Heterotrophic Denitrification of Nitrate-Contaminated Water Using Different Solid Carbon Sources

Biodegradability and COD release of polylactic acid (PLA), polycaprolactone (PCL) and polylactic acid/Poly (3- hydroxybutyrate-co-3-hydroxyvalerate) blend (PLA/PHBV) were determined in water solution with sludge as the inoculum, and the feasibility of using them as carbon sources to remove nitrate from nitrate-contaminated water was also investigated. The experimental results indicate that PLA/PHBV is degraded more rapidly and easily than PLA and PCL. PLA is difficult to be degraded in water solution, so it is unsuitable to be used as carbon source for denitrification. Average denitrification rates supported by PCL and PLA/PHBV were 6.34 and 6.63 mg L-1 h-1 with 7 h HRT under a batch system, respectively. Nitrite was not detected in the treated water after 9-hour operation.