الفهرس 
CHAPTER ONE INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Reverse osmosis desalination plant (RO) is able to produce fresh water with lower total cost than other systems. RO plant consists of four main parts: intake and pretreatment, high pressure pumps, RO membrane and post treatment (disposal and permeate treatment).
Intake, pretreatment, post-treatment and disposal costs of RO seawater desali-nation plant represent about 25% of total cost per cubic meter of purified water product (permeate). The present study investigates the effect of proposed arrange-ments of RO modules of desalination system upon the required feed seawater flow rate for a certain purified water production rate. If the flow rate of seawater is reduced for a proposed modules arrangement, the aforementioned costs will consequently be reduced and hence, the total cost of the permeate will be reduced.
In the present study, the RO plant is divided into stages. Each stage consists of number of modules. The exit brine from a stage is fed to the next stage. Seawater salinity is taken 30000 ppm, 35000 ppm, 40000 ppm, and 45000 ppm while the brackish water concentration is taken 1000, 2000, 30000 and 4000 ppm.
The considered operating parameters are the feed pressure and the feed water concentration with and without booster pumps between stages. The considered design parameters are the membrane materials, which are mainly cellulose triacetate and polyamide while the studied membrane designs are hollow fine and spiral wounded ones. A simulation model of proposed modules arrangements has been developed. The derived governing equations were simultaneously solved using Engineering Equation Solver (EES) algorithm.
The effects of different operating conditions for different design conditions on the ratio of purified water production to feed seawater rates (module recovery) are investigated. Results are presented in charts and tables. The results show that the permeate flow rate for all seawater concentrations increases with increasing feed water pressure. When operating the system at high water feed pressure- for cellulose triacetate membrane (hollow fine module design) - two stages arrangement is adequate, while at low operating pressures, three and four stages produce higher permeate flow rates. In case of seawater concentration of 45000 ppm and low feed pressure booster pumps between stages are required in order to avoid permeate concentration over 500 ppm. The results show that the permeate flow rate for all brackish water concentrations increases with increasing feed water pressure. Operating the system at all water feed pressure - for all the considered concentrations- four stages arrangement is adequate. However, the increase in the system recovery with booster pumps between stages is practically insignificant (less than 3%).