An anodizing facility was struggling to meet a pretreatment permit discharge limit of 10mg/L for Total Phosphorus. If the facility could not retain pretreatment permit limits, they would be at risk for fines and potentially having their permit revoked. Influent water showed an incoming Total Phosphorus averaging 700mg/L. Phosphorus came from the anodizing process rinse waters. pH adjustments, chemical dosing changes, and system changes did not remove enough phosphorus to get below the facility’s discharge limits.
The Hubbard-Hall team, called in by the facility owners to help solve the issue, began by evaluating different chemistries to determine which chemistry would meet discharge criteria consistently.
Hubbard-Hall used the Molybdovanadate Method with Acid Persulfate Digestion – an approach that the HACH company has adapted from Standard Methods for the Examination of Water and Wastewater. A
series of progressive tests were conducted using wastewater from the anodizing process rinses. These samples had a starting Total Phosphorus average of 700mg/L.
With pH maintained at 7.5, the testing was conducted using a HACH DR 890 Colorimeter and HACH Test Method 10127 for High Range Total Phosphorus. This testing process reads total phosphorus from 0-100mg/L. Any test result over 100mg/L is marked as 100mg/L.
During testing, Hubbard-Hall used different chemistry concentrations to find the lowest dosage to achieve desired results.
Based on the bench test results, Hubbard-Hall recommended AquaPure™ Cal 50 Plus, which showed optimal results at just 15ml./ gallon dosage. Working with their local municipality, the facility ran a two-week trial to ensure the bench test results would carry over to the wastewater system while manufacturing was in full production.