Synchronised removal of nitrogen and sulphate from rubber industrial wastewater by coupling of Sulfammox and sulphide-driven autotrophic denitrification in anaerobic membrane bioreactor.

Abstract

Global rubber industry, growing 4-6 % annually with 13.76 million Mt of rubber produced in 2019, significantly impacts the economy. This study explores coupling sulfate-dependent ammonium oxidation (Sulfammox) and sulfide-driven autotrophic denitrification (SDAD) within an anaerobic membrane bioreactor (AnMBR) to treat high-strength natural rubber wastewater. Over 225 days, the AnMBR system achieved maximal chemical oxygen demand (COD), total nitrogen (TN), ammonium nitrogen (NH₄⁺-N), and sulfate sulfur (SO₄^2--S) removal efficiencies of 58 %, 31 %, 13 %, and 45 %, respectively. TN is predominantly removed through Sulfammox (accounting for 49 % of NH₄⁺-N removal), SDAD, and conventional denitrification pathways. Sulfate removal is achieved via Sulfammox (responsible for 43 % of SO₄^2--S removal), and Dissimilatory sulfate-reducing (DSR) processes (contributing 57 % of SO₄^2--S removal). Microbial analysis identified Desulfovibrio and Sulfurospirillum as key microbes, while metagenomic analysis highlighted crucial sulfur and nitrogen cycling pathways. The findings support Sulfammox and SDAD as promising eco-friendly strategies for treating ammonia- and sulfate-rich industrial wastewater.