Anaerobic fermentation of rice straw and chicken manure to carboxylic acids

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Title: Anaerobic fermentation of rice straw and chicken manure to carboxylic acids
Author: Agbogbo, Frank Kwesi
Abstract: In this work , 80 % lime -treated rice straw and 20 % lime -treated chicken manure were used as substrates in rotary fermentors . Countercurrent fermentation was performed at various volatile solid loading rates (VSLR ) and liquid residence times (LRT ) . The highest acid productivity of 1 .69 g / (L ? ? ? ?d ) was at a total acid concentration of 32 .4 g /L . The highest conversion and yield were 0 .692 g VS digested /g VS fed and 0 .29 g total acids /g VS fed , respectively . The continuum particle distribution model (CPDM ) was used to predict product concentrations at various VSLR and LRT . CPDM predicted the experimental total acid concentration and conversion at an average error of 6 .41 % and 6 .55 % , respectively . A fixed -bed fermentation system was designed to perform pretreatment and fermentation in the same unit . High product concentrations ( ~48 g /L ) as well as high conversions (0 .741 g VS digested /g VS fed , F4 , Train B ) were obtained from the same fermentor . CPDM was extended to predict product concentrations in the fixed -bed fermentation system . The model gave a good estimate of the product concentrations and retention time . After biomass fermentation , the residue can be combusted to generate heat . For pretreatment purposes , the use of ash can replace lime . A study was performed using ash as a potential pretreatment agent . Ash from raw poplar wood was effective in pretreating poplar wood ; however , ash from bagasse fermentation residues was not useful in pretreating bagasse . Previous modeling studies indicate that a conversion of 95 % could be achieved with bagasse using countercurrent fermentation . Because lignin constitutes 13 % of the dry weight of bagasse , this means lignin would have to be digested to obtain a conversion of 95 % . Experiments on the fermentation of enzymatically liberated lignin from both poplar wood and bagasse do not show that solubilized lignin was fermented to organic acids by using a mixed culture of marine microorganisms . Two buffer systems (ammonium bicarbonate and calcium carbonate ) were used to compare product concentrations of carboxylic acid fermentations using office paper and chicken manure . It has been demonstrated that the total product concentration using ammonium bicarbonate is almost double the product concentration using calcium carbonate .
URI: http : / /hdl .handle .net /1969 .1 /4973
Date: 2007-04-25

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Anaerobic fermentation of rice straw and chicken manure to carboxylic acids. Available electronically from http : / /hdl .handle .net /1969 .1 /4973 .

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