A pilot-scale deep bed denitrification filter using quartz sand as the filter media was operated under filtration velocity of 5.23 m/h. Nitrate, nitrite, ammonia, and total nitrogen removal rates were relatively high at influent C/N ratios of 4:1 and 5:1. A model was developed using software to simulate the processes operating in the filter and improve the related parameters in the actual operations. The normalized sensitivity coefficient and the mean square sensitivity measure were used for the sensitivity analysis. Results showed that the stoichiometric parameters were the most sensitive, which were related to methylotrophs and biofilm. Measured data were consistent with the simulations. Moreover, the order of significance of factors affecting nitrate nitrogen removal was as follows: influent chemical oxygen demand, influent nitrate nitrogen, and hydraulic retention time. Last, the denitrification dynamic model was obtained at influent C/N ratio of 5:1.
Keywords: Advanced nitrate removal; Deep bed denitrification filter; Influent C/N ratio; Model simulation..