摘要
在确保NaOH对小麦秸秆预处理效果的前提下,通过适当延长预处理时间可减少NaOH用量,进而降低二次污染风险,为小麦秸秆的户用沼气生产提供理论依据。采用自行设计的厌氧发酵装置,研究不同NaOH预处理质量分数和预处理时间对小麦秸秆常温(20℃)厌氧发酵效率的影响。结果显示,在小麦秸秆常温厌氧发酵时,NaOH质量分数为3%时的预处理效果优于质量分数为0和6%的预处理效果;在预处理7~28 d时,纤维素、半纤维素和木质素的脱除率分别为3.66%~8.07%、43.08%~46.43%和47.88%~51.44%;发酵时的初始pH值为8.36~8.47,108~113 d发酵基本完成,累积产甲烷1 565.80~1 833.16 mL,干物质累积产甲烷体积为97.86~114.57 mL/g,产甲烷速率为13.86~16.97 mL/d,甲烷体积分数为50%~58%的持续时间为57~72 d。通过响应面模型试验得到最优预处理条件为:NaOH质量分数为4.36%,预处理时间为12.44 d。该条件下干物质甲烷产量的实测值为113.76 mL/g,与预测值接近,相对误差小于5%,表明模型有效。综合判断,在小麦秸秆常温(20℃)厌氧发酵时,利用质量分数为4.36%(以秸秆干重计)的NaOH对秸秆进行预处理切实可行。
On the premise of ensuring the pretreatment effect of NaOH on wheat straw,wheat straw was pretreated through properly extended pretreatment time to reduce the dosage of NaOH and reduce the risk of secondary pollution,to provide a theoretical basis for household biogas production of wheat straw.Effects of NaOH pretreatment at different mass fractions and times on anaerobic fermentation efficiency of wheat straw with 0,3%,and 6%NaOH respectively pretreated for 7 d,14 d,21 d,and 28 d were studied using the self⁃designed“system of anaerobic fermentation technology”at normal temperature(20℃).The unpretreated wheat straw was used as a control,while the pH of the fermentation broth was not adjusted.The treatment of NaOH mass fraction of 3%was the most effective and better than that of 0 and 6%in the same pretreatment time under anaerobic fermentation of wheat straw at normal temperature.The removal rates of cellulose,hemicellulose,and lignin were 3.66%8.07%,43.08%46.43%,and 47.88%51.44%,respectively,and the initial pH value of fermentation was 8.368.47,and after 108113 d completed fermentation the cumulative methane yields was 1565.801833.16 mL.The cumulative methane yields of dry matte was 97.86114.57 mL/g,the rate of methane production was 13.8616.97 mL/d,and the duration of methane volume fraction 50%58%was 5772 d when wheat straw was pretreated with 3%NaOH for 728 d.Response surface method was used to optimize the pretreatment conditions,and the optimum pretreatment conditions were as follows:NaOH mass fraction was 4.36%,pretreatment time was 12.44 d,the measured values of dry matter methane yields was 113.76 mL/g,which was very similar to the predicted value,the relative error was less than 5%.The results of the validation test indicate that the model was valid.In conclusion,it was feasible to with NaOH mass fraction of 4.36%(measured by dry weight of wheat straw)pretreatment wheat straw under anaerobic fermentation of wheat straw at normal temperature(20℃).
作者
张鸣
李昂
李雪
米璇
ZHANG Ming;LI Ang;LI Xue;MI Xuan(College of Urban Environment,Lanzhou City University,Lanzhou 730070,China)
出处
《安全与环境学报》
CAS
CSCD
北大核心
2024年第1期271-279,共9页
Journal of Safety and Environment
基金
甘肃省自然科学基金项目(20JR10RA283)
甘肃省高等学校创新基金项目(2022B-224)。
关键词
环境工程学
小麦秸秆
厌氧发酵
NAOH
预处理
累积产甲烷体积
响应面
environmental engineering
wheat straw
anaerobic fermentation
NaOH
pretreatment
cumulative methane production volume
response surface
