Mechanism of additional carrier with seasonal temperature changes enhanced ecological floating beds for non-point...

The continuous performance and denitrification characteristics of carriers were investigated in two modified enhanced ecological floating beds (EFBs), one with only ceramsite and the other with ceramsite and extra additional stereo-elastic packing. Over a period of more than 414 days, the extra carrier was found to improve nitrogen removal while enhancing the system's resistance to seasonal temperature variations. The denitrification of all carriers in EFBs was inhibited in practice by seasonal temperature change, especially temperature rose from below 20 °C to above 20 °C and the inhibition rate of nitrous nitrogen (NO₂^--N) reduction was consistently above 91%, which was higher than that of nitrate nitrogen (NO₃^--N). However, the denitrification process including the rate and the resistance to temperature changes of ceramsite in the same EFBs with stereo-elastic packing at different temperatures, was consistently improved. The removal rate of NO₃^--N and NO₂^--N increased by up to 23.5% and 19.5%, respectively. The potential denitrification rates of all carriers increased with time which was also evidenced by in PICRUSt results, which showed that the abundances of predicted functional genes encoding NO₃^--N and NO₂^--N reductase increased over time. The dominant denitrifier also differed over time due to seasonal temperature changes.