科研之友
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摘要
The total nitrogen content (TN) of winery wastewater must be less than 20 mg/L before discharge. The TN of this type of wastewater is composed of NH4+-N, NO3--N, and NO2--N. Based on existing techniques, such as aeration treatment, NH4+-N can be removed easily, but NO3--N and NO2--N are difficult to treat with ordinary methods, leading to the content of total nitrogen not meeting the standards. Therefore, the efficient removal of nitrate from wastewater has become a focus of technical research. In this study, anaerobic biological denitrification technology was used to remove nitrate from wastewater. First, the denitrifying microbial community was established by activated sludge domestication and enrichment in a self-designed up-flow anaerobic sludge blanket (UASB) reactor. The different carbon sources promoting the efficiency of denitrification were screened and quantified. Finally, the bacterial diversity of the system was analyzed using third-generation sequencing technology. The results showed that MicroC was the best for denitrification among the different carbon sources, such as methanol, sodium acetate, sodium succinate, glucose, winery raw water, sodium citrate, and MicroC. The actual target wastewater from the winery (TN = 531 mg/L) was treated using the method described in this study; the NO3--N content of the effluent was less than 1 mg/L, the removal rate reached 98%, and the COD removal rate exceeded 90% when MicroC was used as the carbon source and the C/N ratio = 1.0. Sequencing results showed that the microbial community structure changed as the denitrification progressed. In the early stage of denitrification, Pseudomonas stutzeri and Thioclava sp. were the dominant species to reduce a large amount of nitrate, and the diversity of bacteria was relatively low. In the later period, Stenotrophomonas acidophila became the dominant species to reduce residual nitrate. These results demonstrate that the anaerobic denitrification system that uses MicroC as the carbon source can facilitate low-cost and high-efficiency biological treatment of high-nitrate wastewater from wineries, and Pseudomonas stutzeri played a major role in this system.
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