Study On Thermophilic Aerobic Fermentation Technology Of Dead Pigs

Thermophilic aerobic fermentation is a kind of harmless treatment technology with high degree of reduction,high efficiency and environmental friendliness,which can relieve the treatment pressure of dead pigs in China to a great extent.In this paper,we design a thermophilic aerobic fermentation tank,on this basis,The experiments of Thermophilic aerobic fermentation of dead pigs were carried out with corn stalk,rape stalk,wood chip,rice bran and wheat bran as auxiliary materials,The material form,true protein content,p H value and moisture content of the finished product were used as evaluation indexes,perform excipient screening,And the process optimization test is carried out for the selected auxiliary materials.To make the process meet the requirements of harmless treatment,achieve the goal of maximum reduction.The results as follow:(1)A vertical thermophilic aerobic fermentation tank was designed for this experiment.Fermentation tank is mainly composed of tank,stirring device,ventilation pipe,heating system and control system.The tank body is a sandwich structure with an inner volume of 10 L.Heat the material by means of water bath heating,achieve specified temperature requirements.The hot air flows into the fermenter from the ventilation tube.Air is pumped into the fermenter through a vent,and the flow is regulated by a flowmeter.(2)Corn straw,rapeseed straw,wood chips,rice bran and wheat bran were used as auxiliary materials to carry out Thermophilic aerobic fermentation test of dead pigs.The effects of 5 excipients on the treatment of dead pigs were compared,and the excipients which were most suitable for thermophilic aerobic fermentation of dead pigs were selected.The results showed that rice bran group and corn stalk group had better comprehensive performance,Among the 5 excipients,the decrease of true protein content and p H value of corn straw group were 11.14% and 1.04 respectively,which was slightly weaker than that of rice bran,but better than that of the other three excipients,the finished form score of 10 points,The proportions of 4-mesh sieve and 18-mesh sieve were 100% and 94.6%,However,compared with the rice bran group,the odor dissipation of the corn stalk group was the earliest in the fermentation process,and the water content decreased at an appropriate rate,reaching its lowest point at 36 h.Comparatively speaking,the comprehensive performance of corn straw as auxiliary material is better.(3)Corn stalk was used as auxiliary material to optimize the fermentation temperature,ventilation rate and auxiliary material ratio during Thermophilic aerobic fermentation of dead pigs.In each experiment,with the increase of fermentation time,the true protein content showed a trend of rapid decrease at first,then a slight rise,and finally a small continuous fluctuation.With the increase of fermentation time,p H and water content decreased rapidly at first,and then basically remained unchanged after dropping to the lowest point.The only inactivation condition of fecal coliform is that the temperature is greater than or equal to 60℃.In the temperature test,when the temperature was 60℃,the screening of diseased pig carcasses was the best.The passing rate of 4-mesh sieve was 100%,and that of 18-mesh sieve was 92.6%,and the rancid smell dissipated the fastest.The decrease of true protein content and p H was the biggest: 9.55% and 1.33.The moisture content reaches its lowest point at 36 h.In the ventilation test,when the ventilation rate was 8L/(L·min),the physical morphology score of fermented finished products was the highest,the pass rate of 4-mesh sieve was 100%,the pass rate of 18-mesh sieve was 93.6%,The putrid smell dissipates most quickly,the true protein content and p H decreased the most,were 8.54% and 1.06 respectively.The moisture content reaches its lowest point at 36 h.In the auxiliary material ratio test,When the weight ratio of excipients and pigs is 1:5.5,the morphology score of fermented finished products was the highest,the ratio of passing 4-mesh sieve was 100%,the ratio of passing 18-mesh sieve reached 93.4%,and the rancid smell dissipated the fastest.The decrease of true protein content and p H was the biggest: 8.60% and 0.76,respectively.The moisture content reaches its lowest point at 36 h.Therefore,the optimal process conditions: fermentation temperature 60℃,ventilation rate 8L/(L·min),and auxiliary material ratio 1:5.5.