Nitrification of an anaerobic filter effluent in a flat sheet membrane aerated biofilm reactor

Compared with activated sludge intensification by integrating membrane aerated biofilm reactors (MABRs) to promote sustainable nitrogen removal, treatment of anaerobic reactors effluents with MABRs is scarcely studied. Here the capability of a flat sheet MABR for nitrogen removal and nitrification of real wastewater previously treated in an anaerobic filter was analyzed. Removal of 71-81% of ammonia with 54-72% conversion to nitrate, while eliminating 13-28% of total inorganic nitrogen in water containing 38-80mg ammonia-N/L and 25-78mg COD/L was achieved with aeration at atmospheric pressure. Experimental data in combination with stoichiometry and sequencing suggested a combination of autotrophic and heterotrophic bacteria associated to the nitrogen cycle was present in the biofilm. Nitrogen and ammonia removal rates up to 117mgN/L-d and 258mgN/L-d, respectively evidenced a competitive nitrogen conversion capability of the flat sheet MABR attained with non-pressurized aeration involving potential energy savings. Effluent content (mg/L) of ammonia 10-17, nitrite 13-23, nitrate 21-37 and phosphate 21-45, is suitable for further nitrogen removal or nutrient recovery as dissolved fertilizer for irrigation. [Display omitted] •Benchmark ammonia and nitrogen removal rates were achieved with aeration at 0 kPa•Aeration at atmospheric pressure may represent an economic advantage•Effluent content of ammonia, nitrate and phosphate can be tapped as fertilizer•Nitrogen cycle autotroph and heterotroph bacteria were revealed in the biofilm