Effects of NaOH pretreatment at different mass fractions and times on anaerobic fermentation efficiency of wheat straw at normal temperature
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 8.36-8.47,and after 108-113 d completed fermentation the cumulative methane yields was 1 565.80-1 833.16 mL.The cumulative methane yields of dry matte was 97.86-114.57 mL/g,the rate of methane production was 13.86-16.97 mL/d,and the duration of methane volume fraction 50％-58％was 57-72 d when wheat straw was pretreated with 3％NaOH for 7-28 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 ℃).
environmental engineeringwheat strawanaerobic fermentationNaOHpretreatmentcumulative methane production volumeresponse surface
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