scholarly journals Performance of a small solar-powered hybrid membrane system for remote communities under varying feedwater salinities

2004 ◽  
Vol 4 (5-6) ◽  
pp. 233-243 ◽  
Author(s):  
A.I. Schäfer ◽  
C. Remy ◽  
B.S. Richards
Keyword(s):  
Salt Concentration ◽  
System Performance ◽  
Specific Energy Consumption ◽  
Membrane System ◽  
Hybrid Membrane ◽  
Operating Pressure ◽  
Feed Concentration ◽  
Remote Communities ◽  
Pre Treatment ◽  
Solar Powered

An estimated 1 billion people are living both without access to clean drinking water or electricity. The small photovoltaic (PV)-powered hybrid membrane system described here is designed to address the plight of some of these people. PV and membrane technologies are chosen due to suitability for operation in remote and often harsh conditions. An ultrafiltration (UF) pre-treatment is included to remove bacteria and most pathogens, while a reverse osmosis (RO) or nanofiltration (NF) membrane desalinates the brackish feedwater. Several parameters were examined in order to optimise the system performance, including (i) feed salt concentration, (ii) operating pressure, (iii) system recovery, (iv) specific energy consumption (SEC, kWh/m3), and (v) salt retention. In addition, experiments were performed over a whole day to determine system performance under varying levels of solar radiation. The minimum SEC (relatively high due to the current single-pass mode of operation) varies from 5.5 kWh/m3 at a feed concentration of 1 g/L salt to 26 kWh/m3 at a feed concentration of 7.5 g/L salt, which is the upper limit of the system in terms of salt concentration.

Reducing Energy Consumption for Seawater Desalination through the Application of Reflux-Recycle Concepts from Oil Refining

2013 ◽  
Vol 295-298 ◽  
pp. 1456-1462 ◽  
Author(s):  
K. E. Ting ◽  
H.T. Ng ◽  
H.C. Li
Keyword(s):  
High Pressure ◽  
Energy Consumption ◽  
Specific Energy Consumption ◽  
Low Pressure ◽  
Hybrid Membrane ◽  
Oil Refining ◽  
Pressure Side ◽  
Seawater Desalination ◽  
Feed Concentration ◽  
Membrane Processes

The application of the concepts in oil and gas distillation to membrane desalination process to lower the energy cost for seawater desalination was studied in this paper. Drawing on the close analogy between multistage RO and conventional distillation separation processes, a hybrid membrane processes employing reflux and recycle concepts was developed. Reflux in membrane processes involves taking a portion of the effluent stream on the high pressure side and sending it to the low pressure side of the membrane, while recycle involves taking a portion of the permeate stream on the low pressure side and sending it to the high pressure side of the membrane. A predictive model was developed to study the effect of reflux and recycle on the specific energy consumption (SEC) and permeate quality when compared to conventional systems. In this study, the water permeability coefficients of membranes and brine recycle ratios were investigated. The results show that the SEC for a hybrid membrane processes comprising of RO and NF membrane was lower than conventional methods with the same recovery and feed concentration, suggesting that it is feasible to apply reflux and recycle concepts of distillation on desalination. Through the careful selection of RO membranes and NF membranes, benefits of reflux and recycle can be enjoyed for seawater desalination.

scholarly journals Renewable Energy Powered Membrane Technology: Electrical Energy Storage Options for a Photovoltaic-Powered Brackish Water Desalination System

2021 ◽  
Vol 11 (2) ◽  
pp. 856
Author(s):  
Sheying Li ◽  
Ana P. S. G. de Carvalho ◽  
Andrea I. Schäfer ◽  
Bryce S. Richards
Keyword(s):  
Energy Storage ◽  
Brackish Water ◽  
System Performance ◽  
Specific Energy Consumption ◽  
Lithium Ion ◽  
Membrane System ◽  
Water Desalination ◽  
High Temporal Resolution ◽  
Water Production ◽  
Battery Capacity

