6毕业设计(论文)外文译文封面

毕业设计(论文)

外文文献译文

文献题名：葡萄糖作为单一有机基质强化生物除磷的SBR法

Enhanced Biological Phosphorus Removal in SBR Using

Glucose as a Single Organic Substrate

学院：环境科学与工程学院

专业：环境工程2005级

学生姓名：李凯

指导教师：胡开林

日期：2009年03月31日～06月15日

葡萄糖作为单一有机基质强化生物除磷的SBR法

蒋轶锋、李相昆、冯晓宇、王树涛、王宝贞、刘亚男、陈建孟

摘要：经过对序批式厌氧/好氧反应器（ SBR ）的调查研究发现，可以提供葡萄糖作为一个单一的有机基质来对生物除磷（ EBPR ）进行强化。研究结果表明，EBPR过程中，也可以成功地与葡萄糖发生以外的其他短链脂肪酸（ SCFAs ）。高磷释放和聚羟基血凝素（ PHA ）在厌氧阶段积累时被发现了至关重要的除磷在好氧阶段。在细胞内测量糖原，其储备显示，其中有较高的机会在厌氧条件下以取代能源作用的聚磷。此外，还利用糖原进行碳源植物血凝素的合成，以及正如早先的报道所称那样。然而，所积累的植物血凝素在这个系统主要是以聚羟基（ PHV ）为形式的，而并不是聚羟基丁酸酯，乳酸作为发酵产品还发现可以被大量的释放。应用基本知识，生物化学以及实验结果产生一个概念模型，即利用葡萄糖的代谢糖诱导强化EBPR 。

关键词：强化生物除磷（ EBPR ），序批式反应器（ SBR ），血糖， PHA 1、材料和方法

1.1 SBR 工艺操作

哈尔滨工学院的控制研究中心在水污染实验室安装了的一个具有规模的 EBPR 系统，并将接种物从中播种。将集中的有机组成和矿物成分进行的综合废水被用作试验的原水。为尽量减少基质降解，原料从稀释自来水之前的SBR工艺运行周期中开始准备。

SBR的工作容积为2升，并于操作填充和借鉴的基础上，以8小时周期组成的10分钟灌装或者将其撤消，周期为厌氧2小时，好氧4小时， 1小时和50分钟解决闲置阶段的序列。在厌氧条件下使用磁搅拌器，以及空气泵的使用是保证在有氧条件下才能进行的。1.6L的液体（包括剩余污泥）在最终解决阶段从反应堆中被取消。剩余活性污泥结束时的有氧阶段将泥龄控制在6天，不同的范围内可控制在1480至1920毫克/升。pH和温度在6.5 - 7.1和20 ℃这个范围内进行调整。

1.2 实验的机制

为了更好地调查详细机制的EBPR ，补充序批实验后，在SBR法的基础上进行了性能稳定的EBPR。剩余的污泥结束了一次用蒸馏水循环冲洗来从上一个周期消除残余化合物。立即加入营养物质和葡萄糖后随即开始实验。在这种方式的作用下，化学计量与碳源，磷和动力学除磷之间的关系可以更精确地进行研究。

1.3 取样和分析方法

混合液体样品或者反应堆，立即通过一个过滤器或0.45um匀浆进一步混合反应。超临界流体包括乳酸通过高效液相色谱法分析。同时PHA和糖原的污泥根据测定的方法在Joen和Park;苏丹黑色染色体和甲苯胺蓝色染色体进行了PHA和聚磷颗粒的可视化。正为前面所述，沙田奥林巴斯显微镜用于明显处和相位对比的观察。除非另有说明，在此研究的其他分析是根据相对标准的方法进行的。

2 结果与讨论

2.1 SBR法的性能

运行的SBR法已持续60天。如图1所示，磷释放和去除效率随操作时间的增加而逐渐增加。经过14-17天，磷的去除率达到95 ％? 99 ％，污水磷酸磷只有0.1-0.5毫克/升。葡萄糖在初期试验中，仍然持续到最后的厌氧阶段。但是，随着丁苯橡胶继续运作，葡萄糖清除率增加，并最终葡萄糖几乎可以完全所吸收并立即取得了EBPR的性能。这意味着，P0d制定了一项主动运输机制，承认并将葡萄糖从中期释放在细胞质膜一侧适应后的血糖。

结果发现，极少的 EBPR表现形式总是出现在导致减少磷的厌氧释放阶段。图2显示了厌氧释放磷和磷的去除效率之间基本关系的实验数据。厌氧释放磷计算之间的差异在于初步P04 - P水平和最大磷酸- P水平在厌氧阶段的差异。很明显，除磷效率高与以高厌氧磷释放以及和90 ％的去除率达到5毫克/升或其以上的厌氧P0d磷释放有

