亲水化改性聚氨酯载体的生物膜形成过程特性及其在污水处理中的应用研究
文献类型：学位论文
| 作者 | 冯权 |
| 学位类别 | 博士 |
| 答辩日期 | 2012-05-24 |
| 授予单位 | 中国科学院研究生院 |
| 导师 | 陈洪章 |
| 关键词 | 聚氨酯泡沫载体（PUF） 表面改性 移动床生物膜反应器（MBBR） 微电极 填充率 |
| 其他题名 | Characteristics of Biofilm Formation in Hydrophilically Modified Polyurethane Foam Carriers and The Application in Wastewater Treatment |
| 学位专业 | 生物化工 |
| 中文摘要 | 本文主要是针对聚氨酯泡沫（Polyurethane Foam, PUF）载体在MBBR（Moving Bed Biofilm Reactor）工艺中的应用中存在的问题进行研究。比较了不同PUF载体填充率情况下对COD(Chemical Oxygen Demand)、氨氮的处理效果及长期运行中存在的问题。通过在PUF载体表面改性和直接发泡等方法，提高了生物膜在载体上的形成速度，缩短了成膜时间。用微电极检测了生物膜结构对硝酸根、铵根和溶解氧（dissolved oxygen, DO）传递的影响，对PUF载体结构改进提供理论依据，并从流化的角度分析了填充率对于处理效果的影响及降解动力学参数。论文主要取得的主要研究结果如下所示： (1)研究了填充率对COD、氨氮的处理效果，发现填充率主要是改变了单位体积载体上的COD负荷和载体上的生物膜结构，主要是影响了对氨氮的处理效果。20%、30%和40%填充率对于COD的平均去除率为81%；而对于氨氮的处理效率，40%填充率最先表现出来，稳定的情况下可以达到95%，其次是30%填充率的反应器。当COD负荷在2～4kgCOD/(m3•d)时，载体上生物膜量和COD负荷成正比，但当COD负荷超过4.2 kgCOD/(m3•d)时，氨氮的去除率迅速下降。焦磷酸测序（Pyrosequencing）的结果也说明COD负荷影响了载体上生物膜的结构。采用不改性PUF载体长期运行的结果表明，不改性载体上的生物膜容易集体脱落，而且脱落后需要较长时间重新成膜，严重影响了对氨氮的处理效果。 （2）通过表面涂饰、添加阳离子的方法在降低表明接触角的同时，使载体表明变的粗糙，形成很多微孔结构。丙烯酸乳液及聚氨酯乳液表明修饰后可以将接触角从90度左右降低到30～50度，载体上挂模量提高1.5～2.5倍。通过比较阳离子添加量、材料强度和表面接触角的比较，在配方中添加10%的是最合适的。载体改性后，可以将挂膜时间缩短至5～6d，是不改性载体挂膜所需时间的六分之一。 （3）使用微电极分析了不同生物膜结构内硝酸根、铵根和DO的传递过程，结果表明载体上生物膜的密度、厚度主要是影响了DO的传递，而硝酸根和铵根相对容易扩散进入到载体的内部。因此，通过改变载体的结构、控制单位载体上的COD负荷，可以强化DO在生物膜内的传质，提高脱氮效率。 （4）比较了填充率、曝气量对COD、氨氮降解效果的影响，结果发现曝气量对于氨氮、葡萄糖的降解效果影响不明显，而填充率在25%时有最大的比降解速率，填充率主要是影响了载体在反应器内是否可以自由的移动。当反应器内悬浮微生物浓度较低时，PUF载体对氨氮及葡萄糖的降解呈零级反应。 （5）将上述改性后的PUF载体，按照25%的填充率在北京高碑店污水处理厂进行中试，在5个月的连续运行过程中，使用改性PUF载挂膜时间需要5～6d，对氨氮的去除率为95～98%，即使在温度降低到12℃时，仍然可以保持脱氮效果。对总氮的去除率在70%左右，当进水碳源缺乏时影响总氮的去除效果。 本研究的意义在于通过比较不同填充率PUF载体在MBBR中的应用，得到填充率是影响处理效果的关键因素，并建立填充率选择的依据。通过表面亲水化处理提高了挂膜速度及处理稳定性，开发了多种改性方法，并为载体开发及应用提供了一些理论依据及选择方法。 |
| 英文摘要 | The polyurethane foam (PUF) carriers have been used for wastewater treatment in moving bed biofilm reactor for many years, but many problems still exist. In this thesis, the MBBRs with different packing rates were compared for studying the chemical oxygen demand (COD), ammonium nitrogen removal efficiency and the unknown problems in long running process. The biofilm formation speed was improved significantly through surface modification and adding cation in the formulations. The nitrate, ammonium nitrogen and dissolved oxygen (DO) transfer process in the different structure cubic biofilm attached on the PUF were measured with microelectrode, which provided theoretical basis for the carrier’s structure design. The influence of aeration rates and packing rates for the treatment efficiency were also studied in batch test, which improved that the packing rate was the key parameter. The main achievements were as follows: Firstly, the effects of packing rates to the COD and ammonium nitrogen was studied through building up three MBBRs with 20%, 30% and 40% of reactor volume PUF. The results showed that the biofilm structure and COD loading of per volume PUF carrier were changed by the packing rates, which mainly influence the ammonium nitrogen removal efficiency. The average COD removal efficiency was similarly of 81% in three MBBRs. However, the ammonium nitrogen removal efficiency firstly reached 95% after continuing running 30days and then 30% packing rate reactor, and finally was the 20% packing rate reactor. The biomass attached on the PUF carriers and COD lading of per volume carrier was liner when the COD loading ranged from 2 to 4 kgCOD/(m3·d), However, if the COD loading of per volume carrier exceeds 4 kgCOD/(m3·d), the ammonium nitrogen removal efficiency decreased dramatically. The