新型生物质碳源强化脱氮效果及微生物菌群分析

为了实现城镇污水处理厂深度脱氮效果,以太湖流域某污水处理厂为对象,以生物质废弃物再利用过程中产生的衍生物甘油为主要原料的生物质碳源作为反硝化电子供体,分别研究了缺氧池、深床滤池的反硝化脱氮效果,同时解析了外加生物质碳源前后的微生物群落结构变化特征。结果表明:在缺氧池投加2.5~3.0 t/d生物质碳源时,可使缺氧池硝态氮浓度下降1.67~1.73 mg/L,去除率为52%~68%;在深床滤池投加生物质碳源后,反硝化脱氮过程中约消耗5.27 mg COD可去除1 mg NO₃--N,进而使出水TN能够达到5 mg/L以下,实现了出水TN稳定达到DB 32/1072—2018《太湖地区城镇污水处理厂及重点工业行业主要水污染物排放限值》一、二级保护区的排放限值要求。通过16S rRNA基因序列分析发现,缺氧池和深床滤池微生物优势菌门主要为Proteobacteria、Actinobacteriota、Chloroflexi和Bacteroidota。深床滤池由于工艺条件和生长环境不同,在投加生物质碳源后,Thiothrix、Bacillus、Propionicicella、norank_f_Rhodocyclaceae、Terrimonas等具有反硝化脱氮功能的优势菌群较为突出,有效保证了系统稳定的深度脱氮效果,同时间接降低CO₂排放,对城镇污水厂的碳减排及“碳中和”提供了积极参考。

DENITRIFICATION ENHANCEMENT EFFECT AND MICROBIAL FLORA ANALYSIS OF A NEW BIOMASS CARBON SOURCE

To achieve the deep denitrification effect of wastewater treatment plants, taking a sewage treatment plant in Taihu Lake Basin as an example, the biomass carbon source with derivatives of biomass waste as the main raw material was used as the electron donor for denitrification, and the denitrification effects of the anoxic tank and deep-bed filter were studied respectively. The changes in microbial community structure before and after the addition of carbon sources were also analyzed. The results showed that 1.67~1.73 mg/L nitrate could be removed, when the biomass carbon source dosage was 2.5~3.0 t/d, and the removal rate was about 52%~68%. Meanwhile, the deep bed filter consumed about 5.27 mg COD for every 1 mg NO₃--N removal after adding biomass carbon source in the process of denitrification. Thus, the effluent TN was stable and met the discharge limit requirements of class Ⅰ and Ⅱ protected areas in the Discharge Standard of Main Water Pollutants for Municipal Wastewater Treatment Plant & Key Industries in Taihu Area(DB 32/1072—2018). Through 16 S rRNA gene sequence analysis, it was found that the dominant microbial phyla of hypoxic pools and deep-bed filters were Proteobacteria, Actinobacteria, Chloroflexi, and Bacteroidota. After adding biomass carbon source to deep-bed filter with different process conditions and growth environment, the dominant flora with denitrification function such as Thiothrix, Bacillus, Propionicicella, norank_f_Rhodocyclaceae and Terrimonas were more prominent and further effectively ensured the stable deep nitrogen removal performance of the system. At the same time, the adding of biomass carbon source indirectly reduced carbon dioxide emissions, which made a positive contribution to carbon emission reduction and carbon neutralization.