Design and Performance of Small Scale Solar Powered Water Desalination Systems, Utilizing Reverse Osmosis

2000 ◽  
Vol 122 (4) ◽  
pp. 170-175 ◽  
Author(s):  
K. B. Franc¸a ◽  
H. M. Laborde ◽  
H. Neff

A small scale solar powered desalination system has been designed, analyzed, and optimized with regard to power needs and energy consumption. Both quantities scale linearly with the concentration of the total dissolved salt concentration (TDS) in the feed solution. The desalination of brackish water at a TDS value of 3,000 ppm requires an energy of approximately 1.5 kWh/m3. For seawater at a TDS value of 34,000 ppm, this value increases to 9.5 kWh/m3. The selected type of membrane, the system design, and, in particular, the efficiency of the high pressure pump crucially affect energy consumption. The desalination cost also has been estimated for a small scale system that linearly scale with the TDS value of the feed water. [S0199-6231(00)00104-0]

Author(s):  
Vishnu-Baba Sundaresan

Selective rejection of dissolved salts in water is achieved by large pressure gradient driven flows through tortuous structures and cylindrical nanopores. The flow rate through the membrane is dependent on the area of the membrane and pressure gradient that can be sustained by the membrane. The electrical power required for generating large pressure gradients increases the operational cost for desalination units and limits application of contemporary technologies in a wide variety of applications. Due to this limitation, small scale operation of these desalination systems is not economical and portable. Further, recently proposed desalination systems using carbon nanotubes and nanofluidic diodes have limited lifetime due to clogging and fouling from contaminants in feed water. In order to develop a desalination system that is not limited by cost, scale of operation and application, an active nanopore membrane that uses multiphysics interactions in a surface-functionalized hyperboloidal nanopore is developed. An active nanopore is a shape-changing hyperboloidal pore that is formed in a rugged electroactive composite membrane and utilizes coupled electrostatic, hydrodynamic and mechanical interactions due to reversible mechanical oscillations between the charged pore walls and dissolved ions in water for desalination. This novel approach takes advantage of the shape of the pore to create a pumping action in the hyperboloidal channel to selectively transport water molecules. In order to demonstrate the applicability of this novel concept for water desalination, the paper will use a theoretical model to model the ion rejection properties and flow rate of purified water through an active nanoporous membrane. This article examines the effect of the geometry of the nanopore and frequency of operation to reject dissolved ions in water through a multiphysics model. It is estimated that the neck diameter of the active nanopores is the most dominant geometrical feature for achieving ion rejection, and the flux linearly increases with the frequency of operation (between 2–50Hz). The threshold neck diameter of the nanopore required for achieving rejection from multiphysics simulation is observed to be 100nm. The flux through the membrane decreases significantly with decreasing diameter and becomes negligible at 10nm effective neck diameter.


Author(s):  
Jannatul Ferdows Nipa ◽  
Md. Hasan Tarek Mondal ◽  
Md Atikul Islam

A straw chopper is a mechanical device used to uniformly chop fodder into small pieces to mix it together with other grass and then feed it to livestock. The objective of this research was to design and develop an animal fodder chopping machine to be utilised by dairy farmers within their purchase range. The drawing of these machine parts was undertaken in AutoCAD software and the construction was performed in a local workshop. After development of this machine, performance tests were carried out on a farm. The chopping machine tests were carried out with commonly grown fodder (namely: straw, grass, and maize) in Bangladesh. The performance evaluation of the developed machine was carried out in terms of the chopping efficiency, machine productivity, and energy consumption. The economic analysis of the straw chopping machine was assessed by indicating the cost effectiveness to the poor farmers. Analysis of the data in regard to chopping efficiency and machine productivity varied from 93 to 96% and from 192 to 600 kg×h<sup>–1</sup>, respectively. The energy consumption during the chopping process ranged between 0.0025 and 0.01 kWh for the different types of fodder. The break-even point of the fodder chopping machine was 3 793 kg of cut straw and the payback period was within one year depending on the use.