着密切的关系。因此，有人得出的参与聚磷降解的厌氧反应是对EBPR必要的和以及极好的例证。此外，在实现具有EBPR特性的SBR工艺的同时，更进一步发现在运行初期，即使在同一级别的葡萄糖原料中植物血凝素积累与最终的厌氧阶段具有一定的可比

性。

此外，储存的PHA和聚磷颗粒细胞， PAOs的染色方法如上所述。则污泥分别取自结束时的厌氧和好氧阶段。如图3所示，减少血凝素含量后好氧反应（一，二）意味着植物血凝素被用来作为能量来源产生聚磷存储磷酸盐的培养基，并随后存储聚磷颗粒消耗在以下厌氧阶段（三，四），在这一阶段采取了葡萄糖和补充植物的相应存

储。这是进一步的详细说明了第2.2节符合以前的报告。

2.2 EBPR在分批实验中的代谢机制

在稳定EBPR成立分批实验中，直接在SBR工艺中一次除去了葡萄糖的典型的实验结果显示在图4和图5 。从图4可以发现，磷水平明显提高后，除了葡萄糖，中后期厌氧阶段更逐渐高达15.3毫克磷酸磷/ L。然而，葡萄糖在最初的6分钟完全消失了，附有大量积累的糖源由163毫克C /升下降到121毫克C / L（图5 ）。在血糖降低的解决方案中，糖原在其余的部分厌氧时间内随时间的减少而逐渐下降，因为它参与合成PHA的过程中降低了功耗和碳源。至于植物血凝素模式，这是不同于糖原的并且承担不断增加64毫克C / L降至9毫克C / L的厌氧阶段。鉴定植物血凝试验表明，植物血凝素在细胞中积累组成PHV或者PHA，并且其血凝比率在最终的厌氧阶段约为82 ％。鉴于氧化还原理论，PHV在生产的厌氧阶段过程中采用氧化还原平

衡内的PAOs消耗额外电子从糖酵解糖原，并因此使PAOs达到代谢活动的目的。

基于上述结果，磷释放和吸收血凝形成有机计量关系。每毫克C吸收的葡萄糖。PAOS释放0.09毫克P04 - P.同时积累0.59毫克C的植物血凝素。换言之，PAOS的

葡萄糖美联储丁苯橡胶花费少得多的能源来自聚磷水解比醋酸美联储丁苯橡胶。隐含

的解释是，部分能源使用的这个系统可能是来自糖酵解。其比例累计血凝素为消费基板小于1 ，这表明，并不是所有的C转化为葡萄糖，假定PHA和失踪C因此将用来作为降低功耗，并要求合成能源植物血凝素。因此，PAOS的葡萄糖美联储少聚丁苯橡胶进行磷水解植物血凝素合成醋酸比当被用作衬底。

综上所述，在厌氧阶段清除葡萄糖与释放磷和合成的PHA并不相配合（图4 ）。否则，一个好的解决COD和磷释放关系的方法如图6所示。此外，在计算剩下的葡萄糖溶液中还有盈余C0D。由于观察pH值从7.2下降到初始值6.6，所以假设一些有机酸因而也许被释放葡萄糖所发酵。据分高效液相色谱法析，除了葡萄糖1actate证明存在于之后。但后来考虑在厌氧休息时间，并导致逐步减少多余的化学需氧量如图所示。中间产物乳酸，因为假设的Jeon and Park由PAOS被用来合成血凝素后。

2.3 厌氧条件下EBPR的生化模式

为了简化模型的建立，在厌氧条件下,假设所有的外部基板是用于合成的内部碳储量和没有发生生物量的增长。首先，PAOS迅速提取葡萄糖和储存这些形式的糖原。三磷酸腺苷的糖原贮积是由以下糖酵解糖原而形成的乳酸，而不是水解聚磷。这说明

了在厌氧阶段pH值在下降。可能的途径为糖酵解反应糖原，在电磁脉冲通路或教育途径。由于在最终的厌氧阶段乳酸减少，所以植物血凝素是终端产品并发生厌氧反应最终合成并储存在于细胞内。所需的三磷酸腺苷也提供了糖原酵解以及退化的聚磷与磷释放到其中。为了降低消耗额外的功率（ [ H ]）所产生的糖原酵解，丙酰CoA通过琥珀丙酸途径，采用并实现这一目标，因此，在PAOS进行氧化还原平衡。显然，丙酰辅酶A途径会导致积累的PHB代替PHV，并不是第2.2节所述。三磷酸腺苷作为附加功能的pH值，还需要将乳酸运输进入细胞。根据上述说明，无氧代谢的概念模型提出了为测试系统提供EBPR葡萄糖作为唯一碳源，如图7所示。

