Comparison of Struvite and Brushite Recovery: Model Based Technical and Economic Evaluation and Sensitivity Analysis

In this paper, process modeling was used to compare struvite and brushite based phosphorus (P) recovery alternatives with the available data which can be used for conceptual decision-making for P recovery. A model based technical and economical evaluation of struvite and brushite recovery (using BioWin™ Version 6.0) was conducted for a large Water Resource Recovery Facility (WRRF). The cost effectiveness ($/lb of Premoved) of the P recovery options was determined and sensitivity analysis was conducted to compare the options with and without the sale of the fertilizer product, for chemical cost and other key parameters. This comparative assessment focused on confirming and validating the design basis, technology providers’ estimated P recovery, and chemical needs. This paper is the first application of commercial simulator for side by side comparison of the two P recovery alternatives. Modeling results compared reasonably well with the actual WRRF data for struvite recovery. The model predicted chemical requirement for brushite recovery was similar to literature values for pilot studies. For the testing conditions modeled in this paper (20 MGD WRRF), brushite recovery appears to be slightly more cost effective in terms of $/lb Premoved. However, given the cost variations depending on the location and site specific conditions, the two alternatives appear equal in cost effectiveness.