Water from the reject stream of the Reverse Osmosis (RO) units in Sulaibiya Waste Water Treatment plant (SWWTP) will be used as source water for the Once-Through Steam Generators (OTSG) for the South Ratqa (SR) Phase I project. Using sewage water as source water for steam boilers directly impacts the complexity of the water treatment processes.
Based on the South Raqa steam quality specifications, a water quality requirement has been defined which was found in line with international guidelines. For one of the quality requirements specified (Chemical Oxygen Demand) a tight specification of < 0.1 mg/l was set, which is not often seen in the industry. Instead the industry does define Total Organic Carbon (TOC) as water quality specification, which is closely related to COD. As the water source in the Sulaibiya is coming from a sewage plant (unknown organic components), COD was included as water quality specification.
To deliver the required BFW quality, seven different treatment steps are being installed, which all need to be optimised to ensure the required high plant availability. The major risk area is the requirement to achieve residual chlorine in the water stream coming from the Sulaibiya plant.