根据这一模式，加强水解聚- P是EBPR的关键因素。鉴于基本代谢的原则，如果他们能够获得来自代谢葡萄糖充足的能源，PAOS不会从其他来源寻求能源。在这种情况下，聚磷因此很少有机会参加厌氧反应，其能源供应，这将导致减少除磷能力的好氧反应。这一概念是类似刘军提出的建议，他报告说，控制污泥甲烷含量低的水平将是一个先决条件。反应时间延长厌氧，好氧反应时间减少和控制有限溶解氧水平好氧条件，因此这项研究中提出的优化业务战略取得了EBPR的成功。

3、结论

在实验室EBPR取得了规模化的厌氧/好氧SBR工艺，提供葡萄糖作为唯一碳源。

在有氧的EBPR阶段典型的厌氧反应的高磷释放和植物血凝素合成被成功的发现至关重要。除了厌氧阶段水解聚磷葡萄糖/糖原的形成乳酸是假定供应能源的葡萄糖摄取和植物血凝素积累。主要的PHV累计血凝意味着糖诱导PAOS的机制，以减少功率消耗额外载体内部葡萄糖氧化还原平衡。应用基本知识，生物化学实验结果，生物模型的概念，提出并解释了代谢途径的EBPR系统中利用葡萄糖作为单一基质的理论。

Enhanced Biological Phosphorus Removal in SBR Using Glucose as a Single Organic Substrate

JIANG Yifeng(蒋轶锋) ；LI Xiangkun(李相昆)；FENG Xiaoyu(冯晓宇)；WANG Shutao(王树涛)；WANG Baozhen(王宝贞)；LIU Yanan(刘亚男) ；CHEN Jianmeng(陈建孟)

Abstract：Enhanced biological phosphorus removal(EBPR) was investigated in an anaerobic／aerobic sequencing batch reactor(SBR)supplied with glucose as a single organic substrate．The results illustrated that EBPR process could also occur successfully with glucose other than short chain fatty

acids(SCFAs)．High phosphorus release and poly-hydroxyalkanoate (PHA) accumulation in the anaerobic phase was found vital for the removal of phosphorus during the aerobic phase． The measurement of intracellular reserves revealed that glycogen had a higher chance to replace the energy role of poly-P under anaerobic conditions. Moreover，glycogen was also utilized as the carbon source for PHA synthesis，as well as a red using power as reported earlier．The accumulated PHA in this system was mainly in the form of

poly-hydroxyvalerate (PHV) instead of poly-hydmxybuDrrate(

PHB)，and was inferred to be caused by the excess red using power contained in glucose．Lactate as a fermentation product was also found released into the bulk solution ．Applying fundamental biochemistry knowledge to

the experimental results．a conceptual biochemical model was developed to explain the metabolism of the glucose induced EBPR．

Keywords： enhanced biological phosphorus removal(EBPR)， sequencing batch reactor (SBR )． glucose ，glycogen．Poly-hydroxyalkanoate(PHA)

1、Materials and Methods

1.1 SBR operation

The inoculum was seeded from a lab-scale EBPR system installed in the Water Pollution Control Research Centre of Harbin Institute of Technology。The concentrated synthetic wastewater consisting of organic and mineral components was used as the test raw water．F0r minimizing substrate degradation，the feed was prepared from the frozen stock diluted in tap water immediately prior to the commencement of a SBR operation cycle。

The SBR had a 2 L working volume, and was operated on a fill-and-draw basis with a 8 h cycle composed of 10 min filling／withdrawing，2 h anaerobic，4 h aerobic，1 h settling and 50 min idle phases in sequence。Anaerobic conditions was achieved by a magnetic stirrer，and aerobic conditions by an air pump．1.6 L of liquid(including the wasted sludge)was withdrawn from the reactor at the end of settling phase。Sludge age was controlled at 6 days by discharging excess activated sludge at the end of the aerobic phase，and varied in the range of 1480—1920 mg/L．PH and temperature were adjusted at 6.5—7.l and 20℃，respectively.

