Efficiency and application of aerobic methane coupled to denitrification ultimate denitrification system

Abstract:

[Objective] This research is to analyze the effects of methane concentration, temperature and nitrogen concentration on the aerobic methane coupled to denitrification (AME-D) ultimate denitrification system, the microbial communities in this AME-D system, and the application of this system into the tail water of a sewage treatment plant in Guiyang, China. [Methods] The effects of methane concentration, temperature, and nitrogen concentration on the nitrogen removal efficiency of this system were studied in staged experiments. The microbial community in the system was analyzed by 16S rRNA gene sequencing technology, and changes of the wastewater water quality were analyzed by confocal micro-Raman spectrometer. [Results] With the methane intake ratio of 3%, and the nitrogen concentration of 20 mg/L at 30 ℃, the average removal rates of total nitrogen, ammonia nitrogen, and nitrate nitrogen in the system reached high up to 93.66%, 96.13% and 92.25%, respectively; The dominant methanotrophs in this system were Methylosarcina (1.84%), Methylovulum (0.01%) and Crenothrix (0.14%); the facultative methanotrophs was Methylocystis (1.9%); and the dominant nitroso-bacteria were Nitrosomonas (0.008%), nitrifying bacteria were Nitrospira (0.42%), and denitrifying bacteria were Hyphomicrobium (1.19%) and Pseudomonas (0.61%). Applying this system into the tail water of a sewage treatment plant in Guiyang, the average total nitrogen concentration in the effluent reached 0.96 mg/L, reaching the limit of denitrification. Raman spectrum analysis showed that nitrate nitrogen and nitrite nitrogen can be effective removed in this system. Intermediate products of the oxidized methanotrophs could be alcohols or aldehydes, which can provide the required carbon source for denitrifying bacteria. [Conclusion] AME-D ultimate denitrification was realized by the synergy of microorganisms, including functional microorganisms like methanotrophs, nitroso-bacteria, nitrifying bacteria, and denitrifying bacteria. Research results also exhibited great potential of this system applied into the urban sewage treatment.