A water district in Orange County, California is currently constructing a 265,000 m3/day MF/RO plant for wastewater reuse. Based on 30 years of experience operating a 5 MGD MF/R.O. plant, the district took a novel approach to reducing the cost of consumable scale inhibition chemicals. A competitive bid was issued which took into account feed pH in addition to cost and dosage of antiscalant.
The feed pH was used to calculate an acid dosage rate and the annual cost of sulfuric acid use for pH reduction. This was then combined with the annual cost of the antiscalant in order to select the most cost effective treatment as offered by the various antiscalant manufacturers participating in the bid. The selected treatment was then piloted for 50 days to verify its performance at the dosage and feed pH claimed by the manufacturer.