滴灌系统灌水器生物堵塞特性、评估及机理研究
发布时间：2019-03-17 18:17
【摘要】：滴灌系统灌水器堵塞问题直接影响灌水均匀度、系统寿命和运行效益,已成为制约滴灌技术应用和推广的关键问题之一。尤其是目前水环境污染与水资源紧缺并重,滴灌水源复杂的水质特征使得灌水器堵塞风险更大、机理更复杂,堵塞类型也通常表现为生物堵塞。目前灌水器堵塞问题仍然是困扰滴灌研究领域的国际性难题,其关键在于对堵塞诱发机理不明。本文选择水质特征最复杂、最典型的再生水作为滴灌水源,持续五年通过污水处理厂滴灌灌水器堵塞现场试验及室内滴灌灌水器堵塞模拟试验和精细测试,系统研究了灌水器生物堵塞发生特征,提出了灌水器抗堵塞能力快速评估方法；探索了生物堵塞物质形成和生长过程及其对灌水器堵塞发生的影响途径与诱发机理,为滴灌灌水器新产品抗堵塞设计及滴灌系统安全高效运行提供理论支撑。主要研究内容与结论包括：通过灌水器流量长期、高频测试,确定了两年运行周期内其堵塞参数表现为“波动平衡-启动线性变化-翌年加速线性变化”变化特征,定量描述了灌水器生物堵塞发生过程,摸清了再生水水质、灌水器类型和流道结构参数及灌水频率对灌水器生物堵塞过程的影响。基于灌水器生物堵塞发生特性,从全新角度提出了灌水器抗堵塞能力评估指数(Ia),Ia的关键因素包括流道长、宽深比和近壁面平均剪切力,借助量纲分析理论建立了通过灌水器额定流量和流道结构参数估算Ia的方法,验证了Ia用于快速评估灌水器自身抗堵塞能力的准确性和可行性。借助现代环境微生物学精细方法测试了灌水器生物堵塞物质特征组分,确定了堵塞物质特征组分与灌水器堵塞程度间的“S型曲线”相关关系(R20.92**,p0.01),灌水器堵塞程度随着堵塞物质组分增长表现出“敏感-微敏感-极度敏感”的趋势,摸清了堵塞物质特征组分形成和生长过程对灌水器堵塞发生过程的影响途径。综合考虑营养物质输送和水力剪切力分布的影响,系统研究了灌水器类型和结构参数、滴灌毛管不同位置、肥料类型等因素对堵塞物质形成和生长过程的影响效应,提出了各影响因素下的合理控制阈值。以Logistic生长模型为原型,综合考虑灌水器结构类型、流道几何参数以及毛管位置等关键影响因素,建立的堵塞物质生长动力学模型可以很好地描述堵塞物质组分“生长适应期-快速增长期-动态稳定期”的生长过程(R20.85**,p0.01)。量化了堵塞物质中发挥重要作用的微生物群落的演变特征,确定了灌水器堵塞过程中的关键菌株,深入揭示了灌水器生物堵塞诱发机理,提出了合理的灌水器堵塞控制策略。
[Abstract]:The problem of irrigation clogging in drip irrigation system directly affects irrigation uniformity, system life and operation benefit, which has become one of the key problems restricting the application and popularization of drip irrigation technology. Especially at present, water environment pollution and water resources shortage are equally important. The complicated water quality characteristics of drip irrigation make the clogging risk of emitters more serious and the mechanism more complicated, and the blocking types are usually biological clogging. At present, the clogging problem of emitters is still an international problem in the field of drip irrigation, and the key is that the mechanism of clogging is unknown. In this paper, the most complex and typical reclaimed water is selected as the source of drip irrigation, which has passed the field test of drip irrigation emitters clogging in sewage treatment plant, simulation test and fine test of indoor drip irrigation emitters for five years. The characteristics of biological clogging in emitters were systematically studied, and the rapid evaluation method of emitters' anti-clogging ability was put forward. The formation and growth process of biological clogging material and its influence on emitters blockage and its inducing mechanism were explored, which provided theoretical support for the design of new products of drip irrigation emitters against clogging and the safe and efficient operation of drip irrigation system. The main research contents and conclusions are as follows: through the long-term and high-frequency testing of the emitters flow rate, the blocking parameters of the emitters during the two-year operation cycle are determined to be "fluctuation equilibrium-start linear change-accelerated linear change of the following year". The process of biological clogging of emitters was described quantitatively. The effects of the quality of reclaimed water, the types of emitters, the structural parameters of the channel and the frequency of emitters on the biological clogging of emitters were investigated. Based on the characteristics of biological clogging of emitters, the key factors including length of channel, ratio of width to depth and mean shear force near wall are proposed to evaluate the anti-clogging ability of emitters from a brand-new point of view (Ia), Ia). The method of estimating Ia by rated flow rate and channel structure parameters of emitters was established with the aid of dimensional analysis theory, and the accuracy and feasibility of using Ia to quickly evaluate the anti-clogging ability of emitters were verified. The characteristic components of clogging substances in emitters were tested by means of modern environmental microbiology, and the "S-shaped curve" relationship between the characteristic components of clogging substances and the clogging degree of emitters was determined (R20.92, p0.01). The clogging degree of emitters showed a trend of "sensitive-extremely sensitive" with the increase of blocking material composition. The way of the formation and growth of characteristic components of blocking substances on the clogging process of emitters was found out. Considering the effects of nutrient transport and hydraulic shear force distribution, the effects of the types and structural parameters of emitters, different positions of drip irrigation capillary tubes and fertilizer types on the formation and growth of clogging materials were systematically studied. The reasonable control threshold under each influence factor is put forward. Taking the Logistic growth model as the prototype, the key influencing factors such as the structure type of the emitters, the geometric parameters of the runner and the position of the capillary were considered comprehensively. The kinetic model can be used to describe the growth process of the composition of clogged matter (R _ (20.85), p _ (0.01), which is suitable for growth, rapid growth and dynamic stabilization (R _ (20.85), p _ (0.01). The evolution characteristics of microbial communities which play an important role in the blockage of emitters were quantified, the key strains in the process of emitters blocking were determined, the inducing mechanism of biological clogging in emitters was deeply revealed, and a reasonable control strategy for clogging of emitters was put forward.
