Effect of nitrate on sulfur transformations in sulfidogenic sludge of a marine aquaculture biofilter

Abstract

The effect of NO(3)(-) addition on dissimilatory SO(4)(2-) reduction and sulfide conversion in organic-rich sludge from the digestion basin of a recirculating marine aquaculture system was studied. SO(4)(2-) reduction could only explain a minor fraction (up to 4-9%) of the observed total sulfide production (up to 35 mmol L(-1) day(-1)), indicating that the main source of sulfide in the sludge was not SO(4)(2-) reduction, but desulfuration during the decomposition of organic matter. Although NO(3)(-) inhibited SO(4)(2-) reduction, but not desulfuration, the primary NO(3)(-) mitigation effect was the onset of NO(3)(-)-mediated sulfide oxidation (up to 75 mmol L(-1) day(-1)), partially to elemental sulfur (S(0)). Above NO(3)(-) concentrations of 0.6 mM in the bulk water, the net sulfide production and oxidation zones were moved deeper into flocs and sludge cores, which effectively prevented sulfide from entering the water column. However, the sulfide efflux from the sludge instantly recovered after NO(3)(-) depletion. Thus, the NO(3)(-) level in the water column controls the zonation and magnitude of sulfur transformations in the sludge. The effect of NO(3)(-) relies therefore on its sustained presence in the water column, which in turn depends on a well-functioning nitrification in the mariculture system.

Comamonadaceae OTU as a Remnant of an Ancient Microbial Community in Sulfidic Waters

“…It is also likely that some part of sulfides is generated in sulfidic waters via an alternative pathway, independent of SRB. Schwermer et al reported that desulfuration occurring during the decomposition of S-rich organic matter resulted in large H 2 S release in marine sludge, while microbial reduction of SO 4 2− accounted for only 4–9% of total H 2 S [ 68 ]. Besides, the authors indicated that nitrates in concentration exceeding 0.8 mM inhibited sulfate reduction (but not sulfuration) and induced sulfide oxidation (partially to S 0 ).…”

Environmental Controls on Nitrogen and Sulfur Cycles in Surficial Aquatic Sediments

“…The biogeochemical importance of $N{O}_3^{-}$ use by S-oxidizing bacteria has been widely recognized in marine sediments (Brettar and Rheinheimer, 1991) as well as freshwater sediments (Brunet and GarciaGil, 1996; Whitmire and Hamilton, 2005) and groundwater systems (Engesgaard and Kipp, 1992; Jorgensen et al, 2009). This process is used to mitigate toxic sulfide production in organic-rich sludge through $N{O}_3^{-}\text{ - mediated}$ sulfide oxidation (Schwermer et al, 2010). Vice versa , elemental sulfur has also been applied to wastewater treatment to remove $N{O}_3^{-}$ by coupled sulfur oxidation and $N{O}_3^{-}$ reduction (Sierra-Alvarez et al, 2007).…”

High spatial resolution analysis of the distribution of sulfate reduction and sulfide oxidation in hypoxic sediment in a eutrophic estuary

“…High organic matter in the sediment can stimulate sulfate reduction via consumption of DO followed by a decrease in ORP in sediment or by providing increased quantities of electron donors for sulfate-reducing bacteria (Holmer & Storkholm 2001). Rates of sulfate reduction (R(T-H 2 S)) in this study (<0.26 μmol cm -3 h -1 ) were substantially higher than those of natural sediments in acidic lakes (Kühl et al 1998) and sandy intertidal sediments (de Beer et al 2005) (<0.01 μmol cm -3 h -1 ), while they were comparable to those of anaerobic sewer biofilm (Mohanakrishnan et al 2009) and organic-rich sludge in a marine aquaculture system (Schwermer et al 2010) (<1.0 μmol cm -3 h -1 ). Thus, these results indicate a massive input of organic matter to Tokyo Bay sediments is occurring.…”