scholarly journals Transport Models of Ammonium Nitrogen in Wastewater from Rare Earth Smelteries by Reverse Osmosis Membranes

2020 ◽  
Vol 12 (15) ◽  
pp. 6230
Author(s):  
Shuanglin Gui ◽  
Zhaohuan Mai ◽  
Jiaqi Fu ◽  
Yuansong Wei ◽  
Jinbao Wan
Keyword(s):  
Rare Earth ◽  
Reverse Osmosis ◽  
Membrane Fouling ◽  
Driving Force ◽  
Water Flux ◽  
Ammonium Nitrogen ◽  
Salt Transport ◽  
Salt Flux ◽  
Operating Pressure ◽  
Concentration Difference

Wastewater from rare earth smelteries contains large amounts of ammonium nitrogen (NH4+-N), which causes severe environmental problems. In this contribution, the desalination efficiency of reverse osmosis (RO) was investigated in the treatment of NH4Cl or NaCl solutions from 0.1 to 40 g/L under different operating pressures with a commercial RO membrane. Experimental results showed that when an operating pressure above 30 bar is applied to the 5 g/L NH4Cl solution, the permeate was found to meet the discharge standards of NH4+-N. Compared to NH4Cl, the permeate fluxes of NaCl solutions were higher due to the higher net driving force and lower propensity to membrane fouling. Theoretical models indicate a linear relationship between water flux and the net driving force for both NH4Cl and NaCl solutions. On the contrary, a power function between the salt flux and concentration difference correlated well with the experimental data for salt transport. The equations for water and salt transport obtained by this work would provide a facile and practical means for predicting the membrane performance in design and optimization of RO processes for the treatment of wastewater from the rare earth industry.

scholarly journals Application of forward osmosis in reusing the brackish concentrate produced in reverse osmosis plants with secondary treated wastewater as feed solution: a case study

2016 ◽  
Vol 6 (4) ◽  
pp. 533-543 ◽  
Author(s):  
W. D. Wang ◽  
M. Esparra ◽  
H. Liu ◽  
Y. F. Xie
Keyword(s):  
Reverse Osmosis ◽  
Membrane Fouling ◽  
Water Flux ◽  
Forward Osmosis ◽  
Pump Energy ◽  
Feed Solution ◽  
Disinfection Byproducts ◽  
Treated Wastewater ◽  
Membrane Flux ◽  
Flux Decline

This study evaluated the feasibility of forward osmosis (FO) in diluting and reusing the concentrate produced in a reverse osmosis (RO) plant in James City County, VA. Secondary treated wastewater (STW) was used as the feed solution. Findings indicated that pH had slight effects on the water flux of the FO membrane. As the concentration of total dissolved solids (TDS) in the concentrate was diluted from 12.5 to 1.0 g/L or the temperature in the STW decreased from 23 to 10 °C, the membrane flux decreased from 2.2 to 0.59 and 0.81 L/(m2 h), respectively. The FO membrane showed a good performance in the rejection of organic pollutants, with only a small part of the protein-like substances and disinfection byproducts permeating to the diluted concentrate. During an 89-hour continuous operation, water flux decline due to membrane fouling was not observed. Controlling the TDS in the second-stage FO effluent at 1.5 g/L, approximately 8.3% of the pump energy input could be saved. The consumption of groundwater was reduced from 22.7 × 103 to 10.6 × 103 m3/d. FO was proved to be an effective method in both diluting the discharged concentrate and reducing the energy consumption of RO.

Glomerulotubular balance in a mathematical model of the proximal nephron

1990 ◽  
Vol 258 (3) ◽  
pp. F612-F626 ◽  
Author(s):  
A. M. Weinstein
Keyword(s):  
Tight Junction ◽  
Proximal Tubule ◽  
Water Permeability ◽  
Water Flux ◽  
Salt Transport ◽  
Salt Flux ◽  
Filtration Fraction ◽  
Epithelial Junctions ◽  
Permeability Increase ◽  
Glomerulotubular Balance

A nonelectrolyte model of proximal tubule epithelium has been extended by the inclusion of a compliant tight junction. Here "compliance" signifies that both the junctional salt and water permeability increase and the salt reflection coefficient decreases in response to small pressure differences from lateral interspace to tubule lumen. In previous models of rat proximal tubule, there has been virtually no sensitivity of isotonic salt transport to changes in peritubular oncotic force. With the inclusion of junctional compliance, decreases in peritubular protein can open the junction and produce a secretory salt flux. Thus the model can represent the "backflux hypothesis," as it was originally put forth (J. E. Lewy and E. E. Windhager, Am. J. Physiol. 214: 943-954, 1968). Additional calculations, simulating a tight junction with negligible water permeability, reveal that the quantitative impact of peritubular protein can be realized whether or not there is substantial junctional water flux. The epithelial model of proximal tubule has also been incorporated into a model of the proximal nephron, complete with glomerulus, peritubular capillary, and interstitium. The interstitial compartment is well mixed and interstitial pressure and osmolality are determined iteratively to achieve balance between tubule reabsorption and capillary uptake. For this model, two domains of operation are identified. When interstitial pressures are low, junctions are closed, and filtration fraction has no effect on proximal reabsorption. When interstitial pressures are relatively elevated, epithelial junctions are open, and proximal salt reabsorption changes in proportion to changes in filtration fraction. In neither domain, however, does the model tubule augment salt flux with isolated increases in luminal flow rate (at constant filtration fraction). The absence of a separate effect of tubule fluid flow on salt transport precludes perfect glomerulotubular balance.

