Biological denitrification using cross-linked starch/PCL blends as solid carbon source and biofilm carrier

A novel kind of cross-linked starch/polycaprolactone (SPCL11) was prepared and used as carbon source and biofilm attachment carrier for denitrifying bacteria. The results showed that the average denitrification rate was 0.027 mg NO3-N/(g·h) in batch tests. The continuous fixed-bed experiments indicated that more than 90% NO3-N was removed, the denitrification rate reached 26.86 mg NO3-N/(L·h), and NO2-N concentration was below 0.16 mg/L. The formation of NH4-N was observed, but usually below 1.0 mg/L. Rapid biodegradation of starch on the surfaces of SPCL11 granules could cause an initial excess release of dissolved organic compound (DOC), and shortening HRT from 2 h to 1 h can result in sharp decrease of DOC.