The potential for lithium-ion (Li-ion) batteries and supercapacitors (SCs) to overcome long-term (one day) and short-term (a few minutes) solar irradiance fluctuations with high-temporal-resolution (one s) on a photovoltaic-powered reverse osmosis membrane (PV-membrane) system was investigated. Experiments were conducted using synthetic brackish water (5-g/L sodium chloride) with varied battery capacities (100, 70, 50, 40, 30 and 20 Ah) to evaluate the effect of decreasing the energy storage capacities. A comparison was made between SCs and batteries to determine system performance on a “partly cloudyday”. With fully charged batteries, clean drinking water was produced at an average specific energy consumption (SEC) of 4 kWh/m3. The daily water production improved from 663 L to 767 L (16% increase) and average electrical conductivity decreased from 310 µS/cm to 274 μS/cm (12% improvement), compared to the battery-less system. Enhanced water production occurred when the initial battery capacity was >50 Ah. On a “sunny” and “very cloudy” day with fully charged batteries, water production increased by 15% and 80%, while water quality improved by 18% and 21%, respectively. The SCs enabled a 9% increase in water production and 13% improvement in the average SEC on the “partly cloudy day” when compared to the reference system performance (without SCs).

Biogas desulfurization and biogas upgrading using a hybrid membrane system – modeling study

2013 ◽  
Vol 67 (2) ◽  
pp. 326-332 ◽  
Author(s):  
A. Makaruk ◽  
M. Miltner ◽  
M. Harasek
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Sulfide ◽  
Energy Consumption ◽  
Natural Gas ◽  
Specific Energy Consumption ◽  
Membrane System ◽  
Hybrid Membrane ◽  
Biogas Upgrading ◽  
Efficient System ◽  
High Hydrogen

Membrane gas permeation using glassy membranes proved to be a suitable method for biogas upgrading and natural gas substitute production on account of low energy consumption and high compactness. Glassy membranes are very effective in the separation of bulk carbon dioxide and water from a methane-containing stream. However, the content of hydrogen sulfide can be lowered only partially. This work employs process modeling based upon the finite difference method to evaluate a hybrid membrane system built of a combination of rubbery and glassy membranes. The former are responsible for the separation of hydrogen sulfide and the latter separate carbon dioxide to produce standard-conform natural gas substitute. The evaluation focuses on the most critical upgrading parameters like achievable gas purity, methane recovery and specific energy consumption. The obtained results indicate that the evaluated hybrid membrane configuration is a potentially efficient system for the biogas processing tasks that do not require high methane recoveries, and allows effective desulfurization for medium and high hydrogen sulfide concentrations without additional process steps.

scholarly journals Batch Reverse Osmosis Desalination Modeling under a Time-Dependent Pressure Profile

Membranes ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 173
Author(s):  
Abdeljalil Chougradi ◽  
François Zaviska ◽  
Ahmed Abed ◽  
Jérôme Harmand ◽  
Jamal-Eddine Jellal ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Reverse Osmosis ◽  
Specific Energy ◽  
Energy Demand ◽  
Specific Energy Consumption ◽  
Pressure Profile ◽  
Recovery Ratio ◽  
Feed Concentration ◽  
Energetic Performance ◽  
Feed Volume

As world demand for clean water increases, reverse osmosis (RO) desalination has emerged as an attractive solution. Continuous RO is the most used desalination technology today. However, a new generation of configurations, working in unsteady-state feed concentration and pressure, have gained more attention recently, including the batch RO process. Our work presents a mathematical modeling for batch RO that offers the possibility of monitoring all variables of the process, including specific energy consumption, as a function of time and the recovery ratio. Validation is achieved by comparison with data from the experimental set-up and an existing model in the literature. Energetic comparison with continuous RO processes confirms that batch RO can be more energy efficient than can continuous RO, especially at a higher recovery ratio. It used, at recovery, 31% less energy for seawater and 19% less energy for brackish water. Modeling also proves that the batch RO process does not have to function under constant flux to deliver good energetic performance. In fact, under a linear pressure profile, batch RO can still deliver better energetic performance than can a continuous configuration. The parameters analysis shows that salinity, pump and energy recovery devices efficiencies are directly linked to the energy demand. While increasing feed volume has a limited effect after a certain volume due to dilution, it also shows, interestingly, a recovery ratio interval in which feed volume does not affect specific energy consumption.

