Development of a green reactor for phosphorus recovery from wastewater

Phosphorus is an essential nutrient for plant growth. It cannot be synthesized in the laboratory and is a non-renewable resource. However, it can also contribute to environmental pollution when discharged in wastewater. Therefore, this study aims to recover phosphorus from wastewater through the formation of struvite crystals, which also serve as a slow-release fertilizer. In this study, a lab-scale reactor was developed for phosphorus recovery from synthetic urine. The reactor operated based on gravity flow and hydraulics, thereby eliminating the need for external energy sources. Struvite precipitation was induced by adding a magnesium source at a controlled molar ratio. The study consists of two main phases: struvite precipitation experiments and reactor development. A jar test apparatus was utilized to determine optimal precipitation conditions. The products (struvite crystals) were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) to assess morphology and crystal composition. The reactor used in this study is lab-scale, with a hydraulic retention time (HRT) of 2 h, allowing sufficient time for struvite to settle at the bottom. Jar test results indicated that the optimal phosphorus removal efficiency reaches 100% at pH 8.89. Additionally, the reactor demonstrated a phosphorus recovery rate exceeding 90%, highlighting its potential as a sustainable approach for nutrient recovery.