Aquaculture wastewater treatment using a moving bed biofilm reactor( MBBR)

This paper used a moving bed biofilm reactor( MBBR) to test and analyze aquaculture wastewater treatment. Results indicated that reactor started- up quickly and operated stably in the process of simulated wastewater treatment using MBBR. The removal efficiency for both chemical oxygen demand( COD) and ammonia nitrogen was over 80%,and it reached 50% for total phosphorous( TP),when hydraulic retention time( HRT) was 8 h and DO remained 2. 0 ～ 3. 0 mg·L- 1. Under the condition of organic loading at( 0. 76 ± 0. 03) kg·m- 3·d- 1,the average removal efficiency of total nitrogen( TN) and ammonia was 71. 73% and 98. 42%,respectively,representing the best removal results among all operation periods. To achieve better TN removal rate,organic loading should keep no lower than 0. 5 kg·m- 3·d- 1. TN removal efficiency reached the maximum when dissolved oxygen( DO) was at( 3.00 ±0. 25) mg·L- 1,which was the most suitable to both nitrification and denitrification reactions. To maintain the high removal efficiency of ammonia nitrogen and reduce the nitrite accumulation,DO should keep no less than 2. 0 mg·L- 1in the reactor. Shorter HRT decreased the ammonia removal efficiency and could cause nitrite accumulation. When MBBR was operated in sequencing mode,the removal efficiency of TP was better than that in continuous operation mode. However,nitrite content increased and accumulated at the end of the operation cycle and would be harmful to fish culture.