Free sulfurous acid (FSA) inhibition of biological thiosulfate reduction (BTR) in the sulfur cycle-driven wastewater treatment process

Abstract

A sulfur cycle-based bioprocess for co-treatment of wet flue gas desulfurization (WFGD) wastes with freshwater sewage has been developed. In this process the removal of organic carbon is mainly associated with biological sulfate or sulfite reduction. Thiosulfate is a major intermediate during biological sulfate/sulfite reduction, and its reduction to sulfide is the rate-limiting step. In this study, the impacts of saline sulfite (the ionized form: HSO + SO) and free sulfurous acid (FSA, the unionized form: HSO) sourced from WGFD wastes on the biological thiosulfate reduction (BTR) activities were thoroughly investigated. The BTR activity and sulfate/sulfite-reducing bacteria (SRB) populations in the thiosulfate-reducing up-flow anaerobic sludge bed (UASB) reactor decreased when the FSA was added to the UASB influent. Batch experiment results confirmed that FSA, instead of saline sulfite, was the true inhibitor of BTR. And BTR activities dropped by 50% as the FSA concentrations were increased from 8.0 × 10 to 2.0 × 10 mg HSO-S/L. From an engineering perspective, the findings of this study provide some hints on how to ensure effective thiosulfate accumulation in biological sulfate/sulfite reduction for the subsequent denitrification/denitritation. Such manipulation would result in higher nitrogen removal rates in this co-treatment process of WFGD wastes with municipal sewage.

Anaerobic treatment and resource recovery from methanol rich waste gases and wastewaters

“…[32] studied the S2O3 2disproportionation pathway and showed that the S2O3 2reduction to SO4 2occurs through the formation of sulfite and elemental sulfur (S 0 ) as the intermediates . The slower reduction of S2O3 2compared to SO4 2in this study could be due to the fact that reduction of S2O3 2to sulfide is the rate-limiting step during biological SO4 2or sulfite reduction (Qian et al, 2017).…”

“…Denitrifying anaerobic methane oxidation (DAMO) is regarded as a sustainable option for wastewater treatment plants as DAMO does not require expensive electron donors such as acetate, methanol, or ethanol for the denitrification process (Wang et al, 2017). The DAMO archaea convert nitrate to nitrite using electrons derived from methane, while the DAMO bacteria reduce nitrite to nitric oxide and subsequently nitric oxide to nitrogen and oxygen gas via the inter-aerobic denitrification pathway (Wang et al, 2017). Production of C-4 carboxylic acids, specifically crotonic and butyric acids, from methane was illustrated in engineered…”

“…Desulfomicrobium and Desulfobulbus are among the dominant SRB groups in the sulfite and SO4 2reducing UASB reactors (Qian et al, 2015), as well as S2O3 2reducing biomass. Bacterial species from these two genera can use lactate, acetate, pyruvate, glycerol and methanol as the electron donor and carbon source Qian et al, 2017) to facilitate direct S2O3 2reduction to sulfide or disproportionation to SO4 2and sulfide, followed by reduction of SO4 2to sulfide . Desulfobacter postgatei, Desulfobulbus propionicus…”

“…The adsorption kinetics of Amberlite and Dower was determined for a mixture containing 1 g/L each VFA (total: 6 g/L), at resin concentrations of 25, 50 and 75 g/L. The liquid samples were collected at intervals of 0, 2, 4, 6, 8 and 24 h from the batch bottles that were tested for 1 d and at intervals of 5, 10,15,20,40,60,80, 100 and 120 min from the batch bottles that were tested for 2 h. The percentage adsorption and the equilibrium adsorption capacity were determined using Eq. 8.1 and Eq.…”

“…Additionally, S2O3 2is one of the main intermediates formed during biological SO4 2-/sulfite (SO3 2-) reduction, with its reduction to sulfide being the rate-limiting step (Qian et al, 2017). Although the bioreduction of SO4 2has been extensively studied and applied in full-scale systems [18][19][20], S2O3 2reduction has only been reported in a few studies González-Sánchez et al, 2008;Qian et al, 2017). The objective of this study was, therefore, to examine the effect of SeO4 2-, S2O3 2or SO4 2on methanol utilization for VFA or methane production.…”