scholarly journals Pilot-Scale Investigation of Forward/Reverse Osmosis Hybrid System for Seawater Desalination Using Impaired Water from Steel Industry

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Hanaa M. Ali ◽  
Hanaa Gadallah ◽  
Sahar S. Ali ◽  
Rania Sabry ◽  
A. G. Gadallah
Keyword(s):  
Reverse Osmosis ◽  
Hybrid System ◽  
Membrane Fouling ◽  
Steel Industry ◽  
Water Flux ◽  
Operating Time ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Hybrid Process ◽  
Impaired Water

This paper was focused on the investigation of a forward osmosis- (FO-) reverse osmosis (RO) hybrid process to cotreat seawater and impaired water from steel industry. By using this hybrid process, seawater can be diluted before desalination, hence reducing the energy cost of desalination, and simultaneously contaminants present in the impaired water are prevented from migrating into the product water through the FO and RO membranes. The main objective of this work was to investigate on pilot-scale system the performance of the combined FO pretreatment and RO desalination hybrid system and specifically its effects on membrane fouling and overall solute rejection. Firstly, optimization of the pilot-scale FO process to obtain the most suitable and stable operating conditions for practical application was investigated. Secondly, pilot-scale RO process performance as a posttreatment to FO process was evaluated in terms of water flux and rejection. The results indicated that the salinity of seawater reduced from 35000 to 13000 mg/L after 3 hrs using FO system, while after 6 hrs it approached 10000 mg/L. Finally, FO/RO system was tested on continuous operation for 15 hrs and it was demonstrated that no pollutant was detected neither in draw solution nor in RO permeate after the end of operating time.

scholarly journals Clinical Autopsy of a Reverse Osmosis Membrane Module

2021 ◽  
Vol 3 ◽  
Author(s):  
Graciela Gonzalez-Gil ◽  
Ali Reza Behzad ◽  
Andreia S. F. Farinha ◽  
Chengyan Zhao ◽  
Szilard S. Bucs ◽  
...  
Keyword(s):  
Reverse Osmosis ◽  
Membrane Fouling ◽  
Full Scale ◽  
Operating Pressure ◽  
Reverse Osmosis Membrane ◽  
Polysulfone Membrane ◽  
Membrane Area ◽  
Microbial Cells ◽  
Imaging Results ◽  
Starting Point

The desalination of seawater using reverse osmosis membranes is an attractive solution to global freshwater scarcity. However, membrane performance is reduced by (bio)fouling. Membrane autopsies are essential for identifying the type of fouling material, and applying corrective measures to minimize membrane fouling. Information from full-scale membrane autopsies guiding improved plant operations is scant in the formal literature. In this case-study, a reverse osmosis membrane from a full-scale seawater desalination plant with a feed channel pressure drop increase of about 218% over the pressure vessel was autopsied. The simultaneous determination of microbial cells, ATP, and total organic carbon (TOC) abundances per membrane area allowed estimating the contributions of biofouling and organic fouling. The abundance of microbial cells determined by flow cytometry (up to 7 × 108 cells/cm2), and ATP (up to 21,000 pg/cm2) as well as TOC (up to 98 μg/cm2) were homogeneously distributed on the membrane. Inorganic fouling was also measured, and followed a similar coverage distribution to that of biofouling. Iron (∼150 μg/cm2, estimated by ICP-MS) was the main inorganic foulant. ATR-FTIR spectra supported that membrane fouling was both organic/biological and inorganic. High-resolution SEM-EDS imaging of cross-sectioned membranes allowed assessing the thickness of the fouling layer (up to 20 μm) and its elemental composition. Imaging results further supported the results of homogeneous fouling coverage. Moreover, imaging revealed both zones with and without compression of the polysulfone membrane layer, suggesting that the stress due to operating pressure was heterogeneous. The procedure for this membrane autopsy provided a reasonable overview of the diverse contributors of fouling and might be a starting point to building a consensus autopsy protocol. Next, it would be valuable to build a RO membrane autopsy database, which can be used as a guidance and diagnostic tool to improve the management and operation of RO desalination plants.

