规模化猪场废水处理系统中氧化塘产甲烷和脱氮微生物学机理研究
发布时间：2018-08-28 10:26
【摘要】：氧化塘作为一种基建投资少、运行管理简便、能耗成本较低的污水处理工艺,被广泛应用于规模化猪场厌氧发酵废水的处理。然而,伴随进水中高浓度化学需氧量(COD)和氨氮(NH4+-N)的输入,氧化塘存在温室气体甲烷(CH4)排放量大和氮素去除率低的问题。目前有关氧化塘产甲烷和脱氮过程的研究较少,主要集中在CH4排放通量和氮素去除率方面,有关微生物机制机理及其影响因素的研究尚未见报道。因此,从明确生态影响和满足环保需求的层面,急需开展氧化塘生境中产甲烷和脱氮过程相关微生物学研究,并阐明影响机理,以期为预测控制氧化塘温室气体CH4排放和优化氧化塘废水脱氮处理效能提供理论依据。本研究采集位于我国不同纬度地区的7个规模化猪场废水处理系统中氧化塘的水样及底泥样品,通过样品的理化指标分析,结合荧光定量PCR (qPCR)和Miseq高通量测序等分子生物学检测技术,研究了不同纬度地区规模化猪场废水处理系统中一级氧化塘和浙江省某一规模化猪场废水处理系统中多级氧化塘的产甲烷与脱氮过程相关功能基因丰度和微生物群落多样性变化规律,揭示了影响氧化塘产甲烷过程的关键因素,提出了硫酸盐还原过程对氧化塘氮素去除过程的影响机制,为氧化塘温室气体排放控制和氧化塘工艺脱氮效能的提升提供了理论依据。主要研究结论如下：(1)我国不同纬度地区规模化猪场废水处理系统中一级氧化塘底泥中产甲烷微生物活性和丰度均非常高,表明氧化塘是一个巨大的潜在温室气体CH4排放源。根据测得的一级氧化塘底泥产甲烷和甲烷氧化活性以及我国氧化塘的数量与分布情况估算,我国畜禽养殖业废水处理系统中氧化塘底泥每年排放的CH4量为1.78-2.68 Tg,约占到全球人为CH4排放量的0.56-0.84%。此外,通过对浙江省杭州市某规模化猪场废水处理系统中连续四级氧化塘的水样和底泥理化指标、产甲烷微生物活性及其丰度的分析可以发现,氧化塘进水COD负荷对同一地点多级氧化塘产甲烷过程的影响最为显著。因此,从控制温室气体CH4排放,应对气候变化的角度出发,氧化塘不适合直接应用于养殖废水厌氧发酵液的处理,应通过优化氧化塘前期设计、强化进水固液分离效果和设置相应的生化处理单元来降低氧化塘进水有机质负荷,以减少氧化塘温室气体CH4排放量。(2)运用分子生物学检测技术,对比分析了不同纬度地区一级氧化塘底泥中产甲烷微生物活性、丰度和群落结构与功能的变化规律,发现年平均温度(MAT, mean annual temperature)是影响不同纬度地区一级氧化塘底泥产甲烷过程的关键因素。随着氧化塘所在区域MAT的升高,氧化塘底泥中产甲烷微生物活性和丰度均呈现极显著的上升趋势。高温区氧化塘底泥以WCHD3-30主导的氢营养型产甲烷古菌为主,而低温区氧化塘底泥则以甲烷鬃菌科(Methanosaetaceae)主导的乙酸营养型产甲烷古菌为主。随着氧化塘所在区域MAT的变化,底泥细菌群落结构组成也存在一定的变化规律,并与主导产甲烷古菌营养型的变化规律相吻合。高温区底泥细菌以具有产氢功能的乙酸氧化菌为主；低温区底泥细菌种群大多与大分子有机质降解和产乙酸过程相关。另外,冗余分析(RDA, redundancy analysis)的结果表明,MAT对一级氧化塘底泥中产甲烷古菌群落结构组成的影响最为显著。研究揭示了MAT影响氧化塘产甲烷过程的微生物学机理,并为未来全球气候变暖的趋势下,氧化塘CH4排放量呈现潜在性升高趋势推断提供了理论依据。(3)通过对不同纬度地区的一级氧化塘进出水氮素的测定和比较发现,一级氧化塘NH4+-N去除率均较低,最高去除率不足20%。采用定量PCR研究了氧化塘中氮循环相关功能基因(nifH, AOA amoA, AOB amoA, nirS和nirK)丰度的变化情况。结果表明,一级氧化塘水体和底泥中固氮功能基因(nifH)丰度普遍较高,而氨氧化功能基因(AOA amoA和AOB amoA)丰度极低。Pearson相关性分析的结果表明,一级氧化塘中nifH丰度与NH4+-N浓度呈现显著的正相关关系,氨氧化功能基因丰度与NH4+-N浓度没有表现出任何的显著相关性。一级氧化塘中有可能发生固氮过程并由此促进NH4+-N浓度的升高,而氨氧化过程并没有导致NH4+-N浓度的下降。值得注意的是,一级氧化塘中SO42-浓度与nifH丰度存在显著的正相关关系,且与AOB amoA丰度存在极显著的负相关关系。因此,一级氧化塘中硫循环相关过程可能会强化氧化塘中NH4+-N的生成过程,同时削弱氨氧化过程,最终导致一级氧化塘极低的NH4+-N去除现象。(4)通过对浙江省某一规模化猪场废水处理系统中连续四级氧化塘底泥和水样的理化指标分析、氮循环相关功能基因(nifH, AOA amoA, AOB amoA, nirS和nirK)丰度、硫循环相关功能基因(dsrB和soxB)丰度的测定以及硫酸盐还原过程抑制剂的添加实验,证实了硫酸盐还原过程是导致一级氧化塘脱氮性能低的主要原因。随着氧化塘级数的增加,底泥和水样SO42-浓度、硫酸盐还原功能基因(dsrB)丰度和水体硫化物浓度逐渐下降,硫酸盐还原过程减弱,NH4+-N去除率呈升高趋势。RDA和Pearson相关性分析的结果表明,硫酸盐还原过程生成的硫化物是影响氮循环和硫循环相关功能基因丰度整体变化的最主要因子,并且与氧化塘主要脱氮过程的功能基因(水体中AOB amoA和nirS)丰度均呈现显著的负相关关系,表明硫化物显著抑制氧化塘脱氮过程。另一方面,nifH和dsrB丰度呈现极显著的正相关关系,硫酸盐还原过程的存在可能会显著提高nifH丰度,由此促进固氮过程的发生,从而提高水体和底泥的NH4+-N浓度。抑制剂添加实验的结果表明,一级氧化塘(ZJ1)中的硫酸盐还原过程被抑制后,NH4+-N的去除率提高了5.1-9.5%,ZJ1中硫酸盐还原过程的存在抑制了20.9-32.8%的NH4-N去除。鉴于硫酸盐还原过程对氧化塘脱氮过程的抑制作用,从提高氧化塘脱氮性能的角度出发,氧化塘不适合直接应用于硫化物浓度较高的厌氧发酵出水和SO42-浓度较高的养殖废水、食品厂废水和制药业废水等的处理。
[Abstract]:Oxygen pond is widely used in the treatment of anaerobic fermentation wastewater from large-scale pig farms as a wastewater treatment process with low capital investment, simple operation and management, and low energy consumption. However, with the high concentration of COD and NH4 + - N in the influent, the greenhouse gas methane (CH4) emissions and nitrogen removal from the pond are high. At present, there are few studies on methane production and nitrogen removal process in oxidation ponds, mainly focusing on CH4 emission flux and nitrogen removal rate, but there is no report on the mechanism of microbial mechanism and its influencing factors. Microbiological studies on methane and denitrification processes were carried out, and the influencing mechanism was clarified in order to provide theoretical basis for predicting and controlling greenhouse gas CH4 emission from oxidation ponds and optimizing denitrification efficiency of oxidation pond wastewater. The phase of methane production and denitrification in the primary oxidation pond and the multistage oxidation pond of a large-scale pig farm wastewater treatment system in Zhejiang Province were studied by analyzing the physical and chemical indexes of the samples and combining with fluorescence quantitative PCR (qPCR) and Mosq high-throughput sequencing techniques. The changes of functional gene abundance and microbial