| NaCl浓度对SBBR同步脱氮及N2O释放的影响 |
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| 引用本文： | 巩有奎,任丽芳,罗佩云,彭永臻.NaCl浓度对SBBR同步脱氮及N2O释放的影响[J].农业工程学报,2020,36(3):152-159. |
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| 作者姓名： | 巩有奎 任丽芳 罗佩云 彭永臻 |
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| 作者单位： | 烟台职业学院建筑工程系,烟台 264670;北京工业大学城镇污水深度处理与资源化利用技术国家工程实验室,北京 100124;烟台职业学院建筑工程系,烟台,264670;北京工业大学城镇污水深度处理与资源化利用技术国家工程实验室,北京,100124 |
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| 基金项目： | 国家自然科学基金项目（51508008）;烟职博士科研启动基金（2018002） |
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| 摘 要： | 盐度是影响生物脱氮过程的重要因素。盐度增加会导致生物硝化和反硝化过程中N_2O的产生并释放。该文以添加NaCl的生活污水为研究对象,采用固定填料序批式生物膜反应器(sequencing batch biofilm reactor,SBBR),考察了不同NaCl浓度(0、5、10、15和20g/L)对SBBR脱氮性能及N_2O释放的影响。结果表明,试验NaCl浓度范围内,SBBR出水COD稳定在40～60mg/L。硝化过程NO_2~-/NO_3~-随NaCl浓度增加而增加。NaCl浓度≤10g/L时,NH_4~+-N去除率大于95%,N_2O产率由4.08%(NaCl浓度为0)增至6.72%(NaCl浓度为10 g/L)。NaCl浓度为20 g/L时,驯化后SBBR内平均NH_4~+-N去除率为70%,平均N_2O产率为13.60%。无添加NaCl时,N_2O主要产生于硝化阶段的AOB好氧反硝化过程,SBBR内缺氧区有助于减少N_2O释放;高NaCl浓度条件下,N_2O主要产生于AOB好氧反硝化过程和内源同步反硝化过程,高盐度加剧内源反硝化阶段NO_2~-和N_2O之间电子竞争,抑制N_2O还原,其活性抑制性能与电子受体和初始C/N有关。与硝态氮还原速率和亚硝态氮还原速率相比,氧化亚氮还原速率受NaCl抑制最为明显,是导致高盐度条件下N_2O释放量增加的重要因素。
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| 关 键 词： | 污水 氮 盐分 氧化亚氮 好氧反硝化 内源反硝化 |
| 收稿时间： | 2019/9/23 0:00:00 |
| 修稿时间： | 2020/1/12 0:00:00 |
Effects of NaCl concentration on simultaneous nitrification and denitrification process and N2O emission in SBBR |
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| Gong Youkui,Ren Lifang,Luo Peiyun and Peng Yongzhen.Effects of NaCl concentration on simultaneous nitrification and denitrification process and N2O emission in SBBR[J].Transactions of the Chinese Society of Agricultural Engineering,2020,36(3):152-159. |
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| Authors: | Gong Youkui Ren Lifang Luo Peiyun and Peng Yongzhen |
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| Institution: | 1. Department of Architecture Engineering, Yantai Vocational College, Yantai, 264670, China; 2. National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing 100124, China;,1. Department of Architecture Engineering, Yantai Vocational College, Yantai, 264670, China;,1. Department of Architecture Engineering, Yantai Vocational College, Yantai, 264670, China; and 2. National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing 100124, China; |
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| Abstract: | The sequencing batch biofilm reactor (SBBR) is widely applied in the wastewater treatment due to its strong adaptability to the unstable influent substrate concentrations. The growth environment for microorganisms is different in the outer and inner space of the biofilm, which leads to different microbial community structure in different zones of the system. Salinity is one of the key factors that affect biological nitrogen removal (BNR) performance for domestic wastewater treatment. Higher salinity could also promote the nitrite accumulation. In particular, nitrite accumulation was considered to be a major parameter for affecting the emission of N2O in both nitrification and denitrification stages, and therefore mitigate the environmental benefits of nitrogen removal process. In present study, the feasibility of simultaneous nitrification and denitrification process achievement in a SBBR was evaluated treating domestic wastewater with NaCl addition (0, 5, 10, 15 and 20 g/L) salinity addition. For more detailed insights, the changes of polyhydroxyalkanoate (PHA) and glycogen (Gly) were also analyzed to evaluate the salinity effect on nitrite accumulation and N2O emission. The results showed that with the increase of NaCl concentration, the nitrogen removal efficiency decreased, while the N2O emission ratio increased. The NH4+ removal efficiency was more than 95% as the NaCl concentration was no more than 10 g/L. When the NaCl concentration increased to 20 g/L, the average NH4+ decreased to 70.6%. As the NaCl increased from 0 to 20 g/L, the increment of PHA and Gly decreased from 43.6 mg/g and 34.5 mg/g to 28.2 mg/g and 22.7 mg/g, respectively, while the NO2- accumulation and the N2O emission ratio increased from 1.12 mg/L and 4.08 % to 18.87 mg/L and 13.60%. The more NaCl was added, the higher the ratio of NO2- to NOx- accomplished. The accumulated NO2- contributed to the occurrence of nitrifier denitrification (ND) by AOB. Most nitrous oxide emission was via ND process with NH4+ as electron donor and NO2- as electron acceptor. The higher amount of N2O, formed in the transition zone, could be consumed in deeper regions of the biofilm when the COD was sufficient. In the absence of external carbon source, both PHA and glycogen Gly were used as internal carbon source for the endogenous denitrification. The higher NaCl concentration inhibited the PHA and Gly production, which decreased the internal electron donors for denitrification. The competition for electron between Nir and Nos during the endogenous denitrification process in the deeper region, as well as the nitrifier denitrification of AOB in the transition region, contributed to the high N2O emission, especially in the high NaCl concentration of 15 and 20 g/L. Furthermore, higher NaCl concentration reduced the density of the biofilm, which made it possible for more DO diffusing into the biofilm. It can not be ignored that DO possessed high inhibition on Nos, which attributed to the high N2O emission under high NaCl concentration. The "feast" time increased at a high salinity, revealing the inhibition of microbial activity. High salinity hindered the denitrification rate, and the inhibition degree was dependent on the influent COD/N and terminal electron acceptors. Compared with the nitrate reduction rate (DNAR) and the nitrite reduction rate (DNIR), the nitrous oxide reduction rate (DN2OR) was much more reduced by high salinity. In saline wastewater BNR process, the higher NO2- accumulation, the competion between Nir and Nos, as well as the higher DO concentration in the inner region of the biofilm, led to the increase in N2O yield. |
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| Keywords: | wastewater nitrogen salinity N2O aerobic denitrification endogenous denitrification |
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