Elemental sulfur formation and nitrogen removal from wastewaters by autotrophic denitrifiers and anammox bacteria

•Denitrifying ammonium oxidation (DEAMOX) reactor was tested.•Elemental sulfur (S0) was accumulated with nitrogen being removed as nitrogen gas.•Autotrophic denitrifiers and anaerobic ammonium oxidation bacteria were grown.•The sulfide to nitrate ratio of 1.31:1 could lead to excess accumulation of S0.•Alishewanella, Thauera and Candidatus Anammoximicrobium were the key strains.

Elemental sulfur (S0) formation from and nitrogen removal on sulfide, nitrate and ammonium-laden wastewaters were achieved by denitrifying ammonium oxidation (DEAMOX) reactor with autotrophic denitrifiers and anaerobic ammonium oxidation (anammox) bacteria. The sulfide to nitrate ratio is a key process parameter for excess accumulation of S0 and a ratio of 1.31:1 is a proposed optimum. The Alishewanella, Thauera and Candidatus Anammoximicrobium present respectively the autotrophic denitrifiers and anammox bacteria for the reactor. DEAMOX is demonstrated promising biological process for treating organics-deficient (S+N) wastewaters with excess S0 production.