Pilot Testing Nutrient Recovery from WAS streams for Struvite Control and Recycle Load Reduction

摘要

The F. Wayne Hill Water Resources Center (FWHWRC) is Gwinnett County’s largest and mostadvanced wastewater treatment facility with a capacity of 60 mgd. The FWHWRC uses EBPRand chemical trim to meet a total phosphorus (TP) limit of 0.08 mg/L. In 2009, Gwinnett Countybegan adding magnesium hydroxide (Mag) to their collection system for odor and corrosioncontrol. Struvite precipitation has since become a major issue at the FWHWRC. However, thedigesters at the FWHWRC are now phosphorus limited with respect to struvite formation due tothe Mag addition in the collection system. If Mag addition is halted, the P-recycle load will needto be addressed with increased metal salt addition and if it continues, the plant must address thestruvite formation issues. This project evaluated nutrient recovery options compared withconventional metal salt addition to the digesters or centrate for both struvite control (if Magcontinues) or recycle P load reduction (if Mag is stopped) using bench and pilot scale testing andprocess modeling.