兰州大学机构库 >资源环境学院
缓释碳源填料对城市污水厂尾水脱氮作用研究
Alternative TitleStudy on denitrification of tail water from municipal wastewater treatment plant by slow-release carbon source fillers
范天凤
Subtype硕士
Thesis Advisor赵转军
2021-05-15
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name工程硕士
Degree Discipline环境工程
Keyword缓释碳源 深度脱氮 反硝化滤池 尾水 HRT 微生物群落结构
Abstract近年来,随着城市化进程的发展,城市生态水体补水、绿化用水、城市杂用水等生态环境用水保障不足的问题日益凸显,我国主要通过城市污水厂尾水深度处理回用于生态环境用水,但尾水中TN(其中NO3--N占80%以上)含量高是限制其回用的主要原因,在以生物法脱氮为主的污水厂中,TN的去除受限于水中碳源不足,往往通过外加碳源来提高脱氮效果,植物碳源因其来源广泛、数量巨大、成本低廉而受到了广大学者的关注,但不同植物碳源的释碳速率相差甚远,且单纯投加存在释碳不够持久、效果不稳定等问题,因此本研究对农村地区常见的几种植物碳源材料进行筛选,并采用不同的甲醇-水-NaOH改性体系制备缓释碳源填料,应用于反硝化生物滤池中,对城市污水厂尾水进行深度脱氮。主要研究结论如下: (1)枸杞枝是比较好的植物固体碳源。胡麻秸秆、枸杞枝、大豆秸秆、油葵秸秆和油葵花盘5种植物碳源的碳(C)含量在36.23%~68.64%之间,其中枸杞枝C含量为67.09%,具有较大的释碳潜力。5种植物碳源材料均存在快速释碳期(1-3d)和稳定释碳期(4-22d)两个阶段,稳定释碳阶段枸杞枝的释碳速率最高,可达3.35 mg·(g-秸秆·d)-1。5种植物碳源释碳过程同时满足Ritger-Peppas方程和二级动力学方程,枸杞枝的cm值相对适中且t1/2值相对较大,利于提高反硝化性能并缩短反应器的启动期。相较其他4种植物碳源,枸杞枝浸出液中DOM含有更多的醇类、醛类和小分子有机酸类物质。因此,优选枸杞枝作为植物碳源进行后续试验。 (2)20%甲醇-水-NaOH(1% 浓度)体系是枸杞枝改性的最优条件。使用甲醇(体积占比0%、20%、50%、100%)-水-NaOH体系(简称0%组、20%组、50%组、100%组)对枸杞枝进行改性,改性后枸杞枝纤维素和半纤维素含量占比增加了8.7%~35.2%;各组改性枸杞枝平均反硝化速率依次为20%组>50%组>0%组>100%组>对照组,20%组反硝化速率最高(0.76 mg NO3--N·(g-枸杞枝·d)-1),表明20%甲醇-水-NaOH(1% 浓度)是枸杞枝改性的最佳条件;改性后的枸杞枝表面结构粗糙、不规则且有大量的孔洞产生,适合脱氮微生物附着生长,其反硝化脱氮过程符合Monod动力学方程(R=0.96)。20%甲醇-水-NaOH(1% 浓度)改性的枸杞枝即为制备的缓释碳源,后续试验将使用其作为反硝化滤池填料进行深度脱氮研究。 (3)HRT 3.5h和HRT 6.5h分别为缓释碳源填料强化低硝氮浓度和高硝氮浓度尾水脱氮的最佳HRT。缓释碳源应用于城市污水厂尾水深度脱氮时,在低硝氮浓度(11.70±0.64 mg·L-1)条件下,HRT为1.5h、2.5h、3.5h和4.5h时出水COD在10.82~19.71 mg·L-1之间。HRT 4.5h时NO3--N和TN去除率最高,分别为79.58±6.75%和70.23±5.64%,但相较于HRT 3.5h平均去除率均仅增加了约3%。反硝化滤池对TP基本无去除。HRT为3.5h和4.5 h时缓释碳源填料表面的微生物膜较其他HRT更为密集和厚实,微生物群落多样性更为丰富,检测到主要菌属为Saccharimonadales、OLB14、C10-SB1A和Microtrichales。在高硝氮浓度(21.66±0.51 mg·L-1)条件下,相较于其他HRT(4.5h、5.5h和7.5h),HRT 6.5h的NO3--N和TN去除率最高,分别为69.22±9.53%和60.56±8.57%。同时对比发现HRT 4.5h时低硝氮浓度条件下NO3--N和TN去除率显著高于高硝氮浓度,表明脱氮效果与进水硝氮浓度呈负相关关系。 (4)缓释碳源填料强化尾水脱氮长期运行效能显著。研究缓释碳源填料在典型条件(进水NO3--N浓度为23.04±1.51 mg·L-1,HRT=4h)下的长期运行效果,稳定运行阶段出水COD浓度为15.09±6.18 mg·L-1,缓释碳源组NO3--N和TN平均去除率较对照组(未改性枸杞枝)分别提高了15.31%和14.05%,120d时仍能保持20%以上的NO3--N去除率。相较于对照组,缓释碳源组表面生物膜更为均匀紧凑,微生物群落多样性更为丰富,变形菌门的占比(21.05%)更高,主要细菌属为Microtrichales、 Saccharimonadales和Ilumatobacteraceae,脱氮功能基因的丰富度也更高。表明枸杞枝在经过甲醇(体积占比20%)-水-NaOH体系改性后显著增强了反硝化滤池的脱氮能力。
Other AbstractIn recent years, with the development of urbanization, the problem of insufficient water protection for ecological environment such as urban ecological water replenishment, greening water, and urban miscellaneous water has become increasingly prominent. China mainly uses the advanced treatment of urban sewage plant tail water to reuse it for ecological environment water. However, the high content of TN (more than 80% of NO3--N) in the tail water is the main reason that restricts its reuse. In sewage plants that dominate biological denitrification, the removal of TN is limited by insufficient carbon sources in the water. The denitrification effect is often improved by adding carbon sources. Plant carbon sources have attracted the attention of many scholars because of their wide sources, huge quantities, and low costs. However, the carbon release rates