亚硝化—厌氧氨氧化处理猪场废水研究

猪场废水COD浓度高、氨氮浓度高、悬浮物浓度高，已成为农村面源污染的主要来源，并严重威胁到农村饮用水安全。猪场废水氨氮浓度高、处理难度大，如何采用经济高效的方法，去除氨氮使其达到排放标准，一直是猪场废水处理中面临的重要难题。 厌氧氨氧化是近年受到国内外水处理研究者广泛关注的新型生物脱氮技术，具有不需要外加有机碳源、节省供氧量、降低能耗等优点。虽然国内外研究者对厌氧氨氧化过程的脱氮机理、厌氧氨氧化菌的生理生化特性等进行了多方面的研究，但已有的报道大多以模拟废水为研究对象，以猪场废水为研究对象的报道，在国内外文献中极少有报导。 本论文以猪场废水为主要研究对象，考察了猪场废水的亚硝化过程、厌氧氨氧化的启动过程，并对亚硝化和厌氧氨氧化联合用于猪场废水脱氮进行了探索。 1．论文首先研究了猪场废水的亚硝化过程，考察了废水水质和主要运行条件对亚硝化过程的影响。实验表明：（1）亚硝化阶段反应时间为8到10h时，出水中氨氮和亚硝酸盐浓度比可达到1：1～1：1.23，满足厌氧氨氧化反应对二者比例的要求；达到前述要求时，氨氮去除率达到58.3～65.6 %，亚硝化率在整个过程均保持在97 %以上，COD去除率在59.2～68.6 %；（2）曝气量（溶解氧）对亚硝化过程影响显著，随着曝气量增大，达到厌氧氨氧化要求的氨氮与亚硝酸盐氮浓度比例所需水力停留时间τ越短，pH出现明显下降的时间越短；（3）τ对应的pH在7.8～8.1之间，无需进行pH调节即可满足厌氧氨氧化反应对pH的要求；（4）氨氮和COD降解过程遵循一级反应动力学，氨氮和COD降解的速率常数分别为0.0656～0.0724 1/h和0.0491～0.0664 1/h。 2．在进行亚硝化过程研究的同时，以模拟废水为试验对象，进行厌氧氨氧化启动研究。以反硝化污泥和养殖厂储水池厌氧底泥的混合污泥作为接种污泥，历时大约100天，培育出具有厌氧氨氧化活性的污泥，氨氮和亚硝酸盐氮最高进水浓度分别为223.8 mg/L和171.4 mg/L，去除率最高分别达48%和41.5%，此时二者消耗比例为1.33：1。 3．在猪场废水的亚硝化研究完成和厌氧氨氧化过程初步启动成功后，在模拟废水中逐步加入猪场废水的亚硝化处理出水，逐步实现亚硝化和厌氧氨氧化的组合。亚硝化出水添加到厌氧反应器后，厌氧氨氧化反应仍可继续进行，且去除效率逐步提高。研究发现添加的亚硝化出水中携带的亚硝化细菌在厌氧氨氧化菌膜外层生长并累积，增加了厌氧氨氧化反应基质的传质阻力，妨碍了厌氧氨氧化效率的提高。 4．亚硝化－厌氧氨氧化实际工程应用探索中，生物接触氧化池可在有效去除废水中的有机物的同时实现亚硝化，出水中氨氮和亚硝酸盐比例平均为1.10，可满足后续厌氧氨氧化的要求；在适宜的进水浓度和温度下，ABR池出现了厌氧氨氧化启动的迹象；研究同时发现，水质的波动和气温的变化是工程中影响厌氧氨氧化菌活性的重要因素。 论文的主要创新点在于：（1）以猪场废水为研究对象，以实现厌氧氨氧化为目标，对亚硝化过程进行了比较详细的考察，获得了亚硝化出水满足厌氧氨氧化要求的工艺条件，通过对其COD和氨氮降解过程的考察，得出亚硝化阶段COD降解和氨氮去除的动力学模型；（2）对亚硝化－厌氧氨氧化处理猪场废水进行了探索，确立了影响其污染物去除率稳定的重要因素。 论文的上述研究成果，为厌氧氨氧化技术的实用性研究提供理论依据。 Piggery wastewater, which is characterized by high concentration of COD、ammonium and suspend substance, has become a most important source of non-point source pollution and also severely threats drinking water security in rural area. How to discharge piggery wastewater with the ammonium concentration meeting standard by economical and effective method? This is the most urgent problem in piggery wastewater treatment. As a new biological nitrogen removal technology, Anammox process has been paid more and more attention by researchers all over the world. Anammox has advantages of no need of organic carbon addition, low oxygen consumption and energy consumption. Plenty of investigations have been carried out to the mechanism, physiological and biochemical characteristic of bacteria about Anammox. Most of researches focused on synthetic wastewater, there is rare report about its application in piggery wastewater. In this paper，experimental studies were performed to investigate Sharon process in treatment of piggery wastewater，the start up process of Annammox using synthetic wastewater were studied, the feasibility of applying Sharon-Anammox process in the nitrogen removal of piggery wastewater was evaluated. 