Regarding the algea in raw water which is effective technology in term of algea removal applying DAF or using LG sonic system ?And which is cost effiecint ?

In my understanding, DAF and ultrasonic systems work in different ways.

DAF is usually more effective when algae concentration is already high, especially when there are suspended solids, organic matter, or seasonal algae blooms. It can physically remove algae from the water before filtration.

LG Sonic / ultrasonic systems are more like algae control or prevention technology. It may help reduce algae growth in reservoirs or intake areas, but it normally needs time and depends strongly on water depth, flow condition, algae type, and installation coverage.

For cost efficiency, DAF may have higher chemical and operation cost, but it is more direct for actual algae removal. Ultrasonic system may have lower chemical use, but the final result depends on site condition.

So I would not say one is always better. The right choice depends on:

• algae concentration
• raw water source
• flow rate
• whether the problem is seasonal or continuous
• target SDI / turbidity before RO
• existing pretreatment process

If the issue is already affecting RO security filter ΔP or membrane stability, I would first evaluate the pretreatment data and fouling behavior before choosing the technology.