| 摘要: | 由於水中的含氮污染物是目前最受到關切的污染物之一，其過度排放會對環境造成污染且對人體會造成危害。而台灣民眾環保意識逐漸抬頭，目前我國政府制定法規標準，對於新建造之污水處理廠有較嚴格之標準，且對已建造之污水處理廠排放標準也逐漸採用更高標準的放流水水質管制。目前台灣的污水處理廠大多都是異營脫硝，但在處理C/N 比值較低之污水，脫硝效率不佳，因此，自營脫硝被認為可以替代異營脫硝之反應，因為自營性微生物是利用無機性之電子供體，不需額外添加有機物且產生污泥量較低。
本研究選擇了硫磺 (S0) 作為電子供體，硫磺顆粒不僅可作為電子供體，亦可以當作擔體讓微生物在上面生長形成生物膜。在馴養階段，由於水溶性的硫代硫酸鹽相較固體的元素硫更容易被細菌利用，因此添加硫代硫酸鹽加速硫自營性脫硝菌的生長，經過 90 天成功馴養出硫自營性脫硝菌。
之後，以硫磺 (S0) 作為反應器唯一電子供體的條件下，探討最佳體積硝酸鹽氮負荷，在水力停留時間 1.48 hr，體積硝酸鹽氮負荷為 709.9 g NO3--N/m3·d 時，脫硝率為 60.9±7.6%。因此，以延長水力停留時間至 1.85 hr，降低硝酸鹽氮體積負荷至 567.8 g NO3--N/m3·d，脫硝效率達 80 %。為了評估元素硫脫硝系統之實際應用可行性，因此模擬RO濃排水作為進流水，由於進流水中之難分解有機物可被異營菌利用，作為脫硝之電子供體，此階段為完全脫硝，脫硝率為100%。此外，在各階段硫自營脫硝反應器中，實際硫酸鹽生成量低於理論硫酸鹽生成量，約理論值 76-78% 左右，由於硫酸鹽的生成是硫自營脫硝的缺點，若能減少硫酸鹽生成量是一項潛在的優勢。
反應器從Start-up II-ii 至 Stage III-ii階段，電子供體從元素硫及額外添加的硫代硫酸鹽至元素硫為唯一的供體，Thiobacillus 的相對豐度有逐漸遞減的趨勢；而Sulfurimonas 的相對豐度逐漸遞增，因此，本研究推測 Thiobacillus 似乎傾向於利用硫代硫酸鹽；而Sulfurimonas傾向於利用元素硫。
;Due to the fact that nitrogen pollutants in water are currently one of the most concerning contaminants, their excessive discharge can lead to environmental pollution and harm to human health. As environmental awareness gradually increases among the public in Taiwan, the government has established regulations and standards, setting stricter requirements for newly constructed wastewater treatment plants, and gradually applying higher discharge standards for already established plants. Most of Taiwan′s wastewater treatment plants currently use heterotrophic denitrification. However, for wastewater with a low C/N ratio, the denitrification efficiency is poor. Therefore, autotrophic denitrification is considered a potential replacement for heterotrophic denitrification, as autotrophic microorganisms use inorganic electron donors, eliminating the need for additional organic substances and producing less sludge.
This study selected sulfur (S0) as the electron donor. Sulfur granules not only serve as an electron donor but also as a carrier for microorganisms to grow on, forming a biofilm. During the acclimation phase, as water-soluble thiosulfate is more easily utilized by bacteria compared to solid elemental sulfur, thiosulfate was added to accelerate the growth of sulfur-oxidizing autotrophic denitrifying bacteria. After 90 days, sulfur autotrophic denitrifying bacteria were successfully cultivated.
Subsequently, using sulfur (S0) as the sole electron donor in the reactor, the optimal volumetric nitrate-nitrogen load was explored. With a hydraulic retention time of 1.48 hours and a volumetric nitrate-nitrogen load of 709.9 g NO₃⁻-N/m³·d, the denitrification rate was 60.9±7.6%. Therefore, by extending the hydraulic retention time to 1.85 hours and reducing the nitrate-nitrogen volumetric load to 567.8 g NO₃⁻-N/m³·d, the denitrification efficiency reached 80%. To evaluate the practical feasibility of the elemental sulfur denitrification system, RO concentrate was simulated as influent. Since the recalcitrant organic matter in the influent can be utilized by heterotrophic bacteria as an electron donor for denitrification, this phase achieved complete denitrification with a 100% denitrification rate.
Additionally, in the sulfur autotrophic denitrification reactor at each phase, the actual sulfate production was lower than the theoretical sulfate production, approximately 76-78% of the theoretical value. Since sulfate production is a disadvantage of sulfur autotrophic denitrification, reducing sulfate production could be a potential advantage.
From the Start-up II-ii to the Stage III-ii phase, as the electron donor transitioned from elemental sulfur and additional thiosulfate to elemental sulfur as the sole donor, the relative abundance of Thiobacillus showed a decreasing trend, while the relative abundance of Sulfurimonas gradually increased. Therefore, this study speculates that Thiobacillus seems to prefer utilizing thiosulfate, while Sulfurimonas tends to use elemental sulfur. |
