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Precipitation of Orthophosphate in a Wastewater Treatment Plant

Abstract:

Different individually applied commercial salts at different concentrations are generally used to precipitate contaminants in wastewater. In this study, we developed a treatment complementary to the lagoon system of a wastewater treatment plant by adding a combination of trivalent metal salts to chemically precipitate phosphate contaminants. Laboratory tests were conducted to determine the most efficient treatment for the removal of phosphate in wastewater by analyzing orthophosphate using the ascorbic acid method. Three trivalent metal salts—iron (III) sulfate, aluminum (III) sulfate, and iron (III) chloride—were combined with each other at three different concentrations, obtaining an experimental design involving 27 treatments replicated three times each. Analysis of variance (ANOVA) with Tukey’s test revealed the treatment for which the highest percentage of orthophosphate removal (99.04%) was obtained. Finally, the selected treatment was implemented for field evaluation over three weeks, obtaining an average removal of 93.13%.