1. Sharon process of piggery wastewater was firstly investigated to analyze the effects of water quality and main running parameters, which meet the NH4+-N to NO2--N ratio requirement of successive Anammox. Results showed: (1)During Sharon Process，after 8～10 hours’ reaction the NH4+-N to NO2--N ratio in effluent reached 1:1.0～1:1.23, when the removal percentage of NH4+-N was 58.3～65.6 %, a semi-nitration rate of above 97 % was achieved during the process; meanwhile 59.2～68.6 % of the COD was also removed. (2)The aeration rate（oxygen） had obvious effect on the hydraulic retention time(τ) which met the NH4+-N to NO2--N ratio requirement of Anammox. As aeration rate increased, the hydraulic retention time(τ) was shortened. (3) The pH corresponding to τ was between 7.8 and 8.1, thus it needed no artificial adjustment. (4) The reduction of ammonia and COD followed the first-order reaction kinetics. The velocity constants of ammonia and COD were 0.0656～0.0724 1/h and 0.0491～0.0664 1/h, respectively. 2. The startup of Anammox process using the artificial wastewater was performed simultaneously with Sharon. The aim was to investigate the running parameters of Anammox and make foundation for the combination stage. By using the mixture of denitrifying sludge and anaerobic sludge in tank of the breeding factory, sludge of Anammox activity was cultivated in UASB after 100 days. The removal percentage of NH4+-N and NO2-N were up to 48% and 41.5%, respectively, when the NH4+-N and NO2-N influent concentration were 223.8 mg/L and 171.4 mg/L, respectively, the NH4+-N and NO2-N removal rate was 1.33:1. 3. After investigation of Sharon and startup of Anammox, effluent of Sharon process was added into the synthetic wastewater to combine Sharon and Anammox step by step. It took some time after the addition of Sharon effluent that Anammox reaction continued and the removal rate kept increasing. It indicated that nitrifying bacteria were carried by the Sharon effluent cumulated in the outer layer of Anammox. This enhanced transfer resistance of Anammox reaction and the increasing removal rate was restrained. 4. In the bio-contact oxidation pond of practical project, Sharon process were carried out successfully and organic compounds were removed effectively. An average NO2-N/ NH4+-N rate of 1:1.0 was achieved in the effluent, which met the requirement of successive Anammox. Under condition of suitable influent concentration and temperature, there was evidence that Anammox could start up in ABR. The variety of wastewater and temperature had great affects on Anammox activity in practical engineering. Innovation of this paper: (1) The Sharon process for treating piggery wastewater was discussed in details. Technological parameters that met requirement of Anammox were obtained. The dynamic models of COD and ammonium removal in the process were educed. (2) Sharon-Ananmmox for treatment of piggery wastewater was investigated, and the primary influencing factors was studied. This paper could be a theoretical consult for research of Anammox utility.

