Project Briefing:

Saudi Electric company wanted to install a seawater desalination plant for its South Jeddah Power Plant. The plant will feed the thermal steam generators. So the quality of the water is important.

 Client Requirements:

The plant needs to take seawater from a beach well and desalinate the raw seawater to produce water of the following quantity:

Flow rate: 2 x 3,600 m³/day

TDS: < 42,000 ppm

pH: 8.5

Hardness: < 500 ppm as Ca

So it can be fed to the Thermal Steam Generators:

TDS < 50 ppm

pH: 6 – 8

Hardness: < 20 ppm as CaCO₃

 AES Solution:

AES provided pretreatment to the RO plant including the perchlorination, ferric chloride dosing for coagulation. Two stage of filtration is provided to ensure proper removal of suspended solid. Multimedia filters are followed by sand media filters.

To ensure proper quality of treated water, two passes of RO units are provided. 1st pass will drop TDS to around 350 ppm, while second pass will drop it to less than 50 ppm. Energy recovery turbine is provided to recover energy from the plant high pressure pump which otherwise will be lost in the discharged brine water.

 Conclusion and Results:

The plant was commissioned according to SCECO expectations and complying with specifications.

The treated water was found to exceed specifications as follows:

Conductivity < 3 MicoS/cm

pH: 7.4

Silica: < 1 ppm

TDS < 30 ppm

Hardness: < 10 ppm as CaCO₃

Energy recovery was at least 70% from brine water.