ENHANCING TEXTILE DYE REMOVAL IN EMULSION LIQUID MEMBRANE SYSTEM USING TAYLOR COUETTE COLUMN

2018 ◽  
Vol 80 (3) ◽  
Author(s):  
Adhi Kusumastuti ◽  
A. L. Ahmad ◽  
Rodia Syamwil ◽  
Samsudin Anis
Keyword(s):  
Methylene Blue ◽  
Liquid Membrane ◽  
Volume Ratio ◽  
Interfacial Area ◽  
Membrane System ◽  
Textile Dye ◽  
Feed Concentration ◽  
Emulsion Liquid Membrane ◽  
Low Concentration ◽  
Taylor Couette

Although textile dyes is basically available in very low concentration (10-200 ppm); it should be removed due to the toxicity to human body and environment. Among the existing methods, emulsion liquid membrane (ELM) is a promising method by providing high interfacial area and the ability to remove a very low concentration of the solute. The optimal emulsions were produced using commercially supplied homogeniser. Initially, methylene blue in simulated wastewater was extracted using a Taylor-Couette column. Methylene blue concentration was determined using spectrophotometer. Complete extraction was performed in the designed column. The research obtained optimal extraction efficiency of about 99% at external phase pH of 10, carrier concentration of 9 wt. %, HCl concentration of 0.5 M, initial feed concentration of 20 ppm, volume ratio of emulsion to feed phase of 1:5, extraction time of 5 min, and extraction speed of 600 rpm. 

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 Separation processes for high purity ethanol production

2010 ◽  
Author(s):  
◽  
Peterson Thokozani Ngema
Keyword(s):  
Salt Concentration ◽  
High Purity ◽  
Alternative Fuels ◽  
Water System ◽  
Extractive Distillation ◽  
Operating Pressure ◽  
Extractive Agent ◽  
Relative Volatility ◽  
Vle Data ◽  
Feed Temperature

Globally there is renewed interest in the production of alternate fuels in the form of bioethanol and biodiesel. This is mainly due to the realization that crude oil stocks are limited hence the swing towards more renewable sources of energy. Bioethanol and biodiesel have received increasing attention as excellent alternative fuels and have virtually limitless potential for growth. One of the key processing challenges in the manufacturing of biofuels is the production of high purity products. As bioethanol is the part of biofuels, the main challenge facing bioethanol production is the separation of high purity ethanol. The separation of ethanol from water is difficult because of the existence of an azeotrope in the mixture. However, the separation of the ethanol/water azeotropic system could be achieved by the addition of a suitable solvent, which influences the activity coefficient, relative volatility, flux and the separation factor or by physical separation based on molecular size. In this study, two methods of high purity ethanol separation are investigated: extractive distillation and pervaporation. The objective of this project was to optimize and compare the performance of pervaporation and extraction distillation in order to produce high purity ethanol. The scopes of the investigation include:  Study of effect of various parameters (i) operating pressure, (ii) operating temperature, and (iii) feed composition on the separation of ethanol-water system using pervaporation.  Study the effect of using salt as a separating agent and the operating pressure in the extractive distillation process. The pervaporation unit using a composite flat sheet membrane (hydrophilic membrane) produced a high purity ethanol, and also achieved an increase in water flux with increasing pressure and feed temperature. The pervaporation unit facilitated separation beyond the ethanol – water system azeotropic point. It is concluded that varying the feed temperature and the operating pressure, the performance of the pervaporation membrane can be optimised. v The extractive distillation study using salt as an extractive agent was performed using the low pressure vapour-liquid equilibrium (LPVLE) still, which was developed by (Raal and Mühlbauer, 1998) and later modified by (Joseph et al. 2001). The VLE study indicated an increase in relative volatility with increase in salt concentration and increase in pressure operating pressure. Salt concentration at 0.2 g/ml and 0.3 g/ml showed complete elimination of the azeotrope in ethanol-water system. The experimental VLE data were regressed using the combined method and Gibbs excess energy models, particular Wilson and NRTL. Both models have shown the best fit for the ethanol/water system with average absolute deviation (AAD) below 0.005. The VLE data were subjected to consistency test and according to the Point test, were of high consistency with average absolute deviations between experimental and calculated vapour composition below 0.005. Both extractive distillation using salt as an extractive agent and pervaporation are potential technologies that could be utilized for the production of high purity ethanol in boiethanol-production.

