Experimental Investigation of the Straw Pre-treatment to Enhance Its High Solid Anaerobic Digestion
秸秆高固体厌氧消化预处理实验研究

The straw contains a high content of lignin,which cannot be well utilized by anaerobic bacteria in high solid anaerobic digestion process.This paper presents the experimental investigation of the straw pre-treatment,which aims to destroy the complex structure of the lignin to enhance its high solid anaerobic digestion.The straw is pre-treated in different solutions including NaOH,ammonia,H_2SO_4,and carbamide.The pre-treating effects are expressed by COD concentration dissolved in the solutions and the 14-day biogas generation in the enhanced aerogenic experiment.Different affecting factors,such as the concentration of the chemical solution,the species of the straw,the pre-treatment reaction time,the reaction temperature and the size of the straw,are investigated.The results show that NaOH solution is the most effective pre-treatment chemical among the four different solutions.The experimental results still indicate that the accumulative biogas production can be(1?500) mL(10 g straw) in 14 days after pre-treatment in 4(mg/L) NaOH solution and the dissolved COD in the solution reaches(39?000)(mg/L) after 24 hours.In addition,the experiment shows that the lignin content in the straw is reduced from 28% to 19% after pre-treatment in 1.5%(in weight) NaOH solution,and it can improve the straw treatment efficiency using high solid anaerobic digestion process.