School of Chemistry & Environment, South China Normal University, Guangzhou, China.
School of Chemistry & Environment, South China Normal University, Guangzhou, China; Department of Bioscience, Aarhus University, Aarhus C, Denmark.
Water Res. 2016 Sep 1;100:421-428. doi: 10.1016/j.watres.2016.05.036. Epub 2016 May 11.
Nitrate dosing is commonly used to control hydrogen sulfide production in sewer systems. However, quick rebound of the sulfide concentration after nitrate depletion has been observed and results in more serious odor and corrosion problem. To investigate the mechanism of sulfide regeneration in the nitrate-free period, a laboratory-scale sewer reactor was run for 30 days to simulate sulfide production and oxidation with intermittent nitrate addition. The results show that nitrate addition substantially reduced the sulfide concentration, but the produced elemental sulfur was then quickly reduced back to sulfide in nitrate-free periods. This induced more and more sulfide production in the sewer reactor. Elemental sulfur and polysulfide reductions were found in the sewage in nitrate-free periods, showing their contributions to the sulfide regeneration. Through batch tests, polysulfide was confirmed as the key intermediate for accelerating sulfur reduction during the nitrate-free period in the sewer. Sulfide production rates significantly increased by 65% and 59% in the presences of tetrasulfide and sulfur with sulfide, respectively, at the beginning of the test. While polysulfide formation was prevented by the ferrous chloride addition, the sulfur reduction rate remarkably decreased from 12.8 mgS/L-h to 1.8 mgS/L-h. This indicates that direct sulfur reduction was significantly slower than the indirect sulfur reduction via polysulfide; the latter process could be the cause for the quick rebound of the sulfide concentration in the sewer with intermittent nitrate dosing. Thus, the pathways of sulfur transformations in a sewer, both in the presence and absence of nitrate, were proposed. Microbial community analysis results reveal that some common sulfate-reducing bacteria (SRB) genera in sewer sediment were possible sulfur reducers. According to this finding, the effect and strategy of nitrate dosing for hydrogen sulfide control in sewers should be re-evaluated and re-considered.
硝酸盐投加通常用于控制污水系统中的硫化氢生成。然而，在硝酸盐耗尽后，硫化物浓度会迅速反弹，导致更严重的气味和腐蚀问题。为了研究硝酸盐耗尽期间硫化物再生的机制，采用实验室规模的污水反应器，通过间歇添加硝酸盐来模拟硫化物的产生和氧化，运行了 30 天。结果表明，硝酸盐的添加大大降低了硫化物浓度，但产生的元素硫随后在硝酸盐耗尽期间迅速还原回硫化物。这导致污水中更多的硫化物生成。在硝酸盐耗尽期间，污水中发现了元素硫和多硫化物的还原，表明它们对硫化物再生有贡献。通过批试验，确认多硫化物是硝酸盐耗尽期间污水中加速硫还原的关键中间产物。在试验开始时，存在四硫代硫酸盐和硫的情况下，硫化物的产生速率分别显著增加了 65%和 59%。而亚铁氯化物的添加阻止了多硫化物的形成，硫还原速率从 12.8 mgS/L-h 显著降低到 1.8 mgS/L-h。这表明直接硫还原明显比通过多硫化物的间接硫还原慢；后一种过程可能是污水中间歇添加硝酸盐导致硫化物浓度迅速反弹的原因。因此，提出了硝酸盐存在和不存在两种情况下污水中硫转化的途径。微生物群落分析结果表明，污水沉积物中一些常见的硫酸盐还原菌（SRB）属可能是硫还原剂。根据这一发现，应对硝酸盐投加控制污水中硫化氢的效果和策略进行重新评估和考虑。