THE ROLE OF SEASONAL SALT AND WATER FLUXES IN THE GENESIS OF SOLONETZIC B HORIZONS

1987 ◽  
Vol 67 (4) ◽  
pp. 721-730 ◽  
Author(s):  
S. FULLERTON (nee Landsburg) ◽  
S. PAWLUK
Keyword(s):  
Water Table ◽  
Water Flux ◽  
Dominant Mode ◽  
Salt Transport ◽  
Salt Flux ◽  
Water Fluxes ◽  
Moisture Movement ◽  
Soil Temperatures ◽  
Capillary Movement

Seasonal salt and water fluxes into Black Solonetz soils were evaluated at two sites in east-central Alberta. The dominant mode of moisture movement into the soil pedon was by capillary movement of water upwards from the water table. Solonization occurred in the Bntj horizons as a consequence of salt transport; the salts responsible were NaHCO3 and Na2SO4. Seasonal salt and water fluxes were identified at both research sites. From May to November when soil temperatures were above 0 °C, capillary movement and evaporation were the major mechanisms responsible for salt transport, concentration and deposition. From December to March when soil temperatures were below 0 °C water moved upwards from the water table towards the freezing zone depositing salts upon freezing. Key words: Genesis, solonetzic; season, groundwater, salt flux, water flux

The role of membrane ξ-potential in solute rejection by low-pressure reverse osmosis membrane

2002 ◽  
Vol 2 (5-6) ◽  
pp. 321-328
Author(s):  
H. Ozaki ◽  
N. Ikejima ◽  
S. Matsui ◽  
Y. Terashima ◽  
S. Takeda ◽  
...  
Keyword(s):  
Reverse Osmosis ◽  
Organic Compounds ◽  
Water Flux ◽  
Streaming Potential ◽  
High Water ◽  
Low Pressure ◽  
Bulk Solution ◽  
Inorganic Salts ◽  
Operating Pressure ◽  
Water And Wastewater Treatment

A new generation of reverse osmosis membranes, low-pressure reverse osmosis (LPRO) membranes, have been developed for operation under very low pressure (below 0.5 MPa). LPRO membranes have received attention especially for their application in the field of water and wastewater treatment, to provide a high water flux at low operating pressure while maintaining very good rejection levels of salts and organics. Our previous work on LPRO has shown that the rejection of some inorganic salts and organic compounds depends appreciably on the pH of the bulk solution, probably because LPRO membranes can have an electric charge. In this study we investigated experimentally the effectiveness of different LPRO membranes in separating inorganic salts and organic compounds from a bulk solution with different pH conditions. We also tried to measure membrane ξ-potential by using a streaming potential method. The results indicated that the membrane ξ-potential as well as the ion size or molecular weight of organics can be considered key factors in the rejection of ionic salts and dissociated organic compounds including pesticides and endocrine disruptors.

scholarly journals Removal of Naturally Occurring Strontium by Nanofiltration/Reverse Osmosis from Groundwater

Membranes ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 321
Author(s):  
Yang-Hui Cai ◽  
Xiao Jin Yang ◽  
Andrea Iris Schäfer
Keyword(s):  
Reverse Osmosis ◽  
Membrane Fouling ◽  
Bone Growth ◽  
Water Flux ◽  
Applied Pressure ◽  
Permeate Flux ◽  
Membrane Performance ◽  
Toc Removal ◽  
Naturally Occurring ◽  
The Impact

Removal of naturally occurring strontium (Sr) from groundwater is vital as excessive exposure may lead to bone growth problems in children. Nanofiltration/reverse osmosis (NF/RO) is commonly used in groundwater treatment due to the high effectiveness and simple maintenance of these pressure driven membrane processes. In this research, a pilot-scale NF/RO system was used to desalinate a natural groundwater sample containing high Sr concentration (10.3 mg/L) and “old” groundwater organic matter (70.9 mg/L) from Esilalei in northern Tanzania to understand the removal of strontium by NF/RO. The impact of applied pressure (10–15 bar) and groundwater pH (3–12) on the membrane performance including permeate flux, strontium and total organic carbon (TOC) flux and removal was investigated. Increasing applied pressure was found to enhance the flux by increasing the driving force and enhance Sr and TOC removal by dilution effect (water flux higher than Sr passage). The alkaline pH caused severe flux decline likely due to membrane fouling and scaling, while it slightly enhanced Sr removal of RO membranes, but weakened the TOC removal. In contrast, acidic and neutral pH of groundwater enhanced TOC removal. These findings suggest that appropriately high applied pressure and acidic pH condition of groundwater are recommended to apply to the NF/RO membrane system in groundwater desalination to achieve better membrane performance.

scholarly journals Performance Evaluation and Fouling Propensity of Forward Osmosis (FO) Membrane for Reuse of Spent Dialysate

