Development Of On-line Detection System For Nitrite Nitrogen In Aquaculture

There are many factors affecting aquaculture,of which water quality is the most critical.The water quality parameters to be tested in aquaculture,mainly include nitrite nitrogen(NO2-N),dissolved oxygen,pH value,ammonia nitrogen and so on.Among them,the nitrite nitrogen content should be controlled within 0.1mg/L,otherwise it will cause fish poisoning,or even a large area of death.At present,the commonly used method for the detection of nitrite nitrogen is Artificial colorimetry,which is time-consuming and laborious.With the development of automation technology,wireless communication technology and microcomputer technology,it is significant for the development of aquaculture to develop a low cost and high reliability nitrite nitrogen on-line detection system.Based on the analysis of the detection methods of nitrite nitrogen,an on-line detection system for nitrite nitrogen was developed.The main contents are summarized as follows:(1)The influence of pH value,temperature,coloration time and wavelength on the absorbance of nitrite nitrogen was analyzed,and the corresponding treatment scheme was given.(2)In the process of nitrite nitrogen detection,if color reagent and water sample can't mix sufficiently,the best coloring time is uncertain,and a new method of mixing the medicine is proposed to improve the mixing uniformity of the color reagent,reduce detection error.(3)It is important for me to complete the field detection device of the sampling,dosing,testing as well as related hardware and software design.The hardware circuit mainly includes: STM32F103RBT6 minimum system,LED driving circuit,silicon photovoltaic cell signal conditioning circuit,wireless data transmission circuit and so on.The software program mainly includes: main program,water sample acquisition subroutine,dosing subroutine,data acquisition subroutine,wireless data transmission subroutine and so on.(4)The monitoring software of the host computer is designed to realize the real-time display,data storage,overrun alarm and so on.(5)After the completion of the entire experimental platform,I have done the relevant experiments to verify the usefulness andreliability of the detection system.The research results show that the developed on-line detection system of nitrite nitrogen can realize the on-line detection function of nitrite nitrogen and lower the detection error.Through the analysis and processing of influencing factors,the accuracy of on-line detection is improved to a certain extent.The design of the mixing mechanism and method can effectively improve the mixing uniformity.