[Comparison of Polycaprolactone and Poly-3-hydroxybutyrate-co-3-hydroxyvalerate for Nitrogen Removal]

Two types of biodegradable polymers, polycaprolactone (PCL) and poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV), were used as a denitrification slow-release carbon source and a microbial carrier. By comprehensively comparing their performances in denitrification, carbon release, surface morphology, and material composition as well as their microbial community characteristics, the PHBV was determined as the better performer. It had a shorter denitrification start time, a higher denitrification rate, a lower residual organic matter concentration, and a more stable and sustained denitrification performance than PCL. This is because its surface was rough and contained large amounts of hydrophilic groups such as C-O and C=O, which is easily attached and degraded by microorganisms. As a result, the microorganisms on its surface were diverse. The dominant ones were identified with heterotrophic denitrification potentials, such as Thiothrix, Pseudomonas, Zoogloea, Flavobacterium, and Dechloromonas. Therefore, PHBV is suitable as a carbon source medium for tertiary nitrogen removal.