环境科学专业英语翻译

环境科学专业英语翻译

专业：环境科学

班级：0224121

学号：022412111

姓名：魏亚南

3、 Results and discussion

3、结果与讨论

3.1 Flow velocity distribution in oxidation ditch。

Change of flow velocity has a certain impact onnitrogen removal process of the oxidation ditch, with its plug-flow effect and flow velocity as the variables to control total nitrogen removal efficiency [11]. Flow velocity could not only affect the sludge deposition, but also affect the hydraulic cycle time of the oxidation ditch，the proportion of the residence time of aerobic and anoxic environment, dissolved oxygen, organic matter，and the distribution of sludge concentration directly. In addition, flow velocity was also a direct reflection of the extent of disturbance in the trench, playing an important role in the shape and size of sludge floc directly, which was the key factor of the occurrence of SND process in the

oxidation ditch。

3.1：氧化沟中的流速分布(SND：同步硝化反硝化)

流速的变化对氧化沟的脱氮过程有一定的影响。在控制总氮的去除效率过程中，氧化沟中的活塞流效率和流速是变量。流速不仅直接的影响污泥沉积，也直接影响氧化沟的水力循环时间，好氧和缺氧环境下停留时间的比例，溶解氧，有机物和污泥浓度分布，另外，流速也是氧化沟干扰程度的直接反映，在形成的污泥絮体的形状和大小上扮演重要的角色。污泥絮体在硝化和反硝化过程中是关键因素。

As can be seen from Fig. 3, flow velocity of the oxidation ditch was affected by the aeration and the changes of spatial location significantly, with the average velocity (0.140 m/s) in the trench of operating Condition 2 (opening four aeration wheels) being higher than the mean velocity (0.124 m/s) in Condition 1 (with three aeration wheels in operation). The velocity variations in the horizontal and vertical directions were also obvious,with the average velocity at the bottom, middle, upper part being 0.172, 0.122 and 0.127 m/s, which were significantly higher than the values (0.150, 0.106 and0.115 m/s) under Condition 1. In the two kinds of operating conditions, the flow velocity in the first corner and inside of the cross section 11 was low and there showed the evidence of sludge deposition. Overall, the flow velocity in most of the regions in the two operating conditions of the oxidation ditch was in the range of 0.1−0.2 m/s, with the flow velocity in most of the bottom area generally meeting the requirements of no-deposition flow velocity (0.15 m/s[12]). The power density (18.87 W/m3) in operating Condition 1 was smaller than that in operating Condition2 (24.38 W/m3) with less energy

consumption。

从图3中可以看出，氧化沟中的流速明显受曝气和空间位置变化的影响。在操作条件2下(开放四个充气轮)的沟槽中，平均速度高于在条件1(有三个运转的充气轮)的主要速度。在水平和垂直方向上的速度变化也是很明显的，在底部，中间，上部的平均速度是0.172，0.122，和0.172m/s，这些速度明显高于条件1下的标准（0.150,0.106，和0.115m/s）。在这种操作条件下，第一个拐角处和横截面11里的流速很低，这些显示了污泥沉积的证据。总的来说，氧化沟在这两种操作条件下的大多数的区域，流速在0.1-0.2m/s范围内，这种流速在大多数底部区域通常满足不沉积的流速要求，操作条件1下的功率密度比有少量能量消耗的操作条件2下的要小。

The lower flow velocity in the oxidation ditch wasmore conducive to nitrogen removal by SND [11]. There was a higher flow velocity region under the operating Condition 2, which was not only a waste of energy, but also led to the uniform distribution of the concentration of organic matter and dissolved oxygen in trench. And this made the alternating cycle time of aerobic and anoxic shorter, which was not good for the occurrence of SND process. Therefore, we should minimize the number of the opening aeration wheels under the premise of meeting the aeration demand and reduction of the sludge deposition, in order to promote the occurrence of SND process in the oxidation ditch。

通过SND，氧化沟中的低流速更有利于脱氮。在操作条件2下是一个高流速区，这种条件仅仅是能量的浪费，然而这种高流速导致沟中的有机物和溶解氧的浓度均匀分布，而且，高流速缩短了好氧和缺氧的交替周期时间，这不利于SND工艺的发生。因此，为了促进SND工艺的发生，我们应该在满足曝气需求和减少污泥沉积的前提下减少充气轮的数量。

