Research On On-line Monitoring And Analysis Method Of Trace Total Phosphorus In Situ Water Quality Based On Micro-control Technology

Trace total phosphorus refers to the results of the determination that all forms of phosphorus in water are digested into orthophosphate.It is one of the important indicators to measure the degree of eutrophication in water.At the same time,national statistics of surface water pollution indicators show that total phosphorus exceeds the standard seriously,which is of great practical significance for the determination of total phosphorus in surface water.According to t:he requirement of determination that total phosphorus exist in surface water and municipal wastewater,an on-line monitoring system of trace total phosphorus is established by micro-control technology based on flow injection method and spectrophotometry,and the determination of trace total phosphorus in water is completed.The measurement range of total phosphorus is 1.5 ?g· mL-1.Covering the standard limit of total phosphorus in the surface five classes water and the first class standard of municipal wastewater treatment plant.Firstly,the design of the experimental platform has been completed.By defining the target and analyzing the principle of the experimental platform,the plan of designing the experimental platform is determined.According to the plan,the functional modules are divided,and then the functional modules are integrated to build an experimental platform.The feasibility of subject is verified and the preliminary data acquisition of the subject is completed.Secondly,the prototype design has been completed.Through the requirement analysis of the prototype task,the plan of prototype design is determined.An on-line monitoring system for trace total phosphorus is established base on micro-control technology with the combination of flow injection and spectrophotometry,then the prototype is built and the total phosphorus is determined.The embedded system is designed reasonably to accomplish the specified tasks accurately and efficiently,and then the peripherals of the system are monitored,controlled and managed,mainly including the design of hardware layer,middle layer,system layer and application layer.Thirdly,the mechanical structure design of the prototype has been completed.the mechanical structure of the system is designed based on the requirement analysis by using the knowledge of mechanical design and mechanical principle,which mainly includes the design of shape dimension and the spatial layout about each module.The shape dimension design ensures that the size and shape of the equipment meet the requirements.The reasonable design of the space layout of each module can effectively solve the routing problems and the space utilization problems.Finally,the system integration and experiment have been completed.Computer network technology and integrated wiring technology are used to integrate separate devices,functions and information into a unified and coordinated system.System debugging is mainly divided into PCB hardware debugging,software program debugging and whole machine function debugging.The experimental results show that the correction coefficient of the working curve is 0.99759.The minimum detection limit is 0.01?g mL-1 and the relative standard deviation of repeatability is 4.12%.The recovery of standard addition is between 98.4583%and 102.1167%.The detection period is 27.5 minutes.Waste liquid discharge capacity is 30.2 mL.The system runs steadily and can accurately and efficiently analyze total phosphorus in water,providing technical support for environmental protection and sewage discharge,especially for laboratory,station and portable on-line water quality monitoring.