scholarly journals Using Pressure-Driven Membrane Processes to Remove Emerging Pollutants from Aqueous Solutions

2021 ◽  
Vol 18 (8) ◽  
pp. 4036
Author(s):  
Asunción María Hidalgo ◽  
Gerardo León ◽  
María Dolores Murcia ◽  
María Gómez ◽  
Elisa Gómez ◽  
...  
Keyword(s):  
Water Cycle ◽  
Chemical Separation ◽  
Well Being ◽  
Emerging Pollutants ◽  
Permeate Flux ◽  
High Concentration ◽  
Feed Concentration ◽  
Working Pressure ◽  
Methyl Paraben ◽  
Operating Variables

Currently, there is great concern about global water pollution. Wastewater generally contains substances called emerging pollutants, and if the removal of these pollutants is not given sufficient attention, the pollutants can enter into the water cycle and reach the water supply for domestic use, causing adverse effects on the well-being of people. In order to avoid this menace, a multitude of techniques to reduce the high concentration levels of these substances dissolved in water are being researched and developed. One of the most-used techniques for this goal is the physical-chemical separation of contaminants in water through membrane technology. In this study, different membranes were tested with the objective of investigating the removal of three emerging pollutants: caffeine, metformin, and methyl-paraben. Initially, a nanofiltration (NF) membrane was selected, and the influence of pressure was evaluated in the rejection coefficients and permeate fluxes. Next, a screening of three new membranes to remove methyl paraben was completed. The influence of the operating variables, working pressure, and methyl paraben-feed concentration was checked. Finally, the solution-diffusion model was applied to predict the behavior of the different membranes in the removal of methyl paraben. A good correlation between experimental and calculated values of permeate flux and methyl paraben concentration was obtained.

scholarly journals Stirred cell ultrafiltration of lignin from black liquor generated from South African kraft mills

2016 ◽  
Vol Volume 112 (Number 11/12) ◽  
Author(s):  
Paul Kekana ◽  
Bruce Sithole ◽  
Deresh Ramjugernath ◽  
◽  
◽  
...  
Keyword(s):  
South African ◽  
Black Liquor ◽  
Operating Pressure ◽  
Continuous Mode ◽  
Permeate Flux ◽  
Feed Concentration ◽  
Experimental Conditions ◽  
Stirring Rate ◽  
Stirred Cell ◽  
Batch Cell

Abstract Ultrafiltration of lignin from black liquor was carried out in a stirred batch cell using polyethersulfone membranes. Parameters such as operating pressure, feed concentration, stirring rate and membrane cut-off size were varied and their effects on lignin retention and permeate flux were investigated. The operating pressure, feed concentration and stirring rate were varied in the ranges 150–350 kPa, 3–9% and 200–400 rpm, respectively. The membranes used had cut-off sizes of 5 kDa, 10 kDa and 20 kDa. A one-factor-at-a-time experimental design approach was applied in this study. Retention of lignin increased with increases in operating pressure, feed concentration and stirring rate, but decreased with an increase in molecular cut-off size of the membrane. Permeate flux on the other hand increased with increases in pressure, stirring rate and molecular cut-off size of the membrane but decreased with an increase in feed concentration. The extraction of lignin from black liquor was successfully carried out and extraction efficiencies as high as 86% could be achieved depending on the experimental conditions. The study was concluded with the recommendation of conducting additional experiments using a pilot plant in a continuous mode.

scholarly journals Biocatalytic Reduction of Formaldehyde to Methanol: Effect of pH on Enzyme Immobilization and Reactive Membrane Performance

2021 ◽  
Vol 16 (3) ◽  
pp. 472-480
Author(s):  
Norhayati Abdul Rahman ◽  
Fauziah Marpani ◽  
Nur Hidayati Othman ◽  
Nur Hashimah Alias ◽  
Junaidah Jai ◽  
...  
Keyword(s):  
Enzyme Immobilization ◽  
Enzymatic Reaction ◽  
Feed Solution ◽  
Permeate Flux ◽  
High Concentration ◽  
Enzyme Loading ◽  
Reaction Conversion ◽  
Observed Rejection ◽  
Pes Membrane ◽  
Reactive Membrane

