Switch to Sulphated PAC treatment results in major customer benefits

Double Digit Operational Improvements, Efficiency Gains and Cost Reduction

The Customer

60 MGD water treatment plant in Southeast Asia that historically used liquid Aluminum until water quality changed due to high algae presence.

Increase in Aluminum dosage caused high residual Alum in treated water, which depressed alkalinity, requiring higher dose of hydrated lime. Switching to Aluminum Clorohydrate (ACH) liquid drove up costs, while causing other operational issues. GTI helped customer implement Sulphated PAC treatment, improving overall plant performance and treatment costs.

The Challenge

Alum dosage was increased causing high residual AI in treated water. Alum also depressed the alkalinity of the water, requiring a higher dose of hydrated lime. The plant switched to Aluminum Chlorohydrate (ACH) liquid to control residual AI.

  • Switch to ACH drove up treatment costs (as compared to Alum)
  • ACH created tiny floc and settling issue
  • Lower plant filtered water output
  • Higher sand filter backwashing and higher water loss

Collaborative Innovation

GTI partnered with customer to examine problems with both Alum and ACH. Decision made to switch treatment to GPAC3340 (Sulphated PAC) 12% Al203 high basicity PAC, improving overall plant performance and treatment costs.

  • 20-25% savings in coagulant costs

  • Lowered the treated water cost

  • Plant returned to full capacity at 60MLD

  • Filter runs increased by ~41%

  • Backwash water loss savings of ~ 1,000 m3 per month

  • Improved residual aluminum at compliance levels < 0.2 ppm

  • Reduction in pH depression resulting in 15% savings in lime

  • The Solution

    Reduction in floc settling enabled plant to return to full capacity at 60MLD, while lowering treatment costs (as compared to ACH)


    The characteristics of raw water can change over time, and the same treatment method that worked in the past might not be optimal today. By fully understanding each treatment option and the overall treatment environment, GTI helped this customer select the best product for the job, thereby driving significant operational improvements. We were able to save the customer 15-20% in coagulant costs. The plant quickly returned to full capacity, with longer sand filter runs and reduced water loss due to back washing. Improved residual AI compliance was also achieved, as well as a reduction in pH depression.