Effect of HRT in a continuous flow reactor on orthophosphate removal from swine wastewater and the economic evaluation for the land application.

One of the objectives of this study was to evaluate a laboratory-scale continuous reactor for orthophosphate (OP) removal from swine wastewater and to minimise HRT so as to minimise the volume of reactor such that a continuous-flow device could be developed for land application of swine manure. The laboratory-scale reactor exhibited very high OP removal when the wastewater was enriched with magnesium (Mg2 + ) and the solution pH was increased to 8.5 with NaOH at room temperature. Three different hydraulic retention times (HRT) (150, 90, 40, and 10 min) were tested in the laboratory, and OP removals were 96, 94, 93, and 95%, respectively. Also, in this research, economic evaluation based on the chemical cost, several devices, pumps, and processing of product (minus income) are reported for an up-scale process. The whole process costs $113,756/year.