Thermodynamic stabled CO2 molecules can be biocatalytically reduced to methanol via three cascade dehydrogenases (formate, formaldehyde and alcohol) with the aid of cofactor as the electron donor. In this study, Alcohol dehydrogenase (EC 1.1.1.1), the third step of the cascade enzymatic reaction which catalyzed formaldehyde (CHOH) to methanol (CH3OH) will be immobilized in an ultrafiltration membrane. The enzyme will be immobilized in the support layer of a poly(ether)sulfone (PES) membrane via a technique called fouling induced enzyme immobilization. The objective of this study is to evaluate the effect of varying pH (acid (pH 5), neutral (pH 7) and alkaline (pH 9)) of the feed solution during immobilization process of ADH in the membrane in terms of permeate flux, observed rejection, enzyme loading and fouling mechanism. The experiment was conducted in a pressure driven, dead-end stirred filtration cell. Reaction conversion and biocatalytic productivity will be also evaluated. The results showed that permeate flux for acid solution were the lowest during immobilization. High concentration polarization and fouling resistance cause lower observed rejection for pH 7 and 9. Enzyme loading for pH 5 give 73.8% loading rate which is the highest compared to 62.4% at pH 7 and 70.1% at pH 9. Meanwhile, the conversion rate during the reaction shows that reaction on fouled membrane showed more than 90% conversion for pH 5 and 7. The fouling model predicted that irreversible fouling occurs during enzyme immobilization at pH 7 with standard blocking mechanism while reversible fouling occurs at pH 5 and 9 with intermediate and complete blocking, respectively. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Removal of Monoethanolamine from Wastewater by Composite Reverse Osmosis Membrane

2014 ◽  
Vol 68 (5) ◽  
Author(s):  
Azry Borhan ◽  
Muhammad Muhibbudin Mat Johari
Keyword(s):  
Reverse Osmosis ◽  
Operating Parameter ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Transmembrane Pressure ◽  
Processing Plant ◽  
Permeate Flux ◽  
Feed Concentration ◽  
Desorption Process ◽  
Ro Membrane

Monoethanolamine (MEA) has been vastly used for the removal of carbon dioxide (CO2) in natural gas processing plant. However, during the absorption-desorption process and maintenance activities, a small amount of amine get carries over and discharged into the effluent wastewater stream. Due to its high Chemical Oxygen Demand (COD) and require large volume of water for dilution, therefore treatment of MEA contaminated wastewater is a major concern in most amine sweetening plants. In this research, MEA wastewater generated from PETRONAS Fertilizer Kedah Sdn. Bhd (PFK) was treated via AFC99 tubular thin film composite polyamide Reverse Osmosis (RO) membrane. The effect of operating parameter (transmembrane pressure (TMP), feed concentration and pH) towards permeate flux and MEA rejection were studied to obtain the optimum operating conditions. Experimental results showed that AFC99 membrane is able to reject MEA up to 98% when operated at TMP of 20 bars, feed concentration of 300 ppm and pH of 4. This work shows that the RO membrane was feasible and desirable to be used for removal of MEA contaminants from wastewater. Besides, the treated water fulfills the watering standards.

scholarly journals Ecosystem services from mountain forest ecosystems: conceptual framework, approach and challenges

2020 ◽  
Vol 21 (1) ◽  
pp. 47-68
Author(s):  
Maria Glushkova ◽  
Miglena Zhiyanski ◽  
Stoyan Nedkov ◽  
Rositsa Yaneva ◽  
Lora Stoeva
Keyword(s):  
Ecosystem Services ◽  
Forest Ecosystems ◽  
Water Cycle ◽  
Well Being ◽  
Decision Makers ◽  
Mountain Forest ◽  
Territorial Development ◽  
Mountain Areas ◽  
Mountain Ecosystems ◽  
Wide Range

