Dissertation > Environmental science, safety science > Processing and comprehensive utilization of waste > General issues > Wastewater treatment and utilization

Study on Biogasification of Cassava Dregs by Anaerobic Fermentation

Author LiuJian
Tutor PuYueWu
School South China University of Technology
Course Fermentation Engineering
Keywords Cassava residue Anaerobic fermentation Process -control Gas production rate Methane
CLC X703
Type Master's thesis
Year 2010
Downloads 288
Quotes 3
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Cassava residue (Cassava dregs) as an organic solid waste, its high yield, perishable pollution to the environment, from the point of view of the environment-friendly and waste resources, anaerobic fermentation technology is its scientific treatment compared good way. Thus, the composition characteristics of cassava residue determination of cassava residue the acidification features that biochemical feasibility study, based on cassava dregs single phase intermittent anaerobic fermentation of methane main process parameters were optimized. The experiment measured the moisture content of cassava residue average of 87.6%, the dry residue in the ash content of 2.1% on average, the average (Valatile solid, VS), volatile solids content of 98%, the description the the cassava residue is a typical high-solid organic raw high material component, wherein the starch of the total solids content of 57.12%, accounting for 28.49% of cellulose, lipids, proteins rarely, belonging to the high-carbohydrate, low-protein substances, C / N is an average of 49. Acidification experiments confirmed the cassava residue biodegradability, but vulnerable to acidification, higher solids rate (greater than 8%) conditions acidification process, the rapid accumulation of volatile fatty acids (Valatile fatty acid, VFA) and lead to the initial pH of the reaction system value declined sharply and has remained at a low value. Have a greater adverse impact of of cassava residue acidification characteristics of its the anaerobic fermentation methanation start and carried. The study confirmed that cassava residue vulnerable to acidification, anaerobic fermentation of cassava residue self-regulation starts methanation is feasible, the vaccination rate of fermentation system and solid rate is the key factor, experimentally determined the vaccination rate of 70%, 8% solids The rate of fermentation system without pH control, to guarantee the cassava residue anaerobic fermentation methane smooth start and the best conditions, the gas production rate and the highest methane content for 249.5ml/gVS and 49.6%, respectively. Temperature optimization experiments, the temperature of 35 ℃ favor cassava residue the anaerobic fermentation methanation to achieve the best results. The gas production rate and the highest methane content higher than 25 ℃ and 55 ℃ experimental group 247.8mL / g (VS) and 49.2%, respectively. PH-control study confirmed the fermentation system pH constant to 7 in the regulation of anaerobic fermentation system, the vaccination rate by 70% down to 50% solids was still 8%, fermentation gas production methanation best, cumulative gas production The gas production rate and the highest methane content were 4280mL 232.4 mL / g (VS) 49.7% vaccination rate cut or increase the rate of solids is not conducive to the methanation gas production. On this basis, the use of fermentation pre namely the hydrolyzed acid production stage pH regulation in six, in late methanogenic phase pH regulation 7 process control, the effect of gas production more optimized, gas production rate 254.6mL/gVS, the highest The methane content of 50.9%. According to the experimental results the cassava residue single-phase intermittent anaerobic fermentation biogas process route is divided into two: (i) the external pH regulation, the best technology for the inoculation rate of 70% (seed sludge fermentation accounted for percentage of the total dry matter), solid rate of 8%, fermentation temperature 35 ° C, and in this process, the gas production rate of up to 249.5ml/gVS. (Ii) the optimum external pH regulation vaccination rate of 50%, solid rate of 8%, fermentation temperature 35 ° C fermentation pre-control to 6 pH regulation in the late regulation to 7 segmented regulation in this process under gas production rate of up to 254.6ml/gVS.

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