Study On The Anaerobic Co-digestion Of Furfural Wastewater And Rice Straw

China's annual production of furfural accounts for about 70% of the world's total production,and each ton of furfural produces about 30 m3 of wastewater.The furfural wastewater contains a small amount of sulfuric acid and organic acid and has a high temperature,and adding rice straw to the anaerobic co-digestion can not only fully and effectively utilize the organic acid and heat in the wastewater,but also realize the resource utilization of furfural wastewater and rice straw.which is of great significance to ecological environmental protection and social progress.However,the sulfate in the wastewater has an inhibitory effect on the microbial activity.Accurate understanding of the effect of sulfate on anaerobic fermentation is essential for the successful utilization of furfural wastewater.To this end,the anaerobic co-digestion test of furfural wastewater and rice straw was carried out.The effects of sulfate concentration,substrate concentration and aerobic hydrolysis time on the anaerobic co-digestion of furfural wastewater and rice straw were investigated.The changes of volatile fatty acid content and the changes of aerobic hydrolysis end products during anaerobic fermentation were analyzed,and the effects of various factors on the gas production of anaerobic fermentation were studied.The following results and conclusions were obtained:(1)The fermentation group with the sulfate concentration of 100 mg/L in the fermentation broth had the best fermentation effect in the anaerobic co-digestion process.The TS and VS methanogenic rates were respectively 188.07 m L/g and 175.8 m L/g,which is 1.37 times that of furfural-free wastewater.When the fermented feed liquid contains an appropriate amount of sulfate,the sulfate-reducing bacteria can serve as an organic substrate for the degradation of non-methane-producing bacteria,providing a matrix for methanogens.And sulfate also accelerates the decomposition of propionic acid,lactic acid and other substances,resulting in rapid degradation of volatile fatty acids.Therefore,the addition of furfural wastewater can improve the anaerobic fermentation performance of rice straw.When the concentration of sulfate in the fermentation broth is 100 mg/L,the combined effect of combined anaerobic fermentation is best.(2)Properly increasing the substrate concentration can increase the organic load of the reaction system,promote the degradation of the substrate,and improve the gas production performance of the anaerobic fermentation.The VS/SO42-of the test group with a substrate concentration of 7% was 264.At this time,the degradation rate of lignocellulose and TS and VS at the end of anaerobic co-digestion was the best.The gas production effect is also optimal,and the methane yields of TS and VS are respectively 218.26 m L/g and 233.48 m L/g.Too low or too high substrate concentration is not conducive to anaerobic fermentation gas production,substrateconcentration is too low,will affect the degradation of organic matter,anaerobic microbial utilization of substrate and nutrition is also insufficient.The substrate concentration is too high,the organic load is too large The reaction system has poor fluidity,which may cause the organic substrate to be difficult to fully degrade.(3)Aerobic hydrolysis can destroy the structure of lignin,improve the degradation rate of lignocellulose,and can also convert poorly soluble organic matter into soluble organic matter,and greatly increase the yield of TS and VS.The lignin degradation rate of the test group with aerobic hydrolysis for 8 h was the fastest.The gas production effect of anaerobic co-digestion was also the best in this test group,and the cumulative gas production was higher than that of the test group without aerobic hydrolysis.11.78%,the volumetric gas production rate reached 462.5 m L/(L·d),the TS,VS methanogenic rate increased by 21.75% compared with the test group without aerobic hydrolysis.