완전혼합형 정석탈인반응조에서 미분말 전로슬래그를 이용한 고농도 인의 회수

A phosphate recovery system from artificial wastewater was developed using a completely mixed phosphorus crystallization reactor, in which powdered converter slag was used as a seeding crystal. In preliminary test, the optimal pH range for meta-stable hydroxyapatite crystallization for high phosphorus concentration was observed to be 6.0 to 7.0, which was different from the conventionally known pH range (8.0~9.5) for effective crystallization in relatively low phosphorus concentration less than 5 ㎎/L. The average phosphorus removal efficiency in a lab-scaled completely mixed crystallization system for artificial wastewater with about 100 ㎎/L of average PO₄-P concentration was shown to be 60.9% for 40 days of lapsed time. XRD analysis exhibited that crystalline of hydroxyapatite formed on the surface of seed crystal, which was also observed in SEM analysis. In EDS mapping analysis, composition mole ratio (=Ca/P) of the crystalline was found to be 1.78, indicating the crystalline on the surface of seed crystal is likely to be hydroxyapatite. Particle size distribution analysis showed that average size of seed crystal increased from 28μm up to 50μm, suggesting that phosphorus recycling from wastewater with high phosphorus concentration can be successfully obtained by using the phosphorus crystallization recovery system.