Abstract. One of the most effective technologies for manure utilization is its processing in a drum biofermenter. This technology allows obtaining different products with specified end-use properties in the same installation depending on the operation mode. The created mathematical model is designed to determine the modes, under which the bio-fermentation processes in the processed material are most intensive and feature the least nutrients loss. The model input factors were aeration time (from 3 to 7 min·h -1 per one ton), aeration rate (from 5.5 to 9.5 m·s -1 under the 76 mm pipeline diameter) and drum rotation frequency (three rotations every 6 to 12 hours). The target function was the product temperature reached in the bio-fermenter during manure processing. Experiments with three replications were carried out in the laboratory of bioconversion of organic waste in IEEP on a patented drum bio-fermenter. The starting material was separated solid fraction of cattle manure. Based on the calculation results the error of experiment reproducibility was 1.85. The developed mathematical model allows establishing the effect of individual input factors and their combinations on the target function. After the model analysis the pair interaction of time and aeration rate factors were found to have the most sizable contribution to the temperature variation in the bio-fermenter. The rational modes of drum biofermenter operation were identified to obtain different end products with desired properties and to further optimize the conversion process.Key words: manure, bio-fermentation, mathematical model, drum bio-fermenter, ecology.
IntoductionLivestock production is directly associated with manure formation. Every year its utilisation is becoming an increasingly significant problem. In the North-West of the Russian Federation composting is the basic manure utilisation technique. It allows to obtain the high quality organic fertilizer, which forms the basis for extension of the humus layer of soil and subsequent increase of crop yields [1].Intensification of livestock industry toughens the requirements for the manure utilization technology forcing to introduce new, faster and more efficient processing practices. One such technology is accelerated manure composting in a drum bio-fermenter.The basic condition for successful composting is to provide the microorganisms, involved in aerobic fermentation of manure, with the most comfortable living conditions: sufficient amount of oxygen and optimum temperature [2]. Specific design features of a drum bio-fermenter allow to vary its operation modes in order to receive different products with desired final properties: organic fertilizers or bedding for farm animals [3; 4].The aim of the work was to create a mathematical model of a drum bio-fermenter and to determine the rational modes of its operation to produce bedding and fertilizers.
Materials and methodsThe study was conducted in 2015-2016 in the IEEP Organic Waste Bioconversion Laboratory on a patented drum-type bio-fermenter (Fi...
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