Biological and economical assessment of autotrophic denitrification with S compounds. Autotrophic Denitrification with S compounds

This study compared the rates and microbial community development in batch bioassays on autotrophic denitrification using elemental sulfur (S0), pyrite (FeS2), thiosulfate (S2O32-) and sulfide (S2-) as electron donors. The performance of two inocula was compared: digested sludge (DS) from a wastewater treatment plant of a dairy industry and anaerobic granular sludge (GS) from UASB reactor treating dairy wastewater. All electron donors supported the development of a microbial community with predominance of autotrophic denitrifiers during the enrichments, except for sulfide. For the first time, pyrite revealed to be a suitable substrate for the growth of autotrophic denitrifiers developing a microbial community with predominance of the genera Thiobacillus, Thioprofundum and Ignavibacterium. Thiosulfate gave the highest denitrification rates removing 10.94 mM NO3- d-1 and 8.98 mM NO3- d-1 by DS and GS, respectively. This was 1.5 and 6 times faster than elemental sulfur and pyrite, respectively. Despite the highest denitrification rates were observed in thiosulfate-fed enrichments, an evaluation of the most relevant parameters for a technological application revealed elemental sulfur was the best electron donor for autotrophic denitrification with a total cost of 0.38 € per m3 of wastewater treated.

本研究以单质硫（elemental sulfur, S0）、黄铁矿（pyrite, FeS2）、硫代硫酸盐（thiosulfate, S2O32-）以及硫化物（sulfide, S2-）作为电子供体，对比了自养反硝化批次生物试验中的反应速率与微生物群落演替情况。本研究对比了两种接种物的性能：分别为乳品行业污水处理厂的消化污泥（DS），以及处理乳品废水的UASB反应器厌氧颗粒污泥（GS）。除硫化物外，其余受试电子供体均可在富集过程中促成以自养反硝化菌为优势类群的微生物群落形成。本研究首次证实，黄铁矿可作为自养反硝化菌生长的适宜底物，其富集得到的微生物群落以硫杆菌属（Thiobacillus）、Thioprofundum属及Ignavibacterium属为优势菌属。硫代硫酸盐组的反硝化速率最高，采用DS与GS接种的体系硝酸盐去除速率分别可达10.94 mM NO3-·d⁻¹与8.98 mM NO3-·d⁻¹，该速率分别是单质硫组与黄铁矿组的1.5倍与6倍。尽管硫代硫酸盐投加的富集体系反硝化速率最高，但针对工程化应用的核心参数评估结果显示，单质硫是最适用于自养反硝化的电子供体，其处理每立方米废水的总成本仅为0.38欧元。