秸秆高温干式厌氧发酵的产气特性研究

The Performance of Biogas Production from Crop Straw under High-temperature and Dry Anaerobic Fermentation

试验用作物秸秆与活性污泥混合厌氧发酵制备沼气,研究了活性污泥与麦秸、玉米秸和稻草高温干式发酵的产气规律,加N素调节碳氮比(C/N)及添加生物炭对产气的影响.利用作物秸秆与活性污泥投加量1∶1,厌氧发酵原料总固体(TS)20%,在55℃下厌氧发酵.试验数据表明:1)产气从第5 d产气量开始增加,峰值均出现在第6~9 d,发酵15~25 d产气较为稳定,随后产气量缓慢下降.厌氧发酵7 d时,沼气中甲烷含量均能达到60%左右.按厌氧发酵时长45 d计算,稻草的产气量最大,单位TS累积产气量达到413.7 mL·g^(-1);玉米秸和麦秸的单位TS累积产气量分别为365.2 mL·g^(-1)、345.2 mL·g^(-1).2)调节发酵液的C/N至30∶1,可有效缩短沼气启动时间1~2 d;在沼气发酵微生物活性较低时,表现最为明显,可缩短沼气启动时间≥3 d且累积产气量最高可提高44.9%.3)在厌氧发酵液中添加4%(按发酵秸秆干基计算)的生物炭,并调节发酵液的C/N至30∶1,对麦秸厌氧发酵产气而言,累积产气量可提高38.5%,玉米秸和稻草的累积产气量分别提高6.2%和8.0%.

In this paper,the biogas was prepared by mixed anaerobic fermentation of crop straw and activated sludge.The high-temperature and dry anaerobic fermentation performance of mixed sludge with crop straw including wheatstraw,corn stalk and rice straw and effects of carbon-nitrogen ratio and biochar additive on biogas production werestudied.The anaerobic fermentation results showed as follows:1)Under the ratio of crop straw and activated sludge1∶1,20%of total solid and55℃,the increasing of daily biogas production appeared on the fifth day with a peakvalue at the6th-9th days.Then daily biogas production was stable during the15th-25th days and decreased slowlylater.The methane content of biogas reached about60%on the seventh day.In45days,the cumulative biogas productionwas the highest413.7mL·g-1of rice straw,following365.2mL·g-1of corn stalks and345.2mL·g-1of wheat straw.2)Adjusted the carbon-nitrogen ratio of the fermentation reactants to30∶1could shorten the start-up time of biogasproject by1-2d;when the biogas fermentation microbial activity is lower,the most obvious performance,can shortenthe biogas start time≥3d and the cumulative gas production can be increased by44.9%.3)4%biochar additive(calculated according to the dry basis of the fermented straw)and C/N to30∶1could increase the cumulative biogasproduction by38.5%for wheat straw,following6.2%for corn stalks and8.0%for rice straw.