of different plant carbon sources are very different, and simple addition exists, The carbon release is not long enough and the effect is unstable. Therefore, this study screened several common plant carbon source materials in rural areas, and used different methanol-water-NaOH modification systems to prepare slow-release carbon source fillers, which were used in denitrification biological filters, To carry out deep denitrification on the tail water of the municipal sewage plant. The main research conclusions are as follows: (1) The Chinese wolfberry branches are a better plant solid carbon source. The carbon (C) content of five plant carbon sources such as flax stalks, Chinese wolfberry branches, soybean stalks, oil sunflower stalks and oil sunflower disks is between 36.23% and 68.64%, The C content of Chinese wolfberry branches was 67.09%, which had a great potential of carbon release. The five plant carbon source materials all have two stages: Phase I (1~3 d) was the rapid carbon release stage, and Phase II (4~21 d) was the stable release stage. The carbon release rate of Chinese wolfberry branches is the highest in the stable carbon release stage, which can reach 3.35 mg·(g-Straw·d)-1. The carbon release process of the five plant carbon sources fitted Ritgre-Peppas equation and the second-order kinetic equation quite well. The cm value of the Chinese wolfberry branches is relatively moderate and the t1/2 value is relatively large, which is beneficial to improve the denitrification performance and shorten the start-up period of the reactor. Compared with the other four kinds of plant carbon sources, the DOM in the extract of Chinese wolfberry branches contains more alcohols, aldehydes and small molecular organic acids. Therefore, it is preferred to use Chinese wolfberry branches as a plant carbon source for subsequent experiments. (2) The 20% methanol-water-NaOH (1% concentration) system is the optimal condition for the modification of Chinese wolfberry branches. The Chinese wolfberry branches were modified by the mixture of methanol (0%, 20%, 50% and 100% volumetric ratio respectively, hereinafter referred as 0%, 20%, 50% and 100% group), water and NaOH (1%). The cellulose and hemicellulose content of the modified branches were 8.7%~35.2% higher than those of the raw branches. The average denitrification rates are in the sequence of 20% group >50% group >0% group >100% group >the control group. The denitrification rate of the 20% group was the highest (0.76 mg·(g - Chinese wolfberry branches·d)-1), which indicated that 20% methanol-water-NaOH (1%) was the optimum condition for the modification of the Chinese wolfberry branches. The surface of the modified branches was rough, irregular and had many voids, which was suitable for the growth of denitrifying microorganisms. The denitrification process of the modified branches followed the Monod kinetic equation (R=0.96). The Chinese wolfberry branches modified with 20% methanol-water-NaOH (1% concentration) is the prepard slow-release carbon source, and subsequent experiments will use it as a filling of denitrification filter for