| Abstract |
Amid food, nutrient, and wastewater crises, this study investigated struvite (NH4MgPO46H2O) derived from domestic wastewater as a sustainable solution, utilizing it in hydroponic systems for lettuce production. The research synthesized and compared struvite from both synthetic and real domestic wastewater and assessed its nutrient uptake efficiency across three phases: I) hydroponics without struvite, II) hydroponics with synthetic struvite, and III) hydroponics with struvite from domestic wastewater. Results reveal that struvite from domestic wastewater exhibited a structure similar to synthetic struvite, with an efficient phosphate removal efficiency (90.3%) but without ammonium removal from urine due to the hydrolysis of urea in the wastewater. In Phase I, hydroponic solutions without struvite showed low phosphorus concentrations (1.5 and 4.0 mgP/L). Adding 0.5 g and 1.0 g of chemically synthesized struvite per liter in Phase II significantly increased phosphate levels to 43.9 and 78.9 mgP/L, respectively, demonstrating the effectiveness of struvite in enhancing phosphorus availability. Phase III revealed that struvite from real domestic wastewater released significantly more phosphate (67.2 mgP/L) compared to synthetic struvite (35.7 mgP/L), suggesting the potential of using domestic wastewaterderived struvite for enhanced nutrient supplementation. The supplementation of struvite in hydroponics increased phosphate but not nitrate levels in the hydroponic water. Hydroponic systems supplemented with synthetic and domestic wastewater struvite yielded 1,350.0 and 1,265.3 grams per system (12 heads) respectively, surpassing yields from systems without struvite. Phosphorus and nitrogen use efficiencies for synthetic struvite were 1.8% and 33.9%, and for domestic wastewater struvite 1.9% and 26.0%, respectively. Additionally, struvite sources affected microbial communities, with synthetic struvite favoring nitrifying bacteria (e.g., Nitrospira, Nitrobacter) and domestic struvite promoting microbes associated with organic nutrients (e.g., Altererythrobacter, Litorilinea, Armatimonas). These findings highlight the potential of using domestic wastewater-derived struvite in hydroponics as a sustainable nutrient recovery method, contributing to sustainable agriculture and the circular economy. |