基于碳氮损失和恶臭排放的病死猪辅热好氧发酵工艺参数优化

Optimizing parameters for thermophilic aerobic fermentation of sick and dead pigs based on loss of carbon and nitrogen and emission of odor

为确定病死猪辅热好氧发酵的最佳工艺参数,以病死猪为发酵原料,木屑为辅料,选取辅料配比、发酵温度和通风速率为试验因素,以碳氮损失和总臭气强度为试验指标,开展病死猪辅热好氧发酵正交试验,分析尾气中的有机恶臭物质组分并测定其排放质量浓度,同时测定尾气中氨气和二氧化碳质量浓度;采用极差和贡献率分析方法分析辅料配比、发酵温度和通风速率3因素对碳氮损失和恶臭排放的影响。结果显示:以木屑为辅料的病死猪辅热好氧发酵尾气中能准确定性和定量检测的共有18种恶臭物质:芳香烃类12种、硫醇硫醚类3种、烷烃类1种、酚类1种、无机物1种,其中对甲酚、甲硫醇、二甲基硫醚、二甲基二硫醚和氨气被认定是好氧发酵过程中恶臭气味的主要来源;影响碳氮损失的因素依次为:辅料配比>通风速率>温度,影响总臭气强度的因素依次为:温度>辅料配比>通风速率。综合考虑碳氮损失和总臭气强度,病死猪辅热好氧发酵最佳工艺参数为:辅料配比1∶5.5,发酵温度55℃,通风速率14 L/(L·min)。

The orthogonal experiment of thermophilic aerobic fermentation of sick and dead pigs was conducted to optimize the parameters for thermophilic aerobic fermentation of sick and dead pigs.The sick and dead pigs was used as materials,sawdust as additives,and the ratios of additives,fermentation temperature and ventilation rate as factors,and the losses of carbon and nitrogen and the total intensity of odor as indexes.The components of organic malodorous substances in exhaust gas were analyzed and their emission concentrations were determined.The concentrations of ammonia and carbon dioxide were detected as well.The effects of the ratios of additives,fermentation temperature and ventilation rate on the loss of carbon and nitrogen and the emission of odor were analyzed with range and contribution rate analysis.The results showed that 18 organic malodorous substances in total including 3 sulfur compounds,1 alkane compound,12 aromatic hydrocarbon compounds,1 phenolic compound and 1 inorganic compound were detected qualitatively and quantitatively after thermophilic aerobic fermentation for sick and dead pig with sawdust as additives.Among them,p-cresol,methanethiol,dimethyl sulfide,dimethyl disulfide and ammonia were identified as the main source of odor.The factors affecting the loss of carbon and nitrogen were in the decreasing order of additives ratios>ventilation rate>temperature.The factors affecting the total odor intensity were in the decreasing order of temperature>additives ratios>ventilation rate.Considering the loss of carbon and nitrogen and the total intensity of odor comprehensively,the optimized parameters for thermophilic aerobic fermentation of sick and dead pigs are as follows:the additives ratios of 1∶5.5,the fermentation temperature of 55℃,and the ventilation rate of 14 L/(L·min).