Advances in elemental sulfur-driven bioprocesses for wastewater treatment: From metabolic study to application

Insights into the Superior Bioavailability of Biogenic Sulfur from the View of Its Unique Properties: The Key Role of Trace Organic Substances

“…8,9 Due to the hydrophobicity and low aqueous solubility (0.16 μM in pure water at 25 °C) of chem-S 0 , low particle dispersibility and poor sulfur mass transfer become its main drawbacks and limit the engineering application of chem-S 0 . 1,10 Biogenic sulfur (bio-S 0 ) refers to the S 0 produced by microbial metabolism, which is often observed in the biological desulfurization of H 2 S-rich biogas, natural gas, and sulfidecontaining wastewater. 11,12 Bio-S 0 is usually presented as a micron-sized particle and can be easily separated by gravity settling.…”

“…Sulfur, one of the most common elements on Earth, has active chemical properties and can serve as a microbial nutrient, playing an important role in the biogeochemical element cycle. − In the field of environmental pollution control, zero-valent sulfur (S 0 ) is often used as an electron donor or electron acceptor in biological processes due to its advantages of high safety, low cost, and low biomass yields . The S 0 -driven bioprocesses in wastewater have drawn increasing attention, and substantial progresses have been achieved in laboratory experiments and potential full-scale applications, such as nitrate removal from wastewater, , heavy metal bioleaching from contaminated sediments, , and organic decomposition from excessive sludge .…”

“…The S 0 -driven bioprocesses in wastewater have drawn increasing attention, and substantial progresses have been achieved in laboratory experiments and potential full-scale applications, such as nitrate removal from wastewater, , heavy metal bioleaching from contaminated sediments, , and organic decomposition from excessive sludge . Currently, the S 0 supplied for biological processes is mainly produced by chemical reactions (chem-S 0 ). , Due to the hydrophobicity and low aqueous solubility (0.16 μM in pure water at 25 °C) of chem-S 0 , low particle dispersibility and poor sulfur mass transfer become its main drawbacks and limit the engineering application of chem-S 0 . , …”

“…To date, however, most current studies have focused on the application of bio-S 0 and the optimization of relevant operation conditions. , Few studies have focused on the mechanisms for the superior bioavailability of bio-S 0 over chem-S 0 . Particle size was suggested to be an important factor affecting the bioavailability of S 0 . , The mass transfer efficiency can be enhanced by decreasing the S 0 particle size due to the increase in the specific surface area. , However, Di Capua et al reported that bio-S 0 showed better bioavailability even though bio-S 0 and chem-S 0 had a similar particle size distribution . On the other hand, Janssen et al believed that hydrophilic substances (e.g., polythionates, polysulfides, and proteins) distributed on the surface of bio-S 0 particles (produced from Thiobacillus and Acidithiobacillus) might contribute to the good bioavailability .…”

“…Particle size was suggested to be an important factor affecting the bioavailability of S 0 . 1,3 The mass transfer efficiency can be enhanced by decreasing the S 0 particle size due to the increase in the specific surface area. 18,19 However, Di Capua et al reported that bio-S 0 showed better bioavailability even though bio-S 0 and chem-S 0 had a similar particle size distribution.…”