Mountain ecosystems play an essential role in sustainable mountain development, providing benefits and values to humanity not only for the rich biodiversity they contain, but also because of their important role in climate regulation, water cycle, provisioning of recreation, tourism, cultural or spiritual values. The high biodiversity of the mountain areas allow the provision of a wide range of ecosystem services. However, different impacts to the environment threaten the delivery of these services and, consequently, the quality of life of people, both living in the mountains and outside the mountains. Recognizing, demonstrating and capturing the value of ecosystem services can play an important role in setting policy directions for ecosystem management and conservation and, thus, in increasing the provision of ecosystem services and their contributions to human well-being. Quantifying and mapping of these benefits can also help managers and decision makers to realize the importance of these sites for conservation and to allow the proper understandings of the impacts of mountain forest ecosystems on territorial development and welfare of local populations. The paper aims to outline the relevance and applicability of the ecosystem services approach for the assessment of the condition of mountain ecosystems and the services, they provide, for better understanding by the scientific community and to support decision makers in sustainable management of mountain regions.

scholarly journals A Study on the Relations among Work Pressure, Emotional Intelligence, and Subjective Well-Being of Kindergarten Teachers

2021 ◽  
Vol 73 ◽  
pp. 22-33
Author(s):  
You LI ◽  
Han ZHANG
Keyword(s):  
Emotional Intelligence ◽  
Emotional Labor ◽  
Well Being ◽  
Kindergarten Teachers ◽  
Self Control ◽  
Subjective Well Being ◽  
Working Pressure ◽  
Research Results ◽  
Deviant Behaviors ◽  
Rational Evaluation

The globalization development of the world allows the economic development presenting knowledge. Talent cultivation is similar to long-term investment that the importance cannot be neglected. Moreover, low birth rate in current society has each child being the treasure of the parents, who spoil the children with permissive parenting and do not realize the immaturity and low self-control of children in the preschool stage to result in children's deviant behaviors and teachers’ increasing workload and pressure. Aiming at kindergarten teachers in Jiangsu as the research objects, total 380 copies of questionnaire are distributed, and 277 valid copies are retrieved, with the retrieval rate 72%. The research results are summarized as below: Kindergarten teachers are general people who have emotion and cannot exercise forbearance for everything. For this reason, school organizations should be considerate of kindergarten teachers’ emotional labor problems, parents and the mass society should treat teachers’ work with objective perspective and putting themselves in the place. Using individual emotional intelligence to achieve personal emotional accommodation in the process is an important strategy for kindergarten teachers; In the cultivation process, kindergarten teachers stress on evaluating children's level, strength, and weakness for individualized instruction. Step-by-step design of learning content aims to emphasize the importance of rational evaluation. In this case, special education teachers with better emotional intelligence performance could well apply rational evaluation and emotional accommodation strategies, reduce working pressure, and enhance subjective well-being; Kindergarten organizations could properly support teachers with time flexibility to reduce kindergarten teachers dealing with class affairs or other problems with extra time. Cooperation among people would help deal with problems and promote individual positive affect. According to the research results, suggestions are eventually proposed, expecting to help kindergarten teachers present higher commitment and better effectiveness on the teaching performance to promote the overall education quality.

scholarly journals Effect of on the Membrane Distillation of PVDF Membrane Material Enhanced by Gas-Liquid Two-Phase Flow

2018 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Membrane Surface ◽  
Threshold Level ◽  
Membrane Distillation ◽  
Permeate Flux ◽  
High Concentration ◽  
Two Phase ◽  
Flux Enhancement ◽  
Membrane Performance ◽  
Flux Decline ◽  
Sweeping Gas

This study investigates the membrane performance and fouling control in the bubble-assisted sweeping gas membrane distillation with high concentration saline (333 K saturated solution) as feed. The results show that longer bubbling interval (3 min) at a fixed bubbling duration of 30s can most efficiently increase the the flux enhancement ratio up to 1.518. Next, the flux increases with the gas flowrate under a relatively lower level, but tends to a plateau after the threshold level (1.2 L•min-1). Compared to non-bubbling case, the permeate flux reaches up to 1.623 fold at a higher bubble relative humidity of 80 %. It was also found that greater flux enhancement can be achieved and meanwhile dramatic flux decline can be delayed for an intermittent bubbling system with a smaller nozzle size. These results accord well with the observations of fouling deposition in situ on the membrane surface with SEM.