【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S275.6
，
本文编号：2442567
[Abstract]:The problem of irrigation clogging in drip irrigation system directly affects irrigation uniformity, system life and operation benefit, which has become one of the key problems restricting the application and popularization of drip irrigation technology. Especially at present, water environment pollution and water resources shortage are equally important. The complicated water quality characteristics of drip irrigation make the clogging risk of emitters more serious and the mechanism more complicated, and the blocking types are usually biological clogging. At present, the clogging problem of emitters is still an international problem in the field of drip irrigation, and the key is that the mechanism of clogging is unknown. In this paper, the most complex and typical reclaimed water is selected as the source of drip irrigation, which has passed the field test of drip irrigation emitters clogging in sewage treatment plant, simulation test and fine test of indoor drip irrigation emitters for five years. The characteristics of biological clogging in emitters were systematically studied, and the rapid evaluation method of emitters' anti-clogging ability was put forward. The formation and growth process of biological clogging material and its influence on emitters blockage and its inducing mechanism were explored, which provided theoretical support for the design of new products of drip irrigation emitters against clogging and the safe and efficient operation of drip irrigation system. The main research contents and conclusions are as follows: through the long-term and high-frequency testing of the emitters flow rate, the blocking parameters of the emitters during the two-year operation cycle are determined to be "fluctuation equilibrium-start linear change-accelerated linear change of the following year". The process of biological clogging of emitters was described quantitatively. The effects of the quality of reclaimed water, the types of emitters, the structural parameters of the channel and the frequency of emitters on the biological clogging of emitters were investigated. Based on the characteristics of biological clogging of emitters, the key factors including length of channel, ratio of width to depth and mean shear force near wall are proposed to evaluate the anti-clogging ability of emitters from a brand-new point of view (Ia), Ia). The method of estimating Ia by rated flow rate and channel structure parameters of emitters was established with the aid of dimensional analysis theory, and the accuracy and feasibility of using Ia to quickly evaluate the anti-clogging ability of emitters were verified. The characteristic components of clogging substances in emitters were tested by means of modern environmental microbiology, and the "S-shaped curve" relationship between the characteristic components of clogging substances and the clogging degree of emitters was determined (R20.92, p0.01). The clogging degree of emitters showed a trend of "sensitive-extremely sensitive" with the increase of blocking material composition. The way of the formation and growth of characteristic components of blocking substances on the clogging process of emitters was found out. Considering the effects of nutrient transport and hydraulic shear force distribution, the effects of the types and structural parameters of emitters, different positions of drip irrigation capillary tubes and fertilizer types on the formation and growth of clogging materials were systematically studied. The reasonable control threshold under each influence factor is put forward. Taking the Logistic growth model as the prototype, the key influencing factors such as the structure type of the emitters, the geometric parameters of the runner and the position of the capillary were considered comprehensively. The kinetic model can be used to describe the growth process of the composition of clogged matter (R _ (20.85), p _ (0.01), which is suitable for growth, rapid growth and dynamic stabilization (R _ (20.85), p _ (0.01). The evolution characteristics of microbial communities which play an important role in the blockage of emitters were quantified, the key strains in the process of emitters blocking were determined, the inducing mechanism of biological clogging in emitters was deeply revealed, and a reasonable control strategy for clogging of emitters was put forward.
【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S275.6
，
本文编号：2442567
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