3.2 Distribution of mixed liquor suspended solids(MLSS) in oxidation ditch

The size of activated sludge floc is an important factor which affects the SND process. Generally, the size of activated sludge floc is 20−2 000 μm [13]. When the size of activated sludge floc is 50−110 μm, highly efficient SND process can be obtained, while the floc size is mostly in the range of 60−80 μm and upwards [14]. In the same condition, the higher the sludge concentrations and the smaller the perturbation of the sludge, the more conducive to the formation of larger activated floc is, which is helpful for the SND process。

3.2：氧化沟的MLSS

活性污泥的大小是影响SND工艺的重要因素，通常来说，高效的SND工艺中可以得到大小为50-110um的活性污泥絮体，然而，这种絮体的尺寸大多是在60-80um内，或是更大。在相同条件下，提高污泥浓度和干扰较小的污泥，更有利于形成较大的活性污泥。这种活性污泥对SND工艺是有帮助的。

From Fig. 4, it was shown that when four aeration wheels were in operation ， variations of MLSS in length, width and depth were all relatively small and the degree of mixture was high in the entire trench, which indicated that the disturbance was relatively large, and the proportion to form a large size sludge flocs should be reduced. When opening three aeration wheels，the variations of MLSS both along the flow path and in the vertical direction were larger, such as 1−4 cross section, and the MLSS difference between the neighboring two vertical layers was greater than 1 g/L. Degree of sludge mixture in ditch became worse, but

the disturbance was smaller and more conducive to the formation of large particle flocs, which might promote the occurrence of SND process。

从图4中，可以看出当四个曝气轮在运转，MLSS在长度，宽度，深度的变动都相对较小，整个沟中的混合程度是很高的，这表明这种扰动相对比较大，形成相对比较大的污泥絮体的比例应该减少。当打开三个充气轮，在沿流程和垂直方向上的变动是较大的，如1-4截面，而且，在相邻两垂直层的MLSS的差异大于1g/L，在沟中污泥的混合程度变得更糟，但是这种扰动非常小，更有利于大颗粒絮体的形成，这可能会促进SND工艺的发生。

Considering different influent loadings, by increasing the concentration of sludge and minimizing the number of opening aeration wheels, disturbance of the trench could be reduced, which was more conducive to the process of SND occurrence. However, the increase of sludge concentration would also cause sludge deposition or aggravate the problem of deposition. In the practical operation, it was required to consider the various factors comprehensively and determine the appropriate concentration of sludge。

考虑到不同的进水负荷，通过提高污泥浓度和减少打开充气轮的数量，可以减少槽的扰动，这更有利于SND工艺的发生，然而，污泥浓度的增加会导致污泥沉积或加重沉积问题，在实际操作中，需要考虑各种综合的因素和确定适当浓度的污泥。

3.3 Distribution of dissolved oxygen (DO) in oxidation itch

Dissolved oxygen was the most important parameter to control the SND process occurrence in the oxidation ditch, which could directly affect the changes

of aerobic-anoxic zone and the proportion of the spatial distribution. Controlling a relatively low concentration of dissolved oxygen was more conducive to the formation of aerobic and anoxic environment in the body of floc [15−16], thus creating the condition for the occurrence of SND。

3.3：氧化沟中的溶解氧

溶解氧是在氧化沟中控制SND工艺发生的重要因素，这会直接影响好痒-缺氧区的变化和空间分布的比例。控制一个相对低浓度的溶解氧，有助于在絮体上形成好养和缺氧的环境，于是形成了SND发生的条件。

It can be seen from Fig. 5 that when the mixture was realized through the aeration wheel, the dissolved oxygen concentration increased. When the flow went far away from the aeration wheel downstream, the dissolved oxygen concentration decreased, but aeration wheel has very small impact on the dissolved oxygen concentration upstream. Studies have shown that, SND process occurred only when c(DO)<0.8 mg/L [4, 17]. With the four aeration wheels being in operation, the entirely dissolved oxygen concentration in the trench was generally greater than 2.5 mg/L, the aerobic state was almost in the best condition, and SND condition was destroyed. With three aeration wheels being in operation, the dissolved oxygen concentration in the cross-sections in trench of the oxidation ditch was roughly in the range of 0.5−1.5 mg/L, which indicated uneven distribution along the flow direction and the formation of a large area of anoxic-aerobic alternating zone, creating an ideal condition for the occurrence of SND process。

