基于光谱法的快速水质多参数传感器的技术研究

发布时间：2018-03-02 06:20

本文关键词： 水质监测光谱法干扰因素多参数　出处：《北方工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：水是生命之源,是大自然赋予人类的宝贵财富。由于人类活动对自然资源的不合理利用和对生态环境的破坏,水资源的可持续利用面临重大的挑战。我国的人均水资源占有量低,水资源地区分布不均,水污染逐年加重。这不仅加剧了水资源短缺的矛盾,而且严重威胁人们饮水安全和生命健康。预防和治理水污染不再是简单的环境问题,而是影响国家长远发展规划的战略性问题。实时高效地掌握水体污染情况,是制订实际可用的治理方案和采取有效的水域保护措施的重要前提。因此提高水质在线监测技术,健全水资源监测系统,对防治水污染具有重要意义。目前水质在线监测方式主要为站房式和浮标式,前者发展较早,在我国应用普遍,其检测原理主要为试剂法,能实现多种水质参数的实时检测,但存在系统复杂,投资建设成本高,维护量大,耗能且易造成二次污染等问题;浮标式水质在线监测主要采用光谱法和电极法,全自动监测,系统运行耗电少,建设和维护成本低,投放便捷,采用原位检测,无二次污染。浮漂式水质在线监测虽然起步晚,但由于其显著的优势发展迅速。本课题针对基于光谱法的浮标式水质在线监测的传感器进行了技术研究和设计,选定光谱分析法应用于水质检测,利用物质吸光特性的差异,依据朗伯-比尔定律得出水质参数的浓度和吸光度的关系,进行某种水质参数的定量分析。此方法不需要任何化学预处理,操作简单,测量周期短,尤其是不会对环境构成二次污染,非常适用于水质在线快速检测。由于水中很多离子、有机物的吸收波长包含在紫外-可见光范围内,所以本课题选择紫外-可见吸收光谱法进行应用于水质检测仪器的技术和实验研究。并初步探讨了浊度、温度、其它离子以及环境因素等对光谱检测的影响,研究了传感器信号调理电路设计理论等。针对光谱应用于水质检测功能,设计了单光源和双光源机械结构,提出了占空比调整光源功率从而改变传感器量程的新方法,该方法改变了传统的通过机械结构改变光程来调整量程的方法。搭建实验平台,围绕COD、总磷、总氮和总有机碳四种水质参数,分别进行了信号测试实验、建标实验、样机性能实验和实际水样对比等系列实验。对实验数据进行分析,结果为COD检测值的准确度在-7.4%～8.1%;总磷检测值的准确度在-5.6%～9.4%;总氮检测值的准确度在-9.0%～9.0%;总有机碳检测值的准确度在-4.3%～5.4%;四种水质参数检测值的准确度均低于10%,基本满足检测技术要求,符合国家环境保护标准规定。最后,总结本课题的研究工作,并对不足之处进行了分析和展望。
[Abstract]:Water is the source of life and the precious wealth endowed by nature. Because of the irrational use of natural resources and the destruction of ecological environment by human activities, The sustainable utilization of water resources is facing great challenges. The per capita water resources in China are low, the distribution of water resources is uneven, and the water pollution is increasing year by year. This not only exacerbates the contradiction of water resources shortage, Prevention and control of water pollution is no longer a simple environmental problem, but a strategic problem affecting the country's long-term development plans. It is an important prerequisite for the development of practical available control schemes and effective water protection measures. Therefore, the improvement of water quality on-line monitoring technology and the improvement of water resources monitoring system, It is of great significance to prevent and cure water pollution. At present, the main on-line monitoring methods of water quality are station house type and buoy type. The former is developed earlier and is widely used in our country. The detection principle is mainly reagent method, which can realize the real-time detection of various water quality parameters. However, there are some problems such as complex system, high cost of investment and construction, large amount of maintenance, energy consumption and easy to cause secondary pollution. Construction and maintenance costs are low, easy to put in, in situ detection, no secondary pollution. Floating water quality online monitoring, although the start is late, However, because of its remarkable advantages, the technology and design of the sensor for on-line monitoring of water quality based on spectral buoy are studied and designed. The spectral analysis method is selected to be applied to water quality detection, and the difference of absorptive properties of substance is used. According to Lambert-Beer 's law, the relationship between the concentration and absorbance of water quality parameters is obtained, and the quantitative analysis of certain water quality parameters is carried out. This method does not require any chemical pretreatment, and is simple to operate, and has a short measuring period. In particular, it does not cause secondary pollution to the environment, so it is very suitable for on-line rapid detection of water quality. Because there are many ions in the water, the absorption wavelengths of organic matter are contained in the range of ultraviolet and visible light. Therefore, this subject chooses the UV-Vis absorption spectrum method to carry on the technical and the experimental research which applies to the water quality detection instrument, and preliminarily discusses the influence of turbidity, temperature, other ions and environmental factors on the spectral detection. This paper studies the design theory of sensor signal conditioning circuit, aiming at the application of spectrum in water quality detection, designs the mechanical structure of single light source and double light source, and puts forward a new method to adjust the power of light source to change the sensor range. This method changed the traditional method of adjusting the measuring range by changing the optical path through mechanical structure. The experiment platform was built, and the signal test experiment and the standard experiment were carried out around the four water quality parameters of COD, total phosphorus, total nitrogen and total organic carbon. A series of experiments, such as performance experiment of prototype and comparison of actual water sample, are carried out. The experimental data are analyzed, The results were as follows: the accuracy of COD was -7.4 and 8.1; the accuracy of total phosphorus was -5.6and 9.4; the accuracy of total nitrogen was -9.0 and 9.0; the accuracy of total organic carbon was -4.3and 5.4; the accuracy of the four water quality parameters was lower than 100.It basically met the technical requirements. Finally, the research work of this paper is summarized, and the deficiency is analyzed and prospected.
【学位授予单位】：北方工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212

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