2020 ◽  
Vol 82 (8) ◽  
pp. 1710-1719
Author(s):  
San He ◽  
Xiaozhuo Zhang ◽  
Xingyu Xia ◽  
Chuanjun Wang ◽  
Sulin Xiang

Abstract A new regeneration method of ion exchange resin named Adjacent Bed Electrically Regenerated Ion-exchange (ABERI) was proposed to eliminate the environmental impact of traditional chemical regeneration and improve the economy of replacing chemical regeneration with electrical regeneration. The desalting operation of ABERI was the same as the conventional mixed bed. When the resins were exhausted, anion and cation resins were separated and then packed in a dedicated regenerator adjacently. The resins were regenerated by the H+ and OH− ions produced from a pair of electrodes installed on both sides of the resin bed. By optimizing the regeneration time, current, and feed water flow rate, the energy consumption of ABERI was 0.38 kWh/m3 water; that is, 54% of that of another electrical regeneration technology, membrane-free electrodeionization (MFEDI). Compared with MFEDI, the quality and quantity of purified water produced after regeneration were improved. In ABERI, the average conductivity and the volume (times of bed volumes) of the purified water are 0.9 μS/cm and 109; that is, 75 and 133% of that of MFEDI, respectively. The preliminary economic analysis showed that ABERI offers the potential to regenerate ion exchange resin in an eco-friendly and cost-effective manner.


Author(s):  
Naseer Ahmad ◽  
Anwar Khalil Sheikh ◽  
Mostafa Elshafie ◽  
Hussain Al-Qahtani

This work is related to the design and development of instrumentation, data acquisition and graphical user interface of Photovoltaic driven Reverse Osmosis system for monitoring and performance evaluation purposes. Installed PV system comprises of 12 PV panels, trackers, batteries and inverter whereas RO system is equipped with pre filters, pumps, energy recovery devices and filtration membranes. Proper instrumentation is carried out in PV system to measure the irradiation, temperatures, voltage and current at various points. Moreover various sensors are used to measure the pressures, flows, salinities at RO unit. Signal conditioning circuits are designed to adjust sensor output signals for computer interface. A simple moving average filter is used to suppress the measurement noise. The experimental investigation of PVRO system is carried out by using LabVIEW interface capabilities. The developed system reveals and stores the pronounced impact of measured variables on the PV output power and specific energy consumption of the RO filtration system. The online data display in multi-scale window frame is very informative for system operation and analysis. During the experimental run of PVRO system using the developed DAQ system, the PV system generated 7.5kWh of energy during the whole day operation. Feed water having 7100ppm salinity and its flow rate was set to 850 lit/hour by adjusting the RPM of the high pressure pump. Clean water flow rate is recorded to be at 465 lit/hour having salinity of 115 ppm during the RO operation. Specific energy consumption of RO system comes out to be 2.083kWh/m3 for 7100ppm salinity of feed water.


2021 ◽  
Vol 8 (8) ◽  
pp. 1-8
Author(s):  
Hisham A. Maddah ◽  

Porous high-pressure membranes have been widely used for saline water desalination. However, fouling (concentration polarization) extensively reduces permeate flux in reverse osmosis (RO) and/or nanofiltration (NF) modules. Fouling arises from pore blocking, organic adsorption, cake formation, inorganic or biological precipitation reducing water flux. Herein, we investigated the effect of feed water with various NaCl concentrations on fouling of RO and/or NF and the permeate water flux. A parabolic (or diffusion) partial differential equation (PDE) was used to model salt concentration profile or gradient inside the membrane. Subsequently, the numerical PDE equation, solved by the forward finite difference (FFD) explicit method, estimated flux decline rates resulted from NaCl fouling. It was found that salt accumulation occurs at the feed-side with a noticeable decrease in flux as fouling increases. Previous works reported similar findings as those identified from our analysis: (1) fouling increases with feed concentration and surface roughness, (2) fouling becomes intensified with higher pressure and flux, (3) fouling from long operation times can reduce flux by 65% within 24 h, (4) NaCl fouling can decrease flux rates by 70% (67-22 LMH) for brackish water with an initial concentration of 10000 ppm, and (5) reversible organic fouling may be avoided from lowering flux rates below the membrane critical flux. Results showed fouled RO modules would decrease flux rates from the increased surface polarization, where reverse flow (negative flux) was estimated for feed-side accumulations >10000 ppm for waters with an initial NaCl concentration of 10000 ppm and average diffusivity of 1.3×10-6 cm2/s.


2015 ◽  
Vol 19 (5) ◽  
pp. 1709-1721
Author(s):  
Marjan Arsovic ◽  
Radivoje Topic ◽  
Mirko Komatina ◽  
Milan Gojak

Many regions of the world face the problem of saline water. Water desalination processes, which require significant energy consumption, are a common solution to produce drinking water. This study evaluated the influence of the following process operational parameters on the energy consumption of seawater RO systems: water salinity, permeate recovery ratio, membrane performance and feed water temperature. Optimal operational conditions for the theoretical minimum energy consumption were determined with experiments by varying water qualities and operational parameters. In order to further reduce energy consumption a RO system was integrated with a PV solar system and a pilot PVRO system was built and tested. The results obtained from this study indicated that even though a Solar PV system incurs a huge initial capital investment, it will yield significant benefits in the long run of the RO operational period.


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