scholarly journals New Zealand River Hydrology under Late 21st Century Climate Change

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2175
Author(s):  
Daniel B. G. Collins
Keyword(s):  
Climate Change ◽  
New Zealand ◽  
21St Century ◽  
Climate Model ◽  
Water Cycle ◽  
Well Being ◽  
Cultural Economic ◽  
Low Flows ◽  
Late 21St Century ◽  
The Mean

Climate change is increasingly affecting the water cycle and as freshwater plays a vital role in countries’ societal and environmental well-being it is important to develop national assessments of potential climate change impacts. Focussing on New Zealand, a climate-hydrology model cascade is used to project hydrological impacts of late 21st century climate change at 43,862 river locations across the country for seven hydrological metrics. Mean annual and seasonal river flows validate well across the whole model cascade, and the mean annual floods to a lesser extent, while low flows exhibit a large positive bias. Model projections show large swathes of non-significant effects across the country due to interannual variability and climate model uncertainty. Where changes are significant, mean annual, autumn, and spring flows increase along the west and south and decrease in the north and east. The largest and most extensive increases occur during winter, while during summer decreasing flows outnumber increasing. The mean annual flood increases more in the south, while mean annual low flows show both increases and decreases. These hydrological changes are likely to have important long-term implications for New Zealand’s societal, cultural, economic, and environmental well-being.

scholarly journals Effect of Operating Parameters on Performance of Ultrafiltration (UF) to Fractionate Catfish Protein Hydrolysate

2014 ◽  
Vol 70 (2) ◽  
Author(s):  
D. Novin ◽  
K. F. MD Yunos
Keyword(s):  
Ionic Strength ◽  
Isoelectric Point ◽  
Protein Hydrolysate ◽  
Operating Time ◽  
Regenerated Cellulose ◽  
Operating Parameters ◽  
Permeate Flux ◽  
Feed Concentration ◽  
Effect Of Ph

The effect of pH, ionic strength and feed concentration on performance of ultrafiltration (UF) to fractionate Catfish protein hydrolysate (CFPH) through 5kDa regenerated cellulose (RC) membrane was studied. The highest and lowest permeate flux belonged respectively to pH 9 and isoelectric point (IEP) with flux reduction of 5.75 L/m2.h at pH 9 and 10.98 L/m2.h at pH isoelectric through operating time. Further, by adding the salt, the highest permeate flux and transmission obtained at highest ionic strength of 0.15 M NaCl with 52.96% of transmission (in average). Then, the transmission reached to 54.18% by increasing feed concentration up to 1.5 mg/ml. 

Climate Change and Supply Chain Operations

2011 ◽  
pp. 93-126
Author(s):  
Costas P. Pappis
Keyword(s):  
Climate Change ◽  
Large Scale ◽  
Water Cycle ◽  
Well Being ◽  
Developed Countries ◽  
Sea Levels ◽  
The World ◽  
Stern Review ◽  
Rising Sea Levels

In the previous chapter 3 the focus of the presentation has been on the implications of climate change, as felt globally, for the environment and human societies in developing as well as in developed countries. As noticed there, the Stern Review’s conclusion that “climate change will have increasingly severe impacts on people around the world, with a growing risk of abrupt and large-scale changes at higher temperatures” (Stern Review, 2006) is shared by most scientists and governments. The Review warns that “a warmer world with a more intense water cycle and rising sea levels will influence many key determinants of wealth and well-being, including water supply, food production, human health, availability of land, and the environment” (Stern Review, p. 84).

Influence of feed concentration on the accuracy of permeate flux decline prediction in ultrafiltration

Desalination ◽  
2008 ◽  
Vol 221 (1-3) ◽  
pp. 383-389 ◽  
Author(s):  
M. Cinta Vincent Vela ◽  
Enrique Bergantiños-Rodríguez ◽  
Silvia Álvarez Blanco ◽  
Jaime Lora García
Keyword(s):  
Permeate Flux ◽  
Feed Concentration ◽  
Flux Decline
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