Construction Of Compost Maturity Evaluation System Based On Multi-index

At present,composting still plays an important role in the global waste management strategy.Compost products can be used as a soil conditioner to recover plenty of nutrients and organic matter,which is an environmentally and economically beneficial choice for human beings.However,in order to avoid the negative effects that unripe compost can cause during storage,marketing and use,it is important to evaluate its ripening degree.In recent years,relevant indexes and methods have been proposed for the evaluation of compost maturity at home and abroad.Most of the current evaluation indexes and methods for maturity have some problems,such as complicated process,high test requirements and long test time.Hence,there is an urgent need for a fast,convenient and on-site method or instrument to test the compost maturity.In this paper,the evaluation system of composting maturity based on multivariate index is studied deeply.Based on the principle of chromatographic distribution and ninhydrin coloration,the rapid detection method of composting maturity was explored.In the process of composting,each index of the ripening degree was tested and measured to analyze the trend of its change and the correlation between the indexes.Using attribute recognition theory,the multi-index composting maturity database was developed.STM32 microcontroller was used to develop a fast-measuring instrument for compost maturity.This study realized the rapid and effective evaluation of composting ripening degree,and achieved the purpose of simplifying the steps,shortening the testing time and reducing the testing cost.The main research contents are as follows:(1)Research on the rapid detection method of composting maturity.Based on the principle of chromatographic distribution and the principle of ninhydrin,two fast detection methods of chromatographic distance and chromatic aberration are put forward.The former evaluates the composting maturity according to the migration distance of organic fertilizer filtrate chromatographic peak.The latter is to judge the compost maturity according to the color difference of organic fertilizer filtrate.(2)Research on the change trend of each index in the process of composting.In the process of different C/N treatment,12 evaluation indexes such as temperature,water content,p H,electrical conductivity(EC),sugar content,etc.were analyzed,and cluster analysis was employed to determine the correlation among the indexes.It can be concluded that EC is positively correlated with total nitrogen(TN),total carbon(TC)is negatively correlated with T value(terminal C/initial C/N ratio),chromatographic distance is positively correlated with seed germination percentage(GI),and other indexes are not significantly correlated.(3)Development of composting maturity attribute identification database.The mathematical theory was used to establish the identification model of the maturity attribute,and the database was developed by VF.At the same time,four independent evaluation indexes of high temperature duration,p H,T and GI were selected to establish the identification and evaluation method of the maturity attribute,so as to realize the effective rating of the maturity.(4)Development of compost ripening detection instrument based on STM32.PH,EC and chromatographic distance were selected as required indexes,and color difference,sugar content and water content were selected as alternative indexes.Meanwhile,STM32 chip is selected,and C language is used for program design to develop maturity evaluation instrument based on STM32 which can help realize the rapid evaluation of the compost maturity,and realize the offline work.Also,it can be detected in the field,thus broadening the application scenarios.Finally,GI value and T value which are two commonly used methods of compost maturity evaluation in the industry,together with the attribute recognition model and the STM32-based composting maturity detection instrument were selected to verify and analyze the evaluation results of five groups of C/N treating compost maturity.The results show that the evaluation results of compost maturity of these two methods are highly reliable and have practical application value.