community diversity reveal the key factors affecting methane production in oxidation ponds. The mechanism of sulfate reduction affecting nitrogen removal in oxidation ponds is proposed, which provides a theoretical basis for controlling greenhouse gas emissions and improving nitrogen removal efficiency of oxidation ponds. The conclusions are as follows: (1) The methanogenic microbial activities and abundance in the sediments of the primary oxidation ponds in large-scale pig farm wastewater treatment systems in different latitudes of China are very high, indicating that the oxidation ponds are a huge potential source of greenhouse gas CH4 emission. The quantity and distribution of the ponds are estimated to be 1.78-2.68 Tg of CH4 discharged annually from the sediments of the oxidation ponds in the livestock and poultry wastewater treatment systems in China, accounting for about 0.56-0.84% of the global anthropogenic CH4 discharged. Therefore, from the point of view of controlling greenhouse gas CH4 emission and coping with climate change, oxidation pond is not suitable for the treatment of anaerobic fermentation broth of aquaculture wastewater. By optimizing the pre-design of oxidation pond, enhancing the effect of solid-liquid separation and setting up the corresponding biochemical treatment unit, the organic load in the inlet of oxidation pond can be reduced to reduce the greenhouse gas CH4 emissions. (2) The methanogenic microbial activities in the sediments of oxidation ponds in different latitudes were compared and analyzed by using molecular biological detection technology. It was found that the annual mean temperature (MAT) was the key factor affecting the methane production in the sediments of oxidation ponds in different latitudes. With the increase of MAT in the area where the oxidation ponds were located, the methane-producing microbial activities and abundance in the sediments of oxidation ponds increased significantly. WCHD3-30 dominated methanogenic archaea were dominant in the sediments of oxidation ponds at high temperatures, while methanosaetaceae dominated methanogenic archaea in the sediments of oxidation ponds at low temperatures. In addition, the results of redundancy analysis (RDA) showed that MAT had a significant effect on the degradation of macromolecular organic matter and the production of acetic acid. The study reveals the microbiological mechanism of MAT affecting methane production in oxidation ponds, and provides a theoretical basis for predicting the potential increase of CH4 emissions from oxidation ponds under the trend of global warming in the future. (3) Through the first-order oxidation ponds in different latitudes. The results showed that the removal rate of NH4 + - N in the primary oxidation pond was lower than 20%, and the highest removal rate was less than 20%. The abundance of nitrogen cycling related functional genes (nifH, AOA amoA, AOB amoA, nirS and nirK) in the primary oxidation pond was studied by quantitative PCR. Pearson correlation analysis showed that there was a significant positive correlation between the abundance of nifH and the concentration of NH4 + - N in primary oxidation ponds, and there was no significant correlation between the abundance of NH4 + - N and the abundance of NH4 + - N in primary oxidation ponds. It is noteworthy that there is a significant positive correlation between SO42-concentration and nifH abundance in primary oxidation ponds, and a very significant negative correlation between SO42-concentration and AOB amoA abundance. Cheng may intensify the formation of NH4 + - N in the oxidation pond and weaken the ammonia oxidation process, resulting in very low NH4 + - N removal in the primary oxidation pond. The abundances of AOB amoA, nirS and nirK, the abundances of sulfur cycling related functional genes (dsrB and soxB) and the addition of sulfate reduction process inhibitors confirmed that the sulfate reduction process was the main reason for the low denitrification