Recovery of Struvite Obtained from Semiconductor Wastewater and Reuse as a Slow-Release Fertilizer

This study evaluated the feasibility of using struvite deposit recovered from semiconductor wastewater as a slow-release fertilizer for cultivating Lactuca sativa (lettuce). To the best of our knowledge, the plant availability and fertilizer value of the recovered struvite precipitate have never been studied before. In an assessment, the fertilizing value of struvite deposit was compared with that of commercial fertilizers: complex, organic, and compost. Laboratory pot test results clearly showed that lettuce growth was better facilitated with struvite deposit than with commercial fertilizers. In addition, the fixed amounts of nitrogen, phosphorus, potassium, and magnesium were the highest in the lettuce tissue grown in the struvite pots. At the same time, less mercury, lead, chromium, and nickel accumulated in the lettuce tissue grown in the struvite pots than in commercial fertilizer pots. The optimum struvite dosage for the cultivation of lettuce was found to be 0.938 g struvite/kg soil. The column experiments also showed that the nitrogen-leaching rate of struvite deposits was lower than that of complex fertilizer. Results obtained in our study will contribute to the development of methods for the application of struvite precipitate, produced from semiconductor wastewater by crystallization, in the cultivation of lettuce and other plants.