盐度增加对不同反硝化系统脱氮效能的影响及碳排放对比研究

A comparative study on the effect of increasing salt concentration on denitrification efficiency and carbon emissions of different denitrification systems

为了研究自养反硝化、协同反硝化、异养反硝化的脱氮性能和碳排放量在盐度渐增下的变化情况,构建了3个滤池.实验结果显示,在自养反硝化系统中,进水不加入任何碳源,导致前期出水NO_(3)^(-)-N浓度稍高,随后逐渐稳定下降.当盐度高达12000 mg·L^(-1)时,出水总氮浓度在9~12mg·L^(-1)范围内波动,说明在盐度过高的情况下,自养反硝化系统虽然能保持一定的总氮去除效率,但可能难以完全达到排放标准(TN<10 mg·L^(-1)).实际生产中对于高盐废水的自养反硝化工艺可以通过添加适量碳源形成协同反硝化以达到出水标准.NO2--N的积累取决于NO_(3)^(-)-N浓度的变化和自养反硝化细菌的生存环境.此外,在异养反硝化过程中,由于碳源充足,脱氮效率要强于自养反硝化和协同反硝化.随着盐度的增加和反应器的持续运行,出水NO_(3)^(-)-N浓度平均降至较低水平,总氮去除率稳定在92%左右.研究还发现虽然水力停留时间对去除效果有影响,但随着反应器的持续运行,自养反应器虽然出水总氮浓度一直保持在8 mg·L^(-1)以下,总氮平均去除效率也高达约84.5%.这表明在完全无碳源的情况下,硫基自养反硝化系统对含盐废水(TDS≈6000 mg·L^(-1))也具有良好的抗负荷冲击和耐盐性.自养反硝化系统日均碳排放量比异养反硝化系统减少约53.7%,协同反硝化系统比异养反硝化系统减少约33.4%.自养反硝化经济效益最高且最具有低碳优势.通过高通量测序技术分析,发现盐度的增加导致微生物群落丰度的差异,Patescibacteria可能在异养反硝化过程中更适应高盐阶段,而协同反应器在高盐度的影响下具有更好的稳定性.

In order to study the denitrification performance and carbon emissions of autotrophic denitrification,synergistic denitrification,and heterotrophic denitrification systems under increased salinity,three filters were constructed.The experimental results showed that in the autotrophic denitrification system,no carbon source was added to the influent,resulting in a slightly higher NO_(3)^(-)-N concentration in the initial effluent,which gradually stabilized and decreased.If the salinity reaches 12000 mg·L^(-1),the total nitrogen concentration in the effluent fluctuates within the range of 9~12 mg·L^(-1),indicating that although the autotrophic denitrification system can maintain a certain total nitrogen removal efficiency under high salinity conditions,it may be difficult to fully meet the emission standards(TN<10 mg·L^(-1)).In actual production,the autotrophic denitrification process for high salinity wastewater can achieve effluent standards by adding an appropriate amount of carbon source to form synergistic denitrification.The accumulation of NO2--N depends on changes in NO_(3)^(-)-N concentration and the living environment of autotrophic denitrifying bacteria.In addition,in the heterotrophic denitrification process,due to sufficient carbon sources,the denitrification efficiency is stronger than autotrophic denitrification and synergistic denitrification.With the increase of salinity and continuous operation of the reactor,the average concentration of NO_(3)^(-)-N in the effluent decreases to a lower level,and the total nitrogen removal rate stabilizes at around 92%.The study also found that hydraulic retention time has an impact on removal efficiency,as the reactor continues to operate.Although the total nitrogen concentration in the effluent of the autotrophic reactor remains below 8 mg·L^(-1),the average removal efficiency of total nitrogen remains still at about 84.5%.This indicates that the sulfur based autotrophic denitrification system has good resistance to load shock and salinity tolerance for saline wastewater(TDS≈6000 mg·L^(-1))even in the absence of carbon sources. The daily average carbon emissions from autotrophic denitrification are reduced by about 53.7% compared to heterotrophic denitrification, while synergistic denitrification reduced by about 33.4%. Autotrophic denitrification has the highest economic benefits and the most low-carbon advantage. Through high-throughput sequencing technology analysis, it was found that the increase in salinity leads to differences in microbial community abundance. Patescibacteria may be more adapted to the high salinity stage in heterotrophic denitrification, while the synergistic reactor has better stability under the influence of high salinity.