Research And Application On Ammonia Nitrogen On-line Detection System Based On Ammonia Gas Sensitive Electrode

As the ammonia nitrogen pollution problem is still serious in the main water areas and riverways of China, a stable, accurate, dependable ammonia nitrogen on-line detector is required for the protection and harnessing of water environment. The existing ones almost have some deficiencies, for example the measuring ranges can not reach the water quality testing standard, and solution proportioning methods are not good enough, which reduces the accuracy. This article develops a ammonia nitrogen on-line detection system based on ammonia gas sensitive electrode.By thoroughly investigating and surveying vast literatures on ammonia nitrogen detection technology, ammonia gas sensitive electrode technology is chosen, as it can’t be affected by other factors like ions in the water and turbidity, its solution proportioning is not complicated to control and the waste water is pollution free. In order to increase the accuracy and enlarge the measuring ranges, the theory of standard work curve of ammonia gas sensitive electrode has been used; The solution proportioning method has been improved. The ammonia nitrogen on-line detection system includes a master control system and a water samples collecting subsystem. The system is based on the STM32microprocessor and S7-200PLC. The master control system is in charge of data analysis, operation and command. The water samples collecting subsystem is used to control PLC which solves problems like the interference caused by large current which produced by the on/off of water pimps and magnetic valves. Meanwhile, the system reserves lots of expansion interfaces, which is convenient for updating and optimizing. The software design of system is based on μC/OS-Ⅱ embedded real time operating system. System migration and mission planning had been achieved, which enhances the work efficiency of system and optimizes the system resources.The system was proved stable and reliable,it was able to achieve the desired design goals, we make the prospect for the future development and improvements of monitoring platform.