不同预处理方式对玉米秸秆结构及产气特性的模拟研究

Simulation of Structure and Biogas Production Properties of Corn Stalk Relative to Pretreatment Method

以玉米秸秆为原料,在25℃条件下,分别采用沼液及不同含量的NaOH溶液对秸秆进行预处理,研究NaOH投加量与秸秆纤维结构、预处理料液理化性质以及产能特性之间的关系.结果表明,采用4mg·g-1 NaOH溶液预处理7d后,料液中COD浓度已基本稳定,溶液pH值在7～8之间,可直接装罐发酵.利用扫描电镜观测预处理后秸秆结构变化状况,发现经4mg·g-1NaOH溶液预处理后的秸秆表层结构粗糙、多孔,有助于厌氧微生物与可发酵底物的接触,产气量是未经预处理玉米秸秆的5.5倍,其干物质产气率为225.8 mL·g-1.综合考虑产气效率、生产成本及工程操作,采用4mg·g-1NaOH溶液预处理秸秆更利于工程推广应用.

An experiment was carried out using biogas slurry and NaOH solutions different in concentration to pretreat corn stalks at 25℃ for biogas production to explore relationships of NaOH dosage with fiber structure of the pretreated corn stalk physico-chemical properties of the pretreatment solution, and energy production characteristics. Results show that 7 days after pretreatment with NaOH solution 4 mg· g-1 in concentration, COD concentration in the pretreated material solution became basically stable, with pH ranging between 7 and 8. At that time, the material was ready to be packed into the biogas tank for fermentation. A scanning electron microscope （SEM） was used to observe changes in fiber structure of the pretreated corn stalks. It was found that the corn stalks pretreated with 4 mg·g-1 NaOH became rough and porous on the surface, thus facilitating contact of anaerobic microbes with the substances, and eventually increasing biogas production by 4. 5 times as compared with the use of untreated corn stalks, reaching 225.8 mL ·g-X dry matter. Taking anaerobic diges- tion performance, pretreatment cost and engineering operation into consideration, the method of using 4 mg· g-1 NaOH so- lution to pretreat corn stalks is easier to be extended.