Reducing Phosphorus Recovery Operating and Capital Costs at Nansemond WWTP by Using Low Solubility Magnesium Sources

Over the past few year’s Ostara has developed an alternative chemistry that has demonstrated an improvement in the economics of operating a Pearl® nutrient recovery system. A full-scale trial with one of the three Pearl® 500 reactors at HRSD’s (Hampton Roads Sanitation District) Nansemond site has been running since June 2018, demonstrating a cost reduction in chemicals purchases of over 60%. Over the course of the trial the system has achieved comparable ortho-phosphorous removal, production efficiency, and product quality to MgCl2 and NaOH operation. In addition, this change has allowed for the capacity of the existing Pearl® system to be increased. The reduction in chemical cost was accomplished by switching from the use of soluble reagents (magnesium chloride and sodium hydroxide) to a sparingly soluble slurry of magnesium oxide as the primary reagent.