Membranes ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 438
Author(s):  
Chaeyeon Kim ◽  
Chulmin Lee ◽  
Soo Wan Kim ◽  
Chang Seong Kim ◽  
In S. Kim
Keyword(s):  
Active Layer ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Chronic Renal Disease ◽  
Membrane Surface ◽  
Water Flux ◽  
Forward Osmosis ◽  
Salt Flux ◽  
Future Research ◽  
Spent Dialysate

The number of chronic renal disease patients has shown a significant increase in recent decades over the globe. Hemodialysis is the most commonly used treatment for renal replacement therapy (RRT) and dominates the global dialysis market. As one of the most water-consuming treatments in medical procedures, hemodialysis has room for improvement in reducing wastewater effluent. In this study, we investigated the technological feasibility of introducing the forward osmosis (FO) process for spent dialysate reuse. A 30 LMH of average water flux has been achieved using a commercial TFC membrane with high water permeability and salt removal. The water flux increased up to 23% with increasing flowrate from 100 mL/min to 500 mL/min. During 1 h spent dialysate treatment, the active layer facing feed solution (AL-FS) mode showed relatively higher flux stability with a 4–6 LMH of water flux reduction while the water flux decreased significantly at the active layer facing draw solution (AL-DS) mode with a 10–12 LMH reduction. In the pressure-assisted forward osmosis (PAFO) condition, high reverse salt flux was observed due to membrane deformation. During the membrane filtration process, scaling occurred due to the influence of polyvalent ions remaining on the membrane surface. Membrane fouling exacerbated the flux and was mainly caused by organic substances such as urea and creatinine. The results of this experiment provide an important basis for future research as a preliminary experiment for the introduction of the FO technique to hemodialysis.

Analysis and calculation of the process of low-pressure reverse osmosis during recycling of hygienic water

2019 ◽  
pp. 28-36
Author(s):  
Leonid S. Bobe ◽  
Nikolay A. Salnikov
Keyword(s):  
Mass Transfer ◽  
Reverse Osmosis ◽  
Life Support ◽  
Space Station ◽  
Low Pressure ◽  
Operating Pressure ◽  
Life Support System ◽  
Cleaning Agent ◽  
The Difference ◽  
Pressure Channel

Analysis and calculation have been conducted of the process of low-pressure reverse osmosis in the membrane apparatus of the system for recycling hygiene water for the space station. The paper describes the physics of the reverse osmosis treatment and determines the motive force of the process, which is the difference of effective pressures (operating pressure minus osmotic pressure) in the solution near the surface of the membrane and in the purified water. It is demonstrated that the membrane scrubbing action is accompanied by diffusion outflow of the cleaning agent components away from the membrane. The mass transfer coefficient and the difference of concentrations (and, accordingly, the difference of osmotic pressures) in the boundary layer of the pressure channel can be determined using an extended analogy between mass transfer and heat transfer. A procedure has been proposed and proven in an experiment for calculating the throughput of a reverse osmosis apparatus purifying the hygiene water obtained through the use of a cleaning agent used in sanitation and housekeeping procedures on Earth. Key words: life support system, hygiene water, water processing, low-pressure reverse osmosis, space station.

Removal of Residual Nutrients and Chemical Additives From Secondary Sewage by Reverse osmosis

1975 ◽  
Vol 10 (1) ◽  
pp. 101-109
Author(s):  
H. Kirk Johnston ◽  
H.S. Lim
Keyword(s):  
Reverse Osmosis ◽  
Membrane Fouling ◽  
Pilot Plant ◽  
Waste Treatment ◽  
Iron Chloride ◽  
Treatment Technique ◽  
Chemical Additives ◽  
Cellulose Acetate Membranes ◽  
Municipal Wastewaters ◽  
Nutrient Solutions

Abstract The suitability of reverse osmosis as a renovation technique for the treatment of municipal wastewaters has been assessed. Cellulose acetate membranes capable of 70% and 90% NaCl rejections were employed in both laboratory and pilot plant studies to evaluate the efficiency of this technique in removing the residual precipitant chemicals generally employed in phosphorus removal programs (iron chloride, alum, and lime) and the nutrients (phosphates, nitrates and ammonia) characteristic of municipal wastewaters. Secondary sewage and raw sewage as well as prepared nutrient solutions were employed in the course of this program. Both laboratory and pilot plant studies indicated consistently outstanding removal efficiencies for the species examined, almost independent of the nature of the waste solutions being treated. Permeation of the purified effluent was subject to significant reductions due to membrane fouling. This characteristic was most pronounced for the more permeable (less selective) membranes. Routine chemical and physical cleanings enable satisfactory flux levels to be maintained, thereby suggesting that reverse osmosis may become a viable municipal waste treatment technique.

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