Managing Severe Biofouling at Seawater Intake during Summer Algal Bloom
Posted by Eng. Sarah Al-Rashid • 14 responses
Eng. Sarah Al-Rashid
Lead Desalination Operator • Yanbu Desalination Plant
"We are observing a massive Red Tide bloom along the Red Sea coast. Water temperature is 34°C with chlorophyll-a exceeding 18 µg/L. Cartridge filter differential pressure is spiking every 12 hours. We are dosing sodium hypochlorite followed by SMBS neutralization, but bio-slime is still carrying over into the first-stage RO lead elements. Any advice on shock dosing versus DAF pre-treatment?"
Dr. Takeshi Morita (Verified Expert)
Toray Global Process Lead • 30+ Years RO Experience
"Continuous chlorination in summer often lyses algal cells, releasing intracellular organic matter (AOM) which acts as severe nutrient source for secondary biofouling downstream of SMBS de-chlorination."
Recommended Action: Switch from continuous chlorination to intermittent shock chlorination (10-15 ppm for 30 minutes twice daily), and increase ferric chloride coagulation to 3.5 mg/L prior to medium media filtration.