performance of the primary oxidation pond. The results of RDA and Pearson correlation analysis showed that sulfides formed during sulfate reduction were the most important factors affecting the overall changes of functional gene abundance related to nitrogen cycle and sulfur cycle, and were related to oxygen. The abundances of functional genes (AOB amoA and nirS) in the main denitrification processes in the ponds were negatively correlated, suggesting that sulfides significantly inhibited the denitrification process in the ponds. The experimental results showed that the removal rate of NH4 + - N increased by 5.1-9.5% and the removal rate of NH4 - N by 20.9-32.8% in the first-order oxidation pond (ZJ1) when the sulfate reduction process was inhibited. From the point of view of improving the denitrification performance of oxidation pond, oxidation pond is not suitable for the treatment of anaerobic fermentation effluent with high sulfide concentration, aquaculture wastewater with high SO42-concentration, food factory wastewater and pharmaceutical wastewater.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：X713
[Abstract]:Oxygen pond is widely used in the treatment of anaerobic fermentation wastewater from large-scale pig farms as a wastewater treatment process with low capital investment, simple operation and management, and low energy consumption. However, with the high concentration of COD and NH4 + - N in the influent, the greenhouse gas methane (CH4) emissions and nitrogen removal from the pond are high. At present, there are few studies on methane production and nitrogen removal process in oxidation ponds, mainly focusing on CH4 emission flux and nitrogen removal rate, but there is no report on the mechanism of microbial mechanism and its influencing factors. Microbiological studies on methane and denitrification processes were carried out, and the influencing mechanism was clarified in order to provide theoretical basis for predicting and controlling greenhouse gas CH4 emission from oxidation ponds and optimizing denitrification efficiency of oxidation pond wastewater. The phase of methane production and denitrification in the primary oxidation pond and the multistage oxidation pond of a large-scale pig farm wastewater treatment system in Zhejiang Province were studied by analyzing the physical and chemical indexes of the samples and combining with fluorescence quantitative PCR (qPCR) and Mosq high-throughput sequencing techniques. The changes of functional gene abundance and microbial community diversity reveal the key factors affecting methane production in oxidation ponds. The mechanism of sulfate reduction affecting nitrogen removal in oxidation ponds is proposed, which provides a theoretical basis for controlling greenhouse gas emissions and improving nitrogen removal efficiency of oxidation ponds. The conclusions are as follows: (1) The methanogenic microbial activities and abundance in the sediments of the primary oxidation ponds in large-scale pig farm wastewater treatment systems in different latitudes of China are very high, indicating that the oxidation ponds are a huge potential source of greenhouse gas CH4 emission. The quantity and distribution of the ponds are estimated to be 1.78-2.68 Tg of CH4 discharged annually from the sediments of the oxidation ponds in the livestock and poultry wastewater treatment systems in China, accounting for about 0.56-0.84% of the global anthropogenic CH4 discharged. Therefore, from the point of view of controlling greenhouse gas CH4 emission and coping with climate change, oxidation pond is not suitable for the treatment of anaerobic fermentation broth of aquaculture wastewater. By optimizing the pre-design of oxidation pond, enhancing the effect of solid-liquid separation and setting up the corresponding biochemical treatment unit, the organic load in the inlet of oxidation pond can be reduced to reduce the greenhouse gas CH4 emissions. (2) The methanogenic microbial activities