Pressure drops of single and two-phase flows through T-type microchannel mixers

In this paper, preliminary experimental results are presented on pressure drop characteristics of single and two-phase flows through two T-type rectangular microchannel mixers with hydraulic diameters of 528 and 333 mum, respectively. It is shown that both N-2 and water single-phase laminar flows in microchannels, with consideration of experimental uncertainties, are consistent with classic theory, if additional effects, such as entrance effects that will interfere with the interpretation of experimental results, are eliminated by carefully designing the experiments. The obtained pressure drop data of N-2-water two-phase flow in micromixers are analyzed and compared with existing flow pattern-independent models. It is found that the Lockhart-Martinelli method generally underpredicts the frictional pressure drop. Thereafter, a modified correlation of C value in the Chisholm's equation based on linear regression of experimental data is proposed to provide a better prediction of the two-phase frictional pressure drop. Also among the homogeneous flow models investigated, the viscosity correlation of McAdams indicates the best performance in correlating the frictional pressure drop data (mean deviations within +/-20% for two micromixers both). Finally it is suggested that systematic studies are still required to accurately predict two-phase frictional performance in microchannels. (C) 2004 Elsevier B.V. All rights reserved.

The effects of sediment transport on grain-size distributions

Changes in statistics (mean, sorting, and skewness) describing grain-size distributions have long been used to speculate on the direction of sediment transport. We present a simple model whereby the distributions of sediment in transport are related to their source by a sediment transfer function which defines the relative probability that a grain within each particular class interval will be eroded and transported. A variety of empirically derived transfer functions exhibit negatively skewed distributions (on a phi scale). Thus, when a sediment is being eroded, the probability of any grain going into transport increases with diminishing grain size throughout more than half of its size range. This causes the sediment in transport to be finer and more negatively skewed than its source, whereas the remaining sediment (a lag) must become relatively coarser and more positively skewed. Flume experiments show that the distributions of transfer functions change from having a highly negative skewness to being nearly symmetrical (although still negatively skewed) as the energy of the transporting process increases. We call the two extremes low-energy and high-energy transfer functions , respectively. In an expanded sediment-transport model, successive deposits in the direction of transport are related by a combination of two transfer functions. If energy is decreasing and the transfer functions have low-energy distributions, successive deposits will become finer and more negatively skewed. If, however, energy is decreasing, but the initial transfer function has a high-energy distribution, successive deposits will become coarser and more positively skewed. The variance of the distributions of lags, sediment in transport, and successive deposits in the down-current direction must eventually decrease (i.e., the sediments will become better sorted). We demonstrate that it is possible for variance first to increase, but suggest that, in reality, an increasing variance in the direction of transport will seldom be observed, particularly when grain-size distributions are described in phi units. This model describing changes in sediment distributions was tested in a variety of environments where the transport direction was known. The results indicate that the model has real-world validity and can provide a method to predict the directions of sediment transport

土壤持水特征测定中质量含水量、吸力和容重三者间定量关系I.填装土壤

在试验过程中,通常采用一个土样进行连续试验来测定土壤的持水特征。此时,土样的有机质、黏粒矿物类型和阳离子交换量等性质基本保持不变,而土壤的容重在水力学和机械压力共同作用下会发生很大的变化。因此,我们认为实测的土壤持水特征不再是土壤吸力和含水量相对应的一条曲线,而是由土壤质量含水量、吸力和容重三变量共同确定的一个曲面。本文在Brooks-Corey土壤水分特征曲线模型的基础上,提出了两种描述土壤质量含水量、吸力和容重三变量关系的曲面模型,分析了模型的优缺点和适用条件,并采用离心机石蜡控容重法实测了四种质地填装土壤的三变量特征曲面。研究结果表明:土壤持水特征是由土壤质量含水量、吸力和容重三变量共同确定的一个曲面这一假设是合理的;类似于Brooks-Corey模型的两种幂函数经验曲面模型能够合理地描述填装土壤的实测数据,决定系数均大于0.94;模型Ⅰ的拟合效果略好于模型Ⅱ,但模型Ⅱ包含两个物理意义明确的参数,具有一定的优势。这一研究将为校正容重变化对土壤水力学参数的影响提供新的途径。

