Task

Evaluate a novel low-cost process to:
1. treat high silica content cooling tower blowdown
2. maximize recovery of treated water
3. reduce blowdown disposal
thus minimizing deep well disposal requirements.

Action

IntelliFlux was installed to optimize a treatment train including desilication chemical dosing, Inclined Plate Clarifier, UF and RO units through an integrated SCADA level automation platform. The objective was to:

• • • Synergistically manage precipitant dosage for the chemical desilication
    • Monitor the recycle rate of the UF to optimize the floc sizes for solids removal
    • Manage recovery of the RO process by maintaining a consistent RO feed quality.

The UF system was operated in crossflow mode, recycling the concentrate to the clarifier unit as a closed loop system. The in-line mixing was complemented by shear induced aggregation in the crossflow UF modules, until the UF filtrate turbidity was reduced below an acceptable setpoint. The desilication agent dosing was controlled in response to the influent water turbidity and silica content. The entire process was monitored and mapped against digital twins of the coagulation, inclined plate settling, and UF processes. The feed and UF filtrate turbidity were utilized to adjust the feed and bleed mode UF operation, as well as the chemical dosing.

Result

Simultaneous autonomous optimization of the UF operation with desilication chemistry dosing maintained a sustainable RO feed quality and throughput, allowing the RO unit to maximize water recovery.

The pilot demonstrated:

• 77% recovery with the single stage RO operation, yielding a treatment cost of $0.65-0.75 /m3
• 81% reduction in brine disposal volume
• Generation of a solid waste which can be classified as a non-hazardous waste.