Optimization and modeling of process parameters for nutrient recovery from sewage wastewater

Abstract

Nitrogen (N) and phosphorus (P) contamination in wastewater pose significant environmental challenges. Recovering these elements as struvite not only mitigates environmental pollution but also aligns with sustainable development goals by recycling valuable resources. This research hypothesizes that optimized recovery methods can enhance the efficiency and effectiveness of struvite crystallization, addressing existing challenges in conventional techniques. To achieve optimal removal and recovery of N and P from sewage, a response surface model was employed. This model allowed for the identification of optimal process conditions and the elucidation of interactions among various components. Key variables impacting struvite recovery were identified using the Plackett–Burman design, while the central composite design was used for further optimization. The study determined the optimized parameters for phosphate recovery to be an Mg:P ratio of 1:2, pH of 10.5, additive concentration of 350 ppm, and a precipitation time of 30 min. Thermogravimetric analysis indicated that the residual amounts were below 50%. Additionally, the size and surface morphology of the final product were influenced by the process parameters, particularly the Mg:P ratio and pH. An inexpensive, quick, and efficient method to recover struvite fertilizer with a minimum demand of time and chemicals is established toward SDG 2 and 6.