Study on carrier optimum filling ratio of two-stage MBBR for treatment of reverse osmosis concentrate from high-quality water reclamation of WWTP effluent

A pilot nitrosation-denitrification two-stage moving bed bio-film reactor (MBBR) was developed for the advanced nitrogen removal of high N ${\mathrm{H}}_4^{+}$ -N and salinity reverse osmosis concentrate, which was produced from the high-quality water reclamation of wastewater treatment plant (WWTP) effluent. The removal effect of N ${\mathrm{H}}_4^{+}$ -N, N ${\mathrm{O}}_3^{-}$ -N, COD_Cr and other pollutants was compared under carrier filling ratio (FR) of 51%, 42% and 32%, respectively. The results showed that the average N ${\mathrm{H}}_4^{+}$ -N removal rate was 67.0%±4.0%, 71.3%±8.9% and 73.2%±6.1%, when the FR was 51%, 42% and 32% in the nitrosation MBBR, and the optimal FR was 32%. In the denitrification MBBR, the average N ${\mathrm{O}}_3^{-}$ -N removal rate was 73.1%±4.2%, 63.7%±9.4% and 64.9%±10.4%, when the FR was 51%, 42% and 32% respectively. Taking account of economical availability, 32% was selected as the optimum FR.