菌剂挂膜3D-RBC联合BCO工艺处理养猪沼液废水

针对养猪沼液废水寡营养、高氨氮的水质特征，该研究采用耐高氨氮、适应贫营养生长的异养硝化-好氧反硝化（Heterotrophic Nitrification-Aerobic Denitrification，以下简称HN-AD）菌挂膜启动三维结构生物转盘+生物接触氧化反应器（3D-RBC+BCO）组合工艺对沼液进行处理。该文研究了3D-RBC+BCO组合工艺在真实沼液条件下的启动过程及污染物去除效果，重点考察了溶解氧（Dissolved Oxygen，DO）浓度和C/N比2个关键因素对组合工艺污染物去除效果的影响。同时，借助高通量测序技术对DO和C/N比优化过程中微生物群落结构的变化规律进行解析。结果表明：在真实沼液条件下，采用HN-AD菌剂挂膜启动方法，仅用12和18 d就分别完成3D-RBC和BCO反应器的挂膜启动，同时组合工艺对COD、NH4+-N和TN的去除率分别稳定在94.8%、95.7%和80.1%，出水优于城镇污水厂排放一级B标准。在对3D-RBC反应器DO和C/N比的优化过程中，增设底曝后COD、NH4+-N和TN等指标的去除率分别降低了25.4%、15.4%和15.5%。高通量测序结果显示，增加底曝后3D-RBC盘片生物膜中微生物菌属的数量小幅下降，但HN-AD优势菌属的种类与丰度显著降低，导致脱氮效率下降；贫营养型Acinetobacter、Pseudomonas菌属是3D-RBC可以对真实沼液高效脱氮的关键，提高C/N比会显著降低其丰度，进而影响脱氮效果。

Treatment of pig biogas slurry wastewater by microbial inoculum 3D-RBC combined with BCO process

Abstract: Discharge of aquaculture wastewater from large-scale pig farms has become one of the major pollution sources for agricultural non-point sources in China. After the treatment of anaerobic fermentation for aquaculture wastewater, most of the COD is removed, but the concentration of NH4+-N is still very high, leading to the production of biogas slurry with the low ratio of C/N and high strength of ammonia nitrogen. If the concentration of NH4+-N was high beyond the threshold of conventional denitrification microorganisms, the enrichment difficulty with the seriously unbalanced C/N ratio can occur, while, the low organic matter also affects the removal of total nitrogen. Therefore, it is highly demanding to explore a new biological treatment technology that suitable for this kind of biogas slurry, in order to ensure the sustainable development of industrial aquaculture in animal husbandry. In view of the water quality characteristics of oligotrophic and high ammonia nitrogen, a novel process was proposed to combine three-dimensional rotating biological contactor (3D-RBC) and biological contact oxidation (BCO) reactor using the oligotrophic heterotrophic nitrification-aerobic denitrification (HN-AD) mixed bacteria with high tolerance of ammonia nitrogen as microbial inoculants for the treatment of piggery biogas slurry wastewater. The removal efficiency of pollutants was also evaluated in the combination process under the condition of actual biogas slurry. An emphasis was put on the effects of concentration of dissolved oxygen (DO) and C/N ratio on the removal of pollutant during the treatment. A high-throughput sequencing technology was selected to analyze the change of microbial community structure in optimization process of DO and C/N ratio. The results showed that: (1) In the case of actual biogas slurry, the start-up of 3D-RBC and BCO reactors can be completed in 12d and 18d, respectively, when using the HN-AD mixed bacteria as microbial inoculants for the biofilm formation. The removal efficiency of COD, NH4+-N, and TN in the combined process were 94.8%, 95.7% and 80.1%, respectively, and the effluent water quality can reach the level of Class I-B according the national standard GB 18918-2002. (2) During the optimization of DO and C/N ratios in the 3D-RBC reactor, the removal rates of COD, NH4+-N, and TN were reduced by 25.4%, 15.4%, and 15.5%, respectively, particularly after the addition of the bottom exposure. There was no significantly increase in the removal efficiency of COD, NH4+-N, TN, and TP, whereas, the energy consumption of aeration increased in the combination process. The combined process can be especially suitable to treat the biogas slurry with the low C/N ratio and high concentration of nitrogen. The improved C/N ratio can lead to the decrease in the removal rate of TN , while, increase the cost of carbon in the treatment of 3D-RBC. (3) The biodiversity in the 3D-RBC disc biofilm decreased slightly after the addition of bottom exposure, but the variety and abundance of the dominant genus HN-AD decreased significantly, leading to a decrease in the removal efficiency of nitrogen. When C/N=1 and C/N=3, Pseudomonas and Acinetobacter have relatively high abundance, whereas, its abundance decreased significantly while the nitrogen removal efficiency decreased, when C/N increased to 6. The oligotrophic Acinetobacter and Pseudomonas bacteria can serve as the key materials for the efficient removal of nitrogen from actual biogas slurry in the 3D-RBC. It infers that the decrease of C/N ratio can significantly enhance its abundance, and thereby improve the nitrogen removal.