1.2 Batch experiments for the EBPR mechanism

For better investigating the detailed mechanism of EBPR，supplementary batch experiments were conducted after stable EBPR performance was obtained in the SBR．The settled sludge from the end of a batch cycle was washed several times with distilled water to remove the residual chemicals from the previous cycle. Nutrients and glucose were immediately added at the start of the experiments。 In this manner，stoichiometric relations between carbon source and phosphorus and the kinetics of phosphorus removal could be more precisely studied．

1.3 Sampling and analytical methods

Mixed liquid samples from reactor were immediately either filtered through a 0.45um filter or homogenized for further determination．The SCF including lactate were analyzed by HPLC. Both the PHA and glycogen in sludge were measured according to the method in Joen and Park; Sudan Black staining and Toluidine Blue staining for visualization of PHA and Poly-P granules Were carried out．respectively．as described previously. and tin Olympus microscope was used for bright field and phase contrast observation. Unless otherwise stated, other analysis in this study was performed according to Standard Method.

2 Results and Discussion

2.1 Performance of the SBR

The operation of the SBR had lasted for 60 days. As shown in Fig．1， the phosphorus release and removal efficiency gradually increased with operating time. After about 14—17 days, phosphorus removal efficiency reached up to 95％～99％ with effluent PO4-P of only 0．1—0.5 mg/L．Glucose，in the early period of experiment，still remained until the end of anaerobic phase. But as the SBR operation continued， the glucose removal rate increased and eventually added glucose could be almost absorbed by PAOs instantly once EBPR performance Was achieved. This implies that PAOs had developed an active

transport mechanism to recognize and pick up glucose from medium and release it at cytoplasmic side of the membrane after their acclimation to glucose.

It was found that poor EBPR performance was always resulted form lower phosphorus release in the anaerobic phase.Fig.2 shows the relation between anaerobic released phosphorus and phosphorus removal efficiency based on the experimental data. The anaerobic release of phosphorus was calculated from the difference between the initial P04-P level and the maximum PO4-P level in the anaerobic phase．It is evident that high phosphorus removal efficiency corresponds closely to high anaerobic phosphorus release，and 90％ removal efficiency was reached at 5 mg/L or more of anaerobic P0d—P release．It was therefore drawn that the involvement of poly—P degradation in anaerobic reaction was requisite for an excellent EBPR. Moreover，after achievement of EBPR in the SBR，much more PHA was found accumulated at the end of anaerobic phase as compared to that in the early period of operation even with the same

level of glucose in the feed．

In addition，the stored PHA and Poly-P granules in PAOs cells were visualized by the staining method as described above．The sludge was taken from at the end of the anaerobic and aerobic phases，respectively．As shown in Fig，3，the reduction of PHA content after aerobic reaction(a，b)implies that PHA was used as the energy source to generate poly—P storage by taking up phosphate from the medium，and subsequently，the stored Poly—P granule was consumed in the following anaerobic phase(c，d)to take up glucose and replenish the PHA storage．It was further detailed in section 2．2 and consistent with the previous report．

2.2 Metabolic mechanism of EBPR in batch experiments

After stable EBPR was established, batch experiments were conducted directly in the SBR by one time addition of glucose at the start．The typical experimental results are shown in Fig．4 and Fig．5．It can be found from Fig．4，phosphorus level increased remarkably after the addition of glucose，but grew up more gently up to 15.3 mg PO4-P/L in the later stage of anaerobic phase．The glucose was completely exhausted in the initial 6 min，accompanied with a significant accumulation of glycogen from 121 mg C/L to 163 mg C/L (Fig．5)．After glucose diminished in the solution，the glycogen level gradually decreased in the rest of anaerobic time due to its participation in the

synthesis of PHA as reducing power and carbon source．As to the pattern for

PHA, it was different from glycogen and assumed a continuous increase from 9 mg C/L to 64 mg CL in the anaerobic phase．The PHA identification test revealed that the PHA accumulated in cells was composed of PHV instead of PHB，and the ratio of PHV／PHA was around 82％ at the end of anaerobic phase．This was consistent with Wang et a1 and was inferred that

major metabolic pathway for PHA synthesis in PAOs proceeded by propionyl—COA in addition to acetyl- COA ;and partial conversion of pyruvate to propionyl —COA via succinate-propionate pathway was thereby used for PHV formation. In view of oxidation-reduction theory, PHV production in anaerobic phase was employed to balance the redox inside of PAOs by consuming extra electron from glycolysis of glycogen, and it consequently enabled PAOs

