Elucidating the microbial communities and anaerobic mechanisms of a new biomass capable of capturing carbon and sulfur pollutants for sulfate-laden wastewater treatment

The municipal wastewater of coastal cities contains not only chemical oxygen demand (COD), nitrogen (N), and phosphorus (P) pollutants but also a significant concentration of sulfate (about 30-100 mg S-SO₄/L). This emerging sulfate-laden wastewater, possibly resulting from the disposal of industrial waste or the seawater intrusion in the municipal wastewater, poses noteworthy operational problems like odor emissions, localized pipe corrosion, and inhibition of conventional biological treatment. To resolve these problems, we have recently developed a new sulfur-cycle enhanced biological phosphorus removal (SC-EBPR) process capable of removing COD, N, and P and controlling sulfide production. This study investigates the possibility of cultivating SC-EBPR biomass under various influent COD and sulfate concentrations (with initial organic carbon (C) to sulfur (S) ratios of 1, 2, and 3 g C/g S), which dominanted by sulfate-reducing bacteria, sulfur-oxidizing bacteria and unknown bacteria. Moreover, anaerobic batch experiments were conducted for (i) elucidating the fundamental mechanisms of carbon uptake/poly-hydroxyalkanoates formation (1.8-3.8 mg C/(gVSS h)), sulfate reduction/sulfur storage (0.9-1.9 mg S/(gVSS h)), and poly-phosphate degradation/P release (0.6-3.0 mg P/(gVSS h)), and (ii) understanding a new anaerobic pathway of simultaneous intracellular uptake of carbon and sulfur (as verified by carbon balance with only 5-10% error). Finally, a possible way of implementing the new SC-EBPR biomass in high-sulfate wastewater treatment was discussed.