A Case Study in Partnership and Trust

Evaluation of aluminum sulfate (alum) vs. Poly-aluminum Chloride in municipal water treatment plant

The Customer

19 MGD conventional treatment facility treating river water source in southern U.S., serving over 50,000 customers

Plant experienced recurring pH problem at least 3-4 times during summer months when low alkalinity conditions set in. Partnering with GTI helped identify and treat seasonal alkalinity problem with new coagulant.

The Challenge

Seasonal low alkalinity water conditions

The water treatment plant experienced a reoccurring pH problem at least three to four times during the summer months when low alkalinity conditions set in.

Aluminum sulfate in the traditional alum water treatment program further compounded the problem by consuming alkalinity and reducing pH below the plant’s 6.0 limit.

Collaborative Innovation

Customer partnered with GTI to identify proper treatment solution
  • Joint discovery of seasonal alkalinity problem
  • Identification of new coagulant to prevent alkalinity issue while maintaining compliance with established regulatory guidelines and optimizing critical treatment parameters
  • Improved effectiveness at pH >7

  • Reduced chemical dosage

  • Lowered total chemical costs

  • Lower residual aluminum levels in treated water

  • Zero lime dosage required for post-treatment pH adjustment

  • Improved corrosive index of the treated water from <6 pH to >6 pH

  • The Solution

    Switched from aluminum-based (alum) chemistry to Polyaluminum Chloride (PACl) coagulation chemistry, resulting in
    • Lower consumption of alkalinity
    • Improved effectiveness over broader pH range
    • Reduced chemical dosage and chemical costs within treatment process
    • Lower residual aluminum levels in treated water
    • Improved treated water quality, including lower TDS and sulfate levels
    • Lower sludge production
    • Reduced need for post-treatment pH adjustments using lime, thereby improving capital costs, operating conditions and maintenance requirements

    Dose (ppm) in Different Raw Water Conditions – Alum vs GPAC 2350


    When disruptions occur in raw water sources, Gulbrandsen’s staff of experienced account managers are on hand to help diagnose and solve difficult treatment challenges. By switching from alum-based chemistry to Polyaluminum Chloride coagulation chemistry, this customer found a highly efficient approach to coagulation that drove material cost savings, as well as higher water quality results.