Effect of spatial location on denitrification performance with poly（butylene succinate）media

Poly (butylene succinate) (PBS) was used as both biofilm carriers and solid carbon source to remove nitrate from marine aquaculture wastewater with a low C/N ratio by denitrification in packed bed reactor. In this laboratory experiment, the performance of denitification, micro biomass adhering to the PBS granules and the weight loss of PBS were studied. Main contents and results were as follows. The denitrification reactor was started up at nitrate (NO3--N)concentration of 50 mg/L and hydraulic retention time (HRT) of 4 hours. This bioreactor performed well on nitrogen removal, the removal efficiency of nitrate averaged at 99.50% on the 20th day. The experiments on biomass and weight loss of PBS showed that spatial location had an important influence on micro biomass and the weight loss. The micro biomass and weight loss of PBS taken from the top, middle and bottom layer were 7.65×108, 1.48×109, 3.64×109 CFU/cm3 and 0.3517, 0.6749, 3.9336 g. And PBS granules taken from different locations had a significant difference on the removal ability of nitrater, nitrite and total nitrogen. The nitrate removal efficiency of PBS taken from the top, middle and bottom layer averaged at 38.479%,72.128% and 99.233%, respectively. The nitrite concentration increased gradually in the first 9 hours, the concentrations were 9.7075,7.2982, 10.0527 mg/L respectively. And in the following 14 hours, the concentrations decreased gradually, they were 6.9351, 5.3473,0.2119 mg/L. The removal efficiency of total nitrogen were 58.3449%, 70.0623%, 99.1570%, respectively.