| Anaerobic fermentation technology is a good technical way to solve the treatment of livestock and poultry manure.At present,the common application is wet anaerobic fermentation technology(concentration 6~10%).Due to its low controlled fermentation concentration,there are disadvantages such as low treatment efficiency,high energy consumption,difficult utilization and consumption of biogas slurry.However,for the current widespread treatment of livestock and poultry fresh manure,if can based on the original state of fresh manure,do not do concentration adjustment,directly into the anaerobic pool,adopt half-dry method anaerobic fermentation(13~25%),can significantly improve the efficiency of livestock and poultry manure treatment,save water and energy consumption,can overcome the shortcomings,make biogas engineering industrialization operation has good economic,environmental and social benefits.According to the literature,fresh pig manure in the semi-dry method of anaerobic fermentation engineering practice key technical parameters research,this paper with fresh pig manure as raw material for the anaerobic fermentation mode,inoculation rate,mixing parameters,continuous operation test,etc,the reasonable operation parameters for fresh pig manure semi-dry method of anaerobic fermentation treatment engineering application to provide technical support.The main conclusions are as follows:(1)Under medium temperature(35℃),the total mass of fixed fermentation liquid remains unchanged,and the inoculation rate is optimized for anaerobic fermentation of fresh pig manure(concentration 8%)and anaerobic fermentation of semi-dry(concentration 17%)respectively,and then compare the effect of wet and semi-dry anaerobic fermentation under their appropriate inoculation rate.The results show that the suitable inoculation rate of wet anaerobic fermentation of fresh pig manure is 40%,50%,65.8% higher,while the VS degradation rate is similar,indicating higher fermentation efficiency and biogas yield and basically the same VS degradation rate than wet anaerobic fermentation.Therefore,semi-dry anaerobic fermentation is more suitable for the treatment of fresh pig manure,and its suitable inoculation rate is 50%.(2)Under medium temperature(35℃)and inoculation rate of 50%,Optimization test of dry anaerobic fermentation and mixing parameters of fresh pig manure,Through the stirring observation test,Determine that the appropriate mixing time is 4 min;With the fixed mixing intervals and the mixing duration being constant,The stirring speed of 30 r/min significantly promoted the gas production effect of semi-dry anaerobic fermentation of fresh pig manure,The cumulative gas production is 14.7% and 20% higher than that at 15 r/min and 45 r/min, respectively;At a constant mixing speed and mixing duration,To get the stirring interval of 2h,obviously promoted the effect of anaerobic fermentation of fresh pig manure,The cumulative gas production at 1 h and 3 h was increased by 20.6% and 25.3%,respectively.Therefore,the suitable mixing parameters for semi-dry anaerobic fermentation of fresh pig manure are: mixing speed of 30 r/min,mixing interval of 2 h,and mixing time of 4 min.(3)Fixed temperature,mixing parameters,fermentation liquid concentration and other conditions,HRT=25,20,20,15,10 d,the influence of fresh pig manure continuous anaerobic fermentation,the longer HRT in a certain range,the better the degradation effect,shorten HRT,daily gas will increase,but the degradation effect is reduced,HRT will cause fermentation system acidification,form a pathological pool,so HRT in continuous anaerobic fermentation of fresh pig manure at 20 d.(4)Using the Box-Behnken center combination design principle of Design Expert 8.0.6,Under other conditions such as fermentation temperature,material and liquid concentration,The average daily gas volume and VS degradation rate of continuous anaerobic fermentation of fresh pig manure were analyzed by three factors: HRT,mixing interval and mixing speed,The following conclusions are obtained: the importance of three factors on the average daily gas volume and VS degradation rate is: HRT> mixing interval> mixing speed;Through the model optimization and verification,The optimal parameter combination is: HRT is 19 d,mixing interval is 2 h,mixing speed is 30 r / min,The actual average daily gas output is 23.48 L,The degradation rate of VS was 56.47%,The average volume gas yield rate was 2.35 L /(L d).(5)Through the use of optimized fresh pig manure semi-dry continuous anaerobic fermentation key technical parameters,get fresh pig manure semi-dry continuous anaerobic fermentation average volume gas yield of 2.53 m3/(m m d),VS degradation rate can reach53.4%,and fresh pig manure semi-dry anaerobic fermentation has the advantages of water saving,energy efficiency,environmental protection,emission reduction,suitable for widely application. |
PDF Full Text Request