller footprint. However, the design of spiral wound reverse osmosis (RO) membranes used in desalination does not allow for backwash or air scouring, thus rendering the RO membrane highly susceptible to fouling. Pretreatment for the RO system is therefore essential to ensure a long service life of the RO membranes. For waters containing suspended solids of up to 75 mg/L (such as that in the SingSpring Desalination Plant at Tuas, Singapore), conventional pretreatment methods (such as dissolved air floatation and filtration (DAFF), chemical dosing and cartridge filtration) require regular operator intervention to produce a permeate of reasonably quality. Ultrafiltration (UF) as a pretreatment for seawater desalination can offer better treated water, lower operating costs, a smaller footprint, and flexibility in dealing with poor or varying feed water quality. By improving the pretreatment permeate water quality, reducing operating costs and the footprint, capital expenses can be lowered. Greater stability is also achieved during times of poor or variable feed water conditions (such as periods of algalbloom). A pilot study was conducted at SingSpring to track the performance of Hyflux's Kristal® 2000 hollow fiber UF membranes as pretreatment for the seawater reverse osmosis (SWRO) system. The results of the pilot study will enable the design of future large-scale UF-SWRO membrane projects for seawater desalination.

Characterization of seawater reverse osmosis fouled membranes from large scale commercial desalination plant

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Reverse Osmosis ◽  
Large Scale ◽  
Retention Rate ◽  
Local Level ◽  
Microscopic Analysis ◽  
Transmembrane Pressure ◽  
Hydraulic Permeability ◽  
Seawater Reverse Osmosis ◽  
A Chain

The objective of this work is to study the ageing state of a used reverse osmosis (RO) membrane taken in Algeria from the Benisaf Water Company seawater desalination unit. The study consists of an autopsy procedure used to perform a chain of analyses on a membrane sheet. Wear of the membrane is characterized by a degradation of its performance due to a significant increase in hydraulic permeability (25%) and pressure drop as well as a decrease in salt retention (10% to 30%). In most cases the effects of ageing are little or poorly known at the local level and global measurements such as (flux, transmembrane pressure, permeate flow, retention rate, etc.) do not allow characterization. Therefore, a used RO (reverse osmosis) membrane was selected at the site to perform the membrane autopsy tests. These tests make it possible to analyze and identify the cause as well as to understand the links between performance degradation observed at the macroscopic scale and at the scale at which ageing takes place. External and internal visual observations allow seeing the state of degradation. Microscopic analysis of the used membranes surface shows the importance of fouling. In addition, quantification and identification analyses determine a high fouling rate in the used membrane whose foulants is of inorganic and organic nature. Moreover, the analyses proved the presence of a biofilm composed of protein.

A benchmarking study of Indian seaports

2019 ◽  
Vol 13 (1) ◽  
pp. 88-102
Author(s):  
Sajeev Abraham George ◽  
Anurag C. Tumma
Keyword(s):  
Financial Performance ◽  
Future Research ◽  
Data Envelopment ◽  
Operational Parameters ◽  
Two Stage ◽  
Content Type ◽  
The Public ◽  
Port Authorities ◽  
Financial Performance Measures ◽  
The Government

Purpose The purpose of this paper is to benchmark the operational and financial performances of the major Indian seaports to help derive useful insights to improve their performance. Design/methodology/approach A two-stage data envelopment analysis (DEA) methodology has been used with the help of data collected on the 13 major seaports of India. The first stage of the DEA captured the operational efficiencies, while the second stage the financial performance. Findings A window analysis over a period of three years revealed that no port was able to score an overall average efficiency of 100 per cent. The study identified the better performing units among their peers in both the stages. The contrasting results of the study with the traditional operational and financial performance measures used by the ports helped to derive useful insights. Research limitations/implications The data used in the study were majorly limited to the available sources in the public domain. Also, the study was limited to the major seaports which are under the Government of India and no comparisons were carried out with other local or international ports. Practical implications There is a need to prioritize investments and improvement efforts where they are most needed, instead of following a generalized approach. Once the benchmark ports are identified, the port authorities and other relevant stakeholders should work in detail on the factors causing inefficiencies, for possible improvements in performance. Originality/value This paper carried out a two-stage DEA that helped to derive useful insights on operational efficiency and financial performance of the India seaports. A combination of the financial and operational parameters, along with a comparison of the DEA results with the traditional measures, provided a different perspective on the Indian seaport performance. Considering the scarcity of research papers reported in the literature on DEA-based benchmarking studies of seaports in the Indian context, it has the potential to attract future research in this field.

Sign in / Sign up

Export Citation Format

Share Document