Defining the Benefits of Harvesting Struvite from Dewatering Sidestreams

The anaerobic digesters at the Des Moines Wastewater Reclamation Authority receive and treat hauled high-strength organic wastes from other sources. The facility faces significant phosphorus-related maintenance challenges and antic ipated regulations could create further phosphorus (P) treatment challenges. Struvite accumulation downstream of the anaerobic digesters is creating major operations and maintenance problems as well as increasing costs due to operator labor requirements for cleaning process equipment and piping. Possible nutrient management limits to the facility’s biosolids land application program will effectively reduce the mass of biosolids that be applied per hectare of land because of high phosphorus concentrations. Further, it is expected that a future effluent P limit of approximately 1 mg /L may be instituted which would require modifications to the plant’s liquid treatment processes. This analysis found that recovering phosphorus from the plant’s dewatering sidestream through struvite harvesting would be a cost-effective solution to address most of these challenges.