陕北水蚀风蚀交错区两种生物结皮对土壤饱和导水率的影响

该文以陕北水蚀风蚀交错区普遍发育的地表和地上两种生物结皮为研究对象,分别以3种非生物结皮(无结皮、物理结皮、去除生物结皮)为对照,使用盘式入渗仪测定其饱和导水率。结果表明:与无结皮土壤相比,两种类型生物结皮均可极显著降低土壤饱和导水率;与去除生物结皮土壤相比,两种类型生物结皮对土壤饱和导水率的降低均不显著;与有物理结皮发育的土壤相比,地表生物结皮对土壤饱和导水率的降低不显著,而地上生物结皮对土壤饱和导水率的降低显著。一方面,两种生物结皮对土壤饱和导水率均有明显降低作用,预示生物结皮在降雨活动中可能会增加径流、降低入渗,阻碍研究区水分亏缺条件下的植被恢复和生态与环境建设。另一方面,与不同的对照相比,生物结皮对土壤饱和导水率的影响截然不同,该结论可在一定程度上解释当前有关生物结皮影响土壤水分入渗方面所存在的分歧。

黄土塬区不同地形部位和土地利用方式对土壤物理性质的影响

在黄土塬区王东沟流域采集不同地形部位和不同土地利用方式下土壤样品,测定其颗粒组成、容重和饱和导水率,借助变异系数、非参数检验等方法研究了不同地形部位和不同利用方式对土壤物理性质的影响.结果表明:土壤物理性质在水平方向和沿垂直剖面都存在变异,但在同一地形部位或同一土地利用类型内,容重和颗粒组成基本相似.水平方向,饱和导水率属强变异,粘粒和砂粒含量属中等变异,粉粒含量和容重属弱变异;沿垂直剖面,土壤的粒级分布具有连续性,但0~25cm的土壤容重和饱和导水率与下层土壤差异显著.沿坡面从上向下,土壤趋向粘重,但饱和导水率增大;其中上坡位和中坡位的土壤性质相似,在相关研究中可以进行合并.草地与其他利用方式下的土壤性质差异显著,主要受地形部位的影响;耕地和果园的土壤性质相似且不同于其他利用类型,表明人为干扰对土壤物理性质有重要影响.

迷宫流道转角对灌水器抗堵塞性能的影响

以转角分别为45.0°、60.0°、67.5°和75.0°的齿形流道灌水器为研究对象,应用CFD流场速度数值分析、PIV颗粒运动轨迹线和速度观测对比以及浑水抗堵塞测试相结合的方法,研究了转角对灌水器水力性能和抗堵塞能力的影响。结果表明转角与流量系数及流态指数均呈负相关关系,而灌水器的抗堵塞能力随着转角的增加呈下降趋势。综合分析转角对水力性能和抗堵塞性能的影响,提出迷宫流道结构灌水器的合理转角为60.0°。

黑龙江省安达市草地碱化后土壤物理性状变化

调查了安达市盐碱地生物资源环境研究中心试验区羊草Leymus chinensis地土壤物理性状,包括土壤硬度、含水量、饱和导水率、粒径分布、剖面特征和土壤温度等。阐明土地碱化对土壤物理性质的影响,为安达市以及松嫩平原生态环境的修复和土地资源的永续利用提供科学依据。同时,讨论了地下水化学成分和土壤冻融变化对碱化的可能影响,认为在没有植被覆盖的条件下,冻融变化会加剧土壤的碱化程度。

推求土壤水分运动参数的简单入渗法──Ⅱ.实验验证

预报土壤中水分流动需要的土壤导水特性可通过观测水平土柱的入渗过程来确定，这一观测过程的分析是基于对Richards方程求积分解。土壤水分特征曲线中的参数由观测的水平立柱的特征湿润长度和吸力来确定，非饱和土壤导水率由已确定的特征曲线中的参数和测定的饱和导水率导出。供试土壤有三种，它们的质地从砂壤到粘壤。由这种方法所确定的这三种土壤的水分特征曲线与实测的特征曲线符合良好，所确定的砂壤的非他和导水率与实测值的比较令人满意。利用数值法和积分法分别计算了土壤含水量剖面，计算结果吻合良好，说明了这种方法的合理性。