engage well in metabolic activities with a specific purpose．Based on the above results，the stoichiometric relations of phosphorus release and PHA formation per absorbed organic were calculated．For every mg C of absorbed glucose．PAOs released 0.09 mg P04-P．with simultaneous accumulation of 0．59 mg C of PHA. It is worthy to point out that the ratio of mg p／mg C in the glucose—fed SBR was only 1／7 of that in the acetate —fed SBR (data not shown)． In other words， PAOs in the glucose-fed SBR spent much less energy derived from poly-P hydrolysis than in the acetate-fed SBR． The implied explanation is that part of the energy used in this system was probably obtained from the glycolysis of glycogen．The ratio of accumulated PHA to consumed substrate is less than 1, and it suggests that not all C in glucose was transformed into PHA and the missing C was therefore postulated to be utilized as reducing power and required energy for the PHA synthesis. Thus， PAOs in the glucose—fed SBR underwent less poly-P hydrolysis and PHA synthesis than when acetate was used as a substrate．This also gives explanation for the vulnerable EBPR performance in Carucci et a1．

As delineated above. The removal of glucose did not coincide with the release of phosphorus and the synthesis of PHA in the anaerobic

phase(Fig．4)．Otherwise, a good relation between COD in the solution and phosphorus release was observed，as shown in Fig．6．Moreover, there is a surplus of C0D over that calculated based on the remaining glucose in the solution．Some organic acids were thereby suspected released from the glucose fermentation

due to the observed pH drop from initial value of 7．2 to

6．6．By analysis with HPLC, 1actate was proved to exist in medium after the addition of glucose． But it was subsequently taken up in the rest anaerobic time， and which resulted a gradual diminish of surplus COD shown in Fig．6． The intermediate product of lactate， as postulated by Jeon and Park was used to synthesize PHA by the PAOs afterwards．

2．3 Biochemical models for EBPR under anaerobic conditions To simplify the establishment of the model， it is assumed that all the external substrate is utilized for the synthesis of internal carbon reserves and no biomass growth takes place under anaerobic conditions． At first． PAOs rapidly took up glucose and stored them in the form of glycogen． The requirement of ATP for the glycogen storage was supplied by the following glycolysis of glycogen with the formation of lactate，rather than the hydrolysis of poly—P．This explains the drop of pH at the be ginning of the anaerobic phase．There are two possible pathways for the glycolysis reaction of glycogen：the Embden-Meyerhof—Parnas(EMP) pathway or the Entner —Douderoff(ED)pathway．Due to the diminishing of lactate at the end of the anaerobic phase，PHA being the terminal product of the anaerobic reaction was finally synthesized and stored in the cells． The required ATP was also provided by the glycogen glycolysis as well as the degradation of poly-P with phosphate released into the medium． In order to consume the extra reducing power([H])generated from glycogen glycolysis， propionyl—CoA via succinate —propionate pathway was employed to achieve such a goal and consequently redox in PAOs was balanced．Obviously， propionyl—CoA pathway would lead to an accumulation of PHV instead of PHB, As described in Section 2.2．Additional ATP as a function of pH was also required for the transport of lactic acid into cells．Based on the above description，a conceptual anaerobic metabolic mod el was proposed for the test EBPR system supplied with glucose as a sole

carbon source，as shown in Fig．7．

According to this model，enhanced hydrolysis of poly-P is the key factor for EBPR． In view of fundamental metabolic principle， PAOs would not seek energy from other sources if they could derive adequate energy from metabolizing glucose alone． In this situation， poly-P therefore has little chance to participate in anaerobic reaction to supply its energy， and it would result in a reduction of phosphorus removal ability in aerobic reaction． This concept is similar with that proposed by Liu J，in which he reported that the control of sludge CH content to low level would be a prerequisite for achieving excel lent EBPR . Extending anaerobic reaction time，decreasing aerobic reaction time and controlling limited DO level in aerobic condition were thus proposed in this research as the optimal operational strategies for a successful EBPR achievement.

3、Conclusion

The EBPR was achieved in a lab-scale anaerobic／aerobic SBR supplied with glucose as the single carbon source． Typical anaerobic reaction of high phosphorus release and PHA synthesis was found critical for the success

of EBPR in aerobic phase．In addition to hydrolysis of poly-P．glycolysis of glucose／glycogen with the formation of lactate was postulated to supply energy for glucose uptake and PHA accumulation in anaerobic phase．The predominant of PHV in accumulated PHA means that the glucose-induced PAOs had the mechanism to consume extra reducing power contained in glucose for balancing the internal redox．Applying fundamental biochemistry knowledge to the experimental results，a conceptual biological model was proposed to explain the metabolic pathway of an EBPR system using glucose as the single substrate.