Nutrients removal from municipal wastewater by chemical precipitation in a moving bed biofilm reactor

In this study, a combined chemical precipitation and moving bed biofilm system was used to treat municipal wastewater. The moving bed biofilm reactor (MBBR) has been tested for nitrogen removal through simultaneous nitrification and denitrification (SND). The SND could be successfully established at DO of about 2 mg/l, and about 89.9% of total nitrogen (TN) removal efficiency through SND had been achieved in the system. Iron(II) sulphate heptahydrate solution was dosed onto the top of MBBR at varying ratios of total phosphorus to iron(II). The performance of the system with respect to BOD, COD, TN removal was not significantly affected by chemical dosing. The phosphorus removal efficiency increased with increasing dose. To meet EC requirements, the most favourable chemical dosing ratio was 1:1.3 (weight ratio P:Fe). The combination of highly efficient nitrogen removal, obtainable in a MBBR and effective phosphorus removal by chemical precipitation with iron(II) should be an ideal option for the total nutrient removal from municipal wastewater.