Department of Water Resource and Sanitation, Federal University Lavras, Aquenta Sol, Lavras, Minas Gerais, 37200-000, Brazil.
State University of Minas Gerais, João Monlevade Unit, Brasília Avenue, 1304 - Bau, João Monlevade, Minas Gerais, 35930-314, Brazil.
Environ Sci Pollut Res Int. 2020 Dec;27(34):43125-43137. doi: 10.1007/s11356-020-10263-8. Epub 2020 Jul 29.
To ensure microbial activity and a reaction equilibrium with efficiency and energy saving, it is important to know the factors that influence microbiological nitrogen removal in wastewater. Thus, it was investigated the microorganisms and their products involved in the treatment of kennel effluents operated with different aeration times, phase 1 (7 h of continuous daily aeration), phase 2 (5 h of continuous daily aeration), and phase 3 (intermittent aeration every 2 h), monitoring chemical and physical parameters weekly, monthly microbiological, and qualitative and quantitative microbiological analyzes at the end of each applied aeration phase. The results showed a higher mean growth of nitrifying bacteria (NB) (10) and denitrifying bacteria (DB) (10) in phase with intermittent aeration, in which better total nitrogen (TN) removal performance, with 33%, was achieved, against 21% in phase 1 and 17% in phase 2, due to the longer aeration time and lower carbon/nitrogen ratio (15.7), compared with the other phases. The presence of ammonia-oxidizing bacteria (AOB), the genus Nitrobacter nitrite-oxidizing bacteria (NOB), and DB were detected by PCR with specific primers at all phases. The analysis performed by 16S-rRNA DGGE revealed the genres Thauera at all phases; Betaproteobacteria and Acidovorax in phase 3; Azoarcus in phases 2 and 3; Clostridium, Bacillus, Lactobacillus, Turicibacter, Rhodopseudomonas, and Saccharibacteria in phase 1, which are related to the nitrogen removal, most of them by denitrifying. It is concluded that, with the characterization of the microbial community and the analysis of nitrogen compounds, it was determined, consistently, that the studied treatment system has microbiological capacity to remove TN, with the phase 3 aeration strategy, by simultaneous nitrification and denitrification (SND). Due to the high density of DB, most of the nitrification occurred by heterotrophic nitrification-aerobic. And denitrification occurred by heterotrophic and autotrophic forms, since the higher rate of oxygen application did not harm the DB. Therefore, the aeration and carbon conditions in phase 3 favored the activity of the microorganisms involved in these different routes. It is considered that, in order to increase autotrophic nitrification-aerobic, it is necessary to exhaust the volume of sludge in the secondary settlers (SD), further reducing the carbon/nitrogen ratio, through more frequent cleaning, whose periodicity should be the object of further studies. Graphical abstract.
为了确保微生物的活性和反应平衡具有效率和节能，了解影响废水生物脱氮的因素非常重要。因此，研究了在不同曝气时间下运行的犬舍废水处理中涉及的微生物及其产物，第 1 阶段（每天连续曝气 7 小时），第 2 阶段（每天连续曝气 5 小时）和第 3 阶段（每 2 小时间歇曝气），每周监测化学和物理参数，每月进行微生物学分析，并在每个应用曝气阶段结束时进行定性和定量微生物分析。结果表明，在间歇曝气阶段，硝化细菌（NB）（10）和反硝化细菌（DB）（10）的平均增长率较高，总氮（TN）去除率达到 33%，优于第 1 阶段的 21%和第 2 阶段的 17%，这是由于曝气时间较长，碳/氮比（15.7）较低，与其他阶段相比。在所有阶段都通过使用特定引物的 PCR 检测到氨氧化细菌（AOB）、亚硝化单胞菌属亚硝酸盐氧化细菌（NOB）和 DB。16S-rRNA DGGE 分析显示，所有阶段均存在 Thauera 属；第 3 阶段存在 Betaproteobacteria 和 Acidovorax；第 2 阶段和第 3 阶段存在 Azoarcus；第 1 阶段存在梭菌属、芽孢杆菌属、乳杆菌属、Turicibacter 属、红假单胞菌属和 Saccharibacteria 属，它们与氮的去除有关，其中大多数通过反硝化作用进行。可以得出结论，通过微生物群落的表征和氮化合物的分析，一致地确定，在所研究的处理系统中，通过同步硝化反硝化（SND）具有去除 TN 的微生物能力，采用第 3 阶段曝气策略。由于 DB 的高密度，大多数硝化作用是通过异养硝化-好氧进行的。反硝化作用是通过异养和自养形式发生的，因为较高的氧气应用速率不会损害 DB。因此，第 3 阶段的曝气和碳条件有利于这些不同途径中涉及的微生物的活性。有人认为，为了增加自养硝化-好氧，需要通过更频繁的清洁从二级沉淀池（SD）中排出更多的污泥体积，进一步降低碳/氮比，清洁的周期性应成为进一步研究的对象。