Development of Solar-Powered Microcontroller-Relay-Based Control System Omnidirectional Wheelchair

2021 ◽  
pp. 181-191
Author(s):  
Patrick Uche Okafor ◽  
Ndidi Stella Arinze ◽  
Osondu Ignatius Onah ◽  
Ebenezer Nnajiofo Ogbodo
Keyword(s):  
Power Supply ◽  
System Performance ◽  
Performance Test ◽  
Reference Signal ◽  
Control Mechanisms ◽  
Solar Module ◽  
Dc Motors ◽  
Solar Powered ◽  
Physically Challenged ◽  
Test Result

A solar-powered omnidirectional wheelchair is implemented for physically challenged persons. The framework was mounted on the wheels that were connected with two direct current (DC) motors. The ratings of the battery and solar module were determined using system voltage (12V). A 7,805-voltage regulator was used to supply 5VDC to the AT89352 microcontroller. The microcontroller was programmed to provide a reference signal to the motor. The motor provides the needed torque to drive the wheels through interconnected relays. The relays are energized by the microcontroller and omnidirectional movement achieved through relays connected with microprocessor and micro switches, eliminating the need for joysticks and complex control mechanisms. System performance test result showed that the auxiliary solar power supply of the wheelchair increased the travel range by approximately 86% compared with that of a wheelchair powered by battery alone.

scholarly journals A modified fouling index (MFI40) and fouling predicting approach for ultrafiltration of secondary effluents

2018 ◽  
Vol 9 (1) ◽  
pp. 67-82 ◽  
Author(s):  
B. J. Cai ◽  
I. Baudin ◽  
H. Y. Ng
Keyword(s):  
Standard Deviation ◽  
Treatment Process ◽  
Pilot Scale ◽  
Operating Pressure ◽  
Combined Effects ◽  
Positive Role ◽  
Secondary Effluents ◽  
Pre Treatment ◽  
Modified Fouling Index ◽  
Turbidity Increase

Abstract Fouling indices for evaluating fouling propensity of secondary effluents (SEF) as feed of ultrafiltration (UF) systems are important parameters for the design and operation of the UF process. However, limited fouling indices have been developed and applied for UF feedwater. This study (i) established a modified UF fouling index (MFI40) by raising operating pressure from 30 psi in a traditional MFI test to 40 psi. Standard deviation of MFI40 tests was lower than that of traditional MFI by 68.6%, indicating better stability and repeatability of MFI40. It (ii) investigated the combined effects of UF feedwater characteristics on MFI40. Biopolymers and turbidity played a dominant and secondary positive role in the MFI40, respectively. The effect of conductivity on MFI40 changed from positive to negative with a turbidity increase. It also (iii) validated the MFI40 in both laboratory- and pilot-scale UF membrane units, and UF fouling rates were linearly correlated to the MFI40 of their feeds, and (iv) explored the practical use of the MFI40. It was applied to determine the maximum allowable UF feedwater quality (MFI40max), which could be used to select an appropriate pre-treatment process. A fouling predicting model was established based on the feedwater MFI40 and the operating flux, with an average predicting error of 26.8%.

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