deep denitrification research. (3) HRT 3.5h and HRT 6.5h are the best HRTs for slow-release carbon source fillers to enhance the denitrification of tail water with low nitrate nitrogen concentration and high nitrate nitrogen concentration. When the slow-release carbon source is used in the deep denitrification of the municipal sewage plant tail water, under the condition of low nitrate nitrogen concentration (11.70±0.64 mg·L-1), the effluent COD is between 10.82~19.71 mg·L-1 when HRT is 1.5h, 2.5h, 3.5h and 4.5h. The removal rate of NO3--N and TN was the highest at HRT 4.5h, 79.58±6.75% and 70.23±5.64%, respectively, but the average removal rate was only increased by about 3% compared with HRT 3.5h. The denitrification filter basically does not remove TP. When HRT is 3.5h and 4.5h, the microbial film on the surface of the slow-release carbon source filler is denser and thicker than other HRTs, and the microbial community diversity is more abundant. The main bacterial genera detected are Saccharimonadales, OLB14, C10-SB1A and Microtrichales. Under the condition of high nitrate nitrogen concentration (21.66±0.51 mg·L-1), compared with other HRTs (4.5h, 5.5h and 7.5h), HRT 6.5h has the highest removal rate of NO3--N and TN, 69.22±9.53% and 60.56±8.57%, respectively. At the same time, the comparison found that the removal rate of NO3--N and TN under the condition of low nitrate nitrogen concentration at HRT 4.5h was significantly higher than that of high nitrate nitrogen concentration, indicating that the denitrification effect was negatively correlated with the influent nitrate nitrogen concentration. (4) The slow-release carbon source enhances the long-term operation efficiency of tail water denitrification. When studying the long-term operation effect of the slow-release carbon source filler under typical conditions (the influent NO3--N concentration is 23.04±1.51 mg·L-1, HRT=4h), the effluent COD concentration in the stable operation stage is 15.09±6.18 mg·L-1, the average removal rate of NO3--N and TN in the slow-release carbon source group was increased by 15.31% and 14.05%, respectively, compared with the control group(unmodified Chinese wolfberry branches), and the NO3--N removal rate was still more than 20% at 120 days. Compared with the control group, the surface biofilm of the slow-release carbon source group is more uniform and compact, and the microbial community diversity is more abundant. The proportion of Proteobacteria (21.05%) is higher. The main bacterial genera are Microtrichales, Saccharimonadales and Ilumatobacteraceae. The abundance of denitrification functional genes is also higher. It showed that the Chinese wolfberry branches were modified by methanol (20% by volume)-water-NaOH, which significantly enhanced the denitrification capacity of the denitrification filter.
Pages94
URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/459495
Collection资源环境学院
Affiliation
资源环境学院
First Author AffilicationCollege of Earth Environmental Sciences
Recommended Citation
GB/T 7714
范天凤. 缓释碳源填料对城市污水厂尾水脱氮作用研究[D]. 兰州. 兰州大学,2021.
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