pyrosequencing results of the biofilm also indicated that the COD loading influenced the bacterial community which related with the ammonium removal efficiency. The serious problem using unmodified PUF carrier was the biofilm detached irregular, which leaded to the effluent ammonium nitrogen concentration increased dramatically. Secondly, the contact angle decreased when the PUF surface was modified with surface modifier and adding cation in the foam formulations, which make the surface roughness, formed many microporous on PUF surface or increasing cation content. The contact angle decreased from 90 degree to 30-50 degree when the surface was modified with acrylic emulsion and polyurethane emulsion. The biomass attached on PUF carrier increased of 1.5 to 2.5 times. The mass ratio of 10% of cation in the foam formula was optimal by comparing the relation of the amount of cation adding amount, strength of the material and contact angle. The steady biofilm formation time on the PUF carrier decreased to 5-6 day after modification, it was only sixth of the normal PUF carrier needed. Thirdly, the nitrate, ammonium nitrogen and DO transfer process in different structure biofilm were measured with microelectrode. The resulted indicated that the biofilm density and thickness were the key parameters which influenced the DO transfer in the biofilm, however, the nitrate and ammonium nitrogen is relatively easy to transfer into the inner side of biofilm. Therefore, strengthening the DO transfer distance in the biofilm can improve the ammonium removal efficiency by design the carrier structure, controlling the COD loading of per volume PUF carrier. Fourthly，the influences of packing rate and aeration volume to the COD and ammonium nitrogen removal efficiency were compared in batch test. The results indicated that the aeration rate had little influence to the ammonium nitrogen and glucose removal efficiency. When the packing rate was 25%, the glucose specific decreasing rate obtained maximum. Increasing the packing further, the PUF carriers cannot move freely, which may influence the treatment efficiency. The glucose and ammonium nitrogen decreased as zero order reaction when the suspended sludge concentration was changed from 0 to 400mg/L. Fifth, the pilot experiment was performed in Gao Bei Dian wastewater treatment plant in Beijing of China, which used the modified carriers by adding cation in the formula and the packing rate was 25%. The results indicated that the biofilm formation time was only 6days. The ammonium nitrogen removal efficiency was 95%-97% when the reactor reached steady state even when the temperature decreased to 12 ℃. The total nitrogen removal efficiency was 55%, but the total nitrogen removal efficiency decreased when the influent COD was below 150mg/L. In conclusions, the insights of this research lie in finding that the packing rate was the key parameter for treatment efficiency by compared different packing rates MBBRs, and establish the principle of packing rate selection. The biofilm formation speed and processing stability were improved by surface modification; several methods for surface modification were developed. Moreover, some principles and theatrical basis for carrier design and selective was proposed. |
| 语种 | 中文 |
| 公开日期 | 2013-09-25 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1831]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 冯权. 亲水化改性聚氨酯载体的生物膜形成过程特性及其在污水处理中的应用研究[D]. 中国科学院研究生院. 2012. |
入库方式： OAI收割
来源：过程工程研究所
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