A Case Study in Quick Response,
Successful Trial and Product Conversion

Customer partners with GTI to identify and treat cyanobacteria issue in raw water reservoir

Case Study

The Customer

Potable water treatment plant

2 MGD potable water treatment facility located in southeastern U.S. supplied by 114-million-gallon raw water reservoir. Had been successfully using GTI high basicity polyaluminum chloride (PACl) coagulant for nearly a year.

The Challenge

Unidentified cyanobacteria issue in raw water reservoir resulted in increased coagulant consumption from 1,200 to 3,260 pounds per day
  • Variation in source water pH (increasing during the day, decreasing at night)
  • Greenish color observed visually in raw water and elsewhere within treatment plant, including settling tanks
  • Unusual ‘grassy’ odor
  • Filter surface scums
  • Decreased filter run times
  • Difficulty in maintaining a finished water chlorine residual
  • Difficulty meeting turbidity goals

Collaborative Innovation

Customer partnered with GTI to identify and treat issue
  • After jointly ruling out any coagulant product quality issues, operating anomalies pointed to conditions in the raw water reservoir.
  • Alongside almost zero water movement, it was discovered that the lagoon had been exposed to unusually high temperatures over a prolonged period of time resulting in the growth of cyanobacteria.

GTI designed a series of jar tests to find the best coagulant solution that would better react to seasonally changing water conditions.


  • Variation in source water pH


  • Decreased filter run times


  • Difficulty in maintaining a finished water chlorine residual


  • Difficulty meeting turbidity goals

    • The Solution

    3-week trial successfully met all water utility’s goals

    Summary

    Cyanobacteria is often difficult to detect and treat in potable water treatment systems. As plant personnel increasingly face operational challenges posed by warmer raw water sources, Gulbrandsen will be ready with targeted solutions. Our staff of talented account managers are trained to diagnose and solve difficult water treatment challenges. By narrowing down Gulbrandsen’s wide range of polyaluminum chloride products through observation and analysis, we were quickly able to propose the most operator friendly and cost-effective solution to control this troublesome contaminant.

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