推求土壤水分运动参数的简单入渗法 I.理论分析

预报非饱和土壤水分运动必须首先获得土壤水分运动参数。土壤水分运动参数包括土壤水分特征曲线和导水率。本文使用积分方法求解了一维水平非饱和土壤水分运动问题，根据其解建立了推求非饱和土壤水分运动参数的简单入渗法，用以推求ｖａｎ Ｇｅｎｕｃｈｔｅｎ特征曲线模型中的参数α和ｎ。α和ｎ是根据湿润区的特征长度、吸渗率和土壤的饱和导水率（ｋｓ）来确定的，而非饱和导水率可由α、ｎ和Ｋｓ确定。这一新的简单入渗法是基于Ｒｉｃｈａｒｄｓ方程和土壤导水特征的闭合型方程。简单入渗法提供了利用瞬态水流方法来确定土壤水分特征曲线而替代通常的平衡法。简单入渗法是一个全新的、简捷的确定土壤导水特性的方法。

根径向水流导度测定技术的改进

根系径向流的水力学性质主要是根的径向水流导度 ,它取决于根径向水流通道的状况。利用改进的现有原位测定根系径向水流导度的蒸腾计技术 ,设计了一个简便的 4室吸水测定装置 ,可一次性获得根木质部水势和根径向水流导度 ,缩短测定时间 10min ,确保测定精度。然后用改进的装置测定了生长在不同水分条件下冬小麦(TriticumaestivumL .)根系的径向水流导度 ,结果显示根系的平均径向水流导度为 4.6 3× 10 -7m·s-1·MPa-1,并随连体植株水分胁迫程度的增大而降低。

侵蚀细沟水力学特性及细沟侵蚀与形态特征的试验研究

本文进行了一系列水槽试验 ,研究不同长度的侵蚀细沟在坡度及入流量影响下的浅水水流水力学特性、侵蚀量及细沟的形态特征 .所采用的土壤材料为砂壤土 ,试验使用四种入流流量 ,四种坡度 ,四种细沟长度 .记录水流速度、沟宽及径流中的泥沙含量 ,并用多元回归方法分析了它们与坡度、入流量或它们的交互项之间的关系 .提出了一种数学模型来描述试验中沟宽的周期性形态变化 .提出了通过试验得出的不同细沟长度的产沙量来确定水流输沙能力的方法 ,并得出出测定输沙能力的采样长度为 2～ 4m ,通过对细沟形态变化分析进一步说明了所确定的水流输沙能力采样长度的正确性

不同坡度草地含沙水流水力学特性及其拦沙机理

参照黄土区侵蚀降雨和坡面片蚀产沙特征,采用恒流泥沙输送装置模拟坡面上方来水来沙,探讨不同坡度草地含沙水流的水力学特性及其对上方来沙的拦蓄机理。结果表明,草地坡面的水流弗劳德数随坡度增大而增加,而阻力系数与坡度呈反势。按明渠水流的一般标准,不同坡度草地水流均为层状缓流。草地坡面拦沙效应随坡度增大而减小,且径流前期的减沙作用较后期更为显著。不同坡度草地坡面的出流泥沙平均直径和大颗粒(>10μm)泥沙含量均显著小于上方来沙,这说明草地的拦沙效应主要体现在对大粒径泥沙的拦蓄上。

干旱下植物气孔运动的调控

概述了植物气孔对大气干旱和土壤干旱的反应 ,认为植物气孔对大气干旱的反应并不是一种反馈机制 ;并就干旱条件下植物气孔运动的水力学和化学信号调控机制进行了简要论述 ,认为虽然化学信号调控干旱下气孔运动更为广泛 ,但 ABA不是唯一的化学信号 ,水分关系影响了信号的产生、运转和气孔对信号的敏感性 ,干旱条件下水力学和化学信号共同调控着植物的气孔运动

压力室测定根系导水率方法探讨

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