NaOH预处理对木薯渣厌氧发酵产沼气的影响

摘要

为研究NaOH预处理对木薯渣厌氧发酵产沼气的影响,采用不同质量浓度的NaOH溶液(0.5％、1.0％、2.O％和3.0％)对木薯渣进行浸泡处理,浸泡温度100℃,持续时间3h,以去离子水处理木薯渣作为对照.浸泡处理后残渣经过水洗,在发酵温度为35℃、初始pH为7.0条件下,以厌氧污泥为接种物(接种比3∶7,干重计)进行中温厌氧发酵.碱预处理可降低木薯渣中淀粉、纤维素和木质素的含量,随预处理中NaOH浓度增加,其中木质素的去除率依次为60.1％、80.6％、83.6％和86.1％.在厌氧发酵初期,对照组和碱预处理后木薯渣残渣均发生快速酸化和VFA累积,添加NaOH,调节pH有效避免了VFA的持续累积,发酵结束后各反应器内VFA均低于350 mg/L.NaOH预处理提高了木薯渣的产气效率,最佳的NaOH浓度为0.5％,此时沼气产率为0.427 m3/kg VS,比对照组提高了68.3％.%The effect of NaOH pretreatments on characteristics of the biogas production of cassava dregs was studied by the experiment.NaOH solution with the concentration of 0.5％,1.0％,2.0％,3.0％ was used to soak cassava dregs for 3 h at the temperature of 100 ℃,with the treatment of deionized water as the control.After the pretreatment,batch digestion of cassava dregs was conducted with anaerobic sludge as inoculum (inoculum-substrate ratio,3∶ 7,dry weight for 43 d in five self-manufactured anaerobic fermentation reactors,under the condition of 35 ℃,pH 7.0.Alkaline pretreatment degraded more of starch,cellulose,lignin than semi-cellulose,and the efficiency removals of lignin were 60.1％,80.6％,83.6％ and 86.1％ for NaOH of 0.5％,1.0％,2.0％ and 3.0％ respectively.The continuous accumulation of VFA in all digesters was avoided by the addition of NaOH solution,even though rapid acidification and accumulation of VFA happened in the initial stage of anaerobic digestion.After the digestion ended,VFA decreased to below 400 mg/L in each digester.Compared with the control,biogas yield of pretreated cassava dregs increased significantly.The pretreated cassava dregs with NaOH concentration of 0.5％ had the best biogas production yield 0.427 m3/kg VS,which was 68.3％ higher than that of the control.