Experimental investigation on the performance of a small reverse osmosis unit

  • M. Elsayed
  • H. A. Refaey
  • O. E. Abdellatif
  • R. Y. Sakr
  • R. I. Afify
Technical Paper


In the present work, the performance of a small reverse osmosis RO (house scale) desalination unit is experimentally investigated. The influence of test parameters such as salinity of the feed water (2000–3000 ppm), feed water temperature (29–41 °C), and feed flow rate (1.25–1.75 L/min) is considered. The results illustrate that the increase in feed water salinity by about 50% leads to an increase of permeate salinity by about 50%, while permeate flow rate and recovery ratio percent decreases by about 25 and 30%, respectively. Furthermore, for feed salinity less than 2500 ppm, as feed flow rate increases from 1.25 to 1.75 L/min, the salt rejection ratio and permeate flow rate increase from 5 to 7%, respectively, while feed pressure decreased by 16% and recovery ratio percent decreased by 37%. The results demonstrate that increase in feed temperature from 29 to 41 °C leads to an increase in the permeate salinity, while feed pressure and salt rejection ratio percent decrease by about 4 and 6%, respectively. Finally, empirical correlations for permeate salinity, permeate flow rate, feed pressure, recovery ratio percent, and salt rejection ratio percent as functions of feed water flow rate, feed temperature, and feed concentration are obtained.


Reverse Osmosis (RO) Flow rate Temperature Salinity Recovery ratio Salt rejection 



Net-driving pressure


Reverse osmosis


Total dissolved solids


Pelton wheel turbine


Pressure exchanger


Thin film composite


Brackish water revers osmosis


Part per million


Polyvinyl chloride


Ultrafine depth filtration


Specific energy consumption

List of symbols




Recovery ratio percent


Salt rejection ratio




Flow rate


Salt concentration


Specific energy consumption of the high pressure pump, kWh/m3


Membrane surface area, m2


Membrane permeability, L/m2 h bar


Membrane flow rate factor, L/h bar










Hydraulic pressure losses factor (α = Pc/Pf)


Concentration polarization (CP) factor


Osmotic pressure, bar


Membrane reflection coefficient


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Copyright information

© The Brazilian Society of Mechanical Sciences and Engineering 2018

Authors and Affiliations

  1. 1.Mechanical EngineeringHigher Technological InstituteTenth of Ramadan CityEgypt
  2. 2.Mechanical Engineering Department, Faculty of Engineering at ShoubraBenha UniversityCairoEgypt

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