Application of a H2-based MBfR in advanced nitrogen removal from real municipal secondary effluent

Abstract

A potentially scalable configuration of a H₂-based MBfR was developed in this study to test the feasibility of treating real secondary effluent. Synthetic water was first fed for biofilm attachment, and afterwards, the influent was switched to real secondary effluent once efficient denitrification was achieved. The biofilm reduced 15 mg N per L nitrate to 5 mg N per L with a maximum nitrate removal flux of 1.0 g N per m² d. Kinetic parameters of q_max and K were also estimated to be 0.08 mg NO₃⁻-N mg per VS d and 0.56 mg NO₃⁻-N per L, respectively, using the finite difference method. Spearman's correlation analysis showed that the microbial community diversity increased as sulfate was introduced in real secondary effluent. Desulfomicrobium and Desulfotomaculum were most influenced by SO₄²⁻ loading among dominant bacteria. Cost assessment demonstrated that this MBfR system showed both lower operation cost (0.67 CNY per t) and smaller footprint (0.20 m² t⁻¹ d⁻¹), thus demonstrating considerable advantages over other advanced nitrogen removal technologies.