菌藻共生系统对序批式反应器处理养猪废水脱氮除磷效果及微生物群落结构的影响

Nitrogen and phosphorus removal of sequencing batch reactor with algae treating piggery wastewater and microbial community structure

摘要:

[背景] 养猪废水作为高浓度有机废水，是导致我国农业面源污染的主要因素之一。目前采用菌藻共生系统处理养猪废水越来越受到关注，与传统序批式反应器（Sequencing Batch Reactor，SBR）相比，藻辅助SBR具有提高脱氮除磷效果、增加污泥活性和降低能源消耗的特点。[目的] 针对SBR中菌藻共生系统对养猪废水脱氮除磷效能的影响，比较分析菌藻共生系统与常规SBR系统中污泥特性及微生物群落结构特征差异。[方法] 在室温条件下分别平行运行SBR+微藻（R1）和作为对照系统不添加微藻的SBR （R2）。监测R1和R2系统废水处理效果，污泥的粒径、沉降性和代谢产物等污泥特性。利用变性梯度凝胶电泳（Denaturing Gradient Gel Electrophoresis，DGGE）技术分析R1和R2系统中的微生物种类和分布。[结果] 与对照R2反应器相比，R1的化学需氧量（Chemical Oxygen Demand，COD）去除率提高了5.1%，NH₄⁺-N提高了20.3%，总氮（Total Nitrogen，TN）提高了19.4%，总磷（Total Phosphorus，TP）提高了23.9%。进一步对反应器中的污泥特性进行分析发现，与R2相比，R1的胞外聚合物（Extracellular Polymeric Substances，EPS）平均含量提高3.7%，可溶性微生物产物（Soluble Microbial Product，SMP）平均增加了38.5%。同时R1的污泥粒径较R2提高了14.8%，污泥体积指数（Sludge Volume Index，SVI）值较R2降低了11.7%，污泥的好氧呼吸速率（Specific Oxygen Uptake Rate，SOUR）较R2提高了64.8%，而且稳定的菌藻共生系统的形成进一步减少反应器出水中的悬浮固体浓度，表明藻类的添加对R1污泥特性具有改良作用[结论] R1反应器形成的菌藻共生体系可进一步优化微生物群落结构，其中放线菌纲（Actinobacteria）、α-变形菌纲（Alphaproteobacteria）和γ-变形菌纲（Gammaproteobacteria）为R1反应器的主要菌群，对养猪废水的处理起到重要作用。R1反应器中的藻类主要为链带藻属（Desmodesmus）和尖带藻属（Acutodesmus），对养猪废水的脱氮除磷起到重要作用。

Abstract:

[Background] As high concentration organic wastewater, piggery wastewater was one of the main factors that lead to area-source pollution of agriculture in China. At present, an increasing number of researchers focused on piggery wastewater treatment with bacteria-algae symbiotic system. Compared with the traditional sequencing batch reactor (SBR), the algal-assisted SBR showed better performance in nitrogen and phosphorus removal, sludge activity improvement and energy consumption reduction. [Objective] Aiming at the influence of algal-bacterial symbiosis system on the nitrogen and phosphorus removal, the distinction on sludge characteristics and microbial community structure were anlyzed between the algal-bacterial symbiosis system and the conventional SBR. [Methods] The algal-assisted SBR (R1) and the conventional SBR (R2) were operated in parallel at room temperature to study the performance of piggery wastewater treatment. The sludge characteristics were also observed, such as sludge particle size, sludge settleability and microbial metabolites. Denaturing gradient gel electrophoresis (DGGE) was used to analyze the microbial community structure in R1 and R2 systems. [Results] compared to the R2, chemical oxygen demand (COD), NH₄⁺-N, total nitrogen (TN) and total phosphorus (TP) were increased by 5.1%, 20.3%, 19.4% and 23.9%. The average values of extracellular polymeric substances (EPS) and soluble microbial product (SMP) in the R1 were 3.7% and 38.5% higher than that in the R2, respectively. Compared to that of R2, the sludge particle size of R1 was increased by14.8%, due to the adhesion of algal to the sludge. In addition, the SVI value of R1 was 11.7% less than that of R2, indicating a poor settleability of sludge in the R1. The sludge specific oxygen uptake rate (SOUR) of R1 was 64.8% higher than that of R2. The formation of stable bacteria algae symbiosis system further reduced the concentration of suspended solids in the effluent of the R1, which further indicated that the addition of algae could improve the characteristics of R1 sludge. [Conclusion] Actinobacteria, Alphaproteobacteria and Gammaproteobacteria as the dominant species in the R1 played an important role in the piggery wastewater treatment. The major Chlorophyta were Desmodesmus and Acutodesmus which had a significant effect on nitrogen and phosphorus removal.