Research On Online Detection Method And System Of Ammonia Nitrogen In Aquaculture

Fining breed has gradually replaced the extensive one as the predominant mode,which has the following characteristics: intensive culture density and high economic efficiency and so on.However,intensive culture density often leads to the conversion of nutrients nitrogen into toxic ammonia nitrogen.When the ammonia nitrogen concentration exceeds 2.00mg/L,aquatic organisms will appear toxic symptoms,or even they will die in huge numbers.Therefore,it is necessary to periodically detect ammonia nitrogen concentration in aquaculture water.However,the detection technology of ammonia nitrogen is relatively backward in our country,whose reason lies in the lack of cheap high-precision low-concentration ammonia nitrogen on-line detection equipment,which is dedicated to aquaculture.Because the concentration of ammonia nitrogen in aquaculture water is low,which requires higher detection accuracy,but the high-precision laboratory ammonia nitrogen detection equipment is difficult to be generalized due to higher prices and complex operation.Therefore,most of breeding plants are still mainly using portable ammonia nitrogen analyzer or ammonia nitrogen test paper to detect the concentration of ammonia nitrogen,which have the following problems: serious detection error,low detection limit,reagent waste and so on.In order to solve the above problems,this paper presented an online detection method and system of aquaculture ammonia nitrogen.The main research contents are as follows:(1)The influencing factors of ammonia nitrogen detection accuracy were analyzed theoretical and experimental,which include reagent preparation method,reagent and ammonia nitrogen chemical reaction and absorbance detection,and according to the analysis results the corresponding optimization measures were put forward to reduce detection error,decrease the detection limit,improve the detection resolution of low concentration.(2)The environment of online detection changes greatly in one year,in order to avoid the impact of environmental changes on the field detection accuracy,LSSVM processing algorithms was used.The temperature,absorbance peak and peak time were taken as input and ammonia nitrogenconcentration was taken as output.LSSVM processing algorithms achieved online detection accuracy compensation,without the need to add additional functional components.(3)The online detection system of aquaculture ammonia nitrogen was developed,which consists of field detection device and monitoring terminal,and the hardware and software design was completed.Hardware circuit mainly has the minimum microprocessor system,photoelectric detection,temperature detection and GPRS communication circuit,the software has the control program,AD sampling program,display program and wireless communication program and so on.In addition,custom data packet,Error control and breakpoint continuingly technologies were taken to improve communication reliability.(4)The accuracy,stability,repeatability and contrast experiment of the detection system were carried out respectively,in order to verify the performance of the on-line detection system of aquaculture ammonia nitrogen.The experimental results showed that the LSSVM method used to detect the low concentration of ammonia nitrogen improved the detection accuracy,and achieved the function of precision compensation.Online detection system of aquaculture ammonia nitrogen has the high accuracy,stability and repeatability.The average of standard deviation and relative standard deviation is 0.0107mg/L and 1.28% respectively.The online detection system realizes the high precision detection of low concentration ammonia nitrogen in aquaculture water,which overcomes some shortcomings,such as large detection error,high detection limit and serious waste of reagents.