in the sediments of oxidation ponds in different latitudes were compared and analyzed by using molecular biological detection technology. It was found that the annual mean temperature (MAT) was the key factor affecting the methane production in the sediments of oxidation ponds in different latitudes. With the increase of MAT in the area where the oxidation ponds were located, the methane-producing microbial activities and abundance in the sediments of oxidation ponds increased significantly. WCHD3-30 dominated methanogenic archaea were dominant in the sediments of oxidation ponds at high temperatures, while methanosaetaceae dominated methanogenic archaea in the sediments of oxidation ponds at low temperatures. In addition, the results of redundancy analysis (RDA) showed that MAT had a significant effect on the degradation of macromolecular organic matter and the production of acetic acid. The study reveals the microbiological mechanism of MAT affecting methane production in oxidation ponds, and provides a theoretical basis for predicting the potential increase of CH4 emissions from oxidation ponds under the trend of global warming in the future. (3) Through the first-order oxidation ponds in different latitudes. The results showed that the removal rate of NH4 + - N in the primary oxidation pond was lower than 20%, and the highest removal rate was less than 20%. The abundance of nitrogen cycling related functional genes (nifH, AOA amoA, AOB amoA, nirS and nirK) in the primary oxidation pond was studied by quantitative PCR. Pearson correlation analysis showed that there was a significant positive correlation between the abundance of nifH and the concentration of NH4 + - N in primary oxidation ponds, and there was no significant correlation between the abundance of NH4 + - N and the abundance of NH4 + - N in primary oxidation ponds. It is noteworthy that there is a significant positive correlation between SO42-concentration and nifH abundance in primary oxidation ponds, and a very significant negative correlation between SO42-concentration and AOB amoA abundance. Cheng may intensify the formation of NH4 + - N in the oxidation pond and weaken the ammonia oxidation process, resulting in very low NH4 + - N removal in the primary oxidation pond. The abundances of AOB amoA, nirS and nirK, the abundances of sulfur cycling related functional genes (dsrB and soxB) and the addition of sulfate reduction process inhibitors confirmed that the sulfate reduction process was the main reason for the low denitrification performance of the primary oxidation pond. The results of RDA and Pearson correlation analysis showed that sulfides formed during sulfate reduction were the most important factors affecting the overall changes of functional gene abundance related to nitrogen cycle and sulfur cycle, and were related to oxygen. The abundances of functional genes (AOB amoA and nirS) in the main denitrification processes in the ponds were negatively correlated, suggesting that sulfides significantly inhibited the denitrification process in the ponds. The experimental results showed that the removal rate of NH4 + - N increased by 5.1-9.5% and the removal rate of NH4 - N by 20.9-32.8% in the first-order oxidation pond (ZJ1) when the sulfate reduction process was inhibited. From the point of view of improving the denitrification performance of oxidation pond, oxidation pond is not suitable for the treatment of anaerobic fermentation effluent with high sulfide concentration, aquaculture wastewater with high SO42-concentration, food factory wastewater and pharmaceutical wastewater.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：X713
【参考文献】
相关期刊论文 前10条
1 Chong Wang;Jiane Zuo;Xiaojie Chen;Wei Xing;Linan Xing;Peng Li;Xiangyang Lu;Chao Li;;Microbial community structures in an integrated two-phase anaerobic bioreactor fed by fruit vegetable wastes and wheat straw[J];Journal of Environmental Sciences;2014年12期
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