Monitoring of Potassium Content in Wastewater Treatment Plants

Partially treated wastewater can potentially provide a reliable and constant source of water and nutrients for hydroponic crop production. It is essential to determine the macronutrient content of the effluent, such as nitrogen (N), phosphorus (P), and potassium (K), to maximize the yield. Nitrogen (N) and phosphorus (P) measurements are essential daily tasks to be fulfilled, measurements were applied for multiple sources of K content only in this study, determining the exact daily content and concentration pattern. Influent and effluent K levels were measured separately. According to measurements, it was observed that the concentration of K decreased significantly during treatment, with varying values as the wastewater passed through different treatment stages. Two locations with dissimilar technologies were sampled: Etyek, Hungary, semi-continuous batch system with suspended sludge, and South-Pest, Hungary, a continuous activated sludge system. The results were 39,7 mg/l in the influent and 7,5 mg/l in the effluent in Etyek, while South-Pest contained 28,9 mg/l in the influent and 24,5 mg/l K in the effluent respectively. Furthermore, the potassium content was measured in the Return Activated Sludge (RAS) line of South-Pest and found 50,8 mg/l concentration, however, it is being removed from wastewater with the Wasted Activated Sludge (WAS) in activated sludge systems.