从图5中可以看出，当这种混合通过曝气盘实现，溶解氧的浓度增加。当水流远离曝气盘下游，溶解氧浓度减少，然而，充气轮对溶解氧的浓度影响很小。有研究表明，只有当溶解氧浓度小于0.8mg/L时，SND工艺才会发生。当有四个充气轮在运行中，沟内全部的溶解氧浓度大于2.5mg/L，好氧状态几乎在最佳条件下，而且SND条件被破坏。当有三个充气轮在运行中，氧化沟中的槽的横截面上，溶解氧浓度大致范围是0.5-1.5mg/L，这表明沿水流方向的不均匀分布，缺氧-好养交替区大面积的形成，对SND工艺的发生创造了一个理想的条件。

3.4 Distribution of soluble components in oxidationditch

Based on the traditional nitrogen removal theory，it is considered that dissolved oxygen condition for nitrification and denitrification processes is contradictory. The higher the concentration of dissolved oxygen within the reactor is, the more conducive to nitrification process.However, under low dissolved oxygen condition, the growth rate of nitrifying bacteria is low. In this condition, the lower the dissolved oxygen concentration, the more conducive to the denitrification process. Therefore, in the simultaneous nitrification and denitrification process, the supply of the dissolved oxygen should be optimized。

3.4:氧化沟中水活性组分的分布

基于传统的脱氮理论,溶解氧条件对硝化过程被认为是矛盾的。在反应器中，溶解氧的浓度越高，越有利于硝化过程，然而在低浓度条件下，硝化细菌的溶解率很低，在此条件下，溶解氧的浓度越低，越有利于反硝化过程。因此在同步硝化和反硝化过程中，溶解氧的供应应被优化。

As can be seen from Fig. 6(a), under the operation Condition 1, along with the advancing of nitrifying process, the NH4+ concentration reduced gradually. To the end of the oxidation ditch system (sections 8−13), the dropping trend slowed down. This indicated that nitrification was almost completed without being inhibited. As can be seen from Fig. 6(b), under the operation Condition 1,along the flow direction, TN concentration decreased. In some low DO regions, such as sections 1−4, sections 6−7, and the lower part of the outer ditch, denitrifying bacteria consumed organic matter in water as the carbon source, taking nitrate and nitrite as electron acceptor, and then the nitrate nitrogen was reduced to the gaseous nitrogen to complete the denitrification process. To the end of the oxidation ditch system， the dropping trend slowed down. This indicated that denitrification was almost completed。

从图6（a）中可以看出，在操作条件下，随着硝化的推进过程，NH4+的浓度逐渐减少。在氧化沟系统的末端，这个下降趋势减缓，这表明硝化过程在没有被抑制的情况下基本完成。从图6(b)中可以看出，在操作条件1下沿水流方向，TN浓度下降，在一些低溶解氧的区域，如1-4节，6-7节和外沟底部，反硝化细菌消耗水中的有机物作为碳源，以硝酸盐和亚硝酸盐作为电子受体，然后硝态氮被还原为气态氮，反硝化过程完成。到氧化沟的末端，这个下降趋势减缓，这表明反硝化作用基本完成。

As can be seen from Figs. 6(c) and 6(d), under the operation Condition 2, the TN concentration reduced appreciably in the front of the oxidation ditch under the influence of dilution of circulation water。With the flow of water, TN and NO x- concentrations were essentially unchanged, indicating that there was no denitrification basically in the oxidation ditch system. The results proved that high

DO concentration was destructive to SND。

从这些图形中可以看出，在操作条件2，在循环水稀释的影响下，在氧化沟前，TN浓度明显减少。伴随着水的流动，TN和NoX-的浓度基本不变。这表明在氧化沟系统中基本上没有反硝化作用。结果证明高浓度的溶解氧破坏BND。